(D.M. Procida) wrote:

It's pretty clear that the lock on the aperture ring mechanism is
faulty, and gets stuck just before f11. It can be moved past this by
holding down the lock button (though I can hear a metallic click as it
goes past).

The lock button should stay down until the ring is in the A position,
but it rises after f8. What are the chances of having this repaired at a
reasonable cost, or even of doing it myself?


Bearing in mind that you are in the UK, a reasonable cost to repair
this lens would be about GBP 30 to 40. However, that is probably a
lot more than the lens cost you. Doing it youself might be an option,
but inexperienced hands can do a lot of damage to a perfectly good
lens.

Personally, I would return the lens to the seller and demand a refund,
then find another example that doesn't need work.

I would strongly recommend that you should look for an SMC Pentax-A
50mm f/1.7, which is one of the best 50mm lenses ever made for an SLR
of any brand.

The 50mm f/2 is not a bad lens but the f/1.7 is an outstanding
performer for very little more money. It has excellent sharpness and
very low chromatic aberration and works extremely well on both film
and digital bodies.