trap-focus with autofocus lenses!

fishy · 09-12-2009, 12:19 AM

Someone on this forum, in another thread here said you can adjust focus manually (if you don't have a quick-shift lens) by pressing the lens release button. Unfortunately I can't remember the exact thread, or the genius with this suggestion. Today I found time to play a bit with my FA50, and found that it allows trap focus! (at least on my K10D) I'm a very happy camper. Until someone tells me this will burn out the AF motor (it does keep trying to adjust focus, but just spins free)
Just be careful you don't actually remove the lens, but I found that very unlikely.
Just one of those little things that keep me a happy reader

dlacouture · 09-12-2009, 02:48 AM

Hummm, that was me, I think...

We could dub this "the poor man's Quick-shift" (PMQS)...

Two other way for Trap-focus (but they cannot be used as Quick-shift) :
- tape the AF socket so the shaft cannot connect (same as the PMQS above, but the lens is locked)
- do not mount the lens fully into the camera (but you lose the aperture control...)

fishy · 09-12-2009, 05:43 AM

Well then, I owe you thanks. This is much better than messing with tape (tried, didn't like) or half mounting lenses, (I do like apertures). I was so disappointed trap focus didn't work with the new *s set to MF & camera to AF. Hope they can fix it with a firmware update. Until then, this'll do nicely.

*heliphoto* · 09-12-2009, 08:50 AM

A long while ago, I posted a thread on that technique for quasi-quick-shift, but it's not my idea - just passing on something I read elsewhere... could have been dlacouture but I don't know

.

Glad it's working out for you. I thought that the * lenses turned to MF were supposed to to allow this, but I haven't tried it recently.

Eruditass · 11-06-2009, 01:25 PM

Originally Posted by dlacouture

Hummm, that was me, I think...

We could dub this "the poor man's Quick-shift" (PMQS)...

Two other way for Trap-focus (but they cannot be used as Quick-shift) :
- tape the AF socket so the shaft cannot connect (same as the PMQS above, but the lens is locked)
- do not mount the lens fully into the camera (but you lose the aperture control...)

Will the tape stop the motor from spinning?

Does anyone know which contact to short so it thinks there is no AF capability for M42 lenses? Is it one, a couple, or all of them? I'm going to cut a small piece of tin foil and put it on scotch tape so it doesn't stick out and is less of a hassle.

Eruditass · 11-06-2009, 01:33 PM

Originally Posted by heliphoto

A long while ago, I posted a thread on that technique for quasi-quick-shift, but it's not my idea - just passing on something I read elsewhere... could have been dlacouture but I don't know .

Glad it's working out for you. I thought that the * lenses turned to MF were supposed to to allow this, but I haven't tried it recently.

That is amazing - I think it should be here or in the SLR lens discussions, or this thread should be in there or SLR lens, or...

Eruditass · 11-06-2009, 02:31 PM

Originally Posted by Eruditass

Will the tape stop the motor from spinning?

Does anyone know which contact to short so it thinks there is no AF capability for M42 lenses? Is it one, a couple, or all of them? I'm going to cut a small piece of tin foil and put it on scotch tape so it doesn't stick out and is less of a hassle.

Ok, so I did some experimenting and all you need to do is short out ONE (any one) of the pins on the lower left. I use one of the end pins for ease. This will prevent aperture information from being transmitted and will enable trap-AF. This will turn all F + lenses into M or K lenses - you need to input FL, so it is unfortunate for zooms.

I have a tiny square piece of foil with a slightly larger clear tape around it that I attach to the lens body and it stays when attaching my F 50/1.7 and obviously M42 lenses. For me this is better than holding the lens release for trap-AF (which will make it keep spinning). I tape this to my M42 adapter when I'm not using it.

but the lens release is awesome for quick shift focusing on non QS lenses (no need to switch AF/MF back and forth, just push button , MF, and release) and doesn't seem to harm the AF screw (you can move it when you let go to hear it click back into place. When you place a lens on it won't be completely lined up anyway.)