k10d and smc-m mettering

KungPOW · 03-04-2008, 07:36 PM

Borno,

Thanks for your post! Did changing the screen affect metering with your other lenses? Did it change how the camera metered you DA lenses (I am assuming you have the kit lens, or something similar)?

Thanks.

petez · 03-05-2008, 08:48 AM

Originally posted by Lowell Goudge

that is correct, the K10D can't control the apature of a manual lens, it only allows it to open to the mechanical limit of the lens as set by the apature ring.

There seems to be a limit though of how far it will stop the lens down. I have 2 Tamron lens both with min aperature of f32. I get no change in metering when going from f22 to f32 on either lens.

Pete

bubuli · 03-05-2008, 09:08 AM

This has been a great thread. I've learned a few things and confirms my observation as well...However, I have a few more questions...maybe somebody here would be able to enlighten me.

I am using M42 (screw-mount) lenses on a K10D with a genuine M42/K Pentax adapter. I set the lens lever to "Manual". at f1.4, there is a one stop reading difference between Aperture priority and Manual program with the green button--e.g., if i set to Av and the reading is 1/500s...when i set it to M and press the green button, reading is 1/250s! the difference gets less as you shrink the aperture...with my quick test the difference becomes 1/3 stop by the time it's f16.

Can somebody explain why there's a difference??

thank you!

**Lowell Goudge** · 03-05-2008, 09:27 AM

Originally posted by petez

There seems to be a limit though of how far it will stop the lens down. I have 2 Tamron lens both with min aperature of f32. I get no change in metering when going from f22 to f32 on either lens.

Pete

It may be that you are going beyond the limits of the metering. I have run into this before.

One way to tell, and it is the only test I regularly do when I get a new (used manual) lens, is to take a series of test shots, (my favourite subject is a concrete block wall, but any uniform surface will do) and use the green button to check the exposure at each apature click. I don't go by the reading but actually take the shots and plot grey scale vs f-stop.

It may be that the camera, with the adjustment increment you have set (eithe 1/2 or 1/3 stop) plus changes in lighting that you don't notice, result in the same shutter speed.

Also, on some tamrons, F22 was the maximum, although F32 is indicated on the adaptall lens mount. Look at the actual apature as you click it around. does it actually change?

borno · 03-05-2008, 09:53 AM

Originally posted by KungPOW

Borno,

Thanks for your post! Did changing the screen affect metering with your other lenses? Did it change how the camera metered you DA lenses (I am assuming you have the kit lens, or something similar)?

Thanks.

Hey KungPOW, Most of my lenses are KA and have not noticed any adverse exposure on my body(I use raw). I don't use M lenses much now but like the grid on the LL 60. I'd check it out but I don't like swapping out the screen because of the dust potential

**Lowell Goudge** · 03-05-2008, 10:50 AM

Originally posted by borno

There are some threads on the problem if you do a search, most find the k10d will overexpose when at apertures smaller than f4 with manual lens (km). Mine was about 1.5 f stops over at f 8. I put in a *ist D focus screen and it works for me. DOF and green button were both off on mine.

Any chance on a set of test shots, with either paved road or block wall as the subject, using green button on any Manual apature lens, with the *istD focusing screen installed in the K10D.

I am quite interested in how this performs.

I also note the LL60 screen is not in the optional accessories list for the K10D, are they infact really interchangeable?

Thanks

**Ash** · 03-05-2008, 01:06 PM

I have the K10D with the LL-60 screen, and it seems to meter OK with my M 200/4 (tested at f/4 only to date), but I don't have any other MF lenses to test on at the moment.

On the other hand, metering is a little out of whack with my FA 100/2.8 on A aperture setting. Go figure... I have to take the aperture ring off A setting (make it an M lens) to get decent exposure.

So what others have said about the LL-60 fixing the metering problems for M lenses, probably does the reverse for some AF lenses...

But metering with my other zooms (Tamron 28-75, DA 16-45) has been fine...

**Lowell Goudge** · 03-05-2008, 02:38 PM

Originally posted by Ash

I have the K10D with the LL-60 screen, and it seems to meter OK with my M 200/4 (tested at f/4 only to date), but I don't have any other MF lenses to test on at the moment.

On the other hand, metering is a little out of whack with my FA 100/2.8 on A aperture setting. Go figure... I have to take the aperture ring off A setting (make it an M lens) to get decent exposure.

So what others have said about the LL-60 fixing the metering problems for M lenses, probably does the reverse for some AF lenses...

But metering with my other zooms (Tamron 28-75, DA 16-45) has been fine...

I guess the question is, on the FA lens, are you under exposing and is it constant (with lens in AE position) over the entire f stop range?

**Lowell Goudge** · 03-05-2008, 03:32 PM

Originally posted by bubuli

This has been a great thread. I've learned a few things and confirms my observation as well...However, I have a few more questions...maybe somebody here would be able to enlighten me.

I am using M42 (screw-mount) lenses on a K10D with a genuine M42/K Pentax adapter. I set the lens lever to "Manual". at f1.4, there is a one stop reading difference between Aperture priority and Manual program with the green button--e.g., if i set to Av and the reading is 1/500s...when i set it to M and press the green button, reading is 1/250s! the difference gets less as you shrink the aperture...with my quick test the difference becomes 1/3 stop by the time it's f16.

Can somebody explain why there's a difference??

thank you!

Unfortunately (I guess) I don;t have any experience with M42 lenses. I have never seen this, and the only way I could possibly check for a similar problem would be to see if my 50mm F1.4 K mount meters the same wide open in Av mode as it does in green button manual mode.

bubuli · 03-05-2008, 04:09 PM

Originally posted by Lowell Goudge

...would be to see if my 50mm F1.4 K mount meters the same wide open in Av mode as it does in green button manual mode.

Yes, can you try that? I'm curious to know. thanks, Lowell!

**Lowell Goudge** · 03-05-2008, 04:50 PM

Originally posted by bubuli

Yes, can you try that? I'm curious to know. thanks, Lowell!

Note, my K10D, using latest firmware, meters the same in Av mode and Green button manual when wide open.

Test done with SMC 50mm F1.4

borno · 03-05-2008, 05:00 PM

If it helps I did a quick check with my a-50mm f1.4 and got the same shutter speed at f1.4 with lens in a at f1.4 and manual using aperture ring and green button(with ds screen) I get a little under exposure at 2.8 and then it's ok at smaller apertures.Remember if you use matrix metering it goes to center weighted in m mode (I'm pretty sure) My histogram is a little left of center when shooting a plain wall

**Ash** · 03-06-2008, 04:14 AM

I've tried different aperture settings with the FA 100/2.8 on my K10D with LL-60, and the results are the same throughout - overexposure by 1.5 to 2 stops. So to correct this, I've had to set EV to -2.0 just to get it right, which limits me if I wanted to underexpose it any more - but again, I can simply take the aperture ring off A and the problem is solved...

bubuli · 03-06-2008, 05:45 AM

thanks, Lowell and Borno. Borno, I tried every metering mode and saw the same behaviour.

I ordered the LL-60 yesterday based on Borno's recommation (and by reading other threads here and on rest of the "internets"). I'll report my findings here.

hinman · 03-06-2008, 05:13 PM

Thank you for all information. I have to rethink how i do manual metering. For me, I don't get excited with the idea of changing focusing screen just for the purpose of using M42 lens. A compromise that one has to consider and confirm metering with newer digital lens. And the solution seems to address users of K10D but I have not heard of K100D solutions.

I have used many manual lens including M42 lens on my K100D. A bit more work but quite satisfactory for many of my amateur shooting needs. My approach of metering is always counting on the M mode with AE-L/green button for stop down metering. And I adjust timing dependent on the preview of shots and results of shots. Usually the adjustment on a particular f/stop is constant but I have not run into the case of both overs exposure and under exposure in two ends of aperture range

When I started on m42 lens, I use Av mode initially and I use the preview and the final picture to adjust the Ev compensation but I quickly find the limit in +2 Ev compensation, and the needed compensation needed more frequently in indoor setting for my Pentacon 50mm f/1.8 and I have changed to abandon the Av almost completely and rely on M mode with stop down metering and adjustment on shutter.

03-05-2008, 09:08 AM	#33
bubuli New Member Join Date: Mar 2008 Location: Monroe, NJ Posts: 6	One more question... This has been a great thread. I've learned a few things and confirms my observation as well...However, I have a few more questions...maybe somebody here would be able to enlighten me. I am using M42 (screw-mount) lenses on a K10D with a genuine M42/K Pentax adapter. I set the lens lever to "Manual". at f1.4, there is a one stop reading difference between Aperture priority and Manual program with the green button--e.g., if i set to Av and the reading is 1/500s...when i set it to M and press the green button, reading is 1/250s! the difference gets less as you shrink the aperture...with my quick test the difference becomes 1/3 stop by the time it's f16. Can somebody explain why there's a difference?? thank you!

03-06-2008, 05:13 PM	#45
hinman Veteran Member Join Date: Oct 2006 Location: Fremont, CA Photos: Albums Posts: 3,473	Thank you for all information. I have to rethink how i do manual metering. For me, I don't get excited with the idea of changing focusing screen just for the purpose of using M42 lens. A compromise that one has to consider and confirm metering with newer digital lens. And the solution seems to address users of K10D but I have not heard of K100D solutions. I have used many manual lens including M42 lens on my K100D. A bit more work but quite satisfactory for many of my amateur shooting needs. My approach of metering is always counting on the M mode with AE-L/green button for stop down metering. And I adjust timing dependent on the preview of shots and results of shots. Usually the adjustment on a particular f/stop is constant but I have not run into the case of both overs exposure and under exposure in two ends of aperture range When I started on m42 lens, I use Av mode initially and I use the preview and the final picture to adjust the Ev compensation but I quickly find the limit in +2 Ev compensation, and the needed compensation needed more frequently in indoor setting for my Pentacon 50mm f/1.8 and I have changed to abandon the Av almost completely and rely on M mode with stop down metering and adjustment on shutter. Last edited by hinman; 03-06-2008 at 05:52 PM.

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03-04-2008, 07:36 PM	#31
KungPOW Veteran Member Join Date: Nov 2007 Location: Vancouver, Canada Photos: Gallery Posts: 1,699	Borno, Thanks for your post! Did changing the screen affect metering with your other lenses? Did it change how the camera metered you DA lenses (I am assuming you have the kit lens, or something similar)? Thanks.

03-05-2008, 08:48 AM	#32
petez Forum Member Join Date: Jan 2008 Location: Corvallis Oregon Posts: 71	Originally posted by Lowell Goudge that is correct, the K10D can't control the apature of a manual lens, it only allows it to open to the mechanical limit of the lens as set by the apature ring. There seems to be a limit though of how far it will stop the lens down. I have 2 Tamron lens both with min aperature of f32. I get no change in metering when going from f22 to f32 on either lens. Pete

03-05-2008, 09:27 AM	#34
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by petez There seems to be a limit though of how far it will stop the lens down. I have 2 Tamron lens both with min aperature of f32. I get no change in metering when going from f22 to f32 on either lens. Pete It may be that you are going beyond the limits of the metering. I have run into this before. One way to tell, and it is the only test I regularly do when I get a new (used manual) lens, is to take a series of test shots, (my favourite subject is a concrete block wall, but any uniform surface will do) and use the green button to check the exposure at each apature click. I don't go by the reading but actually take the shots and plot grey scale vs f-stop. It may be that the camera, with the adjustment increment you have set (eithe 1/2 or 1/3 stop) plus changes in lighting that you don't notice, result in the same shutter speed. Also, on some tamrons, F22 was the maximum, although F32 is indicated on the adaptall lens mount. Look at the actual apature as you click it around. does it actually change?

03-05-2008, 09:53 AM	#35
borno Veteran Member Join Date: Nov 2006 Location: md-usa Photos: Gallery \| Albums Posts: 2,580	Originally posted by KungPOW Borno, Thanks for your post! Did changing the screen affect metering with your other lenses? Did it change how the camera metered you DA lenses (I am assuming you have the kit lens, or something similar)? Thanks. Hey KungPOW, Most of my lenses are KA and have not noticed any adverse exposure on my body(I use raw). I don't use M lenses much now but like the grid on the LL 60. I'd check it out but I don't like swapping out the screen because of the dust potential

03-05-2008, 10:50 AM	#36
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by borno There are some threads on the problem if you do a search, most find the k10d will overexpose when at apertures smaller than f4 with manual lens (km). Mine was about 1.5 f stops over at f 8. I put in a ist D focus screen and it works for me. DOF and green button were both off on mine. Any chance on a set of test shots, with either paved road or block wall as the subject, using green button on any Manual apature lens, with the istD focusing screen installed in the K10D. I am quite interested in how this performs. I also note the LL60 screen is not in the optional accessories list for the K10D, are they infact really interchangeable? Thanks

03-05-2008, 01:06 PM	#37
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	I have the K10D with the LL-60 screen, and it seems to meter OK with my M 200/4 (tested at f/4 only to date), but I don't have any other MF lenses to test on at the moment. On the other hand, metering is a little out of whack with my FA 100/2.8 on A aperture setting. Go figure... I have to take the aperture ring off A setting (make it an M lens) to get decent exposure. So what others have said about the LL-60 fixing the metering problems for M lenses, probably does the reverse for some AF lenses... But metering with my other zooms (Tamron 28-75, DA 16-45) has been fine...

03-05-2008, 02:38 PM	#38
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by Ash I have the K10D with the LL-60 screen, and it seems to meter OK with my M 200/4 (tested at f/4 only to date), but I don't have any other MF lenses to test on at the moment. On the other hand, metering is a little out of whack with my FA 100/2.8 on A aperture setting. Go figure... I have to take the aperture ring off A setting (make it an M lens) to get decent exposure. So what others have said about the LL-60 fixing the metering problems for M lenses, probably does the reverse for some AF lenses... But metering with my other zooms (Tamron 28-75, DA 16-45) has been fine... I guess the question is, on the FA lens, are you under exposing and is it constant (with lens in AE position) over the entire f stop range?

03-05-2008, 03:32 PM	#39
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by bubuli This has been a great thread. I've learned a few things and confirms my observation as well...However, I have a few more questions...maybe somebody here would be able to enlighten me. I am using M42 (screw-mount) lenses on a K10D with a genuine M42/K Pentax adapter. I set the lens lever to "Manual". at f1.4, there is a one stop reading difference between Aperture priority and Manual program with the green button--e.g., if i set to Av and the reading is 1/500s...when i set it to M and press the green button, reading is 1/250s! the difference gets less as you shrink the aperture...with my quick test the difference becomes 1/3 stop by the time it's f16. Can somebody explain why there's a difference?? thank you! Unfortunately (I guess) I don;t have any experience with M42 lenses. I have never seen this, and the only way I could possibly check for a similar problem would be to see if my 50mm F1.4 K mount meters the same wide open in Av mode as it does in green button manual mode.

03-05-2008, 04:09 PM	#40
bubuli New Member Join Date: Mar 2008 Location: Monroe, NJ Posts: 6	Originally posted by Lowell Goudge ...would be to see if my 50mm F1.4 K mount meters the same wide open in Av mode as it does in green button manual mode. Yes, can you try that? I'm curious to know. thanks, Lowell!

03-05-2008, 04:50 PM	#41
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by bubuli Yes, can you try that? I'm curious to know. thanks, Lowell! Note, my K10D, using latest firmware, meters the same in Av mode and Green button manual when wide open. Test done with SMC 50mm F1.4

03-05-2008, 05:00 PM	#42
borno Veteran Member Join Date: Nov 2006 Location: md-usa Photos: Gallery \| Albums Posts: 2,580	If it helps I did a quick check with my a-50mm f1.4 and got the same shutter speed at f1.4 with lens in a at f1.4 and manual using aperture ring and green button(with ds screen) I get a little under exposure at 2.8 and then it's ok at smaller apertures.Remember if you use matrix metering it goes to center weighted in m mode (I'm pretty sure) My histogram is a little left of center when shooting a plain wall

03-06-2008, 04:14 AM	#43
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	I've tried different aperture settings with the FA 100/2.8 on my K10D with LL-60, and the results are the same throughout - overexposure by 1.5 to 2 stops. So to correct this, I've had to set EV to -2.0 just to get it right, which limits me if I wanted to underexpose it any more - but again, I can simply take the aperture ring off A and the problem is solved...

03-06-2008, 05:45 AM	#44
bubuli New Member Join Date: Mar 2008 Location: Monroe, NJ Posts: 6	thanks, Lowell and Borno. Borno, I tried every metering mode and saw the same behaviour. I ordered the LL-60 yesterday based on Borno's recommation (and by reading other threads here and on rest of the "internets"). I'll report my findings here.