Digital Photography For What It's Worth: User-to-user help for digital photographers in general and Oly Camedia users in particular. Click to go to home page.

 

 

Digital Photography For What It's Worth

Trailside stream, Sibley Volcanic Preserve, Orinda, CA. Click to see 800x600. [C-2000Z]

Marks major topics. Click to see Limited Warranty section on the home page. Auxiliary Lenses for Oly C-Series Digitals

What to know before you buy

On this page—

Last updated July 27, 2004


Why Auxiliary Lenses?

Marks the gotchas For consistency, all focal lengths in this article will be given in terms of their equivalent focal lengths (EFLs)  on a 35 mm film camera unless otherwise stated.

You can greatly extend the functionality of your already versatile Oly C-series digital rangefinder with filters and auxiliary lenses from Olympus and other vendors, much as you would a 35 mm film SLR. The fast, crisp 3x zoom lenses found on most C-series cameras are great assets, to be sure, but that 3x (32-96 or 35-105 mm EFL) zoom gets you only so close to your subject and sometimes fails to encompass nearby objects in their entirety. Macro performance on C-series cameras prior to the C-5050Z could certainly be improved as well. The legendary image-stabilized 10x (38-380 mm EFL) zoom lens on the C-2100UZ and the superb non-stabilized 8-10x lenses on C-7xxUZ model get you close enough in most situations, but telephoto, macro and wide-angle auxiliary lenses can still be quite useful on these cameras — particularly a wide-angle auxiliary with that 38 mm minimum EFL.

Marks the gotchas

The only auxiliary lenses I can personally recommend for Oly C-series digitals are the Oly B-300 1.7x teleconverter and the Oly WCON-07 0.7x wide-angle converter. Both are excellent.

B-300 mounting details are discussed below ad nauseum, and the WCON-07 mounts in a similar fashion. Suffice it to say here that on C-series rangefinders, the B-300 and WCON-07 should be attached using the original Oly CLA-1 lens tube and a suitable single-ring or double-ring mount. The C-7xxUZ cameras take a CLA-4 lens tube instead.* On the C-2100UZ, you'll need only a single 49-55 mm step-up ring. 

I have no direct experience with any of the other lens setups mentioned in this article, but I've compiled some helpful and fairly reliable information about them from trusted sources. You'll have to judge for yourself whether any of the lenses covered here are suitable for your use.

* Note: I know too little about C-7xxUZ models to cover them here with any confidence. Some of the lens considerations discussed no doubt apply, but where the fit ends, I have no idea. 

Adaptable Lens Types

Most of the auxiliary lenses adaptable to Oly C-series digitals fall into one of these 4 categories: 

Converters, more formally known as conversion lenses, are afocal auxiliary lenses that mount outboard of your camera's native lens. They feed the native lens pre-refracted light, usually with a goal of lengthening or shortening the final focal length. On a maximally zoomed C-5050Z, for example, a 1.7x teleconverter will multiply the effective EFL from 105 mm to 179 mm (105 * 1.7 = 179). With the native lens at minimum zoom, a 0.7x wide-angle converter will shorten the EFL from 35 to 25 mm.

The perfect conversion lens causes no light loss and produces images free of peripheral (off-axis) blurring, distortion and chromatic aberration (prismatic color separation). Nor does it cause vignetting, at least at the zoom settings one would normally use with the auxiliary — maximum zoom with a teleconverter, minimum with a wide-angle. But perfection is hard to come by, and trade-offs are just as pervasive in the auxiliary lens arena as they are in photography in general.

Quality varies widely among the many converters on the market today, and prices vary accordingly. Test before you buy if at all possible, particularly with wide-angle converters. (The image flaws introduced by an optically poor wide-angle converter can be dreadful.) There's no way around the money vs. quality trade-off, but some lenses, like the 1.5x Oly A-200 teleconverter, seem to be exceptional values.


Teleconverters

Digital images can be "blown up" only so much on screen or on paper before pixellation and other artifacts set in. It's therefore critically important to fill as much of the digital frame with your subject as possible at the scene. In so doing, you effectively maximize the number of sensels (CCD or CMOS sensor photosites) projected onto your subject, and that can only optimize your cropping and printing options down the line.

Moving up on the subject often suffices to fill the frame, but how close can you get to a skittish  lizard, loons out on the lake or a sunlit wild flower clinging to a canyon wall across a raging stream? And even if you could get closer, your composition may call for the uniquely compressed perspective that only a long focal length can afford. To do such long shots justice on a C-series camera, you'll need to extend your optical reach with a teleconverter — a conversion lens that effectively increases the your camera's maximum EFL. 

The 1.45x to 5x teleconverters covered in this article are all of excellent optical quality with no light loss and varying degrees of vignetting at full zoom. Unfortunately, the greater the magnification, the greater the likelihood of vignetting at some or all zoom settings.

For the C-2020Z and C-5050Z, my favorite teleconverter is the legendary discontinued and now much sought-after 1.7x Oly B-300. Those lucky enough to get their hands on a B-300 tend to hang on to them, but used B-300s still show up on ebay now and then, often at exorbitant prices. Fortunately, Oly's current 1.7x TCON-17 teleconverter may be a viable alternative. It's said to be similar to the B-300 in design and quality, but I can't confirm that.


Wide-Angle Converters

To do sweeping vistas and large subjects justice without the hassle of panorama capture and stitching, you'll need to broaden view of your camera's built-in zoom lens with a wide- angle converter. When you can't get far enough away from your subject to capture all of it in a single frame at minimum zoom, a wide-angle conversion lens may well save the shot. Even if you can back off far enough, you may prefer the punchy "in your face" perspective that only a short focal length can bring. With its relatively long minimum focal length of 38 mm, the C-2100UZ will frequently benefit from a wide-angle converter.

Wide-Angle Perspective

C-5050Z Lens Configuration Native at full zoom Native at minimum zoom with 0.7x wide-angle converter
EFL 105 mm 25 mm
Camera-subject distance ~10 m ~2 m
In each lens configuration, the black 350Zs filled the viewfinder frame at the scene, but the resulting photos have very different perspectives and impacts. Perspective at 105 mm [C-5050Z] Perspective at 25 mm with the help of a 0.7x conversion lens  [C-5050Z]

Note that wide-angle lenses are often asymmetric — i.e., p >1, where p is the ratio of entrance to exit pupils. The simplified hyperfocal equation 

h1 = f2 / (N * c)

breaks down for asymmetric lenses. Be sure to field-test any hyperfocal calculations made for wide-angle lenses using this equation.  

The Oly 0.7x and 0.8x wide-angle converters covered in this article are of excellent optical quality and value with no light loss and varying degrees of vignetting above minimum zoom.

For the C-2020Z and C-5050Z, my personal wide-angle converter pick is the 0.7x Oly WCON-07. New WCON-07s were readily available for $125 on Amazon. com as of 2Q2004. Duplicating the ultra-wide angle (~16 mm) view of human vision without distortion, blurring or chromatic aberration is an optical goal that even the most expensive wide- angle lenses can only hope to approach, but this lens does an excellent job for the money.


Macro Converters

Marks areas under contruction--stay tuned. Click to review Limited Warranty section on the home page. Under construction...

With a macro converter mounted, your camera can focus at shorter camera-subject distances than the native lens would normally allow, but the resulting enlargement of the subject often comes at the expense of depth of field (DOF) and light loss. Macros are optically superior to close-up lenses, but the latter require no exposure correction and are easier to carry and work with on any camera capable of mounting round screw-on filters.

In extreme close-up work, DOF may dwindle to a few millimeters. To mitigate loss of DOF, use your macro at the narrowest possible aperture and align the camera back (CCD or CMOS sensor) with the dominant plane of your primary subject. Good lighting is key. Zoom in your camera and back away as needed to avoid blocking incoming light or agitating animal subjects.

SLR-style primary (focal) macro lenses can cast incoming light well beyond the edges of the image receiver, be it film or CCD. The resulting effective decrease in aperture can require substantial exposure compensation. For a primary macro lens with final magnification M, the exposure correction in f-stops is approximately 2 * log2(1 + M / p), where p is the ratio of entrance to/ exit pupils. Typically, p > 1 for wide-angle lenses, while p ~ 1 for most other lenses. Kodak's superb online Guide to Better Pictures offers an applicable macro exposure correction table.

Whether afocal macro converters require similar exposure compensation, I'm not sure. If you're shooting with automatic exposure, it's largely academic, but be careful with manual exposures and expect to provide more light than you might guess. Fortunately, a digital camera will allow you to examine your macro shots before leaving the scene.

Close-up Lenses

This article deals only with converters adaptable to Oly C-series digitals. The completely generic filter-like close-up lenses are described in detail the Filter options for digital cameras article elsewhere on dpFWIW


Vignetting

Cost, weight, handling and adaptation concerns certainly enter the lens equation, but vignetting is perhaps the most vexing issue you'll face with conversion lenses on digital cameras.

Vignetting is the unwelcome dark peripheral circular masking seen when attachment hardware (filter rings, step-up rings, lens barrels, etc.) shows up in the periphery of the captured image, as you'll see amply illustrated below. Vignetting tends to appear at wider angle zoom settings and usually gets progressively worse as the zoom is widened further. For some camera/lens tube/step-up/converter combinations, vignetting may affect all available zoom settings.

Marks the gotchas The farther forward you mount a given conversion lens relative to the image receiver, the more likely you are to encounter vignetting, particularly at wide angles.

Thus, setups incorporating longer lens tubes or multiple step-up rings are subject to greater vignetting.

Bear in mind that a little vignetting isn't necessarily a fatal flaw in a lens or filter—after all, it can always be cropped away in post-processing. However, it does limit your possibilities. Unfortunately, I know of no way to predict from specs which camera/converter combinations are subject to vignetting, so research or test before you buy. I'll include any vignetting information I have on good authority in the sections below.


First Steps—Lens Tubes and Step-up Rings

To mount auxiliary lenses on most Oly digital rangefinders, you'll first need a suitable lens tube—the shorter the better to minimize lens vignetting, at least with teleconverters. Think of a lens tubes as add-on version of the lens shroud built into the body of the C-2100UZ. Typically, you'll also need one or more step-up rings—the thinner and fewer the better, also to minimize vignetting. Depending on the converter, you may or may not need a step-up ring for the C-2100UZ's 49 mm lens thread, but you certainly won't need a lens tube for it.

Lens-mounting platforms are discussed thoroughly in the First Steps section of the dpFWIW article Filters for popular Oly digitals. Here, I'll simply re-emphasize that

Marks the gotchas To mount lenses on most Oly C-series digitals, the shortest possible lens tube is the best, and that's still the Oly CLA-1 for most rangefinders. 

For C-series cameras through the C-5050Z, the Oly CLA-1 lens tube remains the shortest around at 22.9 mm (not counting the 41 mm thread for the camera). With some hard-to-predict exceptions, you'll need a step-up ring or shim ring to mount filters safely on a lens tube this short, but you'll be much better off with the CLA-1 when it comes time to mount your teleconverter.

Oly C-7xxUZ series cameras use the CLA-4 adapter, which is very similar to the CLA-1. The wider-angle C-5060WZ and C-8080WZ cameras use the more strongly flared CLA-6 and CLA-8 adapters, respectively. I know very little about these setups.


The Oly B-300—A Worthy 1.7x Teleconverter

Marks the gotchas Alas, Oly discontinued the venerable B-300 sometime around mid-2001. New B-300s have become very hard to find, and used ones fetch top dollar on eBay.

To get in closer than the typical Oly rangefinder's 3x, 35-105 mm EFL zoom lens allows, I highly recommend the Olympus B-300 HQ Converter 1.7x telephoto lens originally made for Oly's iS-3 35 mm zoom film camera. The B-300 brings an Oly rangefinder's 105 mm maximum zoom setting to equivalence with a 35 mm camera using a 179 mm lens. On the C-2100UZ, the 380 mm maximum zoom setting or the native lens stretches out to a walloping 646 mm! Final focal lengths on the wider-angle C-3000Z and C-3030Z top out at 163 mm. 

The B-300 is widely recognized as a "great piece of glass" by many digital camera users, including finicky Sony enthusiasts who take great pride in their Zeiss lenses. A new B-300 cost ~$125 as of 1Q2001, but plan to pay through the nose for a used B-300 now—if you can find someone willing to part with theirs.

Oly B-300 1.7x Converter on a C-2000Z (single-ring mount)
  • Oly CLA-1 lens tube (43 mm end thread)

  • Oly 43-55 mm step-up ring

  • Oly B-300 1.7x telephoto converter lens sans cap
Oly C-2000Z with mounted CLA-1 conversion lens adapter awaiting 43-55 mm step-up ring and B-300 1.7X telephoto converter. Click to see 640x480 version. [D-340L] Oly C-2000Z with CLA-1 conversion lens adapter, 43-55 mm step-up ring and B-300 1.7X telephoto converter lens mounted. Click to see 640x480 version. [D-340L]

Oly claims that the B-300 requires no exposure correction on the IS-3, and that's been true in my experience on the digital side. The B-300's biggest flaw may well be its lack of an outer thread, but I've found suitable inboard workarounds for filter mounting. The B-300 looks front-heavy and even a bit improbable on Oly's compact digital rangefinders, but the setup feels solid, secure and reasonably well-balanced in use.

For more detailed B-300 specs, visit the Unofficial Oly IS-series data sheet and keep scrolling.


Digital Applicability

Oly Rangefinders (C-20x0Z, C-30x0Z, C-5050Z, etc.)

Marks the paydirt The B-300 is a superb choice for any Oly rangefinder—provided certain simple precautions are taken with the C-3000Z and C-3030Z. With proper mounting, the B-300's relatively narrow gap in vignette-free focal lengths makes it a very nice fit indeed. Filter mounting may be an issue for some users, and blockage of viewfinder and onboard flash will always pose challenges, but minor problems like these can't offset the many charms of the B-300.

Oly C-2100UZ

Marks the paydirt Oly officially recommends the B-300 for the C-2100UZ, and Joe Shepard finds the two "a good combination" in the field. Joe reports no vignetting above ~8.5x zoom (549 mm final) when mounted with a single average-thickness 49-55 mm step-up ring. He reports that the tripod-mounted combination is quite stable.

Sony DSC-F series Cameras

Lens-conscious Sony Cybershot users consider the B-300 an excellent addition to the superb Zeiss 5x zoom lenses on their DSC-F505, DCS-F707 and DCS-F717 cameras.

Piggybacking With Other Teleconverters

Marks the paydirt The B-300 can also be mounted outboard of other teleconverters like the EagleEye OpticZoom with very impressive results, as detailed below.


B-300 Mounting Options

For starters, please note that

Marks the gotchas The B-300 does NOT come with a step-up ring.

Yes, step-ups do ship with other Oly-brand converter lenses, but there's little point with the B-300. The required ring size(s) will vary tremendously depending on your camera, on your choice of lens tube (rangefinders only), and perhaps on your standard filter size as well.

Single-Ring B-300 Mounts for Oly Rangefinders

Marks the paydirt With a CLA-1 lens tube, any single 43-55 mm step-up ring of reasonable thickness will mount the B-300 safely on most C-series cameras, but Kenko's ultra-thin 43-55 mm ring causes lens crashes, at least on the C-3000Z and C-3030Z. Oly's average-thickness SUR4355 ring is safe to use with the CLA-1 on these 2 models.

Lens tubes other than the CLA-1 will generally take different rings. Thin rings—e.g., pricey brass B+Ws or inexpensive, ultra low-profile Kenkos—will certainly help minimize the added vignetting these longer tubes bring without the risk of lens crashes, but there will still be a significant net increase in vignetting.

Marks the paydirt With its built-in lens thread, the C-2100UZ needs only a single 49-55 mm ring. A low-profile Kenko or B+W ring might well extend the attainable range of vignette-free final focal lengths.

I initially chose the standard CLA-1/43-55/B-300 single-ring mount for my C-2020Z and C-5050Z using Oly's widely-available, high-quality 43-55 mm step-up. The excellent B-300 vignetting limits reported and illustrated below are based on just this configuration.

However, I soon discovered that single-ring B-300 mounts have 2 serious drawbacks:

  1. Single-ring mounts unavoidably entail extra ring changes, regardless of the standard filter size in effect.

  2. Worse yet, they severely limit the use filters with the B-300.

What to do? Split the single ring.

Double-Ring B-300 Mounts for Oly Rangefinders

Marks the paydirt As a frequent 49 mm filter and lens hood user, I've turned my B-300 into yet another 49 mm accessory by going to a double-ring mount, which is nothing more than 

  • A 43-49 mm ring permanently attached to my CLA-1

  • A 49-55 mm ring permanently attached to the B-300

This arrangement allows me to mount the B-300 in lieu of or even on top of my 49 mm filters without ever futzing with the 43-49 mm ring.

Unbridled vignetting anxiety blinded me to this possibility for many moons, but the urge use my B-300 for infrared work finally prevailed. I'm happy to report that interposing a pair of average-thickness Tiffen 43-49 mm and 49-55 mm step-ups between my CLA-1 and B-300 only negligibly increases B-300 vignetting on my C-2020Z. Replacing my standard thickness Tiffen 49-55 ring with a lower profile Kenko brings a negligible improvement.

My double-ring CLA-1/43-49/49-55/B-300 setup is 100% vignette-free above about 2.2x zoom. Adding in a single-ring filter bumps the vignetting threshold up to about 2.4x zoom; a double-ring polarizer takes it a bit higher still, but the threshold remains comfortably below full (3.0x) zoom. Lew Jansen's C-3000Z/CLA-1/43-49/polarizer/UV/49-55/B-300 stack shows no vignetting at maximum zoom, even with the wider lens found on the C-3000Z and C-3030Z. (Note that Lew's setup is equivalent to 5 rings between the B-300 and the CLA-1!)

This experience leaves me with no ready explanation for the few RPD posts I've seen reporting vignetting at full zoom with a double-ring mount on some C-series cameras. Overly thick (e.g., plastic) rings or intermediate rings smaller than 49 mm might contribute.

C-30x0Z/CLA-1/43-55/B-300 Lens Crashes!

Dorothy Parker's famous line, "You can never be too rich or too thin." doesn't necessarily apply to step-up rings—at least not when it comes to mounting the B-300 on a C-3000Z or C-3030Z.

Lew Jansen, a frequent RPD contributor, asked me to share a potential hazard C-30x0Z owners face with the B-300: 

Marks the gotchas The C-3000Z and C-3030Z zoom lens will crash into the rear lens of a B-300 mounted with a single exceptionally thin 43-55 mm step-up ring on an Oly CLA-1 lens tube. 

Lew considers his Kenko 43-55 step-up ring "a little thin," and indeed, the folks at The Filter Connection claim that Kenkos have the lowest profiles of all their step-up rings—lower even than their B+Ws. With the too-thin Kenko between his B-300 and CLA-1, the lenses crash, but unscrewing the B-300 half a turn or mounting it on top of a filter solves the problem. 

Marks the paydirt The good news: Chris Pallas of RPD has confirmed for me that this is not a problem with a single average-thickness Oly SUR4355 43-55 mm step-up ring. My SUR4355 ring stands ~5.0 mm tall above a flat surface. Nor is it likely to be a problem with the C-x040Z.

C-3000Z and C-3030Z owners with step-up rings of the "too thin" variety would do well to consider the double-ring mount approach.


Filters and the B-300

At times, filters can be downright indispensable—polarizers, GNDs and infrared filters in particular. Mounting a teleconverter doesn't change that. The trick is to find a workable way to mount both at once. When you have the choice, filters are best placed in front of the conversion lens to reduce focus shifts, vignetting and flare. With no front threads, the B-300 doesn't offer that option. The B-300 instruction sheet explicitly warns against inboard (rear-mounted) filters, but with some attention to detail, inboard filters can work well with the B-300.  

Teleconverter-Filter Synergies

These images illustrate the value of combining a teleconverter and a filter. 

At right are resized and sharpened but otherwise untouched B-300 shots taken at full (3.0x) zoom with and without an inboard polarizer. By filtering out unwanted atmospheric scatter, the polarizer markedly enriches mountain detail and color saturation. 

Note the lack of vignetting—even with the double-ringed polarizer mounted inboard of the B-300.

Mt. Evans (14,264 ft) from Washington Park, Denver, CO; full zoom with 1.7x B-300 teleconverter and inboard polarizer. Click for 800x600 version. [C-2020Z]

B-300+Polarizer

Mt. Evans (14,264 ft) from Washington Park, Denver, CO; full zoom with 1.7x B-300 teleconverter =without= polarizer. Click for 800x600 version. [C-2020Z]

B-300 - Polarizer

Conversely, the photos at right were taken with an R72 IR filter at full (3.0x) zoom with and without a B-300 teleconverter. Both were post-processed in a similar manner.

The teleconverter makes a dramatic difference in composition and feel, as usual. The inboard IR filter brings an exceptional clarity and that inimitable IR look. Together, the long lens and the IR filter make a powerful team, despite the unorthodox inboard filter arrangement.

Mt. Evans (14,264 ft) from Washington Park, Denver, CO; full zoom with  an R72 IR filter with a 1.7x B-300 teleconverter. Click for 800x600 version. [C-2020Z]

R72 + B-300

Mt. Evans (14,264 ft) from Washington Park, Denver, CO; full zoom with an R72 IR filter =without= a teleconverter. Click for 800x600 version. [C-2020Z]

R72 - B-300

Inboard Filters

Marks the paydirt Inboard filters turn out to be quite workable with the B-300 using a double-ring mount with little added vignetting. My CLA-1<43-49<filter<49-55<B-300 setup produces no vignetting at ~2.4-3.0x (~84-105 mm) zoom. Lew Jansen reports no vignetting at maximum (3x, 96 mm) zoom with a C-3000Z<CLA-1<43-49<polarizer<UV<49-55<B-300 stack—even with the C-3000Z's wider lens. Note that Lew's setup is equivalent to placing 5 step-ups between the CLA-1 and B-300!

IMO, the insignificant vignetting hit double-ring mounting brings is a small price to pay for a must-have filter effect. I'm still on the lookout for increased lens flare, but so far, so good. The only other downside to consider is a mechanical one:

Marks the gotchas Take care to support the weight of the B-300 when mounting it on top of rotating filter like a polarizer or a round GND. 

The B-300's lack of light loss makes it a particularly good teleconverter choice with highly attenuating filters like my infrared R72

The Oly C-180 and C-210 teleconverters mentioned below also lack outer threads, but neither has a vignette-free zoom range to accommodate inboard filter mounting.

Marks content that should probably be confirmed independently An interesting RPD post from Charlie Dilks once proposed adding a filter mount to the B-300 by screwing an empty 77 mm metal filter ring into the plastic outer rim and optionally gluing it into place with epoxy. Apparently, 77 mm is a nice fit with the B-300. I haven't tried this and can't recommend it; if you decide to try it, you're on your own.


B-300 Vignetting on the C-20x0Z

Oly seldom mentions the B-300 in official listings of lenses compatible with its digital cameras, perhaps because

Marks the gotchas On most Oly rangefinders, the 1.7x B-300 converter produces circular vignetting at zoom settings wider than or equal to ~2.0x (70 mm) when mounted on a CLA-1 lens tube with a single 43-55 mm step-up ring.

Marks content that should probably be confirmed independently The vignetting will be a little worse on the wider-angle C-3000Z and C-3030Z, especially if mounted with a double-ring setup to avoid lens crashes, but even then, there'll be no vignetting at full zoom.

The B-300's generous vignette-free zoom range leaves room for conveniences like double-ring mounting and inboard filter mounting without taking on vignetting at full zoom. 

According to Joe Shepard, the B-300 vignettes only below ~8.5x zoom (549 mm final) on the C-2100UZ when mounted with a single average-thickness 49-55 mm step-up ring.  That leaves a vignette-free zoom range of 549-646 mm!

Vignetting Happens

Such wide-angle vignetting is common among teleconverters. In my experience, it's no great concern with the B-300 if it's mounted properly.

Note that any mounting setup unnecessarily increasing the distance between the CCD and the B-300 will aggravate vignetting. For example, several RPD posts have noted B-300 vignetting at all C-20x0Z zoom settings with the long Tiffen 41-49 mm Custom Camera Mount.

B-300 Vignetting on the Oly C-2000Z (CLA-1/43-55/B-300 mount)

Zoom setting 35 mm = 1.0x 71 mm = 2.0x 105 mm = 3.0x
B-300 Yes Yes Yes
Subject Hazy view of San Francisco looking west from Vollmer Peak
Click for 640x480

(~100KB)

35 mm (1.0X) zoom with 1.7X converter. Click to see 640x480 version. [C-2000Z] 71 mm (2.0X) zoom with 1.7X converter--only a trace of vignetting remains. Click to see 640x480 version. [C-2000Z] 105 mm (3.0X) zoom with 1.7X converter. Click to see 640x480 version. [C-2000Z]
Click for 800x600

133 KB

213 KB

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A look at the focal lengths found at the limits of zoom and vignetting with the illustrated C-20x0Z<CLA-1<43-55<B-300 setup is reassuring. The bare camera covers 35-105 mm focal lengths, while the camera plus B-300 covers 119-180 mm, all without vignetting. Vignetting is unavoidable only in the 105-119 mm range, just beyond the reach of the bare C-20x0Z. 

To operate in this relatively narrow 105-119 mm focal length gap without vignetting, you'd have to resort to another teleconverter (perhaps the Oly 1.45x), but it's hard for me to imagine a need to fill this gap that would justify the expense or hassle of a 2nd weaker lens.


B-300 Viewfinder and Flash Obstruction

At full zoom, the worst case, the mounted B-300 blocks roughly the bottom 50% of an Oly rangefinder's viewfinder—right up to the center of the cross-hairs. The B-300 remains quite workable nonetheless:

  • First, use the still-visible viewfinder cross-hairs to center your target.

  • Fine-tune the composition with the LCD. For tripod work, go ahead and shoot off the LCD, but...

  • For handheld shots, switch back to the viewfinder for actual shooting to minimize camera shake.

However, a much more effective way to beat the viewfinder obstruction is the Xtend-A-View LCD hood, which allows shaded handheld LCD framing without giving up solid brow support.

The substantial shadow cast by the lens with the built-in flash is largely a non-issue: A more powerful external flash would probably be needed in any situation requiring the B-300 given Oly's minimum recommended camera-subject distance of 5 m (16.4 ft).

Marks content that should probably be confirmed independently I don't know how much onboard flash shadowing the B-300 will cause with the C-2100UZ, but the camera's pop-up flash should help on that front. With the C-2100UZ's TTL electronic viewfinder, obstruction a non-issue.


B-300 Samples

Here are a few instructive if uninspired handheld samples taken with my old C-2000Z with and without the 1.7x B-300 teleconverter. Here I used a single-ring CLA-1<43-55<B-300 mount. (The double-ring mount I now prefer adds minimally to the vignetting shown here but wins on convenience and flexibility.) Low-light situations aside, camera shake hasn't been a problem in my handheld B-300 shots.

B-300 Samples with the C-2000Z (CLA-1<43-55<B-300 mount) 
Zoom setting 35 mm = 1.0x 105 mm = 3.0x
B-300 No Yes No Yes
Subject 1. Eroded contact between the steeply east-dipping Moraga Basalts (brown) and Orinda Conglomerates (gray), all 9-10 Ma, east Caldecott road cut, Hwy 24, Orinda, California, looking SE.
Click for 640x480

(~80-110KB)

35 mm (1.0X) zoom without 1.7X converter. Click to see 640x480 version. [C-2000Z] 35 mm (1.0X) zoom with 1.7X converter--note vignetting. Click to see 640x480 version. [C-2000Z] 105 mm (3.0X) zoom without 1.7X converter. Click to see 640x480 version. [C-2000Z] 105 mm (3.0X) zoom with 1.7X converter. Click to see 640x480 version. [C-2000Z]
Subject 2. SUV parked on the north side of the same roadcut, looking roughly west.
Click for 640x480

(~70 KB)

35 mm (1.0X) zoom without 1.7X converter. Click to see 640x480 version. [C-2000Z] 35 mm (1.0X) zoom with 1.7X converter--note vignetting. Click to see 640x480 version. [C-2000Z] 105 mm (3.0X) zoom without 1.7X converter. Click to see 640x480 version. [C-2000Z] 105 mm (3.0X) zoom with 1.7X converter. Click to see 640x480 version. [C-2000Z]

For another detailed and well-documented test of the B-300 on a C-2000Z, see Pekka Saarinen's excellent site.


The Oly 1.45x Teleconverter—A Less Expensive Alternative for Oly Rangefinders

The Oly TCON-14 1.45x teleconverter seems to qualify as "good glass" on RPD, at least for Oly rangefinders like the C-20x0Z, C-30x0Z and C-4040Z, but the limited focal length gain it affords leaves me unenthused. 

Marks the gotchas Oly flatly recommends against the 1.45x for the C-2100UZ. 

probably due to excessive vignetting stemming from the step-down from the camera's 49 mm lens thread to the converter's 46 mm thread.

The 1.45x ships with a 43-46 mm step-up ring for mounting via the Oly CLA-1 lens tube. Its construction is generally similar to that of the B-300, but the 1.45x is unique among Oly converters in that it snaps into its step-up ring via two spring-loaded "quick-release" tabs like those on the C-2020Z or later rangefinder lens caps. That's a substantial convenience, but like the B-300, the 1.45x teleconverter lacks a front filter thread. Using filters with the 1.45x will run into the same snags encountered with the B-300.

For more information on the 1.45x, see this Unofficial Oly IS-series data sheet.

Experienced photographer and dpFWIW contributor Tom Lackamp has posted an informative series of 1.45x sample shots here. Tom's kindly confirmed for me that, like the B-300,

Marks the gotchas The Oly 1.45x converter vignettes at C-20x0Z zoom settings wider than or equal to ~2.0x (70 mm) when mounted on a CLA-1 with the single provided 43-46 mm step-up ring. 

The vignette-free focal lengths of ~101-152 mm reachable with the 1.45x nicely extend the 35-105 mm range of the bare camera for ~$75-90 as of May, 2000.  (BTW, Oly's $30 cash rebate on the 1.45x expired as of 4/30/00.) For ~$125, the B-300 1.7x teleconverter delivers 119-180 mm focal lengths without vignetting.

Tom tells me he's quite happy with his 1.45x. He gets best results with it at apertures of ~f/4 through f/5.6, as has been his experience with many film camera lenses.


Oly C-210 1.9x, C-180 1.7x, and A-200 1.5x iS-series Teleconverters

Here we cover a number of Oly teleconverters originally designed for iS-series 35 mm zoom SLRs. Most have been discontinued, but these lenses still turn up on ebay as of 2Q2004, often as warrantied factory refurbs offered directly by Olympus America.

The 1.5x A-200

I have no experience, direct or indirect, with the small, light Oly A-200 HQ 1.5x teleconverter Oly originally made for its iS-1000 and iS-2000 35 mm zoom SLRs, but it gets very good press, particularly among C-2100UZ users. And contrary to rumor, the A-200's still available for ~$80 as of 3Q2002. The A-200 has plastic rear threads and no front filter threads. I see on the Digital Photography Review Oly Talk Forum that on the C-2100UZ, the A-200 is clearer at short to middle distances than at long distances. Amy Walters' teleconverter comparison will give you a good idea of how the A-200, B-300 and C-210 perform and vignette on the Oly C-2100UZ and the Sony DCS-F707. Whether the A-200 vignettes at full zoom on Oly rangefinders, I don't know. I won't cover the A-200 further here, but by all accounts, it's a worthy consideration when 1.5x is magnification enough. 

The 1.9x C-210 and 1.7x C-180

The compact Oly C-210 and C-180 teleconverters also have many attractive qualities, but both produce vignetting across all Oly rangefinder and C-2100UZ zoom settings—even when mounted on rangefinders with the Oly CLA-1 lens adapter and a single step-up ring. The vignetting at full zoom is generally mild and is more noticeable on the C-3000Z and C-3030Z rangefinders than on other Oly rangefinders.

C-210 and C-180 construction is similar to that of the B-300, but these lenses differ considerably in size and form factor, as the photos below show. Their lack of vignette-free zoom ranges promises to make filter use much more challenging than with the B-300.

Marks content that should probably be confirmed independently Mounting the C-180 and C-210 on these cameras with an ultra low-profile Kenko step-up ring might reduce vignetting at the risk of potential lens-lens crashes. If Kenko makes the requisite 43-52 mm rings, be careful. B+W also makes thin rings. Kenko and B+W rings can both be had at The Filter Connection

Marks content that should probably be confirmed independently How well suited the C-180 might be to the C-2100UZ, I'm not sure, but Amy Walters' teleconverter comparison will give you a good idea of how the A-200, B-300 and C-210 perform and vignette on the Oly C-2100UZ and the Sony DCS-F707. Oly recommends the B-300 for the C-2100UZ.

For more information on the Oly A-200, C-210 and C-180 teleconverters, see this Unofficial Oly IS-series data sheet.


The 1.9x C-210

Oly's hard-to-find C-210 HQ 1.9x teleconverter shares the fast "Galileo telescope" design of the B-300 1.7x but mounts with a 52 mm thread instead. Oly developed this lens for its IS-30 DLX 35 mm film zoom camera, among others. On an IS-30 set at full 110 mm zoom, the C-210 reaches a focal length of 210 mm. At 105 mm full zoom on a C-20x0Z, one might expect the C-210 to reach ~200 mm. C-210 mounted Dave Tatosian's Oly C-2020Z, courtesy Dave Tatosian.

Oly never mentions the C-210 in official listings of lenses compatible with the C-20x0Z, presumably because...

Marks the gotchas The 1.9x C-210 causes vignetting at all zoom settings on the C-20x0Z, but it's minimal at full zoom. 

The vignetting will be greater on the wider-angle C-30x0Z, but by how much, I don't know.

However, according to dpFWIW contributor Dave Tatosian, the vignetting is minimal at full 3x zoom. On the upside, the C-210 is considerably smaller than the B-300, as the photo at right shows.

As of late 1999, the C-210 listed for $90-100.

Oly C-210 and B-300 converters side by side, courtesy Dave Tatosian.

The Small, Affordable 1.7x C-180

Don Palmer of Travel and Trail Images and Mikhail Surin have both written to recommend the small, light and affordable Oly C-180 HQ 1.7x teleconverter at right. Mikhail provided the bottom image; Don, the others. The squirrel was 20 ft above Don's head; the lizard was 25-30 ft away.

At full zoom, this pocketable lens takes 35-105 mm C-series zoom lenses to a maximum EFL of 180 mm with little if any light loss. As with other Oly teleconverters, the images are sharp. The C-180 mounts on a 52 mm thread.

Thanks to its compact design and cylindrical form factor, the C-180 blocks much less viewfinder and onboard flash than the substantially heavier, bulkier and pricier 1.7x B-300 converter. 

Oly makes the C-180 for its IS-10 35 mm SLR, among others. For more detailed specs on the C-180, visit this Unofficial Oly IS-series data sheet.

When mounted on the C-20x0Z with a CLA-1 lens tube and a single 43-52 mm ring, the C-180 produces barely perceptible vignetting in the corners of the frame at full 3x zoom according to both Don and Mikhail. The vignetting will be greater on the wider-angle C-3000Z and C-3030Z, but by how much, I don't know. Mikhail speculates that the vignetting on the C-20x0Z might disappear with a thinner than usual step-up ring, but too thin a ring might invite a lens-lens crash, at least on the C-3000Z and C-3030Z.

Marks the paydirt The C-180 is an attractive teleconverter for Oly digital rangefinders in many respects, but the required 43-52 mm step-up ring can be hard to come by. As of 1Q2001, the C-180 went for $78 at www.cameraworld.com. High-quality B+W 43-52 mm step-up rings go for around $28 at B&H Photo (special order, 6-10 weeks) and the Filter Connection, but BugEye Digital offers an inexpensive KALT ring for $6.50. If the B+W rings turn out to be thinner than the KALTs—and I don't know that they are—lesser vignetting might justify the extra cost.

 

Oly C-180 mounted on the C-2000Z, courtesy Don Palmer. Click to see larger version. [D-340R]
Squirrel from 20 feet via the C-180, State Capitol, Topeka, Kansas; courtesy of Don Palmer. Click to see 532x399 version. [C-2020Z]
Six-inch collared lizard from 25-30 feet via the C-180, Topeka, Kansas; courtesy of Don Palmer. Click to see 640x480 version. [C-2020Z]
Oly C-180 mounted on the C-2020Z, courtesy of Mikail Surin. Click to see 741x600 version. [?]
Marks the gotchas The 1.7x C-180 causes vignetting at all zoom settings on C-series cameras, but it's minimal at full zoom. 

On the relative merits of the C-180 vs. the Oly 1.45x converter, Mikhail writes,

... they both have their advantages, the 1.45x being somewhat more versatile in that it allows some zooming without vignetting, but on some occasions the C-180's longer reach may be useful. I haven't noticed any need for EV adjustment with the C-180; the comparison samples of 3x zoom and C-180 [in the on-line album noted below] were all taken without any adjustments.

For additional sample images, see Mikhail Surin's C-180 album, which also includes Tiffen +7 and +10 close-up lens samples.


Marks content that should probably be confirmed independently Other Workable Auxiliary Lenses

Additional Oly Offerings

The conversion lenses listed below are the only lenses I've ever seen Oly officially claim to be compatible with their C-series digital rangefinders. (The conspicuous absence of the B-300 is puzzling, to say the least.) All were originally developed for Oly IS-series 35 mm film cameras or for older Oly digital SLRs—the D-500, D-600L and D-620L. All get consistently good to rave reviews on RPD with regard to image quality, but some users mark them down for their plastic construction and lack of outer filter threads.

Oly Conversion Lenses Officially Compatible with the C-series rangefinders
Lens Final focal lengths  for a C-series 35-105 mm lens) Step-up ring needed for the CLA-1 Street Price as of 2Q2004
WCON-07 0.7x wide-angle 24.5 - 74 mm 43-55 mm, included ~$125 on Amazon or B & H Photo
WCON-08E "B-28" 0.8x wide angle 28 - 81 mm 43-55 mm, included ~$40 from Oly via ebay
TCON-14 1.45x tele 50 - 150 mm 43-46 mm, included ~$85 street before $30 Oly rebate
MCON-40 "B-Macro HQ" n/a 43-55 mm, included ~$110 on Amazon
FCON-02 Fisheye n/a 43-55 mm, included ~$250 on Amazon

The popular 1.45x teleconverter is discussed in more detail above

Marks the gotchas Don't even think about buying lenses at the on-line Olympus Emporium.

Their prices are so outrageous, I refuse to link the site. As of 2Q2004,  Amazon and B & H Photo usually stock most of these lenses at half Oly's price. Olympus America also sells many of these lenses as factory refurbs or new units with defective packaging at auction on ebay, where they often go for 3-4 times less.

Oly 0.8x Wide-Angle Converter

The 55 mm 0.8x "B-28" WCON-08E  wide-angle converter draws consistent praise on RPD with regard to optical quality. Ron Goodenow describes it as "very sharp and free of distortion". Vignetting is nonexistent at all C-2020Z zoom settings, and the same presumably applies to all C-series cameras with a 3x 35-105 mm zoom lens. The only downside—the fairly large and heavy B-28 blocks even more viewfinder and onboard flash than the B-300

Marks content that should probably be confirmed independently Oly recommends the B-28 for the C-2100UZ, but with a resulting minimum EFL of 30 mm, a wider- angle converter would seen desirable. I don't know if the WCON-07 is compatible with the C-2100UZ.

Oly 0.7x Wide-Angle Converter

The 55 mm 0.7x WCON-07 wide-angle converter matches the 0.8x B-28 in optical quality while providing a substantially increased field of view. Based on its size and shape, it probably blocks the flash and viewfinder even more the the B-28.

I use the WCON-07 with my C-2020Z and C-5050Z and find it an excellent lens with no light loss and few peripheral flaws. It produces no vignetting at minimum zoom (35 mm EFL) on these cameras. I have yet to define the onset of vignetting at higher zoom settings.

Marks content that should probably be confirmed independently Oly Fisheye Kit

Oly's FCON-02 Fisheye Conversion Lens Kit includes a multicoated 180-degree fisheye lens, a nodal-point tripod rotator, IPix software and two adapters for point-and-shoot cameras. According to Oly's blurb, it's only compatible with D-series Oly digitals. To what extent it's adaptable to Oly rangefinders or the C-2100UZ, I have no idea. The kit goes for ~$250 at www.amazon.com as of 2Q2004.

Oly Converter Wrap-up

You won't go wrong with Oly's venerable line of conversion lenses. As of 4Q2004, many can still be had for reasonable prices from 3rd-party vendors or on ebay. Note that using filters with these Oly converters would likely raise the same challenges encountered with the B-300 teleconverter.


Other Commercial Conversion Lenses

EagleEye OpticZoom

Marks content that should probably be confirmed independently EagleEye of the UK offers an expensive but very tempting 5x OpticZoom teleconverter. Targeted initially at the Oly rangefinders and the Nikon CoolPix 950 and 990 but adaptable to quite a few other cameras, this cylindrical black-anodized aluminum-bodied lens has 37 mm inner and outer threads. At ~250 gm and 49x170 mm at full length, the OpticZoom should cure any case of lens envy.

To mount the OpticZoom on a CLA-1 lens tube on an Oly rangefinder, you'll need  a 43-@ mm step-up ring and a special separately-sold flat @-37 mm adapter ring, where @ can be 43, 46 or 49 mm, depending on your existing equipment. (Reading between the lines, EagleEye seems to be recommending @ = 46 mm for these Olys.) To minimize  vignetting, I'd be very tempted to try the thinnest possible step-up here, particularly on the C-20x0Z, which seems to have a bit more zoom lens clearance than the C-3000Z and C-3030Z.

The manufacturer claims that the OpticZoom requires a minimum 2.5x zoom lens setting on the host camera, presumably to escape vignetting. However, most RPD reports tell of minimal vignetting on the C-20x0Z at full (3.0x) zoom. EagleEye acknowledges similar vignetting with the Oly C-2500L.

Brian Mathers of RPD reports "negligible" light loss and, past about 50% full zoom, no vignetting at all with the OpticZoom on his 2.3MP FujiFilm MX-2900Z, which has a 3x, 35-105 mm zoom lens similar to that on the C-20x0Z. Using a $14 37-55 mm step-up ring from EagleEye, Brian mounted an Oly B-300 1.7x teleconverter outboard of his OpticZoom for a walloping final 25.5x magnification to 893 mm! Brian finds this lens combination "ideal" for birding.

Marks the gotchas With the 5x OpticZoom on a C-20x0Z, you'd need other teleconverters to cover 105-525 mm focal lengths without vignetting.

As of 4Q2000, the OpticZoom goes for US$224 direct with shipping and handling to US and Canadian addresses. To that, you'll need to add at least another $14 for that special flat @-37 adapter ring. For another $50, you can get a collar-style tripod mount for the OpticZoom. 

How this converter would fare on the C-2100UZ, I have no idea.

Tiffen Converters (as of 1Q2002)

Tiffen still makes decent filters, but their converter lens offerings for digital cameras have been consistently weak. They now offer a 2.0x teleconverter and a 0.5x "super wide angle" converter, both with  49 mm mounting threads for direct attachment to the separately-sold Tiffen 41-49 mm Custom Camera Mount for Oly digital rangefinders. You can view and price all these pieces bundled as a set at BugEye Digital

Marks content that should probably be confirmed independently I have no hands-on info on the quality of the Tiffen 2.0x, but in late 1999, then-frequent RPD contributor Eduardo Suastegui posted several fairly damning test shots before returning his Tiffen 2.0x. Many other RPD posts reported similar results around that time. Eduardo next posted test shots of equally poor quality taken with a Kenko KVC-200hi teleconverter before settling on the Oly B-300. His now defunct digital photography pages also illustrated the significant increase he found in B-300 vignetting when mounted on an Tiffen lens tube as opposed to an Oly CLA-1.  

To Tiffen's credit, their own digital lens page forthrightly acknowledges peripheral "distortion and softening" and minimal vignetting with the 0.5x at full wide angle zoom. A dpFWIW visitor e-mailed me that he returned a Tiffen 0.5x because of "just awful" chromatic aberration, which Tiffen claims is typical of extreme wide angle lenses. (They may both be right. Any lens experts care to comment?) Look closely and you can see the vignetting and chromatic aberration in the deep peripheral shadows in a 0.5x sample photo on another page, but the shadows largely mask these flaws. Tiffen also offers 37 mm 0.65x and 1.5x converters.

Further Options

Marks content that should probably be confirmed independently Among others, Raynox and Kenko offer a variety of converters adaptable to C-series cameras, but I have no good information on any of these options. Eduardo Suastegui once posted some disappointing test shots taken with a Kenko KVC-200hi teleconverter, but they're no longer available. 


Close-up Lenses

For a detailed discussion of close-up lenses with sample images, see the close-up section in the dpFWIW article Filter options for digital cameras.


Lens and Filter Cleaning

Everyone has their own lens and filter hygiene routine. Some of the cleaning routines I've seen posted on RPD border on religious ritual, but it's certainly better to be safe than sorry with expensive optics, especially with the built-in lenses found on most consumer-grade digital cameras.

When it comes to cleaning optics, prevention is by far the safest cure. Lens caps keep dirt from ever reaching your glass. Permanently-mounted protective filters are controversial at best, but few would question their use in really dirty environments. I keep my armored C-2000Z, C-2020Z and C-5050Z lenses capped as much as possible and add a protective filter when things get really nasty. With this arrangement, I seldom have to clean the built-in camera lenses.


First, Remove the Particulates Safely

The first rule of lens cleaning is simple enough:

Marks the gotchas Never wipe a lens or filter without first safely removing the accumulated loose particulate matter.

Camera shops carry special blower brushes for this purpose. A dry blow with your own breath is safe in most climates, but lens and filter infections can occur in the tropics. If you don't have a soft brush to finish the job, use a pressure-free dusting with a clean lens cloth dangled, not rubbed, against the glass.


Then Wipe Safely

If you must wipe your lenses and filters, do so very, very gently, after safely removing any loose particulates clinging to the surface. 

Marks the gotchas Never wipe a dry lens or filter.

In temperate and cooler climates, it's perfectly safe to fog the lens with several breaths before wiping. Make sure you supply enough moisture, but don't spit on the glass. For stubborn smudges, dampen the cloth with a cleaning solution specially made for coated optics and follow the directions supplied with the fluid. (When in doubt, assume that your lenses and filters are coated.) To protect glues that might be present, don't pour any liquid directly onto your glass surfaces. 

Marks the gotchas Ammonia-based products like Windex will damage optical coatings. 

For safe, effective wiping, I've taken to carrying a washable, untreated microfiber lens cloth. It works equally well on lenses, filters and the LCD. Mine came with my last set of prescription lenses, but camera and high-end sunglass shops also sell them. Unlike shirttails and regular tissue paper, microfiber cloth lifts grease instead of just pushing it around. Microfiber cloth by itself won't abrade glass or coatings, but it can pick up and retain dangerous grit, especially if carried loose in a pocket, as I used to do. 

Marks the gotchas Grit embedded in any cloth or tissue can seriously damage your optics, glass and coatings both.

If you go the microfiber cloth route, wash your cloth more frequently than you think you need to and carry it in a grit-tight container, not loose in your pocket. Light-colored cloths show their dirt sooner. White cloths have no dyes that could be leached onto your optics by alcohol-based cleaning fluids. 

A clean microfiber cloth is probably at least as safe as a dedicated disposable lens tissue. A fresh tissue guarantees the absence of damaging grit, but some claim that any tissue is inherently more abrasive than a clean microfiber cloth.

Marks content that should probably be confirmed independently Steve Anderson kindly wrote to tell me of a new 3M CD & DVD Cleaning Cloth that may be an equally attractive alternative. According to 3M, it's "great for eyeglasses and cameras, too!" It comes in a CD jewel case, can be washed hundreds of times and sells for under $6.

Marks content that should probably be confirmed independently Several RPD denizens also swear by the LenPen, but I have no experience with it.


Focal Length vs. CCD Resolution

Quick, for printed output at fixed printed subject size, what's better—a camera with a high-resolution CCD and a 3x lens maxed out at 105 mm, or a camera of lesser CCD resolution with a longer native lens?

Marks the paydirt The answer: Whichever lens-CCD combination puts the greater number of pixels on the subject at any given camera-subject distance. The more subject pixels—or alternatively, the smaller the pixel size at the subject—the more options you'll have at post-processing, and the sharper your prints will be.

To maximize the number of subject pixels, just follow the standard photographic wisdom: Fill the frame with your subject. If you can do that with both cameras, the higher resolution CCD will produce the better print, all other things (particularly lens quality) being equal. But when you've zoomed in all the way and moved in as close as you can, and the subject is still less than full-frame in one or both cameras, the winning lens-CCD combination gets harder to predict.


Figure of Merit

dpFWIW contributor and physicist Rick Matthews offers a useful comparative index proportional to the number of pixels applied to an arbitrary subject at an arbitrary distance from the camera.  Rick's figure of merit (FM) for a lens-CCD combination is given by 

    FM =  FL2 * ImagePixels / 106 =  FL2 * HorizPixels * VertPixels / 106

where ImagePixels = the total number of megapixels in the raw image and FL is final focal length expressed in 35 mm camera equivalents. This last stipulation automatically corrects for variations in CCD dimensions.

For the 2.1 megapixel C-20x0Z at maximum resolution and zoom, for instance,

    FM = (105 mm)2 * 1600 * 1200 / 106 = 11,025 * 1.92 = 21,168

with a bare lens, while 

    FM = (180 mm)2 * 1600 * 1200 / 106 = 32,400 * 1.92 = 62,808

with the 1.7x B-300 teleconverter mounted. As you can see, the greater the FL, the greater the number of pixels applied to any given area.  In this case, the 1.7x increase in FL triples the number of subject pixels because 1.7~ 3.

Now consider two different lens-CCD combinations, cam1 and cam2, cam1 being the higher resolution of the two. The ratio of pixels applied to any given subject by these cameras is

SubjectPixels1 / SubjectPixels2 = FM1 / FM2 = (HorizPixels1/HorizPixels2) * (VertPixels1/VertPixels2) * (FL1 / FL2)2

at constant camera-subject distance and printed subject size.

For cameras with the same image aspect ratio—say, 4:3—this ratio conveniently reduces to

SubjectPixels1 / SubjectPixels2 = FM1 / FM2

= (HorizPixels1/HorizPixels2)2 * (FL1 / FL2)2

= [(HorizPixels1 * FL1) / (HorizPixels2 * FL2)]2

= [(HorizPixels1 / HorizPixels2) * (FL1 / FL2)]2

depending on how you prefer to work the numbers.


Comparing Camera-Lens Systems

The crossover focal length FL1x where SubjectPixels1 = SubjectPixels2 (or FM1 = FM2) at fixed camera-subject distance occurs at

    FL1x = FL2 * HorizPixels2 / HorizPixels1

FL1x is where hi-res cam1 begins to outperform cam2.

You're better off with the higher resolution cam1 only if it can reach a focal length

    FL1max > FL2max * HorizPixels2 / HorizPixels1,

where FL2max is the greatest focal length cam2 can muster.

Take, for example, the 3.3MP Oly C-3030Z (cam1) with 3x zoom lens reaching a maximum FL of 96 mm and the 2.1MP C-2100UZ (cam2) with a 10x zoom reaching 380 mm. To throw more pixels on a given distant subject than the C-2100UZ, the C-3030Z would have to reach a crossover focal length of

 FL1x = 380 * 1600 / 2048 = 297 mm

but it could do so only with the aid of a 3x teleconverter.

Marks the paydirt Checking the crossover focal length is critical step when comparing cameras with differing CCD resolutions and maximum focal lengths.

Note that the 10x Oly C-2100UZ turns in figures of merit over 3 times greater than any of the higher MP cameras in the comparison below despite its 2.1 MP CCD. Left to right, the cameras are listed in order of figure of merit at full zoom without a teleconverter.

camera

oly c-20x0z

oly c-30x0z

oly c-5050z

 oly e-10

sony dsc-f505v*

oly c-2100uz

teleconverter mag

none

1.7

none

1.7

none

1.7

none

1.7

none

1.7

none

1.7
Nominal MP 2.1 2.1 3.3 3.3 5.2 5.2 4.0 4.0 3.3 3.3 2.1 2.1
min fl (mm) 35 59 32 54 35 69 35 59 38 65 38 65
max zoom 3 3 3 3 3 3 4 4 5 5 10 10
max fl (mm) 105 180 96 163 105 180 140 238 190 323 380 646
image pixels horiz 1600 1600 2048 2048 2560 2560 2240 2240 1856 1856 1600 1600
image pixels vert 1200 1200 1536 1536 1920 1920 1680 1680 1392 1392 1200 1200
megapixels in image 1.92 1.92 3.15 3.15 4.92 4.92 3.76 3.76 2.58 2.58 1.92 1.92
figure of merit 21,168 62,208 28,991 83,784 54,190 156,609 73,758 213,163 93,266 269,539 277,284 801,247
* An RPD post claims excellent results with the 1.7x Oly B-300 and the 0.8x B-28 converters on the Sony DSC-F505v.

Additional Considerations

Rick Matthews' figure of merit neatly addresses an important layer in a complex, many-layered process leading to final image quality. Equally important aspects of lens performance like speed, resolution (line pairs per mm), contrast, distortion and aberration deserve attention as separate layers. Unfortunately, the integrated lenses found in most digital cameras turn each layer into a potential trade-off. Lens speed is a spec easily obtained from online camera reviews, but the other lens issues just mentioned remain very difficult to assess reliably in real-world shopping scenarios.

IMO, ease and flexibility in mounting teleconverters, filters, lens hoods and other lens accessories should also weigh heavily in lens considerations.

Once digital cameras with interchangeable lenses become commonplace, one can begin to separate the lens and camera decisions. Until then, lens and CCD issues will have to compete right alongside other important but unrelated camera features when it comes time to face the many trade-offs inherent in any considered digital camera purchase.


What About the C-2100UZ and Later Oly Rangefinders?

Marks content that should probably be confirmed independently I'm no expert on all of the ways in which and the C-2100UZ and later Oly rangefinders depart from the C-2020Z and C-5050Z, but I am aware of the following differences pertinent to this article:

  • The slightly shorter maximum zoom (96 vs. 105 mm in 35 mm equivalents) unique to the C-3000Z and C-3030Z slightly reduces all final teleconverter focal lengths quoted above by 8.6%.

  • The slightly shorter focal length at widest angle (32 vs. 35 mm at minimum zoom) unique to the C-3000Z and C-3030Z will slightly exacerbate all the C-series vignetting issues noted above.

  • The C-2100UZ's superb built-in 10x 38-380 mm zoom lens obviates the need for a teleconverter in most situations. It's 38 mm widest angle should help with vignetting. Oly recommends its B-300 telephoto, B-28 wide angle and B-Macro converters for the C-2100UZ. Click here for further C-2100UZ auxiliary lens details.

  • I'm not familiar enough with the C-7xxUZ series to say anything intelligent about it.

To my knowledge, this article otherwise applies fully to all Oly digital rangefinders and to the C-2100UZ as well. If you find anything else that doesn't fit, please let me know at dpFWIW@cliffshade.com.


References and Links  

(See also the home page links.)

Unofficial Oly IS-series data sheet—for the adventurous, a useful, well-illustrated resource on Oly's IS-series 35 mm film cameras. Converters and other accessories made for the IS series can in some cases be adapted to Oly digitals, as the Oly converter options noted above attest.

Rowell, Galen, Mountain Light, 2nd ed., Yolla Bolly Press, Sierra Club Books, San Francisco, 1995.

Philip Greenspun's macro article—comprehensive and well-illustrated, on photo.net, of course.

David Jacobson's lens tutorial—comprehensive and technical but sparsely illustrated, this photo.net article runs into a companion technical article on illumination by John Bercovitz. 

Securely enclosing the zoom lens of your Olympus C-2000 Zoom—one of many expertly-written and illustrated digitalkamera.de Tips and Tricks, this one on permanently armoring the C-2000Z.


Unless explicitly attributed to another contributor, all content on this site © Jeremy McCreary

Comments and corrections to Jeremy McCreary at dpFWIW@cliffshade.com, but please see here first.

URL: http://www.cliffshade.com/dpfwiw/c-2000z/lenses/index.htm