Lens Hacking Made Easy: Praktica M60 26mm f/5.6 to Leica Thread Mount

Time for another edition of Lens Hacking Made Easy. Our subject this time is a basic one, the 26mm f/5.6 lens originally installed in the Praktica M60, a very simple consumer point-and-shoot. What makes it a good choice for hacking into a Leica Thread Mount? Well, at 26mm it’s quite wide, which is a bit unusual, and as the manufacturer noted it’s a “Glass Lens,” three elements in three groups in fact. I’ll grant you, that’s not the most compelling argument, but it’s a start.

What really makes this project appealing is that the finished product would be incredibly small. Part of the inspiration were the MS Optical series of Perar Super-Triplets, tiny limited production lenses that are not much bigger than body caps; while I had no delusions that this lens would come anywhere close to the quality of the MS Optical unit, and certainly would not have the same flexibility, it could at least be just as compact.

As an extra bonus, the simplicity of the donor camera makes the conversion particularly easy. You see, the M60 is a fixed-focus camera, so there’s no need to covert the focusing mechanism over into the new mount. Being such a wide lens, it was simple to set a hyperfocal distance of 4m, which means that everything from 2m to infinity should be in focus.

What about at wide apertures, you ask? Not a problem, as the M60 lens is an f/5.6. I wasn’t able to find any information from the manufacturer about this, but I have a suspicion that it was in fact a fixed aperture as well. Whether it was or not, I decided to simply build it as a fixed f/5.6 lens with no aperture mechanism at all. If used with film you need to be a bit careful about matching film to lighting conditions, but other than that it works just fine; with digital of course it’s even easier to manage by adjusting ISO.

So essentially what we’re looking at here is simply building a solid mount for a very small piece of glass that puts it at the correct distance from the film plane. It’s not a particularly complicated task.

The starting point is a Leica Thread Mount body cap, easily and cheaply available on ebay for a few dollars. All that needs to be done is to drill a hole of the appropriate size, then devise a way to mount the lens at the correct depth. Drilling the hole was accomplished with the help of a purpose-built jig to hold the body cap in place. I used stepped drill bits, which have the added advantage of being self-chamfering, leaving a nice clean edge on the hole.

Once the hole was drilled, it was time to mount the lens. Whenever possible, I prefer to use readily available materials. In this case, I chose some metric copper washers I had on my workbench. The holes fit the lens perfectly. I kept the basic mount from the M60, a simple plate into which the lens unit threads. This allowed easy fine tuning of the lens position via the fine threads, as well as providing a stable plate to rest on the washer stack. I determined that I needed four washers to get the proper depth, so I epoxied them together, then epoxied the stack to the back of the body cap.

Once the epoxy was dry, it was a simple matter of temporarily placing the lens in the mount and fine-tuning the focus. My Fuji X-E1 was pressed into duty for the task. A few tweaks and I had things dialed in. Once everything was finalized, I masked off the face of the assembly and painted the back surfaces and the lens recess flat black. After the paint dried I placed the lens into the mount and secured it with a couple drops of white glue; I prefer this for such applications, as it’s easily removed if something goes wrong, but it’s strong enough for non-load-bearing applications and will not adversely affect any types of materials.

Basic testing was done with the Fuji for convenience, but the real test was going to be on film. I already knew there would be some compromises. A quick check of images online showed that the M60 tended to vignette a fair bit, so I figured that would carry over into my conversion, perhaps even moreso, as the lens ended up quite deep in the mount. I had no illusions about image quality either – this was a basic consumer point-and-shoot probably made (as far as I can tell – there were no markings on the camera) in the waning days of East Germany (EDIT: a sharp-eyed reader over at APUG noted that the Praktica M60 bore considerable resemblance to a Fujifilm Clearshot S, and after a quick check around the interweb I’m inclined to agree, so my previous speculation about its origins were quite incorrect) ; I was not expecting much in the way of sharpness and fine detail, especially out toward the corners, where distortion was bound to be fairly pronounced. I screwed it onto one of the Leica IIIcs and loaded up a short roll of FP4+ to see just what I was dealing with.

Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)
Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)

You can make your own judgments from the photos (I suggest clicking for a larger view), but all things considered, it exceeded my expectations. I expected the vignetting to be a lot worse. Center sharpness isn’t too bad, and the softness in the corners is limited to the farthest recesses. There’s some distortion, both the expected distortion of perspective of a wide angle lens and some due to the aberrations in the lens, but it’s not so pronounced as to distract from the overall image. Contrast is pretty good, probably aided by the fact that the depth of the new mount acts as a substantial lens hood.

Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)
Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)

Using it is almost too easy. Mounted on a fully manual camera, I had to resist the automatic reflex to check the lens settings before shooting. While I do have an appropriate external viewfinder, I decided to see how shooting without it worked. Framing obviously involved some guesswork, but with a lens this wide it’s hard to miss too badly; the second shot was taken from the hip without framing at all. It really does turn the camera into a very small point-and-shoot.

Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)
Leica IIIc, Praktica M60 26mm f/5.6 lens hack, Ilford FP4+ in Caffenol C-H(RS)

So there it is, another slightly misguided, perhaps rather pointless lens hacking project brought to completion. It’s not as if I needed to do this, but somehow the challenge of doing it was appealing. I haven’t tried it with color film yet, so I’m not sure what to expect there, but with black-and-white it’s good enough to play with. It’s a nice oddball to throw on the camera every now and again when the mood strikes, and the compactness of it does make it awfully handy.

Lens Hacking Made Easy…Not

Despite the encouraging tone of your fourth grade teacher, trust me, having an active imagination is a curse. As an adult it’s far worse, since you have more control over your own actions and more time to develop bad ideas. In spite of the countless other examples I could bring up, I will confine my comments to one particular result of my over-active brain, a little lens hacking project that I recently undertook.

This started with my acquisition some time ago of an Industar I-50 50/3.5 collapsible LTM lens. It came along with another lens (my FED 50) at no cost. The reasons for this lens being essentially free are simple: one, it had a front element that looked like it had gone ten rounds with a belt sander, and two, it had had its chrome stripped, fake Leitz Elmar markings added, and was a gaudy highly polished brass mess. It probably came from one of those ridiculous ebay fake Leicas that they seem to churn out in Russia these days.

I kept it thinking that one day I would either try to polish up the front element or do something with the mount. The first didn’t happen because I have plenty of other non-abraded, non-pimped-out LTM 50s that work just fine. As the misery of this past winter became more severe, my mind started to think about what I could jam into the mount and actually make work. I’m not sure in what order the various points of inspiration came, but the two main contributors were the Leitz Elmar 35/3.5 and the Nikon L35AF.

The former is a super compact lens that looks perfect on a Barnack Leica. Having recently found myself in possession of such a camera, and not wanting to shell out big money for the scarce wide Elmar, I started to think about building a 35mm lens out of the old I-50. I figured that any number of cheap point-and-shoot cameras could be used to supply the optics, which I would then adapt to the Industar, retaining the aperture setup, the focusing helicoid, and the mount.

But what old compact should go under the knife to give up its precious lens for this project? My requirements were simple: good and cheap. Something produced in large numbers, with a reasonably high quality lens, that would hopefully be easy to take apart and modify. I started investigating the options and fairly soon stumbled across an article about the lens on the Nikon L35AF. Now, you know perfectly well that the internet is full of articles about lenses, many written by people whose sole qualification for providing in-depth technical analysis is that they bought the lens last week and are trying to justify their purchase.

But this article was different – it was written by Nikon engineers and published on Nikon’s own site. What it described was a rather unique 35mm lens: a modified Sonnar formula rather than the more usual Tessar, well-corrected, with high resolution and fairly modern contrast levels. Nikon made a considerable effort to raise the bar for optical quality in compact consumer cameras and appears to have succeeded, judging by the high regard in which the L35AF – also known as “Pikaichi,” or “top notch” in Japanese – is still held.

A quick ebay search turned up plenty of examples. I selected a cheap one that looked used but not abused and apparently didn’t work. No reason to hack up a working camera when a broken one will do just fine. I had it in hand in a week and began stripping it down. This turned out to be quite easy, and very soon the lens assembly was out. I already had the I-50 taken apart, so the process of engineering the mating of the two into an unnatural creation of my own design began.

The optics of the Nikon are entirely contained in a small plastic housing with the helicoid cast into the outer surface and a wide collar with holes to engage the autofocus actuating mechanism. This was very handy, as it meant that I didn’t have to mess around with multiple pieces, and especially with keeping them properly aligned and spaced. The collar was far too wide, but I didn’t need it, so out came the Dremel and off it came. The remaining portion was of a somewhat smaller diameter than the space in the I-50 barrel, so the gap would need filling somehow.

The major engineering challenge was always going to be getting the optical block the right distance from the film plane to achieve infinity focus. In order to make the Industar body work, the barrel was going to have to be cut off and fixed in the collapsed position; this mimicked the look of the Elmar 35 almost exactly. Doing this proved insufficient; even placed as close to the aperture as possible, the glass was too far away, making infinity focus impossible. I had to grind down both the top surface of the mount and the edge of the front plate to get them lower in the body. Fine-tuning would be done later as needed with shims.

Once I got the barrel positioned deep enough, I had to find a way to secure it to the mount, as well as to secure the optical block to the barrel. Related to this was the need to keep the optics as close to perfectly centered as possible. I decided to try something non-destructive first, which turned out to be a fairly good solution: O-rings. A series of different sized rings hold the barrel quite securely in the mount, restricting movement yet easily removed (this is important when hacking together a lens, as you will be assembling and disassembling a lot). The optical block was trickier, as the O-ring had to be snug enough to hold the glass firmly in place, yet also allow it to reach full depth, and at the same time not restrict the turning of the aperture ring. Eventually, after much experimentation, I figured out the right size for this as well.

I was a bit concerned about indexing the aperture, but through a remarkable bit of good luck, the measured apertures calculated out to be close enough to correct (within a few tenths of a millimeter) to simply use the index marks on the lens face (in the Continental scale, 3.5 to 18) to correspond to the modern system from 2.8 to 16. The aperture is directly behind the glass, which is exactly the same setup as the L35AF. It’s also a nice round aperture, unlike the trapezoidal two-blade arrangement on the Nikon.

Leica IIIc, Nikon 35/2.8 Frankenstein, Ilford FP4+ in Caffenol C-H(RS)
Leica IIIc, Nikon 35/2.8 Frankenstein, Ilford FP4+ in Caffenol C-H(RS)

Countless hours of fiddling and fine-tuning were required to get things right (or at least good enough), especially infinity focus. There is really no margin for error with this – it’s either right or it isn’t. My Fuji X-E1 with LTM adapter proved indispensable in this; without a digital camera to check the focus, I would have been using a ground glass, which would have been far more time-consuming and in all likelihood less precise, given the small size of a 35mm film gate.

There are still a few issues. Foremost among these is that the rangefinder coupling of the Industar lens is completely wrong for the wider Nikon optics. I knew this going in, and resolved that this was going to be a scale-focus project from the get-go. As long as infinity was at the right place, everything else could be determined and marked. For starters I established focal points for 1, 2, and 3 meters and marked those. More precision would be nice, but it really isn’t necessary – most of my use will be zone-focused for street photography, set at 3m and moderate aperture.

Leica IIIc, Nikon 35/2.8 Frankenstein, Ilford FP4+ in Caffenol C-H(RS)
Leica IIIc, Nikon 35/2.8 Frankenstein, Ilford FP4+ in Caffenol C-H(RS)

The beauty of the the thing is its size. It’s just tiny, barely bigger than a body cap. The ergonomics are dated, but that’s true of most of my lenses. The glass is recessed well into the barrel, so there’s really no need for a lens hood. True, you need an external viewfinder with most cameras, but even so the whole thing fits easily into a pocket.

I’m not sure I’m entirely happy with the black finish I applied (I wasn’t leaving it polished brass); I may strip it down and try a different color. I also have an idea about adding click stops for the most-used focus settings, at least for 3m. If I can work that out it would be the perfect time to refinish.


Why does this feel like cheating?

I am not a skilled enough photographer to notice while composing a shot all the little background factors that can have an inordinately large effect on the quality of the final image. I often fixate on the main subject when shooting, as I suppose is natural, only to discover after the film is developed that something in the background is distracting. This can be quite irritating.

Back in the days of wet printing, a photographer with the requisite skills could make adjustments in the darkroom. In this (ahem…) wonderful modern age in which we live, there is an easier solution: post-processing. All the old darkroom tricks can be replicated digitally, without all those messy chemicals. Yes, it can be time-consuming, but it can work really well (if you know what you’re doing; I just pretend most of the time). Somehow it always feels like cheating, though.

A single example of how a relatively simple change to a photo makes a big difference in its overall impact may help to illustrate just why you’d want to spend time doing this. You may recall this photo (well, a version of it) from my earlier post on my own mostly vain attempts at street photography:

FED-2 w/ Industar-26, Tri-X
FED-2 w/ Industar-26, Tri-X

The image above is the original photo. The main problem should be readily apparent: the left side of the silhouette of the woman in white is lost in the brightly lit light color of the jacket worn by the man behind her, which also blends into the white building beyond. When I took the shot, the woman’s white outfit stood out; in the photo, its impact is far less because it is not distinct from the background.

Fortunately, this is a relatively simple problem to correct. The man’s jacket is a defined object that can be altered somewhat to make it less noticeable, and thus help to isolate the foreground shape of the woman in white. This will also help to separate the man from the similarly-colored building, creating a greater feeling of depth.

After scanning and loading the photo in GIMP, all I did was added a couple of layers (one for the man’s jacket and one for his hat and the bright spot on his leg; one would have sufficed, but I wanted slightly different shades for the two pieces of clothing), and used a soft-edged brush to cover the areas in question in black. I then shifted the layer type to “grain merge” (whatever that means) and reduced the opacity until I got the sort of effect I wanted. No other changes were made. Then the layers were merged and the image saved as a JPEG.

FED-2 w/ Industar-26, Tri-X
FED-2 w/ Industar-26, Tri-X

The result is an image much closer to the way the scene felt when I shot it. The woman in white stands out, while the man in the jacket fades into the background. Now the viewer’s eye is drawn the same way mine was when I took the photo. It’s a relatively minor change, it does nothing to materially alter the nature or composition of the image, but it makes a big difference in the final result. This sort of adjustment is not going to make a poor photo into a great one, but it can help to create a bit more impact in pictures that might otherwise be relegated to frustrating mediocrity.

But it still feels like cheating.