CS lens mount for Pentax Q

CS lenses are closely related to C mount in that they share the same thread size but just CS has a 5mm shorter flange distance. C to PQ adaptors are plentiful and inexpensive.

So far I found only one CS to PQ adaptor commercially available item from Taiwan company Hawk’s Factory.
Several big name Japanese camera stores advertise it’s existence for mail order purchase only. Though strangely not listed from the Hawks Factory web store. Looks very solidly built but USD70 before shipping is too much for me considering the CS lens I am adapting only cost me about a USD2.

Yodobashi Camera store link

8mm-F2-0-5Megapixel-CS-mount-IR-CCTV-Lens.html

This tiny 8mm lens has an unmarked fixed aperture. Some sites list F1.2, others F2 but most places don’t mention the F stop at all. I estimated myself it is around F2 to F2.2

The solution would be to make a CS-PQ Mount myself.

Ingredients: 1x 3rd party plastic PQ body cap. The 3rd party body caps are great. Made of stiff plastic and importantly have a bayonet mount to confidently lock into the Q’s body. A highly recommended inexpensive upgrade to the original bendy unsecured push-on body cap that came with the camera.

Locking PQ body cap and slim PQ rear lens cap link

Just trace and cut a C sized hole in the body cap and screw in your c mount lens and you are done!
Serendipitously the lens can focus to infinity with the positioning just right as-is.
Comparing with the Pentax 02 Standard zoom I found the field of view to be about 7.5mm but was underexposed at the widest F stop that 02 could manage. To get a similar shutter speed for a similar exposure, I found it roughly matched F2.2 on the 01 Standard Prime. So no gain in light gathering poses over the Standard Prime.
This cctv lens exhibits quite a bit of barrel distortion And is not at sharp as either the 02 or the 01.

The greatest benefit is the very small size and weight. The next is that it makes a fair tilt lens if you loosen it. Having a tilt lens on a Q is a wonderful novelty for me as again the overall Q package is so minute.

Glad I did not spend USD70 on that Hawks Factory CS to PQ adaptor!