Beware cheap Pentax K to M42 adapters

[RichA]

Stick with the Pentax, even if they cost $50.00. I used a cheap Chinese one that looked ok, but its tolerances were so slack, it got
stuck and took me 30 minutes to get if off a camera. Don't want to kaput a $600 body for the sake of saving $40 on a ring.

[kryss]

It sure hurts when you buy a cheap adapter that almost trashes the camera,my first genuine Pentax adapter cost $14.00 back in 80's last one was $73 last year.

[RokkorDoctor]

Cheap adapters can be problematic.

I would always advise a few precautionary steps before using it in anger on a valuable camera/lens:

1. Inspect any locking tabs on the new adapter.
- Do they appear smoothly finished (de-burred, i.e. no sharp manufacturing edges that can dig into the camera/lens mount and get stuck?)
- Do they appear to retract far enough when pressing the release button; i.e. at least as far as the tabs on the OEM lenses/mounts?
2. Inspect the bayonet itself.
- Again, do all edges appear smoothly finished/chamfered without any burrs?
- Are all the lead-ins to push on any locking tabs smooth without burrs?
- Have the edges of the screw recesses on the mating surfaces been de-burred?
3. If you have some vernier/digital callipers, check the adapter thickness at various points to check for mount parallelism (max. 0.05mm deviation, 0.02mm better still.)

Then, crucially, if possible first try the adapter on another less valuable OEM accessory like extension tubes, before putting it on a camera or lens.

Finally, feel for any looseness; sometimes the factory-fitted mount spring(s) may need adjusting if they are too loose. These may be spring clips, or simply machined "fingers" or "slots" in the mount that need some adjustment. Unfortunately, rarely if ever are these springs of the same quality/complexity/finish as the OEM spring arrangement on the camera/lens.

Any leading edges on the bayonet "fingers" usually benefit from application of a very small amount of a very heavy, thick, grease.

Eliminating internal reflections on cheap adapters is a different issue...

EDIT: just noticed I responded to a SPAM revival of an old thread

[stevemark]

[D1N0]

Unless it is an original adapter made by Pentax I just remove the locking spring. They are tight enough without them and I can take tout lenses with the adapter still attached instead of having to screw them out and then unlock the adapter. Thanks spammers :p

[titrisol70]

IN the 80s there were a few off brand adapters that were good, but the new chinese ones are hit or miss.
There is a type that has a huge lip that prevent sinfinity focus and a few others that end with the lens upside down

Luckily, I've found a couple of the original ones over the years

[caspert79]

I usually get a K&F adapter. Good price and quality.

[titrisol70]

I asked a friend who is a M42 guru, he said that form the current batch K&F and Kipon are the ones he recommends
He mentioned a Kipon adapter that has a "lip" and that he uses that for Mamiya an Fuji lenses that don;t have the A/M switch (nor the push-plate in the camera)

[D1N0]

For Pentax there is really only one type of adapter that will work

[piggsy]

I've had 2 nikon F to m4/3 adapters fail, one almost took out my Bokina 90 2.5 when the metal rim separated from the plastic housing while focusing the lens, the other I used with my Tamron 180mm F3.5 macro could easily have taken out the camera as the 3 tiny screws holding the metal rim onto the plastic housing came microns from stripping and detaching and making their way into the shutter/camera body. I think they're just something that is deceptively simple but is actually a mechanical device subject to a fair amount of force in ordinary use. No way around it, needs to be something you inspect closely every now and again.

[Gardener]