The Nikon F-Mount has one of the longest flange distance between the lens and the film/sensor plane, and for this reason, very few lenses can be adapted to Nikon with infinity focus. Whereas Canon, having a shorter lens register, enjoys the capability to adapt and use other lenses, such as Nikon, Leica, OM, M42, etc., and with mirrorless cameras, even more lenses can be adapted. That does not mean Nikon users can not have fun and enjoy manual focus lenses from other lens makers.
In order to use lenses on Nikon cameras, the lens must have very long flange distance, at least a bit longer than 46.50mm. Most medium format lenses are quite a bit longer than this, as in the case of the Wollensak 85mm f3.5, a lens from a Ciro-Flex 6×6 TLR. I shared my experience few days ago, in a post here, and this post will show you how to mount the lens on the Nikon camera, all without any tools.
Here is what you need. If you don’t have the parts you need, the items are linked to either eBay or Amazon and you can purchase them. Most are very inexpensive, with the exception of the helicoid, which costs a bit more, but it’s a reusable item. You can use it with other lenses later on:
- Nikon to M42 short flange adapter — This can be either 1mm or even 2mm in thickness, but I would buy a thinner one as you may need it for other projects that call for thinner adapter.
- 17-31mm M42-M42 Focus Helicoid (Cheap, Better) — This helicoid allows relatively close focus (about 0.5-0.7 meter), and yet able to focus the lens to infinity
- 42mm-52mm step-up ring — Note that the 42mm thread on this adapter is not M42 (1mm pitch), but has a 0.75mm pitch used on most lens filters. It still works, but won’t be able to screw all the way in, but is secured enough.
- 52mm-30mm step-down ring — The rear mount of the Wollensak lens has a 30mm thread, but unfortunately, not the same pitch as this step-down ring. Again, it still works and secured enough.
- Wollensak 85mm f3.5 — A lot of Ciro-Flex TLRs have a non-Velostigmat version of this lens. They should be identical physically.
To mount lens, first you need to remove it from the camera. This is probably the hardest part, as the chamber is very deep and most spanner wrenches won’t work. I cut a piece of cabinet scrape steel plate that’s just wide enough to fit in the slot of the lens retention ring, with about an inch in height. I use a pliers to turn steel plate counterclockwise to loosen and unscrew the retention ring. The lens will come off once the retention ring is off.
For this project, you don’t need the retention ring, as the rear of the lens can screw onto the 52mm-30mm step-down ring. If you really want it secured, you can enlarge the inner hole of the step-down ring slightly larger so that it is just big enough to slide in, and use the retention ring to secure it. However, this changes the distance between the lens and the camera, and you will also need to remove the locking pin on the lens so that the step-down ring can seat flat.
- Screw the lens onto the 52mm-30mm step-down ring. It will only go in a few turns, because the pitch between the two is not exactly the same, but it will be tight and very secured. Do not use excessive force.
- Now screw the 42mm-52mm step-up ring onto the 52mm-30mm step-down ring, like the picture below
- Screw on the 17-31mm focus helicoid onto the 42mm-52mm step-up ring, and attach the M42-Nikon F-Mount adapter to the focus helcioid. It should look like the picture below:
With this setup, the lens focuses slightly pass infinity, which should be fine, and still focuses pretty close. To get exact infinity focus, you will have to invest in a lathe to machine the adapter to the precision required.
All you have to do now, is the mount the lens on your Nikon camera, and shoot. One word of caution. Unlike pretty much everyone else, Nikon chooses to castrate the basic feature of metering when manual focus lenses are mounted on the digital camera in the entry level DSLRs. Full frame, and D7xxx series and most prosumer models retain full metering capabilities, only the very entry level ones do not. Please check with your camera to ensure that it can meter with manual focus lenses, otherwise you will have to manually set the shutter speed/aperture/ISO to obtain proper exposure. Most of all, have fun putting it together and using it!