Make Your Own Topcon Mount Adapter

Since I got the Topcor lenses from the camera show, I have fallen in love with these lenses. I do have other Torcor lenses before these ones, but they come in a completely different mount; not the modified Exakta mount, but one that has aperture control on the camera body, a la DKL. This particular mount, like the Exakta, does not provide a secured and tight fit when a lens is mounted; except it's worse than Exakta. The lenses themselves are well made and I have been scratching my head for months on how to mount them to my camera. As far as I know, nobody makes a mount adapter for it.

The other Topcon - very similar to the DKL mount. Aperture control is on the camera body.

Today it dawned on me that I had a broken Topcon body. Why not make an adapter from the original mount? Why didn't I think of that before? Well, in fact, I tried this with a Kodak Reflex with DKL mount, but no cigar. The mount is too intricately intertwined with other parts of the body that it was difficult to separate the mount with the aperture control intact. But, what have I got to lose? It didn't take long before sweet success arrived! The mount is much simpler than the DKL and aperture control stays unaffected after mount is removed from the body.

Gruesome body parts. The mount we want is on the right.

After the mount is removed, I JB Welded a 58-49mm filter ring (don't have a 58-52mm handy) to the rear of the mount, added a 49-52mm step up ring, and mounted the adapter to the very thin focus helicoid. Very unfortunately, I can't use my favourite Yeenon helicoid as the mount is about 2mm too thick. How I wish I had a metal lathe to shaved off these two millimeters. But, this will do in the meantime. The mount adapter is not perfect. the filter ring I glued/welded on is slightly jagged and is not completely flat, cause the left side of the picture to be slightly softer than the right side. I will need to find a better solution for this. It's workable for the time being.

UV Topcor 35mm f3.5 with mount on helicoid. Note the filter rings.

The other Topcors: Mount, 53mm f2, 35mm f3.5, 135mm f4.

Gorgeous, eh?

Size (Sometimes) Does Not Matter

When it comes to photography, the general perception is that bigger is better. This is true for some areas, of course. Bigger lens usually means better low light performance; bigger camera is usually built for pros. But there are a lot of good stuff that come in small packages. Mirrorless cameras and associated lenses (some anyway), pancake lenses, and of course, tiny enlarging lenses.

Schneider-Kreuznach made quite a few very small enlarging lenses and most of them are really good. The 50mm f4 with 4-bladed aperture, 50mm f4.5, and 80mm f5.6 are few of them. When I tried the 80/5.6 on the Canon 5D Mark II, I was very surprised to find out how good it is. Enlarging lenses are optimized for close up use, but even at infinity, the lens is extremely sharp, from corner to corner on full frame. Not too many lenses can make that claim, and let's not forget that tiny enlarging lenses like this are extremely cheap in the used market. Admittedly, the use of this lens is kind of limited. Even though the focal length is good for portrait, but the small maximum aperture makes it unsuitable if you want shallow depth of field. It's not long enough as a telephoto lens, but if you do make use of it, the optical quality is simply amazing, especially when stopped down to around f8 or f11.

If you like to fiddle with old stuff, it might be worth the $5 to pick one up in the flea market, or photo show. This focal length and the 75mm, is about the shortest focal length you can use on the Canon EOS mount and still get infinity focus. Anything shorter can only be used as macro lenses with a bellows on EOS.

Small Wonder next to a penny - Photo taken with 5D II & EF 40mm f2.8 STM. Click for larger.

On the helicoid - Photo taken with 5D II & EF 40mm f2.8 STM. Click for larger.

New BridgePoint Hospital in the evening. Canon 5D II & Schneider Componon 80mm f5.6. 

Silhouette - Canon 5D II & Schneider Componon 80mm f5.6. 

Using a Focusing Helicoid as a Lens Adapter

One of the most annoying problems with old manual focus lenses, is that over time, some of them would fail to attain infinity focus, due to wear or misalignment. The Vivitar 24mm f2.8 TX lens I looked that the other day was an example. The normal course of action is to get it repaired/adjusted, but this could get expensive. Worse, sometimes after a lens repair, it would have other issues like de-centering or other problems. The solution is to use a focusing helicoid in place of a lens adapter.

Helicoid as an adapter on NEX-5N. Click for larger.

My focusing helicoids were originally purchased to be used with odd ball lenses that don't have focusing mechanisms of their own, like enlarging and projection lenses, but they are equally good, and often better, when used as a lens adapter, because a focusing helicoid would make the lens focus closer than its minimum focus distance, but at the same time allows the lens to focus past infinity. The 18-35mm Yeenon helicoid is just slightly thinner than a dedicated NEX to M42 adapter when not extended. This means all M42 lenses mounted on it will focus pass infinity. This solves the problem for lenses that can not focus to infinity by itself.

Allen Garden - NEX-6 & Vivitar 24mm f2.8 TX & Yeenon Helicoid. Click for larger.

Currently, I can only use M42 lenses on the Yeenon Helicoid, as the helicoid has an M42 mount when fitted with a 52mm to 42mm step-down ring. In actual use, there is almost no different than using just a lens adapter, except you focus with the focusing helicoid or the focusing mechanism on the lens. When using the lens for close-ups, you can rack out the focusing on both the helicoid and the lens to simulate the effect of  an extension tube to achieve macro magnification.

So yes, the helicoid is a very flexible tool.

True Love Cafe - NEX-6 & Isco-Gottingen Westagon 50mm f2 & Yeenon Helicoid.

Using Enlarging Lenses with a Focusing Helicoid on Sony NEX

Unlike projection lenses, enlarging lenses have sort of a "standard" mount.  Most of them have a L39, or 39mm thread mount at the rear.  This is a good thing, because L39-M42 adapters are widely available and very cheap.  If the helicoid you have has an M42 mount on both ends, that's all you really need, if the focal length fits your helicoid.  The majority of helicoids on the market have this configuration and it makes a lot of sense.

Here are the reason why I chose something different: the helicoid with a M42 mount, and 52mm opening: 1. Some of my lenses have very large rear openings and 42mm is not large enough to accept the lens, and a 52mm opening gives me a better chance that the lens would fit.  2. I choose the M42 mount because it's interchangeable.  You can buy the helicoid with specific mounts like NEX E-mount, M43 mount, or Canon EF mount, etc.  With an M42 mount, I can use this helicoid on more than one camera system (I have NEX, M43 and EOS mount cameras), by simply screwing the helicoid onto an M42 adapter, or a c-mount adapter with M42 inner threads.  It has its compromises, of course.  For one thing, when used with enlarging lenses, I would need a M42 to 52mm step-down ring.  This would increase the thickness of the helicoid by about 3mm.

The picture below shows how I normally connect the enlarging lens to my camera.  For this particular lens (Rodenstock 50mm f2.8), it works almost perfectly, infinity focus is just slightly beyond infinity.  So, what happens if your enlarging lenses are longer than 50mm?  Very simple, just add 52mm filter rings.  The last picture shows an 80mm enlarging lens with 3 filter rings added to compensate for the longer focal length.  For very long lenses, like 150mm, it's better to buy a longer helicoid, or use extension tubes instead of filter rings.

It maybe worth mentioning that the c-mount to NEX adapter with inner 42mm thread is now hard to find.  So, it maybe be better to buy a helicoid with the mount of the camera you are using it on, instead of an M42 mount.

How the pieces are put together. Click for larger.

All connected.  In real life, the labels won't line up nicely like the picture. Click for larger.

Mounted to the camera.  Click for larger.

With extension rings (filter rings) for longer lenses. Click for larger.

Making the Leitz Varob 5cm f3.5 Focus to Infinity

Someone e-mail me about using the Leitz Varob 5cm f3.5 enlarging lens on the NEX-5, so I thought it might be a good idea to take some pictures of how I make it work on the NEX-5.  Simple, really, but I do need a thin focus helicoid.  I use a cheap Chinese made 17-32mm with M42 mount on the camera side, and a 52mm thread on the lens side.

If you want to know more about the lens, I wrote a bit about it here.
If you want to know more about the 17-32mm focusing helicoid, I wrote about it here.

First thing I did, was to cut the lens barrel closer to the rear element.  This ensures that the rear element is as close to the camera as possible.  Picture below shows the cut as well as the mounted filter ring:

Len Barrel cut close to the rear element.  Click for larger.

The lens is then mounted and glued onto a name ring of some generic lens which has the perfect opening.  This name ring also screws onto the 52mm filter ring:

Adding spacing rings. I need to add a couple of filter rings to make focus close to infinity, instead of way past infinity. Click for larger size.

Ready to be used with the 17-31mm helicoid. Click for larger size.

Screw the lens onto the focusing helicoid, and voila!  We are ready to take pictures!

Lens on helicoid. Click for larger size.

Lens on camera. Click for larger size.

They Are Here!

I ordered a pair of very thin focusing helicoids from Rainbow Imaging and it arrived today.  Very fast shipping from Hong Kong (they didn't have the 52-42mm version that I wanted in the US location).  However, I knew I made a mistake even before mounting the lens on the 12-17mm.  It's simply too limited.  The focusing range is very short, and is very tight.  The Taylor-Hobson Ortal 75mm f2 could focus to infinity, but  could not focus very close.  But, the 17-31mm works near perfectly, except that it was just a hair shy of attaining infinity focus.  Not really a problem, though, as after I sanded the C-NEX mount a bit, it now can focus to infinity without problem.

I want to say a few words about the quality of these two helicoids.  The workmanship leaves a lot to be desired. The 12-17mm is way too tight to focus.  The 17-31mm has either sand or metal grounds inside the focusing mechanism.  I can feel the grinding when turning the focusing ring.  It's also not very smooth.  My Vivitar 2X macro focusing helicoid is light years better.  Too bad it's just not thin enough.  In any case, it allows me to use the Ortal 75mm f2 lens.

How well does it work?  It works, but the lens is just so heavy.  I kept turning the aperture ring on the front when trying to focus, instead of the focusing ring near the mount.  If you have some good glass worth putting on your camera, but without the focusing ring, this helicoid may be worth it.  I know I will make good use of it as I have so many weird stuff to try it on.

Took the lens out this evening and after dropping Ryan in the music class, I walked around and took some night pictures.  Too bad it was so windy and cold.  My hands were practically frozen after 15 minutes without gloves. The strong wind made sharp pictures almost impossible using a flimsy and tiny tripod, but a few turned out ok.  I really like this lens.  Will update when I get a chance to use it more.

DVP at Night -- NEX-5 & Taylor-Hobson Ortal 75mm f2. Click to see larger.