Problem with Hoya 28mm tight K mount


Link Posted 15/02/2013 - 17:07
I have a Hoya 28mm f/2.8 with K mount off ebay. However, the K mount is VERY tight. Initially I thought it would not fit onto my K-r but after trying it on an old Chinon camera I found that it is just very tight.

I have compared it with my other Pentax K mount lenses and also with some M42 to K mount adaptors and cannot see any obvious difference.
I also checked the dimensions as best I could using digital calipers, but again I can't find any significant difference from my other lenses ?

Has anyone else had a similar problem with this or ANY other lens ?
If so, I would be very grateful to hear if you fixed it ?

I have not yet tried 'blueing' it out but perhaps that is the next step ?



Link Posted 15/02/2013 - 21:20
Hi Peter

My only experience of this was my Vivitar 28mm - it arrived in it's original box with a receipt from 1982 (or similar) an looked new - on the camera it was disturbingly tight but after a few times on the camera it was fine

I can't be sure that yours will be the same time will tell

Hope this helps


K10D, K5 plus plenty of clueless enthusiasm.

My Flickr site link


Link Posted 15/02/2013 - 21:40
I have some M42 to K mount adaptors permanently fixed on my older lenses that are pretty tight, but I see this as more of an advantage than a disadvantage as they are firmly attached to the camera with no chance of them coming off. I don't worry too much about it as they don't get stuck at all, they are just a very snug fit.


Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs


Link Posted 16/02/2013 - 06:53
Hello Peter, I had the same problem with a Promaster Spectrum 7 100mm Macro Lens I bought "Like New" from KEH USA. Being a Master Mechanic, I used fine emery to break down the sharp edges all round the lens mount. I stuck small pieces of paper tape on critical areas to prevent accidental scratches.
The Lens then fitted just fine.
Make sure you use the emery on on all the edges - up, down and the sides. These sharp edges are called burrs and are caused by bad machining practices. You are basically removing these burrs a giving a little taper to the sharp edges. Good Luck.
Bipin - from that far away enchanting land.


Link Posted 16/02/2013 - 08:21
The mount is polished stainless steel, so needs to stay polished preferably to prevent excessive abrasion and wear.

The K mount on the camera can be adjusted if necessary, but I wouldn't use any accessory that seemed to fit badly. Why not sell it on, it might fit another K mount better, and look for something else?
Best regards, John
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