The M42 adapter used on Nikon F can make a huge difference

Started 2 months ago | Discussions thread
petrochemist Veteran Member • Posts: 3,056
Re: The M42 adapter used on Nikon F can make a huge difference

E Dinkla wrote:

petrochemist wrote:

It will make a significant difference yes, but I wouldn't call it a huge difference.

Results from these should be miles better than those with most adapters containing 'corrective optics'. The advantage gained from this adapters will be greater when used with shorter focal lengths.

I'm surprised no-ones made an adapter that fits entirely within the bayonet. this is done regularly for PK adapters - isn't it possible on Nikon F? The screw thread certainly seems to fit inside the bayonet.

For infinity it would still require the M42 lens flange to fall 1mm deeper than where the Nikon camera flange sits. If Markerink's register distances and mount diameter for Nikon F are correct. BTW, mount diameter 44mm could have been measured on the bayonet wings instead of the really open diameter and then there is no 1mm wall thickness available for the adapter. For the Canon EF mount the lists's diameter number is not correct in my experience, 51 instead of the quoted 54mm if the real mount hole is measured. The Nikon camera mount contacts might be in the way too, quite different on a Nikon than on other mounts.

On a Tokina PK lens mount I measure about 44,5mm for it minimum diameter so the actual camera mount hole will be between 45 and 46mm which allows more than 1,5mm wall thickness for the M42 sunken adapter.

Met vriendelijke groet, Ernst
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Yes I've also found a single diameter measurement is not very helpful for bayonet mounts, which effectively have a clear diameter (without the bayonet lugs) & an outer diameter (including the lugs). I've started collecting my own measurements for every mount I have available trying to include lengths of lugs etc. which shows internet data like the table you've supplied isn't very accurate.

My PK mounts are 44.5mm for clear diameter & about 47.4mm across the lugs as well. My measurements for OM mount make the outer diameter around 46.8mm with the clear diameter significantly smaller at 44mm, so it seems the measurements used in the table are not even consistent.

My measurements on F mount lenses suggest a clear diameter of 43mm & a greater diameter of 45.5mm which will be enough to allow a 42mm (outside diameter) thread to fit. A bit tight certainly  but this is required for the existing adapters with <1mm added registration.

I guess with the added depth from the Nikon mount there's no pressing need for reducing adapter depth as focus will typically be too limited anyway.

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