Adapting Pentax K-mount lens to FM2n body

Hello everyone,

My questions is: has anyone successfully adapted a K-mount lens to an F-body?

Background:

I am trying to adapt my pentax lenses to my beloved Nikon FM2n body.

I purchased an adapter from Urth (previousy known as Gobe) which made the mount possible. The DF was very shallow and the image became somewhat sharp above F8 (images attached below). This only occured when using a 50mm, and seemed mostly fine with a 85mm.

 

Upon doing alot of research online, some people say Nikon is an universal "donor" of lenses, while unable to receive any, due to a differented registered distance (F mount = 46.50mm and K-mount 45.46).
 

Yet some people mention that if the adapter has an optical glass (as this one does), the same could be adapted at a loss of the infinite focus "lock".

The manufacturer said the short DF shouldn't occur, and it happened due to a manufacturing error, but the quality seems impecable and I'm dubious its a manufacturing error.

I'm not looking to get a new body or a change lens etc, I'm trying to understand if the adapted should work or if the adaptation is possible.

Thank you for any insights!
 

 

Link to the adapter:

https://au.urth.co/c...h-optical-glass
 

Registered distances discussion:

Anyone here ever converted K mount to F mount and retained full functionality? - PentaxForums.com


 

Hello everyone,

My questions is: has anyone successfully adapted a K-mount lens to an F-body?

Background:

I am trying to adapt my pentax lenses to my beloved Nikon FM2n body.

I purchased an adapter from Urth (previousy known as Gobe) which made the mount possible. The DF was very shallow and the image became somewhat sharp above F8 (images attached below). This only occured when using a 50mm, and seemed mostly fine with a 85mm.

Upon doing alot of research online, some people say Nikon is an universal "donor" of lenses, while unable to receive any, due to a differented registered distance (F mount = 46.50mm and K-mount 45.46).

Yet some people mention that if the adapter has an optical glass (as this one does), the same could be adapted at a loss of the infinite focus "lock".

The manufacturer said the short DF shouldn't occur, and it happened due to a manufacturing error, but the quality seems impecable and I'm dubious its a manufacturing error.

I'm not looking to get a new body or a change lens etc, I'm trying to understand if the adapted should work or if the adaptation is possible.

Thank you for any insights!


Link to the adapter:

https://au.urth.co/c...h-optical-glass

Registered distances discussion:

Anyone here ever converted K mount to F mount and retained full functionality? - PentaxForums.com

While I've never tried the specific adapter you're looking at, I have used an Exakta to PK adapter to mount my Exakta lenses on Pentax DSLRs. The adapter does have a lens to correct for infinity. Overall, it works ok, though it seems more prone to flare...or that could just be the lenses I have which are single coated mostly (or uncoated).

For adapting Exakta, PK and Nikon glass to digital, I picked a (cheap) Sony Nex-C3 which has many lens-less adapters and a 16mp sensor.

I've recently started buying Nikon film bodies because many, like the Nikkormats and F1 and F2, are a steal. I do have the FM and FE also. I've never looked to adapt my Pentax glass to the Nikon because so many of the Nikkor AI/AIs lenses are so cheap... In the past year I've purchased many from 20mm through 200mm. The most I paid for any one was $135 for a mint 35/2 AIs. Try to find a Pentax 35/2 for under $300...



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I haven’t tried this particular adapter, but I haven’t been satisfied with any corrected adapter I have had. It hasn’t been necessary for me to adapt any M42 or K-mount lenses to F-mount as I still have a Spotmatic and a KX left since my Pentax days.