Nerd alert!
I am too heavily invested into Nikon optics to consider jumping ship to play with other legacy lenses, and indeed there are still many optics within Nikon that I am yet to try... but that's a topic for another day.
My interest was pipped when I saw Leitax, sometime back, but lacked the skill then, and the finances to deal with buying Leica R or Contax CY lenses. After about 6 months of stripping lenses, under the kind tutorship of Rick Ho, I feel that I am ready to tackle this, without going to Leica or Contax.
From
https://en.wikipedia.org/wiki/Flange_focal_distance some flange distances are taken:
Mount : Flange Focal Distance : Variance wrt Nikon F mount
Canon FD : 42.00mm : -4.60mm
Minolta SR : 43.50mm: -3.00mm
M42 : 45.46mm : -1mm (roughly)
Pentax K : 45.46mm : -1mm (roughly)
Contax CY : 45.50mm : -1mm
Olympus OM : 46.00mm : -0.5mm
Nikon F : 46.50mm : 0mm
Leica R : 47.00 : +1mm
So no surprises that Leica R is easier to convert, and perhaps -0.5mm for OM is not too bad as well. Clearly Leitax has conversion mounts for Leica R and Olympus OM, but there is also one for Contax CY as well! That is -1mm. It follows that perhaps Pentax K and M42 may be converted as well, or so I postulate.
I did see a webpage where someone adapted an FD lens to Ai, but that required heroic acts, not something a faint heart like mine would want to do.
By searching on the net for suitable conversion mounts, I found mounts for Leica R, and Olympus OM from sources in China (I did find CY-Ai conversion mount but when I wanted to order it disappeared - I have a Yashica ML 50 that could be prime conversion toy). And I have 2 such OM conversion mount (not believing I can afford a Leica R lens anytime soon), but alas I have no OM lens to experiment with (I will search for such a lens or two when I meet Rick in late Oct in Tokyo).
In our local equivalent of e flea mart, I found a Rikenon lens (Pentax K mount) converted to Nikon (
https://carousell.com/p/22647891/?rank=1):
This looks like a case of using a cheap M42-Ai mount adapter, drill the holes, trim the screws by 1mm (or find shorter screws), remove the PK mount, remove the aperture stop-down coupling, and if needed pad the mount up to make the 45.46mm PK flange distance, and hopefully the 0.04mm is enough to clear the mirror! I am assuming the Leitax CY conversion for flange distance 45.50mm is definitely sufficient.
Perusal of Chinese internet pages showed that there are a couple of people that had done similar conversion via the M42-Ai adapter drill-and-remove methods.
So, right now for me it is academic, until November that is, when I:
- take delivery of a couple of M42-Ai adapters
- buy a couple of OM lenses
- buy a couple of M42 lenses
I have a Rikenon XR 50mm f/2 that is prime to be the first experimental subject of mount conversion.
Better optical performance is not a consideration, the nerdy part of wanting to try this out is the main reason. And perhaps along the way to convert a Helios to Ai mount.
I like to ask for your considered opinion, and whether there are loop holes in my reasoning above, and for Dr Lens' opinion especially, on how to estimate or measure if the adapted lens will clear the mirror and the aperture stop-down actuation mechanism! My current assumption is that with the aperture actuation lever on the lens removed, so long as there is nothing protruding beyond the lens mount it should work!
Good (nerdy) day to all!
Thanks for reading. Do feel free to tell me I am stupid, but please give reasons.
