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11-06-2007, 08:38 PM   #1
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Having trouble getting focus confirmation with my M42 lenses

Any one else have this problem? I tried a search, so sorry if this is overlap. A couple of my M42 lenses don't cover the contacts on the camera mount, and it seems that these don't confirm my focus. Is there anyway around that?

Thanks,
Eric

11-06-2007, 09:11 PM   #2
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Confirmation of focus has nothing to do with contacts - it is a process that occurs in the light paths on the way to the viewfinder afaik. Sometimes in very dim light this will happen or on very narrow apertures. Open the aperture right out and check in bright light and see if it works then.

You do have all the custom settings set appropriately: allow aperture ring, allow focus confirmation etc...
11-07-2007, 01:02 AM   #3
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1. For screw mount lenses in the K100D you have to set "FI with S lens used" to "available" in the menu.
2. Did you turn OFF the camera when changing lenses?
3. You said it happens with some M42 lenses only? So it works with others?

Check this (from dpreview):
QuoteQuote:
I have a set of Vivitar extension tubes with black anodized bayonet mount. When I mount these tubes, the focus confirmation light doesn't show. I solved this by glueing aluminum foil on the section that touches the electrical contacts on the camera mount. After that focus confirmation and focus trap works as normal.

The same thing could probably be achieved by removing the anodization, but the aluminum foil can easily be removed.

Anyway, this experience leads me to conclude that your camera does not register that the lens is mounted as none of the contacts are shorted. You might try to short the contacts with aluminum foil in a similar manner and see if that helps.
from:
SR and focus trap not working when....: Pentax SLR Talk Forum: Digital Photography Review
11-07-2007, 01:41 AM   #4
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None of my Takumars cover the contacts and it never affected the focus confirmation. Just make sure you have the "FI with S lens used" (Focus Indicator with Screwmount lens) enabled.

And I very highly recommend the aluminum foil trick for correcting the metering problem. I cut a small 1mm thick piece of foam and wrapped foil around it to make it a bit more sturdy and reusable. And I keep a roll of cellophane tape in my bag for reattaching it as needed. It comes in handy for other stuff too sometimes.

11-07-2007, 06:58 AM   #5
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It's quite possible that it's just low light then, as I notice the problem the most when I'm using my 55mm with a 2x extension. Also, I'm shooting with a K10d... does it have that custom function fI with S lens used I didn't think it did. Yes I turn off the camera when I switch lenses. And yes, it works fine with my 28mm, and sometimes (but mostly not) with my 55mm. I read the article on the aluminum foil, but I don't see follow how that corrects the metering problem. Could you elaborate more? I'm sorry, just trying to figure out this camera and its oddities.

Thanks,
Eric
11-07-2007, 11:51 AM   #6
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Depending on the light level, my focus indication peters out by f5.6 or f8 with the aperture stopped down. It's important to do your focusing still opened out to f4 or wider to avoid that.

I don't have any idea how the foil works; I just know that it does. Without it I had to keep EV at +2, which is the limit and leaves no wiggle room to adjust for backlit situations without switching from Av to M.

As far as whether the K10D has the "FI with S" function....you have the camera, take a look and see.
11-07-2007, 12:00 PM   #7
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QuoteQuote:
Also, I'm shooting with a K10d... does it have that custom function fI with S lens used I didn't think it did.
No, in the K10 there is no need to set this. It's only in the K100.
11-07-2007, 08:01 PM   #8
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QuoteOriginally posted by Mike Cash Quote
Depending on the light level, my focus indication peters out by f5.6 or f8 with the aperture stopped down. It's important to do your focusing still opened out to f4 or wider to avoid that.

I don't have any idea how the foil works; I just know that it does. Without it I had to keep EV at +2, which is the limit and leaves no wiggle room to adjust for backlit situations without switching from Av to M.

As far as whether the K10D has the "FI with S" function....you have the camera, take a look and see.
Hmm, I'm not having a huge problem with the metering, though it is off by about a stop at f2 or smaller. It works perfectly from f4-f11.

11-07-2007, 10:05 PM   #9
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Eric,
Once you get your camera dialed in you'll love shooting with a good screwmount.

QuoteOriginally posted by Mike Cash Quote
And I very highly recommend the aluminum foil trick for correcting the metering problem. I cut a small 1mm thick piece of foam and wrapped foil around it to make it a bit more sturdy and reusable. And I keep a roll of cellophane tape in my bag for reattaching it as needed. It comes in handy for other stuff too sometimes.
I've never tried this tip Mike, but I'm wondering if it effects some lenses more than others.

I don't know why, but the lens which meters closest to the way I want it to just happens to be my 35mm f2 screwmount.
It's right where I want it 95% of the time.

I always thought that metering was the cameras job, so I can't figure out how a lens can make that big of a difference. But it sure seams to
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