How do get a correct exposure with a vintage lens

asko · 05-13-2021, 03:03 AM

I did some research in the internet ant there is something I don`t unterstand. Since there are no electronic contacts between camera and lens, which program-mode sould I use ?
Fully manual ? Aperture priority mode ?
Does the camera somehow "know" which aperture I choose ? What about the metering ?

I would be grateful for a advice.

pschlute · 05-13-2021, 03:22 AM - **2 Likes**

Originally posted by asko

I did some research in the internet ant there is something I don`t unterstand. Since there are no electronic contacts between camera and lens, which program-mode sould I use ?
Fully manual ? Aperture priority mode ?
Does the camera somehow "know" which aperture I choose ? What about the metering ?

I would be grateful for a advice.

Manual mode. Press green button to meter and camera sets shutter speed.

Martin Stu · 05-13-2021, 03:39 AM

Originally posted by pschlute

Press green button

really a useful button

**GUB** · 05-13-2021, 03:48 AM

Manual Mode only for K series and M series (and A series with aperture ring on manual settings) . These are the K mounts before the F series.
AV and Manual mode for M42 thread mounts. That is with the lens aperture setting lever on manual.

EDIT In the instruction manual look in index - lens

Last edited by GUB; 05-13-2021 at 04:00 AM.

**pepperberry farm** · 05-13-2021, 04:02 AM

green button, dude - learn it, live it, it is your friend....

(:

**Lowell Goudge** · 05-13-2021, 04:04 AM - **1 Like**

One thing to consider, is that the camera’s metering system has some nonlinearities which are dependant on the native aperture of the lens.

This was a big discussion topic when the K10 came out, and I tested it on my *istD, K10D, K7D and K5D, and somewhere plotted and posted the results of exposure error as a function of F-Stop. I should really do it also with my K1 MKII as I suspect there is also some error, because I notice with my sigma 70-200/2.8 a tendency to over expose 1 to 1.5 stops when used with the 2x TC. This is due to the camera thinking the lens is F2.8 as the TC feeds lens data straight through without correction, but the actual aperture is double what is reported. This is exactly the same symptom I saw with my K10D and the same lens and TC combo.

Here is the plot I posted way back when.

Understanding the chart.

The chart measures the greyscale value of a frame, the test image was a uniformly sunlit block wall or paved surface, which the camera should interpret as a 18% grey card. Perfect metering is with a greyscale value of 128 (out of the range 0-255). Around the middle of the greyscale value each full stop is an increment of 40-45 greyscale. This linear relationship holds over a greyscale range of about 30-225. At each end of the curve it is “S” shaped, with the next 3 stops at each end having greyscale ranges of 15, 7,and 3 respectively as you approach the ends of the exposure curve

**Cerebum** · 05-13-2021, 04:40 AM

You can use aperture priority, locking exposure on an area prior to focusing, but its hit and miss. The green button is by far the easiest. You still may need a smidge of exposure compensation but it is pretty consistant

mtkeller · 05-13-2021, 04:48 AM

This all changes with a K-3 iii. Just shoot in Av or TAv like you would with a lens with electronic aperture control, but set the aperture on the lens (and hopefully remember to dial it in on the rear e-dial so you get accurate EXIF data).

Sidney Porter · 05-13-2021, 05:59 AM - **1 Like**

You also need to set ability to use aperture in one of the menu items

bdery · 05-13-2021, 06:16 AM

Originally posted by asko

Fully manual ? Aperture priority mode ?

M mode. a mode will always shoot wide open.

Originally posted by asko

Does the camera somehow "know" which aperture I choose ? What about the metering ?

It does not know the aperture, but pressing the green button will make the camera meter by closing the aperture, so you'll get an accurate reading regardless. And if light conditions do not change, you're good to go if you do that once.

**roberrl** · 05-13-2021, 06:25 AM

How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

pschlute · 05-13-2021, 07:20 AM

Originally posted by Cerebum

You can use aperture priority, locking exposure on an area prior to focusing, but its hit and miss. The green button is by far the easiest. You still may need a smidge of exposure compensation but it is pretty consistant

If the OP is using a K-mount "K" or M series lens, or a later lens with the aperture ring off the "A" setting using Av mode is very limiting. Yes it will give correct exposure, but always wide open, irrespective to where he has set the f-stop

**Cerebum** · 05-13-2021, 07:59 AM - **1 Like**

Originally posted by pschlute

If the OP is using a K-mount "K" or M series lens, or a later lens with the aperture ring off the "A" setting using Av mode is very limiting. Yes it will give correct exposure, but always wide open, irrespective to where he has set the f-stop

Very true

sorry, I should have said I was thinking about M42s

stevebrot · 05-13-2021, 12:31 PM

There is lots of good information above, but there is one bit that I did not see that is part of my routine. I have found that stop-down metering is more consistent and accurate in live view than when using the optical viewfinder. With camera in M mode, I meter the subject in live view and switch back to the optical viewfinder for actual shooting. Those settings should remain good until either the light or the subject changes.

Steve

bdery · 05-13-2021, 06:06 PM

Originally posted by stevebrot

There is lots of good information above, but there is one bit that I did not see that is part of my routine. I have found that stop-down metering is more consistent and accurate in live view than when using the optical viewfinder. With camera in M mode, I meter the subject in live view and switch back to the optical viewfinder for actual shooting. Those settings should remain good until either the light or the subject changes.

On which camera? I never noticed this myself, but never looked for it either. With manual lenses, I frequently use live view anyway for the benefits of focus peaking.

05-13-2021, 03:03 AM	#1
asko New Member Join Date: Oct 2020 Posts: 4	How do get a correct exposure with a vintage lens I did some research in the internet ant there is something I don`t unterstand. Since there are no electronic contacts between camera and lens, which program-mode sould I use ? Fully manual ? Aperture priority mode ? Does the camera somehow "know" which aperture I choose ? What about the metering ? I would be grateful for a advice.

05-13-2021, 04:04 AM - 1 Like	#6
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	One thing to consider, is that the camera’s metering system has some nonlinearities which are dependant on the native aperture of the lens. This was a big discussion topic when the K10 came out, and I tested it on my istD, K10D, K7D and K5D, and somewhere plotted and posted the results of exposure error as a function of F-Stop. I should really do it also with my K1 MKII as I suspect there is also some error, because I notice with my sigma 70-200/2.8 a tendency to over expose 1 to 1.5 stops when used with the 2x TC. This is due to the camera thinking the lens is F2.8 as the TC feeds lens data straight through without correction, but the actual aperture is double what is reported. This is exactly the same symptom I saw with my K10D and the same lens and TC combo. Here is the plot I posted way back when. Understanding the chart. The chart measures the greyscale value of a frame, the test image was a uniformly sunlit block wall or paved surface, which the camera should interpret as a 18% grey card. Perfect metering is with a greyscale value of 128 (out of the range 0-255). Around the middle of the greyscale value each full stop is an increment of 40-45 greyscale. This linear relationship holds over a greyscale range of about 30-225. At each end of the curve it is “S” shaped, with the next 3 stops at each end having greyscale ranges of 15, 7,and 3 respectively as you approach the ends of the exposure curve Last edited by Lowell Goudge; 05-13-2021 at 06:31 PM.*

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05-13-2021, 03:22 AM - 2 Likes	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,210	Originally posted by asko I did some research in the internet ant there is something I don`t unterstand. Since there are no electronic contacts between camera and lens, which program-mode sould I use ? Fully manual ? Aperture priority mode ? Does the camera somehow "know" which aperture I choose ? What about the metering ? I would be grateful for a advice. Manual mode. Press green button to meter and camera sets shutter speed.

05-13-2021, 03:39 AM	#3
Martin Stu Pentaxian Join Date: Jan 2019 Posts: 1,115	Originally posted by pschlute Press green button really a useful button

05-13-2021, 03:48 AM	#4
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,760	Manual Mode only for K series and M series (and A series with aperture ring on manual settings) . These are the K mounts before the F series. AV and Manual mode for M42 thread mounts. That is with the lens aperture setting lever on manual. EDIT In the instruction manual look in index - lens Last edited by GUB; 05-13-2021 at 04:00 AM.

05-13-2021, 04:02 AM	#5
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,751	green button, dude - learn it, live it, it is your friend.... (:

05-13-2021, 04:40 AM	#7
Cerebum Site Supporter Join Date: Oct 2017 Location: Lancaster Photos: Gallery Posts: 3,829	You can use aperture priority, locking exposure on an area prior to focusing, but its hit and miss. The green button is by far the easiest. You still may need a smidge of exposure compensation but it is pretty consistant

05-13-2021, 04:48 AM	#8
mtkeller Veteran Member Join Date: Feb 2019 Location: Sioux City, IA Photos: Gallery Posts: 938	This all changes with a K-3 iii. Just shoot in Av or TAv like you would with a lens with electronic aperture control, but set the aperture on the lens (and hopefully remember to dial it in on the rear e-dial so you get accurate EXIF data).

05-13-2021, 05:59 AM - 1 Like	#9
Sidney Porter Veteran Member Join Date: Feb 2012 Location: Columbus Ohio USA Posts: 353	You also need to set ability to use aperture in one of the menu items

05-13-2021, 06:16 AM	#10
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,360	Originally posted by asko Fully manual ? Aperture priority mode ? M mode. a mode will always shoot wide open. Originally posted by asko Does the camera somehow "know" which aperture I choose ? What about the metering ? It does not know the aperture, but pressing the green button will make the camera meter by closing the aperture, so you'll get an accurate reading regardless. And if light conditions do not change, you're good to go if you do that once.

05-13-2021, 06:25 AM	#11
roberrl Site Supporter Join Date: Feb 2010 Location: Oxford, UK Photos: Gallery Posts: 346	How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

05-13-2021, 07:20 AM	#12
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,210	Originally posted by Cerebum You can use aperture priority, locking exposure on an area prior to focusing, but its hit and miss. The green button is by far the easiest. You still may need a smidge of exposure compensation but it is pretty consistant If the OP is using a K-mount "K" or M series lens, or a later lens with the aperture ring off the "A" setting using Av mode is very limiting. Yes it will give correct exposure, but always wide open, irrespective to where he has set the f-stop

05-13-2021, 07:59 AM - 1 Like	#13
Cerebum Site Supporter Join Date: Oct 2017 Location: Lancaster Photos: Gallery Posts: 3,829	Originally posted by pschlute If the OP is using a K-mount "K" or M series lens, or a later lens with the aperture ring off the "A" setting using Av mode is very limiting. Yes it will give correct exposure, but always wide open, irrespective to where he has set the f-stop Very true sorry, I should have said I was thinking about M42s

05-13-2021, 12:31 PM	#14
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	There is lots of good information above, but there is one bit that I did not see that is part of my routine. I have found that stop-down metering is more consistent and accurate in live view than when using the optical viewfinder. With camera in M mode, I meter the subject in live view and switch back to the optical viewfinder for actual shooting. Those settings should remain good until either the light or the subject changes. Steve

05-13-2021, 06:06 PM	#15
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,360	Originally posted by stevebrot There is lots of good information above, but there is one bit that I did not see that is part of my routine. I have found that stop-down metering is more consistent and accurate in live view than when using the optical viewfinder. With camera in M mode, I meter the subject in live view and switch back to the optical viewfinder for actual shooting. Those settings should remain good until either the light or the subject changes. On which camera? I never noticed this myself, but never looked for it either. With manual lenses, I frequently use live view anyway for the benefits of focus peaking.