This article is a wrap up of my documenting my personal experiments with converting compact camera lenses. In my previous articles, I touched on re-mounting lenses on simple 3D printed mounts (Yashica T4) and using complex 3D printed mounts (Olympus Mju II). There has been a 3rd method which I have used and mentioned in my lens modding overview so I’ll end my series of articles on my experiments.

So why stop? Well, in my experiments all I ended up with were a lot of lenses which were sharp in the middle and varying degrees of ‘smeariness’ at the edges. A lot of ‘Lensbaby’ type fun lenses but with not a lot of practical use. OK for portraits and snapshots but not a lot else.

The method of using a surrogate Host lens to rehouse a compact film camera Donor lens is perhaps the most satisfying of the methods I have used so far. By using a host lens, you can usually make use of the host lens’ focusing mechanism, aperture and metal mount. However, there are a specific conditions which the transplant lens which must comply with in order for it to work.

Selection and Preparation

First and foremost, the donor lens needs to have a decent focusing distance whereby it can focus to infinity at a decent distance away from the focusing plane. Lenses for interchangeable lens cameras are all developed to focus to a set distance between the mount of the camera and the camera’s focusing plane, the surface of the camera sensor on digital cameras. This is known as a flange focal distance and varies from manufacturer to manufacturer. With very few exceptions, lenses on film compact cameras were never meant to be interchangeable and need to focus to a very short distance or the camera would hardly be compact.

The donor lens should also be one which achieves focus by moving the entirety of the lens elements as a single unit and not by moving individual elements. It is easy to determine this as these lenses usually have their aperture behind the last element of the lens. More often than not, the aperture will be a combined aperture and shutter mechanism.

The first hurdle which must be overcome is to find a lens which can focus to infinity whilst remaining at least 3mm above the mount of the camera you intend to mount the lens onto. This is a rough estimate and there are ways to mount the lens recessed into the sensor cavity of your camera, but if you do, the image which will be thrown onto your sensor will be at an angle so acute it would make everything but the center of the image, blurry.

Short flange distance poses the biggest challenge to adapting compact film camera lenses in general, as lenses which have short flange distance throw their image onto the focusing plane at very acute angles, regardless of their optical focal length. On film cameras, this is not an issue as the image falls directly onto the film, which is flat. However, digital camera sensors have various transparent layers such as a Infra Red (sometimes with combined anti-aliasing) and focusing detection cells within it’s surface. These elements sit on a thin pane of optical glass, usually not more than 1mm thick,and it is this glass which causes diffraction and edge smearing.

How to determine if your lens can focus to infinity at a suitable distance from the lens mount? The simplest way would be to ‘lens bash’. Find a relatively dust free indoor location with a view which has a view stretching beyond 1km.  Remove the body cap or lens off your camera body and expose the sensor. Keep a dust blower handy. Point the camera body towards the window and turn your camera on. Hold the intended donor lens lens about 2cm away from the lens mount and as centered to your camera sensor as possible. Move the lens slowly back towards the camera sensor whilst looking through the viewfinder or live view of your camera. Use focusing aids like focus peaking if your camera has it. If you can achieve focus on an object over 1km away, at least 3mm before the lens crosses the mount, the lens will have a chance to be successfully transplanted.

The second criteria for transplanting the lens is it’s diameter. If the diameter of the lens is more than 20mm, it cannot be transplanted onto one of the donor lens bodies described below. You can still use the simple mount method or make a complex mount for it using the techniques I have already covered in Project 1 and Project 2.

The first criteria narrows down the field to rangefinder lenses, which usually have a very short flange distance and M42 screw mount lenses* (more on this later)

Being manual focus and mechanically simple are linked. The only autofocus lenses which meet our flange distance requirements above are for modern mirrorless lenses which have complex focusing mechanism which move individual lens elements which immediately disqualify them. Some manual lenses also achieve focus by moving individual elements but regardless of this, the lens will usually focus by moving the main body of the lens away from the camera body when it is at infinity.

At this point, we’ve pretty much narrowed the candidates for host lens to manually focusing rangefinder lenses, the most common of these being those using the Leica M mount and LTM/M39.The last criteria for host lenses is that they have to be cheap and plentiful. Luckily, there are quite a few Soviet era lenses utilizing the LTM/M39 mount which are cheap and in plentiful in supply.

Of these, the Industar 69 (28mm f2.8, M39 mount, half frame) and Industar 50 (50mm f3.5, M39 or M42 mount) come to mind as the Soviets churned them out by the millions. You can pick up individual copies easily for under USD$20 for use as donor lenses, less if you decide to pick up multiple copies as sellers often sell job lots of them. It doesn’t matter if the lens elements on them are damaged, we will be removing them to transplant our compact camera lens on them anyway. Neither does it matter if the focusing is stiff or seized. We will be renovating the lens for our purpose so we can usually fix this provide their is no rust involved.

The only things we need to be mindful of are that these lens barrels are made of aluminum and if this is warped or damaged, we may not be able to focus smoothly. Aside from this, the aperture blades are made of metal which can rust so look out for rusty aperture blades and avoid. If you do end up getting one has rusty aperture blades, you can still make use of the body but remove the aperture.

So which one should you use? The one which I have used the most is the Industar 69 because it has a shorter flange distance than a standard M39 lens, is mechanically simpler and therefore easier to modify and lastly I find that it looks nicer. This lens has a super short flange distance because it was never designed for use on a LTM/M39 camera. It was designed to be a dedicated lens for the, Soviet Chaika half frame camera at a flange distance of 27.5mm, as opposed to the 28.8mm flange distance of a LTM/M39 lens.

I’ve only ever used the Industar 50 for one project which was for a transplanted lens with a 20mm diameter and a long flange distance. This is the only real advantage of the Industar 50, it has a slightly larger lens diameter. For the purpose of describing a lens transplant, I’ll be using the Industar 69, the principle objective steps can be translated to any other donor lens bearing in mind the individual mechanics of the intended host lens.

Step 1: Disassemble lens to core components

First, remove all the lens elements. Remove the lens retaining ring (image 2) using a lens spanner or a rubber lens tool. The retaining ring is a small threaded screw plate which keeps the front lens elements in place. Removing the retaining ring will free the top most lens element and expose a second set of lens elements which are screwed into place with the same thread which the retaining ring screws into. Remove the second set of lens elements using the lens spanner.

Turn the lens over to it’s back and remove the single set of rear lens elements. Use the lens spanner to release the innermost retaining ring, which is attached to the rear element. Be careful not to loosen the outer rings as the outer most ring holds the aperture mechanism in place.

Next, turn the lens to it’s side. There are 3 sets of screws (left image) which screw onto the lens helicoid and hold the lens barrel in place. Remove these screws with a size 0 flat head screwdriver and keep them somewhere safe.

You will now be able to remove the lens barrel completely. Flip the barrel over. There is a single screw post, screwed into the barrel as indicated with the screwdriver in the middle image. Remove this post using a size 2 flat head screwdriver.

Unscrew the center lens helicoid and you will have disassembled the lens to it’s core component. There is an aperture mechanism within the lens helicoid, which is held in by a retaining ring at the rear of the heliciod. I will not disassemble as doing so will release the aperture blades, which are fiddly to reassemble.

Step 2: Clean and Transplant Lens

For the transplanting of the donor lens, we will work extensively with the lens helicoid itself, therefore the first step would be to clean the heliciod. Use IPA or methylated spirit on kitchen towel first, cleaning off as much of the old helicoid grease. Then, finish off using an old microfiber or short piled cloth. You could just use kitchen towels but I find that it does not really get into the grooves as much as cloth. Short or micro pile cloths are recommended as they do not leave behind fibers.

Next, place the donor lens in the cavity where the front elements used to be. The diameter of this cavity, for the Industar 69 is 18.4mm. If your donor lens is significantly smaller in diameter, then I would suggest that you pad out the diameter with either carefully wound tape or 3d print a sleeve to fit around the donor lens. The latter is preferred as it will create a sleeve of consistent width and ensure the lens is centered to the heliciod.

Once the donor lens is secured to the helicoid, replace the lens element retaining ring. Check to see if it obscures the donor lens significantly. If it does, you may want to grind off a little off the center of the retainer. In my experience to date, it is quite unlikely you will need to do so.

Once the donor lens is secured, check that it does not move around within the heliciod cavity. If it does, add more tape or increase the thickness of the 3d printed sleeve. Then, using a, clean, stiff brush apply a thin layer of grease to the helicoid threads. Applying the grease with a stiff brush and in a thin coat is important as too much grease will only only serve to attract dirt at the bottom of the lens mount as any excess it gets pushed down there.

Once you’ve greased the helicoid, clean and re grease the base of the lens, the same way you cleaned and greased the helicoid. You could have done this when you cleaned the heliciod but I recommended cleaning the helicoid first as there is a lot of handling of the helicoid in transplanting the donor lens which could end with a lot mess if the helicoid grease were not removed first. Once everything has been greased, screw the helicoid into the base of the lens and ensure it rotates smoothly. Then, reattach the lens body immediately so that the greased helicoid is not exposed to dust and dirt.

Step 3: Make Mount and Adjust focusing

With the lens facing away from you, twist the focusing ring (lens barrel) anti clockwise until it will not turn any more. Because we have removed the lens focusing limiting post (step 5 of disassembly), the lens barrel should retract into the body by quite a distance. Keep the lens at this minimum distance whilst trying out the different mounting options. This position represents the position the lens should be at infinity and now all you have to do is try out different mounting options and the mounting solution which will enable you to focus to infinity. I’ve listed out a few permutations below to get you started.

Best solution for a naturally functioning lens with adequate flange distance – Host lens (M39) mounted to a M39 to [Your Camera Mount] adapter

Best solution for a naturally functioning lens with short flange distance – Host lens (M39) mounted to a M39 close up adapter to [Your Camera Mount]

Solution for a naturally functioning lens when the flange distance is between adequate and short – Host lens (M39) mounted to a 3d printed adapter to [Your Camera Mount]

Solution for the shorter flange distance, manual focusing with autofocus option – Remove heliciod from the lens base and lens body, print a 3d mount – Lens helicoid (28mm diameter, 1mm pitch) thread to M39 adapter. Mount helicoid as recessed as possible onto the 3d printed adapter and then on to a M39 to Leica M mount adapter. Mount this combination to a Leica M to Sony E mount close focusing adapter for manual focusing or to a Techart LM EA7 Pro mount for autofocus.

Solution for the shortest possible flange distance, awkward focusing – Remove heliciod from the lens base and lens body, print a 3d mount – Lens helicoid (28mm diameter, 1mm pitch) thread to M39 adapter. Mount helicoid as recessed as possible onto the 3d printed adapter and then on to a M39 close up adapter.

Additional modifications (To be added shortly)

Gallery

Conclusions

Of all the methods I’ve used to transplant compact film camera lenses, this has been the most satisfying. If the lens fit all the criteria for this method of transplant, using a donor lens will give you the most natural handling and usable lens of all the methods I’ve tried. However, this is still far away from being a practical lens. What you would use lenses like this and any of the ones I’ve transplanted by other methods for is up to you. Because they weigh next to nothing, I carry one or two around with me quite often just to get the unique rendering of one of my lenses, usually for portraits and the odd street shot. Weather that sounds like something you would do is down to what you shoot. But I believe there’s a place for them, in the same way Lensbaby have created so many fun lenses which would some people would never consider using both others love.

But what about the lens conversions by people like Miyazaki (MS Optical), who also convert lenses from compact film cameras to M mount? Well, firstly, they do not convert all lenses. The ones they convert are converted to M mount by carefully tuning the lenses using optical machines which colimate the lens and detect chromatic aberrations, equipment not easy to get hold of and require in depth knowledge and experience to operate.

This will be the last of my articles regarding transplanting lenses. I have still a few interesting lenses to convert for digital use, like the Konica WaiWai, but whatever I do will be based on the 3 articles I have already written.

I began my experiments with the intention to create a set of “what if” lenses. Highly portable prime lenses with interesting image rendering/characteristics, to supplement my usual photography load out of lenses. Lenses which I could bring about with me when I would not have brought a similar “proper” lens due to weight or space constraints. And, by and large, I’ve managed to do that with one major caveat. They’re not sharp in the edges, for reasons already mentioned, and is the same reason why most vintage ultra wide angle lenses perform poorly when adapted to digital cameras. So, by all means, have a go if you have a defective compact film camera you’re about to sling into the bin. But, if you do, have realistic expectation of the end results.

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