Help with Takumar Lens Focus confirmation

Hi everyone i have 2 Takumar lenses a 50mm f1.4 and a 135mm f3.5 the 50mm lets me use focus confirmation on my istds occasionally and i cant get it to work with the 135mm i'm assuming its hitting a connection sometimes and not on other times. I'm using a genuine Pentax m42 adaptor. Any suggestions welcolme!

There are no electrical contacts between an M42 lens and the camera so it would seem the camera thinks the image is not in focus. Perhaps what you are focussing on doesn't have much contrast for it to work.

John K

That seems the most likely reason, that or horizontal lines like venetian blinds. I've found many manual focus lenses can be a bit hit and miss.

When I use manual focus lens on either K-r or K30 I have the auto focus set on the back button and I hold it down when manually focusing and focus slowly to give the camera a chance and it normally nails it.

Thanks for the reply guys i see what you mean but its seems that on the 50mm once i've attached the lens it either works or it doesn't have used the lens today shooting the family at a Christmas market plenty of light contrast etc and then on santas grotto really low light and again it worked fine. As for the 135mm it has never worked strange one i will persevere!! thanks again for the advice

Try enabling Catch In Focus, put the camera to AF.S and turn the focus ring slowly towards focus while holding the shutter button down, when focus is achieved it will automatically fire. Only Pentax do this and it's a boon.

Thanks Steve I've used catch in focus before and totally forgot about it! will start from tomorrow!

Ah just tried it seems catch in focus doesn't work with M42 lenses i know it works a treat with my K mount manuals! back to the drawing board!

Interesting, I didn't realise that. Note to self ... Don't bother looking for a M42 500mm f4.5

For catch-in-focus, you might have to short the pins on the camera body. If I recall correctly (I've tried it once), just place some tin foil over the contacts when you screw the lens into the camera does the trick.

With regards to focus confirmation:
If you try to focus while you're aperture is alredy closed down, there is often not enough light. Focus with open aperture, next close your aperture.