M42/K Mount question

I have two of these adaptors. One I bought down at the Focus show and one that came with a recent lens.

With one attached it dosn't seem to click into place and just comes unattached with minimum effort (and without pressing the tab on the body). The aperture ring is off to one side as well.

The other one fits into place a lot better but the aperture settings, focus ring etc are all directly underneath the lens.With neither one does the camera give me the option of setting the focal length.

I'm assuming that some adaptors are better than others?

The one I bought is from SRB - no idea where the other is from.

Cheers for that Tim. It seems to work fine - just a tad awkward at times. I might have a dabble at a proper Pentax one just to be certain its doing the right job. The SRB one does seem well made though. I was pointed towards tham by a bloke at the Jacobs stand.

If the M42 lens has a pin it should line up with the plate that stops the lens down otherwise it won't work properly.

By that do you mean change the aperture? Thats my biggest concern as it dosn't seem to be changing as much as it should when I change from f2.4 to f11 for example. The shutter speed doesn't change much at all but there is no exif data to let me know what the settings are.

Since it's an M42 lens you can shoot in Av, and just change the aperture by turning the aperture ring. The camera's metering should be reasonably accurate to a point but if you stop down a lot you might need some exposure compensation. Just keep in mind that at very small apertures it may be difficult to see anything through the viewfinder.

This is all assuming that your M42 lens is a manual one, or at least has a auto/manual switch. If it's an auto-only one (very rare by all accounts) you'll need a special adapter, which is what I think Algernon is referring to.

The button on the camera body doesn't lock M42 lenses in place as they usually aren't wide enough to cover it (some are, and can have a hole carefully drilled to convert them to K mount if you fix the adapter to the lens and remove the little tab which would lock it in place).

The standard M42 stop down mechanism is a pin protruding next to the rear element of the lens. Press this in and the lens stops down to the chosen aperture (M42 bodies have a little paddle to do this). This can be a problem if the lens doesn't have an Auto/Manual switch as the lens won't stop down (K bodies lacking the paddle to depress it). Some people use a thin sliver of plastic superglued over the pin to wedge it down permanently. If there's a switch then just flick it to Manual and all will be well.

As for the SR, it should ask this as soon as you turn the camera on. Are you sure SR is switched on and the camera is properly set up for manual lenses (aperture ring set to "permitted" or whatever the exact wording is)?

It would probably be better if you told us the make and focal length of the lens, so we will have an idea of what's needed for it to work.

A pre-set for instance often doesn't have anything protruding from the back and it doesn't matter where the aperture markings are.

I've got a pre-set on which the mount was held on by 4 equally spaced screws and I rotated it 90deg so that the aperture markings are at the side where I can see them better than under the flash housing.

What camera are you using? On my K-X when its set on remote for the shutter, the Shake Reduction is turned OFF. And now as the SR is OFF the lens length question is not asked by the camera at startup. Without checking it can easily be forgotten, as you can carry on taking pictures with the normal shutter release.
I have a Helios 58 M42 f2 which seemed to catch whilst screwing on with the k mount adapter fitted to the camera. This was the aperture release pin catching. So although the lens has a manual switch I stripped it down and put a small peice of wire insulation on the pin so it was held in the on position. It could have been taken out completely but I never wanted to lose it.

Patty

The lens is the Carl Zeiss Flektogon 2.4/35. I'll do some testing today at different f stops and see what its doing.

Supposed to be a good lens. I've got the CZ 135mm. There shouldn't be any problems, it should have the A/M switch which opens and closes the diaphragm.

Leave it set on M and open and close the aperture with the aperture ring. You should be able to set it up to at least f/5.6 and still focus, probably best (with it being a std. lens) to use the Green Hexagon for focus.

It may still be OK at f/8.... for f/11 and beyond either open up the aperture ring and then focus then close down again OR open and close via the A/M/ switch. Personally I'd just use f/5.6 and leave it closed all the time.

The one that brings the aperture numbers underneath might be a Nikon adapter.

It doesn't actually indicate that its focused - I'm doing it manually. the green light never comes on.

Perhaps test it on a tripod to eliminate any swaying - the green light should come on. Keeping still so it stays on is another matter!

Tried a couple of hundred shots - have other MF lenses where the green light comes on. Does not come on at all with this lens.