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Discovering and Making Images with the Leica 33mm Stemar Stereo Lens

This is a copy of an article that has been submitted for publication in Stereo world magazine

      Discovering and making images with the Leica 33mm f3.5 Stemar Stereo Lens.  After a career in the (used) photographic equipment retail business, I keep busy in retirement pursuing my primary interests, which are travel and personal photography.  A few months ago, while visiting a Leica Dealer in Geneva, Switzerland I was able to examine and study a Leica Stemar Stereo lens set for the first time.  During the last great heyday of stereo photography, I owned a small specialty camera store in Chicago.  Among the things my store was known for was that it was a reliable source for high-quality re-conditioned 3-D cameras and other hard-to-find used collectibles such as vintage Leica (and large format).  Since the 1980’s I have been an active shooter of many different kinds of stereo cameras.   Having had access to my store’s inventory, I think I have made images with most of the popular Realist Format/35mm 3-D cameras that were ever mass produced.  One of the 3-D rarities that had always eluded me was the Leica 33mm f/3.5 Stemar Stereo lens set. There are some easy-to-understand reasons why “back in the day”, I never got near one.  They are fairly rare (only about 1500 sets were made between 1954 and 1957), and few ever came to market. Also, at the time, the Stemar set was prohibitively expensive.  Flash forward to today.  I am noticing a trend with some of the most historically desirable and hard-to-find photographic collectibles.  Many of the most difficult to find items, and the rarest of the rare are now more readily available, and at much lower prices.  This too, seems to be the case with the Leica Stemar lens sets.  Currently, there are quite a number of them on the market (at the end of the article, I will list a few current sources for these lenses).  While still not cheap, recent sales have been at a fraction of what the lenses used to sell for.

     While examining the Stemar at the dealer in Switzerland (and later at Tamarkin’s in Chicago), I was immediately awed by how simple and elegant the whole “kit” is.  The jewellike lens comes with finely made front and rear caps, an intricately made sunshade (for use when not using the prism), a specific bright-line finder that mirrors the vertical format of a full frame 35mm exposure cut in half, and a prism accessory that when bayoneted to the front of the Stemar gives you the lens separation needed for distance (Hyper) stereo separation.  All of the pieces come in a well-made leather case, with each component fitting into its own suede leather compartment.  The lens was ostensibly made in two variants: Leica M bayonet mount and Leica L39 screw mount.  The reality is, they are both, the same lens.  If you find a screw mount version, you only need to find a Leica screw mount adapter to easily adapt the lens to whatever digital camera you are using (even Leica M).  Or, if you find a Leica M version of the lens, you can have your camera repair person remove the M ring so the lens can easily be adapted to non-Leica cameras. The horizontal alignment of the lens is fairly critical.  In the instructions that came with the lens, Leica concisely described how to loosen four screws (two on the side and two on the front), and with the prism installed on the front of the lens and the lens installed on your camera body, you gently rotate the lens using the focus saddle (locked at infinity) till the prism is parallel to the base of your camera and then you re-tighten the four screws.  Pretty easy and straightforward.  This is a well-made and well-designed kit.

     When you discuss what makes one 3-D   camera “better” than the other it usually all goes back to the lens.  In the hierarchy of Realist cameras, folks talk about the three-element f/3.5 over the benefits of the four-element f/2.8 variants.  The basic four-element lens, originally made by Zeiss and called the Tessar, is the same design used by most of the highest-quality 3-D cameras of the “golden era”.  In fact, in minor variants, the Tessar-type lens is the most often copied, and mass-produced lens design in history.  A Leica Elmar is a derivative of a Zeiss Tessar. Stereo Elmar = Stemar.  Manufactured by Leitz at their plant in Midland Canada, the lenses have a nice coating to cut down on flare and facilitate excellent color rendition.  The lenses are only f/3.5.  But, with the restraints of fitting both lenses side by side in the same lens barrel, this was probably the largest/fastest they could make it.  Also, the lens only stops down to f/11.  This is probably a good thing.  Many Tessar-type lenses tend to lose critical sharpness if you stop down too far.  Without the prism attachment, I produced images with fairly even exposures across most of the range.  With the prism unit attached, exposure needs to be increased ½ stop.  At larger apertures I did notice some minor vignetting in the corners (especially in sky tones).  However, stopping the lens down to f/8 once again rendered fairly even exposures.  Overall, I would state that the images made with these matched 33mm Elmar lenses produced a 3-D photograph whose quality is on par with the best I have ever used.

     In 1974, when I trained at the United States Navy School of Photography in Pensacola, Florida, we were trained to do journalistic photography using Leica M cameras and lenses.  Leica has always had a reputation for making ultra high-quality cameras and lenses; that also happen to be somewhat more expensive than most other manufacturers of similar equipment. Most die-hard Leica users will argue that the quality justifies the extra expense.  For many years, I have been using Leica cameras and lenses for my non-3D/Non-Large Format Photography.  Starting over a decade ago I switched from film to full-frame Leica M Digital camera bodies.  Unlike many of the folks whose posts you see online, I do not miss 35mm film.  The current generation full frame digital cameras (All brands, not just Leica) make amazing images.  The digital sensors have a wider dynamic range and, in most cases, less noise/grain than even the finest grain films of yesteryear.  An added bonus is the elimination of inconsistency in film processing, and color balance differences of individual batches of film.  That being said I do miss my transparencies.  Viewing 3-D images with a Red Dot viewer or projected on a silver screen is a visceral experience.   However, the 3-D images made with the Stemar lens on a digital camera and processed to be viewed on a screen (Phone or Monitor), or printed to be viewed with a stereopticon are pretty darn nice!  Getting the images ready to view takes a little work.  Before I discuss that process, I will discuss using/shooting the lens on a modern digital Leica M camera Body.

     The Stemar lens bayonets onto the body like any other M Mount lens.  Focusing can be accomplished by using the coupled rangefinder, peak focus assist (either the rear display or EVF) in live view, or just use zone focusing by stopping the lens down and setting a mid-distance.  Being a slightly shorter focal length, the lenses have a pretty good depth of field when stopped down.  The Stemar can be shot two-ways.  For distances 3 ½ feet to 10 feet, (Leica says the prism is not required), in fact, from experience, I can tell you that when working close, the images made without the prism look more “natural”.  For distances of 10 feet or more, you need to mount the prism accessory to the front of the lens via a pretty hefty/robust bayonet with about a 1/8th turn and a crisp/positive lock.  The front of the prism is protected by a flip-down heavy-duty cover that securely clips shut when you are not taking pictures.  Because of the deep divider between the two lenses that helps to split the single exposure into two, the camara’s light metering system will only work when you are in live view mode and the sensor is exposed.  Using live view to manually set the exposure, or using a handheld meter is always an option.  However, using the auto exposure function in live view mode works well and provides accurate exposures.  A bonus is that when composing on the back of the camera in live view or with the electronic viewfinder, it is easy to see when your camera is perfectly parallel, and the two images are even with each other. Note: there are a couple of variations in the screw mount to M adapters that Leica made.  The big difference is that one version has a bit of a scallop removed from the outer edge of the adaptor ring in the general vicinity of where the ring covers the 6-bit sensor on the mounting surface of the camera body.  In lower-light situations I never had issues with the live view working all the time.  In bright-light situations, I found a lens cleaning cloth wrapped around my index finger cradling the underside of the lens which did the trick of getting the system back online.  It sounds a little “fiddly”.  However, in reality it is no big deal.  In some situations, I did use a meter to manually set my exposure.  I would use the rangefinder to focus the camera and the bright-line finder to compose my images.  The bright-line finder is precise, and accurately frames the shot, and as a bonus, it does have hash marks to help you compensate for parallax when shooting up close.  I hope I did not make working with the Stemar sound too complicated. The reality is that shooting with the lens is reasonably straight forward.  It only took me a few sessions to get comfortable with it.  My biggest obstacle was just getting over the fact that I had had one to shoot with.  I can still remember when a Stemar in mint condition was worth the price of a new car.  Shooting with the lens is just a little more straightforward, than working with the images and bringing them to a proper viewing state.

     Back in the day, when you shot 35mm slides with a Stemar lens, you would view them by placing the image in a special Leica viewer or projecting the slide with a purpose-made stereo lens for a projector.  The nature of 3-D photography is that when you take a film strip and turn it right side up so to properly view an image, the left image is on the right, and the right image is on the left.  The special Leica 3-D slide viewer transposed the images so that you could properly image in stereo.  The raw image as you open it up in Photoshop has the left and right images on the reverse of where they need to be so that the image can be viewed appropriately.   Post-production requires just a little bit of trickery that is not too difficult.

     I start by working with the image and doing the basic “fixes” (both images simultaneously).  Depending on lighting conditions, sometimes I use a little dehaze/clarity in Photoshop Raw.  I also tweak the contrast, color, shadows, and highlights and sometimes crop the top and or bottom as I think it makes sense.  For preparing stereo cards or files that can be shared you only need 1150 pixels of image height.  My raw files start at 5184 pixels.  Therefore, I can crop the top and, or bottom of the image if I want to make it a little bit more “square-like”.   I must substantially reduce the image size before cutting and pasting the images onto the new file.  I have set a new custom template in Photoshop that is 3 ½” x7” and 350ppi.  I have named it Stereo.  I hit create new, open the blank white file, and then I turn to my processed image which has been re-sized to 1150 pixels tall.  I use the Rectangular Marquee Tool to select and copy the left image.  I go to my blank new image, and I paste the left image using the freeform tool and gridlines to move it to the proper place on the right-hand side of the new image.  I repeat the process to select the right-hand image and move it to the left side of the new image.  Merge the layers down, save a copy as .jpg to a folder, and print the image onto a 3 ½’ x7” piece of photo paper (my preference is semi-gloss), and you are done.  One can then email the images to friends for viewing with a basic hand-held viewer (Like the Owl) on their hand-held device.

     A last thought on printing and the image placement on the print.  I like keeping a little bit of blank space between the two images.  That being said, try to set the side-to-side distance between points on the two images to about 65-70mm.  If the two images get too far apart on the print, viewing can be more difficult.

     Although the Leica Stemar lens set now sells for a fraction of what it used to cost, it is still not inexpensive.  There are a lot of these lenses currently being offered for sale on eBay.  Some of them are accurately described as having a little haze in the lenses.  This is normal for a lens more than half a century in age. Lenses need periodic servicing and cleaning.  Fortunately, the Stemar is not a complicated lens.  Most good camera repair technicians should be able to service the lens without it costing an arm and a leg.  There were only so many of these made.  I am now a believer.  If you have the means, I urge you to track one of these sets down and start shooting.