UKH

So I've been admiring all those bird photos posted here - suddenly reminded me that I once had the intention to get out and do some stalking myself, back in the SLR days. I had (still have !) a Pentax MX along with Sigma telephoto/zoom & a barely used 600mm catadioptric (Pentax PK mounts).

Is this kit only fit for a museum, or does anyone still get value out of it ? Can such lenses be adapted to work with new generation DSLR cameras ?

You'll almost certainly be able to find an adapter so you can use your lens on a variety of modern cameras. 

In some cases, modern cameras which have a good sensor and 'In Body Image Stabilisation' make a good old lens great. 

In other cases, a modern 24MP sensor reveals how poor the old lens really was, and the cheapest modern lens will easily outperform it.

A huge variety of adaptors are available, but may or may not be worth the hassle. 

The 600mm cat lens will produce strange (donut shaped) out of focus highlights. They all do.  You can probably get reviews of both lenses in the third party lens section of Pentax forums here - https://www.pentaxforums.com/userreviews/ 

Bear in mind that if you pair them with a cropped format (APS-C or M43) DSLR then you'll only be using the central area of each lens image circle and may avoid the worst optical problems which tend to be at the edges. You'll also get a longer effective focal length. 

If you decide not to proceed you'll always get something for the lenses on the bay. Pentax MX bodies can (in good nick) be valuable and might be best advertised on the UK Pentax forum https://www.pentaxuser.com/

Cheers

Paul 

Thanks - to all , for responses; fresh hope

I believe the problem with the catadioptric only occurs when the background is bright and sparkly; some even suggest it can be an attractive feature :/ Are they still on the market now for DSLR ?

The DSLR choice of formats is a jungle to me; what are the other benefits to choosing cropped format ??

Your Pentax lenses will work with modern Pentax DSLR bodies, most have a function that allows you to set the aperture on the lens body, but obviously not as hassle free as modern PK mount lenses

At least no probs for the catadioptric which has fixed aperture, I think it is f12

Hi Lee. Sorry I have no idea whether cat lenses for DSLR are still on the market. I do use a rather large one for my astrophotography, but that is linked to a specialised astro camera. Yes you are right the doughnut highlights only occur with bright specular reflections. 

As regards the benefits of cropped format, they are cheaper and lighter than full frame. Not so good if you like wide angles, good news if you like teles. I use an APSC Pentax body (K3ii) with my Pentax lenses and I really like it. APSC gives you 1.5 times the focal length. Micro 4/3 cameras like Panasonic or Olympus give you 2 times the focal length. 

As Kevin says, if you were going to keep the Pentax lenses then a Pentax APSC DSLR is an obvious choice. However if buying used watch out for older models which suffer from the "aperture block failure" (says the man who has a new aperture solenoid on the way to attempt open heart surgery to fix a Pentax KS1).

Good luck

Paul

Thanks for all this advice. Yes, I prob would buy second hand, and would of course try to afford the most recent possible.

Good luck with your 'open heart' solenoid surgery - be sure to get a good night's sleep beforehand and be meticulous with the scrub-up

I've just glanced at your website - what a pedigree your presentation of 'low lying mist' prompted me to share this with you:

https://www.flickr.com/photos/leegwood/albums/72157644627176746