K-7 LV metering with manual lenses

Jadran · 01-11-2010, 03:01 PM

What I noticed is that while using manual lenses (all three are M42 mount) with Live View, every time I get exactly 1 stop longer exposure then without LV. So, I'm wondering how the Lv does the metering, in fact?

**Lowell Goudge** · 01-11-2010, 03:23 PM

Originally posted by Jadran

What I noticed is that while using manual lenses (all three are M42 mount) with Live View, every time I get exactly 1 stop longer exposure then without LV. So, I'm wondering how the Lv does the metering, in fact?

live view may be using an exposure calculation on the light actually hitting the sensor where as the normal metering takes light off the focusing screen.

I have not used M42 lenses on the K7 Yet but on the K10 and my *istD they need exposure compensation to genter the histogram

Jadran · 01-11-2010, 03:47 PM

Originally posted by Lowell Goudge

live view may be using an exposure calculation on the light actually hitting the sensor where as the normal metering takes light off the focusing screen.

This sounds like reasonable explanation. But, on AF lenses exposure in Lv and without it is pretty much the same, with same smaller deviations.

Originally posted by Lowell Goudge

have not used M42 lenses on the K7 Yet but on the K10 and my *istD they need exposure compensation to genter the histogram

M42 lenses on K-7 are off meter, that's true, but not near as much as on K10d that I also have. I just couldn't explain that exact difference of 1 stop with Live View

**Lowell Goudge** · 01-11-2010, 04:05 PM

Originally posted by Jadran

This sounds like reasonable explanation. But, on AF lenses exposure in Lv and without it is pretty much the same, with same smaller deviations.

yes but if they correct for the fiewfinder with the knowledge of maximum aperture then the exposure is pretty close because it is already corrected

Quote:

M42 lenses on K-7 are off meter, that's true, but not near as much as on K10d that I also have. I just couldn't explain that exact difference of 1 stop with Live View

true the K 7 metering is better than K10 but I find this is really only at large apertures (below F4, not the smaller apertures

Jadran · 01-11-2010, 05:01 PM

Originally posted by Lowell Goudge

yes but if they correct for the fiewfinder with the knowledge of maximum aperture then the exposure is pretty close because it is already corrected

Probably you are right. I'll compare AF exposure with M42 to find out which is "proper" exposure. It could also mean that M42 lenses constantly underexpose.

Originally posted by Lowell Goudge

true the K 7 metering is better than K10 but I find this is really only at large apertures (below F4, not the smaller apertures

Yes, You re right on that one.

**Lowell Goudge** · 01-11-2010, 05:08 PM

Originally posted by Jadran

Probably you are right. I'll compare AF exposure with M42 to find out which is "proper" exposure. It could also mean that M42 lenses constantly underexpose.

Yes, You re right on that one.

It's all about checking all your lenses and cameras to see how they perform. for exposure I use a block wall or paved road and then plot greyscale of the central 10% for all apertures

As for the M42 lenses under exposing, all of mine do, why should yours be different

here is the metering between K7, K10 with *istD screen, and origonal screen plus *istD

Jadran · 01-12-2010, 12:57 PM

OK, I did same exposure tests with M42 lens, AF lens and my trustworthy Minolta Dynax 7. Same focal lenght, same apertures, spot metering on uniform light wall. Conclusion is this: M42 lenses underexpose apx. 1 stop at all apertures, and LV metering with M42 lenses, which shows 1 stop longer exposure, is pretty near proper exposure.

Good to know.

Lowell Goudge, thanks for your suggestions.

01-11-2010, 03:01 PM	#1
Jadran Senior Member Join Date: Sep 2009 Location: Zagreb Photos: Albums Posts: 105	K-7 LV metering with manual lenses What I noticed is that while using manual lenses (all three are M42 mount) with Live View, every time I get exactly 1 stop longer exposure then without LV. So, I'm wondering how the Lv does the metering, in fact?

01-11-2010, 05:08 PM	#6
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,890	Originally posted by Jadran Probably you are right. I'll compare AF exposure with M42 to find out which is "proper" exposure. It could also mean that M42 lenses constantly underexpose. Yes, You re right on that one. It's all about checking all your lenses and cameras to see how they perform. for exposure I use a block wall or paved road and then plot greyscale of the central 10% for all apertures As for the M42 lenses under exposing, all of mine do, why should yours be different here is the metering between K7, K10 with istD screen, and origonal screen plus istD Last edited by Lowell Goudge; 01-11-2010 at 05:19 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Manual Metering on Pentax DSLRs with Manual and Automatic Lenses	Adam	Pentax DSLR and Camera Articles	20	01-06-2016 03:38 AM
accuracy of K-x metering manual / M42 lenses?	kuuan	Pentax DSLR Discussion	7	01-22-2010 01:01 PM
Metering with Manual lenses..	arbib	Pentax SLR Lens Discussion	21	01-03-2010 10:22 PM
Metering with manual lenses--exasperated!	donutley	Pentax DSLR Discussion	58	10-21-2008 05:43 PM
K10D, manual lenses, and metering	vinzer	Pentax DSLR Discussion	40	06-30-2007 07:54 AM

01-11-2010, 03:23 PM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,890	Originally posted by Jadran What I noticed is that while using manual lenses (all three are M42 mount) with Live View, every time I get exactly 1 stop longer exposure then without LV. So, I'm wondering how the Lv does the metering, in fact? live view may be using an exposure calculation on the light actually hitting the sensor where as the normal metering takes light off the focusing screen. I have not used M42 lenses on the K7 Yet but on the K10 and my *istD they need exposure compensation to genter the histogram

01-11-2010, 03:47 PM	#3
Jadran Senior Member Join Date: Sep 2009 Location: Zagreb Photos: Albums Posts: 105 Original Poster	Originally posted by Lowell Goudge live view may be using an exposure calculation on the light actually hitting the sensor where as the normal metering takes light off the focusing screen. This sounds like reasonable explanation. But, on AF lenses exposure in Lv and without it is pretty much the same, with same smaller deviations. Originally posted by Lowell Goudge have not used M42 lenses on the K7 Yet but on the K10 and my *istD they need exposure compensation to genter the histogram M42 lenses on K-7 are off meter, that's true, but not near as much as on K10d that I also have. I just couldn't explain that exact difference of 1 stop with Live View

01-11-2010, 04:05 PM	#4
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,890	Originally posted by Jadran This sounds like reasonable explanation. But, on AF lenses exposure in Lv and without it is pretty much the same, with same smaller deviations. yes but if they correct for the fiewfinder with the knowledge of maximum aperture then the exposure is pretty close because it is already corrected Quote: M42 lenses on K-7 are off meter, that's true, but not near as much as on K10d that I also have. I just couldn't explain that exact difference of 1 stop with Live View true the K 7 metering is better than K10 but I find this is really only at large apertures (below F4, not the smaller apertures

01-11-2010, 05:01 PM	#5
Jadran Senior Member Join Date: Sep 2009 Location: Zagreb Photos: Albums Posts: 105 Original Poster	Originally posted by Lowell Goudge yes but if they correct for the fiewfinder with the knowledge of maximum aperture then the exposure is pretty close because it is already corrected Probably you are right. I'll compare AF exposure with M42 to find out which is "proper" exposure. It could also mean that M42 lenses constantly underexpose. Originally posted by Lowell Goudge true the K 7 metering is better than K10 but I find this is really only at large apertures (below F4, not the smaller apertures Yes, You re right on that one.

01-12-2010, 12:57 PM	#7
Jadran Senior Member Join Date: Sep 2009 Location: Zagreb Photos: Albums Posts: 105 Original Poster	OK, I did same exposure tests with M42 lens, AF lens and my trustworthy Minolta Dynax 7. Same focal lenght, same apertures, spot metering on uniform light wall. Conclusion is this: M42 lenses underexpose apx. 1 stop at all apertures, and LV metering with M42 lenses, which shows 1 stop longer exposure, is pretty near proper exposure. Good to know. Lowell Goudge, thanks for your suggestions.