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10-13-2011, 11:37 AM   #1
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Making nikon lens fit better?

I'm trying to get a nikon mount lens to fit and was wondering if anyone knew where the lugs/mount were too large and needed to be cut to fit better? The lens in question just barely starts to go on (maybe just a couple of mm of locking rotation). I know some just fit ok but this one doesn't. Its an ai mount and I have already cut the tabs off the aperture ring.

This is my second attempt at a nikon by the way. The first was a nikon tx adapter. I managed to get about half or more rotation (compared to what a normal pentax lens rotates). I wound up grinding and filing so much off that I'm sure much of it wasn't necessarily and it was a giant pain. I never wound up finishing/fine tuning that one as shortly after I got a k mount t4 adapter. Unfortunately the jaws on my dial calipers are too large to get accurate measurements in all areas. I even went so far as to use layout fluid on the tx mount but I think I was getting some false readings.

So does anyone know where it is off dimension and needs to be cut back?

10-13-2011, 11:41 AM   #2
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I haven't cut any bayonet blades. I find that with my cut-the-aperture-ring-protrusions mod, the Nikon lens fits with about 10-12mm of grip. A PK lens has about 15-18mm. The modded Nikon really is a force-fit. To make it more secure, I cut a small notch in the lens base for the Pentax locking pin to engage. That notch is about 1mm wide and deep and 5-6mm long. Hope this helps.
10-13-2011, 12:15 PM   #3
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I have replaced the nikon bayonet base with an M42 to K mount flanged adaptor

this removes the problem all together
10-13-2011, 12:18 PM   #4
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QuoteOriginally posted by RioRico Quote
I haven't cut any bayonet blades. I find that with my cut-the-aperture-ring-protrusions mod, the Nikon lens fits with about 10-12mm of grip. A PK lens has about 15-18mm. The modded Nikon really is a force-fit. To make it more secure, I cut a small notch in the lens base for the Pentax locking pin to engage. That notch is about 1mm wide and deep and 5-6mm long. Hope this helps.
Mine only goes in a mm or 2. It is a tiny light lens so I would think 5-6mm might be enough (more would be nice). The aperture ring protrusions are already cut off. If I can get it to go a little further I will cut a locking notch and call it good. I actually searched through some of your posts but found you had not modified the luges etc. on any nikons. I also searched through the nikkor and impossible lens threads but didn't find much. I'm thinking I might try something like you do with olympus lugs but just to a small extent and see where it gets me (maybe a small long tapered cut). Thats assuming I don't find more info on where it doesn't clear. I will probably try taking measurements again just to see if I find any new discoveries. Thanks for the input.

10-13-2011, 12:21 PM   #5
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QuoteOriginally posted by Lowell Goudge Quote
I have replaced the nikon bayonet base with an M42 to K mount flanged adaptor

this removes the problem all together
If I only had this idea earlier. That would be great for an old Nikon lens (per-AI 300mm) I had, but sold.
10-13-2011, 12:41 PM   #6
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QuoteOriginally posted by RonHendriks1966 Quote
If I only had this idea earlier. That would be great for an old Nikon lens (per-AI 300mm) I had, but sold.
I bought 5 flanged adaptors for the grand total of $26cdn including shipping. I have used 3 to date, one to convert a miranda belows to K mount, one to convert a Vivitar (AKA Kiron) 24mmF2.0 in nikon mount to K mount manual aperture, and one to convert a kiron 28mmF2 in minolta mount to K mount manual aperture.

Not yet converted any true nikons but I still have 2 adaptors.

I also bought a Nikon to PK optically corrected adaptor (works like a 1.25x teleconverter) to try this out on longer lenses.
10-13-2011, 12:47 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
I have replaced the nikon bayonet base with an M42 to K mount flanged adaptor

this removes the problem all together
Yea I have done that on a few minolta's, an olympus and a canon. I was just hoping for an easy fix. If I trash the original nikon mount trying I can still put on a new mount. I don't think I will ever use an m42 adapter again though (unless the mount has to be that thin). A pk-macro adapter has a flange about twice the thickness and give a lot more leway to cut countersinks for the screw heads (i very much prefer to screw it on instead of gluing if possible). Donor mounts work even better (sometimes). I might use an m42 adapter if I was going to glue it though. I just got another donor mount today. I knew from the dark picture it would be bad but I had no idea how bad.
10-13-2011, 12:54 PM   #8
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QuoteOriginally posted by Lowell Goudge Quote
I also bought a Nikon to PK optically corrected adaptor (works like a 1.25x teleconverter) to try this out on longer lenses.
Did you manage to find one with usable quality glass?

10-13-2011, 01:55 PM   #9
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QuoteOriginally posted by ripit Quote
Did you manage to find one with usable quality glass?
define quality

wide open there is a lot of bleeding and not so sharp but stopped down a little using a 50.1,8 it is not too bad as a 62mm lens
10-13-2011, 02:04 PM   #10
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QuoteOriginally posted by Lowell Goudge Quote
define quality

wide open there is a lot of bleeding and not so sharp but stopped down a little using a 50.1,8 it is not too bad as a 62mm lens
Thats kind of what I figured. There is no reason they couldn't make one as good as any 1.4x teleconverter but I'm guessing there is just not enough market for it. So far as I know, there are just the ebay hong kong/China ones? Was yours an ebay Chinese special?
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