Digital Photography For What It's Worth

Filters and lens shades for Oly C-series digitals

What to know before you buy

• First Steps—Step-up Rings and Lens Tubes

• Vignetting

• Round Filters

• Square Filters

• Lens Hoods—The Cure for Flare

• The Short Answer

• The Great Linear vs. Circular Polarizer Debate

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

• References and Links

See also Filter Options for Digital Cameras

Last updated July 27, 2004

First Steps—Lens Tubes and Step-up Rings

You can greatly extend the functionality of your already versatile Oly digital camera with filters and auxiliary lenses from Olympus and other vendors, much as you would a 35 mm film SLR. Many higher-end digital rangefinder and SLR cameras now accept lens accessories using a variety of mounting arrangements, including the Nikon CoolPix 8xx and 9xx series, the Canon PowerShot Gx rangefinders, the Canon IS Pro90, and the Sony DSC-F505x and DSC-F707, to mention just a few.

Lens Tubes for Oly Rangefinders

The lens shroud built into the C-2100UZ camera body has a 49 mm thread for mounting filters and auxiliary lenses. The C-2100UZ needs no lens tube, but to mount lens accessories on an Oly digital rangefinder, you'll definitely an add-on lens shroud like the Oly CLA-1 lens tube. All earlier Oly digital rangefinders through the C-2020Z and C-3030Z also need one or more step-up rings or shim rings to mount filters safely on the CLA-1, as discussed below. With careful testing, it's apparently possible to mount some single-ring 43 mm filters directly on the CLA-1 on C-x040Z models.

The table below summarizes the data I've collected on several commonly available lens tubes. I make no bones about my strong preference for the Oly CLA-1 lens tube, but your needs may differ. In any event, your lens tube choice will determine the shim and step-up ring size(s) needed for subsequent attachments.

As you can see, these lens tubes are not all created equally. The devil's in the details, which are discussed in the following sections.

Oly CLA-1 Lens Tube

(See also the dpFWIW article Lens armor and other useful Oly digital modifications.)

Oly intended filters and auxiliary lenses to attach to its digital rangefinders (C-20x0Z, C-30x0Z, C-40x0Z and later models) via the optional but in my opinion indispensable Olympus CLA-1 conversion lens adapter—a sturdy, well-made metal tube that screws securely into a 41 mm thread just inside the camera's black lens bezel. The CLA-1 offers a 43 mm mounting thread at its business end. (In a sense, it's just an elongated 41-43 mm step-up ring.) Alternate names you might see the for CLA-1 include all combinations of "lens/adapter/accessory tube/sleeve/collar". It still goes for $13-20 on the street.

The CLA-1 is ~22.9 mm long not counting the 41 mm thread for the camera. Oly engineers chose this length to minimize vignetting when the CLA-1 is used to mount auxiliary lenses, particularly Oly's own teleconverters.

Crash!

The short length of the CLA-1 makes it ideal for lens mounting but leaves it a bit too short for the direct mounting of 43 mm filters on Oly rangefinders prior to the C-2040Z, C-3040Z and C-4040Z:

Warning! It's unsafe to mount most 43 mm filters and close-up lenses directly onto the CLA-1 on Oly digital rangefinders prior to the C-x040Z line due to inadequate zoom lens clearance. Some filters may be unsafe on later models as well.

In extended position, the C-2000Z, C-2020Z, C-3000Z and C-3030Z zoom lenses jut out just far enough (~1.5 mm) beyond the end of the CLA-1 to crash themselves into the glass of any single-ring 43 filter mounted directly on the CLA-1. For some single-ring 43 mm filters like the Bowers UV, this doesn't appear to be a problem on the C-2040Z, C-3040Z and C-4040Z, but only testing will tell. The spacing between the glass and the male threads is probably the key variable here.

Crash Test

When in doubt, try David Morgenlender's simple 43 mm filter test on your C-2040Z, C-3040Z or C-4040Z: 

• With the CLA-1 in place, the camera powered on and the zoom lens fully extended, gently screw the filter in question onto the CLA-1.

• Stop turning at the first hint of resistance, then power down the camera. 

• With the lens safely retracted now, see if the filter will screw down any farther. 

If there's still some travel, plan to interpose a 43 mm shim ring between the CLA-1 and that particular filter. If not, you're good to go with that filter, but don't assume that other 43 mm filters will work with your camera without testing them first.

And Crash Again!

On the C-3000Z and C-3030Z, the zoom lens can also crash into to the rear lens of an Oly B-300 teleconverter mounted on a CLA-1 with a single exceptionally thin 43-55 mm step-up ring. Click here for further details. 

This is not an issue on the C-20x0Z; nor is it a problem with average-thickness step-up rings on the C-30x0Z < CLA-1 combination. Where the C-3040Z and C-4040Z stand here, I have no idea.

Bottom Line on the CLA-1

On balance, I think Oly made the correct trade-off with the CLA-1's length: The Oly B-300 teleconverter, for instance, operates without vignetting over a substantially greater range of zoom settings with the CLA-1 than with longer lens tubes like the Raynox, Bower and Tiffen offerings discussed below.

I strongly recommend the CLA-1 as an excellent all-around filter- and lens-mounting platform for all Oly digital rangefinders. If you plan to carry just one lens tube, this is it.

The Tiffen 41-49 mm Custom Lens Mount

Tiffen markets a longer alternative to the CLA-1, a 41-49 mm custom lens mount long enough to accept widely available 49 mm accessories directly without crashing the zoom lens at full extension. The Tiffen tube produces no vignetting with directly mounted 49 mm filters.

However, the extra length has the potentially serious downside of exacerbating vignetting when the Tiffen tube is used to mount auxiliary lenses, particularly teleconverters. To see a comparison of the vignetting encountered with an Oly B-300 teleconverter mounted on a C-2020Z via the Tiffen lens tube vs. the CLA-1, go to Eduardo Suastegui's test page. 

C-3000Z and C-3030Z users should expect even more teleconverter vignetting with this tube due to their wider angle lens (32-96 mm vs. 35-105 on the C-20x0Z, C-3040Z and C-4040Z), but at least Tiffen would prevent lens-lens crashes with the B-300.

Tiffen bundles this tube with a 49-55 mm step-up ring, presumably to allow you to redeploy all those 55 mm filters languishing in your film camera bag. You can view and price this set at BugEye Digital.

I have no personal experience with the Tiffen tube. However, based on Eduardo's careful testing, I can't recommend it for teleconverter mounting on the basis of the vignetting alone. Nor is it stellar as a filter mounting platform. Even there, I fail to see any meaningful advantage over the CLA-1 with a 43-49 mm step-up ring.

The Raynox 41-37 and 41-43 mm Lens Tubes

Like the Tiffen 41-49 mm tube, the aluminum 41-37 mm Raynox lens tube is long enough to mount filters and lenses directly without fear of crashing your zoom lens. Thanks to its tiny outboard diameter, the Raynox allows direct 37 mm filter mounting with the least flash shadowing and viewfinder blockage of all the lens tubes reviewed here—and for some that's a major plus. The lens tube page put together by dpFWIW contributor Rick Matthews nicely illustrates these virtues on the C-2020Z.

Still, there are reasons to be concerned about vignetting with this tube. Relative to the CLA-1, the added length and reduced outboard diameter of the Raynox tube promote vignetting—not just with auxiliary lenses, but even with 37 mm filters mounted directly on the tube on the C-30x0Z. James Stewart of RPD has kindly posted Raynox test images showing mild vignetting at full wide angle with only the Raynox tube and a standard-thickness metal-ringed Tiffen 37 mm UV filter mounted on his Oly C-3000Z. Since C-20x0Z/Raynox users like  dpFWIW contributor Mike Wright have reported no filter-related vignetting with this arrangement, I attribute the difference to the shorter full wide-angle focal length of the C-3000Z and C-3030Z (32 mm vs. 35 mm for the C-20x0Z, C-3040Z and C-4040Z). Relative to the CLA-1 on the C-20x0Z, this can only mean greater vignetting across the board for auxiliary lenses mounted on the C-3000Z C-3030Z via the Raynox.

As of late 1999, filter selection and availability also seemed to be something of an issue at 37 mm, but that may be less of a problem now, thanks in part to the growing popularity of 37 mm gear for the Nikon CoolPix line. Again, see BugEye Digital for Raynox pictures and prices.

I have no personal experience with the 37 mm solution. Some RPD respondents swear by it, at least for filter mounting on the C-20x0Z, but I can't recommend it because of its limitations as a lens mounting platform.

37 ... 37 ... do I hear 43?

Raynox now offers a 41-43 mm lens tube long enough to mount 43 mm filters directly. I have no information on vignetting with this tube, but it's likely to vignette less than the 41-37 mm tube, at least with filters. For now, I merely note its availability at BugEye Digital.

The Bower 41-46 mm Lens Tube

Like the Tiffen and Raynox tubes, the 41-46 mm brushed metal Bower lens tube is long enough to mount filters and lenses directly without zoom lens crashes. The 46 mm outboard diameter will allow direct 46 mm filter mounting without vignetting and with less flash shadowing and viewfinder blockage than 49 mm or larger setups would produce.

As with the Tiffen tube, I'd be concerned about auxiliary lens vignetting with this tube due to the added length relative to the CLA-1 (~29 mm vs. ~23 mm). As usual, C-3000Z and C-3030Z users can expect more converter lens vignetting than other Oly rangefinder users will get with this tube.

At 46 mm, filter selection and availability are tolerable but nowhere near what you'll find at 49 mm. See The Filter Connection for Bower lens tube pictures and prices and a good selection of 46 mm gear. Thanks to Jeffrey Seabrook for his help with the Bower tube.

Right-Sizing for the Future

Settle early on a standard accessory size carefully chosen to minimize the number of step-up rings you'll need to carry and futz with in the field given the accessories you're likely to want or need. For the C-2100UZ, size is joyously simple—49 mm.

For Oly rangefinders, I see the 49, 46 and 43 mm options as your best bets, but there are reports of minimal filter vignetting on the C-3000Z and C-3030Z at 43 mm, presumably due to their wider lens (32-96 mm vs. 35-105 mm for other Oly rangefinders). You might be able to beat this filter vignetting at 43 mm with thin-ring filters and step-ups like those made by B+W and Kenko. None of these sizes cause vignetting in the 20x0 line.

While 43 and 46 mm attachments interfere a bit less with the viewfinder and flash, you'll have a much easier time finding the gear you want at 49 mm. (Concrete examples: In late 1999, my 49 mm Hoya multicoated UV filter came in lots of other sizes but not in 46 mm. My Tiffen 87 IR filter wasn't available in sizes below 49 mm.)

Bottom Line

So, if you're dependent on the onboard flash and need to minimize shadowing, I'd recommend 43 mm on the C-20x0Z, C-3040Z and C-4040Z and 46 mm on the C-3000Z and C-3030Z. 

If you're more concerned about accessory availability than onboard flash shadowing, go with 49 mm instead. At 43-49 mm, I don't consider viewfinder blockage an important factor in this decision, but I wouldn't go any larger than 49 mm on a routine basis.

Accessory size considerations are summarized in the table below. Related lens tube issues must also enter the final equation.

According to several RPD posts, the less trodden 37 mm path also leads to some nice accessory options for Oly digital rangefinders, but I hear that the relatively inexpensive camcorder accessories common at 37 mm seldom come with optics worthy of this camera.

Making a 43-43 mm Shim Ring for the CLA-1

Mounting 43 mm filters on the CLA-1 will minimize flash shadowing and viewfinder blockage, but to do so without lens-filter crashes on the C-2000Z, C-2020Z, C-3000Z and C-3030Z, you'll need to interpose a 43-43 mm shim ring to gain the necessary clearance. With some filters, a shim ring may be necessary on later Oly rangefinders as well.

To my knowledge, shim rings aren't commercially available, but you can make one easily enough by removing the glass from an old or inexpensive 43 mm filter with both male and female threads. (Note: Some low profile filters lack female threads.) Mark Gregory has beautifully illustrated his 43 mm solution here. dpFWIW contributor Ilkka Valkila reports no vignetting with his 43 mm gear on his C-2020Z, even with several stacked 43 mm accessories, but you'll probably get minor filter vignetting on the C-3000Z and C-3030Z with even a single 43 mm filter.

Technical Note: On the C-2000Z, C-2020Z, C-3000Z and C-3030Z, all single-ring 43 mm filters (e.g., UV or IR) and close-up lenses require a shim ring with the CLA-1. Some double-ring 43 mm filters (e.g., polarizers and round GNDs) are apparently safe to mount directly on the CLA-1 on these cameras, and some single-ring 43 mm filters mount safely on the CLA-1 on later models, but it's best to test before you leap here. 

Vignetting

Vignetting occurs when one or more optical housings along the light path to the CCD end up within the camera's field of view. Full-blown vignetting appears an unwelcome black circular mask at the margins of the image, but the onset of vignetting is typically heralded by a subtle darkening affecting only the corners of the image. Unfortunately, this early warning is usually a lot more conspicuous on your monitor that it ever is on your LCD at the scene and will never show up in optical viewfinders on rangefinder cameras.

Generally speaking, the wider the zoom setting, the more likely the vignetting for any given accessory configuration. Conversely, decreasing the diameter of the filter or mounting hardware or increasing the distance between the outermost accessory and the CCD increases the likelihood of vignetting at any given zoom setting. Vignetting is a good reason to pay attention to filter size and mounting methods.

With filters, vignetting is often limited to the widest angles your zoom lens can muster, but with some teleconverters, it can plague the entire zoom range.

Since vignetting tends to be more problematic with converter lenses than with filters, you'll find it discussed and illustrated in greater detail in the dpFWIW article Auxiliary lenses for popular Oly digitals.

On Oly rangefinders, you'll get no filter vignetting with 46-55 mm gear. On the C-20x0Z, you can also use 43 mm filters without vignetting. If you stick with thin metal-ringed filters and avoid the cheap thick-ringed plastic camcorder jobs, I hear you won't even see filter vignetting at 37 mm on the C-2000Z and C-2020Z, but you will on the wider-angle C-3000Z and C-3030Z. The C-x040Z rangefinders are unknown quantities here. 

I have no experience with the C-2100UZ but doubt that vignetting will be a problem with 49 mm filters mounted directly on the lens. Converter lens vignetting is for the most part uncharted territory at this point.

Round Filters

Round screw-on filters are the most easily used and commonly available of the optical filters adaptable to the Oly Camedias. For a general discussion of optical filters and their uses, see the generic dpFWIW article Filter options for digital cameras.

This section focuses on the 49 mm round screw-on filter solution for Camedia rangefinders because

• It works well with all Oly rangefinders.

• I have no first-hand experience with other round filter sizes.

• The C-2100UZ's enclosed zoom lens and 49 mm filter thread naturally favor 49 mm accessories.

The C-2100UZ lens design and pop-up flash eliminate the viewfinder and flash blockage issues discussed below. The C-2100UZ mounts 49 mm filters directly with no need for a lens tube, and lens-mounted accessories can't block the its electronic TTL viewfinder. Enough said about this fabulous camera.

Oly Camedia Rangefinders

The typical Oly rangefinder setup illustrated below includes an Oly CLA-1, a Tiffen step-up ring, a mostly protective Tiffen UV filter and a Kalt lens cap totaling $55 delivered from cameraworld.com as of May, 1999.

A Typical C-20x0Z 49 mm Filter Setup Oly CLA-1 conversion lens adapter (43 mm end thread) 43-49 mm step-up ring 49 mm filter or close-up lens 49 mm lens cap (optional but recommended)

Depending on the thickness of the filter, the CLA-1, step-up ring, filter and cap together add 0.5-0.6" to the depth of the camera beyond the fully extended zoom lens. The seated lens cap is almost half of that. Since the Camedias were never meant to be pocket cameras, I don't mind the increased depth. In fact, the added depth makes the camera fit more securely inside my small and medium-sized camera bags. The added weight is negligible.

For further details and illustrations, see the Lens Armor section of dpFWIW article Lens armor and other useful Oly digital modifications.

Size Matters on Camedia Rangefinders

Vignetting isn't a problem with 46 mm and larger accessories mounted on Camedia rangefinders using the CLA-1. On the C-20x0Z, C-3040Z and C-4040Z, you can even use 43 mm filters without vignetting, but note this safety warning if you do.

What you will see on all Camedia rangefinders is variable viewfinder blockage and flash shadowing, even with the bare CLA-1. The larger the gear mounted, the more you'll get. The lens tube page put together by dpFWIW contributor Rick Matthews nicely illustrates these problems on the C-2020Z.

The images below show what to expect in the C-2000Z and C-2020Z viewfinder with a 49 mm filter in place. 

C-2020Z Viewfinder Encroachment with a 49 mm Filter on the CLA-1 At widest angle (35 mm, 1.0X), the 49 mm step-up ring and filter came up to the road-driveway boundary in the viewfinder, as simulated in the photo on top. At mild zoom (54 mm, 1.5X ) zoom, the step-up ring and filter have just slipped out of view at right.

This degree of encroachment has yet to get in my way. In fact, I rarely even notice it anymore. Besides, seeing a bit of filter in the viewfinder has its virtues. I find it rather handy to be to able confirm through the viewfinder that the rotating ring of my polarizer is oriented properly for the shot at hand. And the opportunity to notice a lens cap tab in the viewfinder saved more shots than I care to admit.

With the CLA-1 as your lens tube, using 43 mm gear is the best you can do to minimize viewfinder blockage. dpFWIW contributor Ilkka Valkila reports no vignetting with his 43 mm equipment on the C-2020Z, even with several stacked 43 mm accessories, but you'll probably get slight vignetting with even a single 43 mm filter on the C-30x0Z.

Flash Shadowing

A more serious problem for users dependent on an Oly rangefinder's internal flash is shadowing of the flash by the CLA-1 and any mounted accessories. My 49 mm filter casts a small shadow at lower left in photos taken with the onboard flash alone. Even the bare CLA-1 casts a shadow, but it's barely noticeable.

Of course, with external flash, shadowing related to filters and other attachments becomes a non-issue. Mounting 43 mm gear will minimize both onboard flash shadowing and viewfinder encroachment. To mitigate onboard flash shadowing with whatever gear you have, try these additional tricks:

• Hold a white card at 45° just above the onboard flash tube to help fill in the shadow.

• Hold a plain white piece of paper in front of the flash tube as a diffuser (expect to lose about one stop to the paper).   

And Why Not 55 mm?

In my opinion, 49 mm is the largest filter size suitable for compact cameras like the Oly Camedia rangefinders. Experience with a 43-55 mm step-up ring has convinced me that 

55 mm filters are simply too large for the C-20x0Z and C-30x0Z.

Specific lenses like the Oly B-300 1.7X teleconverter may require a 55 mm step-up ring, and you'll certainly need one to recycle those 55 mm filters in your film camera bag. But if you're buying new filters for routine use, I see no good reason to accept these clear 55 mm disadvantages:

Compared with a 49 mm filter, a 55 mm filter Blocks much more of the viewfinder at most zoom settings. Casts a larger shadow in the onboard flash beam. Prevents the camera from resting squarely on its base when set on a flat surface, as shown at right. Looks awkwardly large on the camera.

Square Filters

Most of the comments above pertain directly to round screw-on filters. However, square filters in lens-mounted holders like those pioneered by Cokin can also be adapted to digital rangefinders—with a few trade-offs.

Square special effects filters offer certain advantages round filters can't match, most notably when the desired effect isn't meant to cover the entire field of view. You can rotate and translate square filters relative to the camera lens to position the effect precisely. Square filters also allow precise stacking of filters for complex additive effects. These flexibilities come in particularly handy when using graduated neutral density (GND) filters, but they require good TTL control for best results. Plan to rely on the camera's LCD for precise filter alignment and framing, using an LCD shade as needed.

Square filters come in optical resin and glass. Resin squares can be surface-dyed after casting or "dyed in the mass" while liquid. The latter process is said to result in greater accuracy. With both sides of the filter exposed to the air, the resin squares can be a challenge to keep clean because the resin tends to attract and hold dust via the magic of static electricity, particularly in dry air. 

Cokin Square Filters

In response to my March, 2000 RPD request for information on Cokin filters, dpFWIW contributor Ilkka Valkila kindly posted this fact-filled reply: 

[me] To avoid vignetting, the www.cameraworld.com website =strongly= recommended the Cokin P series for lenses of short focal length, so I went with P based the very short focal lengths typical of digital camera lenses, including mine.

[ilkka] The "short focal length" probably means "wide angle", not the actual focal length. I haven't used Cokin filters with my 24 mm (f/2.8) lens, but I just tried the A series filter holder on it and it's not visible (even when rotated) in the Canon T90's viewfinder which shows 94 % of actual picture area, so vignetting is no big problem even with a fairly wide angle lens. It could be a problem with a larger aperture or even wider angle lens.

[me] Unfortunately, now that the P series gear is here, I see that it's =way= too big for my C-2000Z. I haven't removed the pieces from their packaging pending return for A series gear, but I estimate that the mounted P filter holder alone will block at least 60% of my viewfinder. I could live with 50% or less, but 60%+ is untenable.

[ilkka] I tried the A series filter holder on the CLA-1 with step-up rings (43-49 and 49-52) and the top of the holder is something like 45-48 % of the height of the viewfinder and blocks about 1/3 of the area in wide angle. In tele position it's about 40% of the height and 1/6 of the area.

[me] So, has anyone tried the Cokin A series with an Oly C-20x0Z or comparable digital camera? Was there any vignetting? If so, at what zoom setting did it first appear?

[ilkka] There seems to be no vignetting even when the [A] holder is as far away from the lens as mine is now. There are the glassless 43 mm ring, the 43 mm skyfilter and two stepup rings between the CLA-1 and the Cokin holder, so even if there would be any hint of vignetting, it could be reduced by moving the holder closer to the lens. BTW, the holder is 77 mm wide and high.

To summarize Ilkka's findings and my own,

Cokin filter holders block substantial portions of the onboard flash beam and viewfinder on any Oly rangefinder, particularly the larger System P holders and filters.

That makes System A the Cokin size of choice for Oly rangefinders. System A attachments produce no vignetting at 43 mm or larger sizes and block the viewfinder and flash much less than their System P counterparts. Unfortunately,

Cokin-brand square GNDs are not reliably neutral.

To get truly neutral square GNDs, you must look to other manufacturers, who seem to offer only System P products. As of 3Q2000, no one but Cokin offered System A GNDs. 

The photo at right shows a Cokin System A holder (top center), a larger System P holder (far right) and their respective G2 filters overlapped in their supplied cases.  The Cokin adapter ring required to mount the holder is not shown. The car key at bottom right is for scale only.

Flash Blockage

External flash (EF) is clearly the solution for accessory-related obstruction of the onboard flash beam on Oly rangefinders. (EF solves lots of other problems, too.) Of course, flash shadowing isn't likely to be a big concern with a GND filter used primarily for outdoor landscapes under bright skies, but it might easily become an issue with other square filter types.

LCD vs. Viewfinder

Using the LCD to overcome viewfinder obstruction on Oly Camedia rangefinders brings complications related to camera steadiness and LCD visibility. The electronic TTL viewfinder on the C-2100UZ largely eliminates these problem.

Camera Shake

Framing handheld shots via the LCD with the camera held away from the head is a recipe for camera shake. Looking through the viewfinder with the camera held firmly against the brow provides a much-needed 3rd point of camera support that substantially enhances steadiness, even with a monopod for vertical support. (Mechanically and physiologically, it's much easier to steady your head than your hands.)

Framing with the LCD potentially carries all the advantages of TTL control when a tripod eliminates the steadiness issue, and it's unavoidable in macro and panorama modes on the Camedia. But to use the LCD to good effect under these conditions, you have to be able to see it, and that can be quite problematic in bright conditions, as discussed below and elsewhere on dpFWIW.

Workarounds

The most effective way I know to beat viewfinder obstruction and poor LCD visibility and camera shake all at once is the Xtend-A-View LCD hood, which allows shaded handheld LCD framing without giving up solid brow support.

That said, I've developed a tolerance for  viewfinder obstruction from working with my large Oly B-300 teleconverter—even without the Xtend-a-View hood. Like the Cokin System A filter holder, the B-300 blocks about 50% of the height of my viewfinder at full zoom. For handheld shots, I'm quite willing and able to work around that by

• Centering roughly with the viewfinder,

• Fine-tuning framing with the LCD,

• Memorizing the equivalent aim as seen in the unblocked portion of the viewfinder, and then

• Squeezing off the shot while aiming with the viewfinder to minimize camera shake.

After a few B-300 shots, I often find myself using just the upper half of the viewfinder, but it's a skill I seem to have to relearn from one B-300 or Cokin outing to the next.

Test: Cokin System A Graduated Neutral Density Filters

Below are initial results with two Cokin System A GNDs—a 1-stop Cokin G1 (No. A120) and a 2-stop G2 (No. A121). Resized but otherwise raw preliminary G2 samples appear in the table below.

G2 in pocket	G2 in hand	G2 in place

I should have had the transition a little lower in the last shot, of course, but at least the angle's close. An LCD sunshade would have improved LCD visibility substantially on this bright sunny spring day.

With this GND under bright skies, I find that

• Foreground colors are more saturated

• Dark foreground details are better preserved

• Sky details are enhanced

Similar benefits can be had by eliminating atmospheric scatter with a polarizer under certain circumstances, but GNDs don't create the dark banding that often mars the sky in wide-angle polarizer shots. 

Using the Cokin GNDs

Having had no prior GND experience, I started with the practical grad tips provided on the Singh-Ray GND page. In a nutshell, they advise to 

• Spot meter on the foreground before positioning the transition.

• Position the filter transition at the narrowest possible aperture, as greater depth of field makes it easier to see. Then set aperture as desired for the shot.

• Slide the filter back and forth as needed to make the transition more conspicuous.

While practicing the spot metering tip above, I stumbled onto 2 equally important tips for digital users:

• To make the transition even easier to see while positioning it, hold the shutter down halfway to lock exposure. That keeps the LCD from adjusting to the exposure changes reported by the meter as the GND moves around.

• If spot metering, keep the shutter halfway depressed until time to make the exposure. Otherwise, let up on the shutter momentarily to reset the metering before exposing.

  ---

Cokin GND Challenges

Using a Cokin-style filter on an Oly digital rangefinder has its challenges.

Viewfinder Blockage

Viewfinder obstruction with the System A holder has been tolerable at around 45-48%, just as Ilkka Valkila reported above. For certain shots, the resulting framing hassle is well worth the sliding GND capability gained. 

LCD Visibility

A much more difficult problem is inadequate TTL control due to poor LCD visibility in bright sunlight—the very condition GNDs are most commonly called upon to overcome. This gotcha can seriously hamper precise GND positioning, which is all the more critical at short digital camera focal lengths. I'm tinkering with a pocket-sized view-camera-style opaque shroud to shade my eyes and the camera back during GND sessions, but I'm also investigating a commercial LCD sunshade.

Dust

Dust has been another unexpected snag potentially exacerbated by the short focal length of my lens. The Cokin GND optical resin avidly attracts and holds dust—on both surfaces! I had a heck of a time keeping it clean during its shakedown run on a dry windy spring day. You can see the dust clinging to my G2 in the "G2 in hand" photo above, but fortunately, it's not conspicuous in "G2 in place" image, even in the 1600x1200 original.

Tint

I'd heard from a reasonably reliable source that Cokin GNDs are not always perfectly neutral, and that seems to be the case at least with my G2, which appears to impart a slight reddening at the transition. Note that many companies besides Cokin make filters for the Cokin System P holder—and some of these are apparently preferred precisely for their reliable neutrality—but few System A alternatives are available.

Lens Hoods—The Cure for Flare

Flare is an image artifact caused by unwanted reflections set up inside the camera. The most obvious cases of flare come from shooting too close to a bright light source like the sun. The lovely pentagonal UFOs seen hovering over San Francisco Bay in the infrared shot at right is flare from the sun.

Gross flare manifest by one or more conspicuous ghost images of a light source outside the field of view, is almost always a fatal image flaw, as in the image above, but flare's not always that obvious. Any light entering the camera from beyond its field of view can rob your images of contrast, even when the bright sources are all behind you. I think of flare manifest only as reduced saturation or contrast as diffuse flare. Since diffuse flare can be difficult to see coming, many photographers practice anti-flare measures on a routine basis. 

The more glass/air interfaces in the lightpath to the CCD, the more likely flare becomes. Multicoated filters and lenses may subdue flare, but anti-reflective coatings can only do so much. Shading the lens from stray light remains the definitive solution.

Shade

Shade is shade, so feel free to keep direct sun off your lens with the shadow of a tree, a building or even a cap or a hand held just out of the field of view. When simple measures fail, a camera-mounted lens hood or lens shade can save the day against flare. Generic lens shades are usually cylindrical in shape, but shades dedicated to specific lenses have 4 deep cut-outs carefully shaped and positioned to minimize the chance of vignetting at the corners of the frame while maximizing shading of the lens along the edges of the frame. With any shade design, there will always be a trade-off between vignetting and coverage. For that reason, shading a zoom lens may require either a set of hoods or one or more adjustable shades, like the rubber Hoya Multi-Angle reviewed below. 

Oly digital rangefinders seem particularly susceptible to flare. Several RPD posts have made the same observation, but how these rangefinders compare with the C-2100UZ and other digital cameras, I don't know. Some photographers keep lens hoods in place at all times to thwart flare, wherever it may come from, and to protect their precious optics. But a permanent lens hood on a rangefinder camera becomes yet another source of LCD-dependence—with all visibility and steadiness issues that entails.

For more information on flare and lens shades, see Robert Monaghan's lens flare article. 

Hoya Multi-Angle Rubber Hood

The inexpensive, flexible, well-made and well-designed 3-position Hoya Multi-Angle Rubber lens hood is an excellent flare solution across the full range of C-20x0Z zoom settings. The Hoya packaging claims the hood to be "suitable for most lenses from 35mm to 200 mm", and that seems about right. With its 75 mm diameter, the hood's outer rim subtends angles of 32°, 44° and 72° at the 49 mm mounting ring in its tele, standard and wide-angle positions.

On my C-20x0Z, the Hoya hood suppresses flare very effectively. It blocks about 45% of the height of the viewfinder in all 3 positions, but not to worry: For framing, it can easily be bent out of the way with a single finger—even when working one-handed. On release, the rubber hood snaps back into shape for the exposure. Any effective hood would produce similar viewfinder obstruction, of course, but a flexible hood like the Hoya provides a very simple work-around. 

My 49 mm hood can cause vignetting, but it's usually easily controlled with hood, zoom and occasional perspective (subject-camera distance) adjustments. Mounted over a single-ring UV filter, for instance, I see vignetting only in the hood's fully extended "tele" position—and then only at the widest angles (i.e., zoom settings of 1.2x and lower). With a double-ring polarizer, I get similar vignetting with the hood in standard position and commensurately greater vignetting in tele position. Vignetting isn't a practical problem, even with several filters mounted between the lens and the hood.

I now consider the very workable Hoya Multi-Angle hood an indispensable addition to my camera bag.

The Short Answer on Filters

C-2100UZ

The C-2100UZ mounts 49 mm filters and accessories directly on its lens thread with no need for a lens tube. Viewfinder obstruction isn't an issue with the electronic TTL viewfinder on this camera. I'd expect the pop-up onboard flash to be fairly immune to shadowing by lens-mounted accessories.

C-20x0Z, C-30x0Z and C-4040Z

IMO, the 49 mm round filter setup detailed above is an excellent solution for all Oly rangefinders, the more so because you're more likely to find all the accessories you want at 49 mm. However, if you're confident that you can find all the gear you need at 43 or 46 mm, the smaller sizes will interfere a bit less with your viewfinder and onboard flash. 

Remember, if you choose to mount 43 mm filters on the CLA-1 lens tube, you'll have to use a 43 mm shim ring on the C-2000Z, C-2020Z, C-3000Z and C-3030Z and also with some filters on the C-x040Z to prevent lens-filter crashes. Test first.

Unless you have a bagful of 55 mm film camera filters you're loathe to replace, I see no good reason to adopt 55 mm as your routine filter size in view of the vast selection of 49 mm filters readily available.

IMO, none of the lens tube alternatives to the CLA-1 are suitable for lens mounting. For that reason alone, I can't recommend any of them.

If viewfinder and onboard flash interference are you main concerns, the 37 mm route causes the very least. It's a viable option for filter mounting and lens armor on the C-20x0Z, C-3040Z and C-4040Z, but filter vignetting makes it a poor choice for the wider-angle C-3000Z and C-3030Z.

For a brief overview of optical filters in general, see the generic dpFWIW article Filter options for digital cameras.

The Great Linear vs. Circular Polarizer Debate

Their ability to mount polarizers for outdoor work is valuable indeed, but the manuals for the C-2100UZ and the Oly digital rangefinders never clarify the practical issue of compatibility with linear polarizers. It turns out that

Linear polarizers work perfectly on Oly rangefinders and the C-2100UZ 

but coming to that conclusion took some doing.

Way back in May, 1999 or thereabouts, Olympus tech support told me by phone that the C-20x0Z requires a circular polarizer. At the time, that made some sense. I'd read that linear polarizers are incompatible with the auto-focus and metering optics found in many current film cameras, so I bought a circular polarizer to be safe.  The tactic worked: My C-2000Z functioned perfectly with a circular polarizer (as did my later C-2020Z), and I duly reported that result here.

The Case for Linear

Fast forward now to March, 2000 and this e-mail from dpFWIW contributor Jay Scott:

I chose a circular polarizer because of your report. But it didn't make sense to me: the CCD itself should be an excellent sensor for both metering and autofocus. Why would they add a beam splitter and another sensor? There also doesn't seem to be any reason to fold the optical path with a mirror.

When my filter arrived I decided to test it. A circular polarizer turned backward is a quarter-wave plate, which does nothing interesting to unpolarized light, followed by a linear polarizer, so light comes out of it linearly polarized. I reversed my circular polarizer and held it in front of the lens to see whether a linearly polarized light be OK. If the filter works the same in both directions, then the camera doesn't need a circular polarizer.

Sure enough, it worked the same both ways. Exposure remained fine as I rotated the polarizer, and test shots showed no focus problem. I think a linear polarizer is enough.

My own subsequent testing with a linear polarizer confirmed Jay's results.

Face It, We're On Our Own

I don't know about you, but I find it harder and harder to know what to believe with regard to complex electronic products these days. The Oly tech support rep I first talked to regarding workable polarizers on the C-2000Z clearly didn't know the answer. He was fully prepared to take a wild stab at it without saying so, but I insisted that he ask someone who really knew. After nearly 10 minutes on hold, he came back on and said that a "development engineer" said "circular".

Go figure. Someone at Olympus has the definitive answer, of course, but how do I access that person, and how do I know for sure when I have?

IMO, that's precisely where user-to-user (U2U) help comes in. Let's face it—we're largely on our own out here, and we'll just have get used to figuring out most of these details for ourselves.

If you have a camera other than a C-2100UZ or an Oly digital rangefinder, you'll just have to decide for yourself which polarizer risk to take—spending too much for a circular polarizer vs. getting potentially unsatisfactory results in unspecified situations with a linear.

As Jay points out, the circular's more likely to work with all your cameras, including your next one.

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

I'm no expert on all of the C-2100UZ and later Oly rangefinder departures from the C-2020Z, but I am aware of the following differences pertinent to this article:

• The slightly wider angle lens found on the C-3000Z and C-3030Z (32 vs. 35 mm at minimum zoom) will slightly exacerbate all the vignetting issues noted above. In particular, these lenses are too wide-angle for the Raynox lens tube. The C-3040Z and C-4040Z return to the 35-105 mm focal lengths of the C-20x0Z.

• With C-x040Z models, some single-ring 43 mm filters will mount safely on the CLA-1, but test first. 

• The C-2100UZ's slightly longer lens (38 vs. 35 mm at minimum zoom) will help with all the vignetting issues noted above.

• The C-2100UZ's electronic TTL viewfinder and pop-up onboard flash eliminate viewfinder blockage and make flash shadowing less likely.

• 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 the C-2100UZ and all Oly digital rangefinders. 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.)

General

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

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

Robert Monaghan's filter article—a wealth of authoritative information and links. His lens flare article is also worthwhile.

UV and Polarizing Filter FAQs—a well-written and informative FAQ section within a site that otherwise appears to be largely under construction.

Suppliers

Camera World—When I purchased most of my auxiliary lenses, filters, adapters and step-up rings here in 1999-2000, I gave them high marks on selection, price, shipping and handling charges, return handling and website, even though their prices could often be beat. I haven't had occasion to deal with them since Ritz camera took over.

The Filter Connection—Lots and lots of filters, filter information and filter-related camera accessories, including lens hoods and multicoated filter cleaners. Better yet, you can even discuss your filter purchases with a real live knowledgeable human here.

The Singh-Ray Gallery—A great place to see a variety of filters in action in the hands of pros. Singh-Ray makes high-end filters, both rounds and squares for the Cokin System P holder.

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.