Weird mirror lens metering issue

GibbyTheMole · 11-02-2010, 06:24 AM

Hi.

My wife has a cheap Kalimar 500mm mirror lens that she uses on her *ist-D. When using the lens, the metering works fine on her *ist-D, but when I use it with my K-100D, the metering is consistently underexposed by a couple of stops. All other lenses work fine on my K-100D.

Anybody got an explanation why this might be happening? Has anyone else here used a mirror lens successfully on a K-100D?

I was kind of surprised it would work properly on one body & not the other, since they're both basically the same camera.

Cheers,
Bob :-)

**Lowell Goudge** · 11-02-2010, 08:32 AM

some cameras seem to like having pin 7 of the mount shorted, this is the data pin, otherwise they meter funny. Is the lens painted or anodized at the mount point"

SOldBear · 11-02-2010, 10:59 AM

Originally posted by GibbyTheMole

...since they're both basically the same camera.

They're not

The metering problem with manual lenses is well-known with Pentax K-xxD and K-xxxD bodies. *ist series did not have this problem. In fact, one way to fix the metering problem with K10D and K20D is to replace the stock focusing screen with one for the *ist series. The K-7 is better but still not perfect.

If your camera doesn't have user-replaceable focusing screen, you'll have to learn to adjust accordingly.

GibbyTheMole · 11-03-2010, 05:26 AM

I don't think there are any pins on the lens mount, since it's a T-mount lens with a Pentax adapter.

Not a big issue, tho... I can just use +2 stops exposure compensation when I use that lens.

Thanks,
Bob :-)

ovim · 11-03-2010, 05:53 AM

Originally posted by GibbyTheMole

I don't think there are any pins on the lens mount, since it's a T-mount lens with a Pentax adapter.

Not a big issue, tho... I can just use +2 stops exposure compensation when I use that lens.

Thanks,
Bob :-)

He meant the contacts on the body. Place a piece of tin foil between the lens and the contacts so that they are shorted. That should help.

11-02-2010, 06:24 AM	#1
GibbyTheMole Veteran Member Join Date: Nov 2009 Location: Iowa Photos: Albums Posts: 2,275	Weird mirror lens metering issue Hi. My wife has a cheap Kalimar 500mm mirror lens that she uses on her ist-D. When using the lens, the metering works fine on her ist-D, but when I use it with my K-100D, the metering is consistently underexposed by a couple of stops. All other lenses work fine on my K-100D. Anybody got an explanation why this might be happening? Has anyone else here used a mirror lens successfully on a K-100D? I was kind of surprised it would work properly on one body & not the other, since they're both basically the same camera. Cheers, Bob :-)

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11-02-2010, 08:32 AM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	some cameras seem to like having pin 7 of the mount shorted, this is the data pin, otherwise they meter funny. Is the lens painted or anodized at the mount point"

11-02-2010, 10:59 AM	#3
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Originally posted by GibbyTheMole ...since they're both basically the same camera. They're not The metering problem with manual lenses is well-known with Pentax K-xxD and K-xxxD bodies. ist series did not have this problem. In fact, one way to fix the metering problem with K10D and K20D is to replace the stock focusing screen with one for the ist series. The K-7 is better but still not perfect. If your camera doesn't have user-replaceable focusing screen, you'll have to learn to adjust accordingly.

11-03-2010, 05:26 AM	#4
GibbyTheMole Veteran Member Join Date: Nov 2009 Location: Iowa Photos: Albums Posts: 2,275 Original Poster	I don't think there are any pins on the lens mount, since it's a T-mount lens with a Pentax adapter. Not a big issue, tho... I can just use +2 stops exposure compensation when I use that lens. Thanks, Bob :-)

11-03-2010, 05:53 AM	#5
ovim Veteran Member Join Date: Sep 2008 Location: Tre, Finland Photos: Gallery Posts: 1,229	Originally posted by GibbyTheMole I don't think there are any pins on the lens mount, since it's a T-mount lens with a Pentax adapter. Not a big issue, tho... I can just use +2 stops exposure compensation when I use that lens. Thanks, Bob :-) He meant the contacts on the body. Place a piece of tin foil between the lens and the contacts so that they are shorted. That should help.

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