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

Started 3 months ago | Discussions thread
Sittatunga Senior Member • Posts: 3,155
Re: The M42 adapter used on Nikon F can make a huge difference
1

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
No photographer's gear list is complete without the printer mentioned !

I've just checked my Nikon SLR in an idle moment. The 44mm measurement is the clear diameter inside the bayonet lugs; the internal diameter of the mating surface is 47mm. The bayonet lugs are about 1.2mm behind the mating plane, so about 160 microns further from the film plane than the Pentax register distance.  That means that, even without an adapter at all and with an M42 lens less than 47mm outside diameter, you're not going to get infinity focus with a short focal length lens.

The mating surface of my Helios 44M is about 51.7mm external diameter and it's only ⅒mm proud of the body of the lens, so it definitely can't rest on the bayonet lugs. Holding the lens tight against the camera (there's no point for me in an M42-F adapter as my digital cameras are Canons) I can focus to a maximum of about 3m.

The mating surface of my older Jupiter 9 is about 48mm external diameter and it's only ⅒mm proud of the body of the lens, so it can't rest on the bayonet lugs either. Holding the lens tight against the camera I can focus to a maximum of about 6m.

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