EV Problems (Underexposing) w/ DA* 50-135mm

**montman** · 01-15-2010, 01:10 PM

I have a K20D and find in my personal opinion it underexposes by about .3. So I just adjust EV by +.3 for all my lenses except the DA* 50-135. I have to set the compensation to about +1.5 or 2.0 to get a decent exposure. I typically shoot with multi segment metering unless I have a subject backlit by the sun I will use spot. Any body else have this problem or know how to fix it? All in all my metering with the DA* 50-135 seems to be very inconsistent.

Marc Sabatella · 01-15-2010, 02:24 PM

Can you post shots that demonstrate the problem you are seeing, with EXIF intact?

**Ash** · 01-15-2010, 02:36 PM

Please do, this doesn't sound quite right.

**Rense** · 01-15-2010, 02:41 PM

Never experienced such problems with my K20d (but with legacy glass)....

Doesn't sound right as Ash said...

**montman** · 01-15-2010, 02:50 PM

I will try to get some shots up with the EXIF tonight. Thanks again for the help.

**montman** · 01-15-2010, 06:36 PM

Ex 1
1/4000 2.8 ISO 200 Aperture Priority EV 0 Spot

Ex2
1/800 f2.8 ISO200 Apature Pirority EV+2 Spot

Ex3
1/40 F7.1 ISO400 Apature Priority Multi Seg EV +7/10

flyer · 01-15-2010, 06:56 PM

Looking at all the sky included in your pictures, I'd say it's understandable that you need that much compensation.

Those aren't good pictures to illustrate your point. You should try to post pictures of the same subject, preferably with more or less balanced lighting, using your different lenses against the 50-135. Then, we could form an opinion and see if you indeed have a problem with your lens or not. On top of that you used spot metering, and metered from the sky. Try it with matrix metering, you'll get better results for that kind of pictures.

**montman** · 01-15-2010, 07:04 PM

Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10.

ma318 · 01-15-2010, 07:20 PM

Originally posted by montman

Ex 1
1/4000 2.8 ISO 200 Aperture Priority EV 0 Spot

When using spot metering, it may be best to put the camera in manual mode.
Then aim the center spot circle in the view finder onto your subject (e.g. on the subject's face). Manually adjust either the shutter speed or aperture so that the spot meter in the view finder indicates +1EV. You need +1EV because Caucasian skin is typically 1 stop brighter than 18% grey. Then recompose and shoot.

When using spot metering, you will need to manually compensate for the tone of the subject you are spot metering on - unless its tone is 18% gray. If it is lighter then 18% gray, you have to increase the compensation manually. If it is darker then 18% gray, you have to decrease the compensation manually.

PentaxPoke · 01-15-2010, 07:23 PM

Did you try cleaning the contacts? That seems to be the answer to most things around here.

I do recall my DA*'s (16-50 and 50-135) requiring a bit more + compensation than my other lenses. I seem to recall it being at least 0.5 higher. I never knew why that was the case. Yours is obviously more extreme though.

flyer, I think the OP sounds like he knows what he is doing. Spot metering on the foreground subject when backlit, is exactly the recommended procedure. montman, I assume you focused, exposure locked, and then recomposed for picture 1, or did you use a different af point select, and locked metering point to the AF point?

**montman** · 01-15-2010, 07:58 PM

Again my bad. I should have had the first examples use multi segment metering. ma318 Right after these shots I switched to manual. I have manly been using manual with this lens. For all the shots without the snow I was practicing shooting into the light so again bad examples to use I have found manual to work best when shooting into the light. It’s example there that worries me. Even with the first two examples if it was spotted on the sky, the sky is seems underexposed.

Look at example two, even if it is not spotted on the subject, at EV+2 something in that picture should be completely overexposed but nothing is.

ma318 · 01-15-2010, 07:59 PM

Originally posted by montman

Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10.

One suggestion for a control test. Assuming you have another lens that can shoot at the exact same setting (focal length, aperature) as your DA* 50-135mm, do the following.

1) On a tripod take a test shot with DA* 50-135mm with matrix metering in Av mode in an environment where the lighting does not change. Note down the aperture, shutter speed, ISO, and focal length.

2) Replace the DA* 50-135mm with another lens and shoot the same scene on a tripod in manual mode with same aperture, focal length, shutter speed and ISO.

If the exposure of the two photos are quite different then I guess there may be something wrong with your DA* 50-135mm. Maybe the aperture is not really what it says it should be due to aperture linkage misalignment in the lens???

**montman** · 01-15-2010, 08:10 PM

ma318- I will give that a try tommorow.

ma318 · 01-15-2010, 08:17 PM

Originally posted by montman

Again my bad. I should have had the first examples use multi segment metering. ma318 Right after these shots I switched to manual. I have manly been using manual with this lens. For all the shots without the snow I was practicing shooting into the light so again bad examples to use I have found manual to work best when shooting into the light. It’s example there that worries me. Even with the first two examples if it was spotted on the sky, the sky is seems underexposed.

Look at example two, even if it is not spotted on the subject, at EV+2 something in that picture should be completely overexposed but nothing is.

If you spot on the sky, it will be underexposed because the sky is brighter than 18% gray. The spot meter will always try to set the exposure so that the subject you spot metered on will end up exposed to 18% gray. That's why you have to manually increase compensation probably by 1.5 to 2 stops for the sky.

Here is a link on using spot metering.

What is spot Metering - Spot Metering Examples

Marc Sabatella · 01-15-2010, 10:37 PM

Originally posted by montman

Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10.

No, I don't think so. The sky - which completely dominates this pictures -is being rendered somewhat brighter than 18% gray. I'd say that's pretty much exactly what would be expected when not making any effort to keep the sky from determining exposure. It would be a little darker than 18% gray without the compensation, a little brighter with.

As for shot #2, if the spot was on the brightest part of the image - which it pretty much is - then no, 2 compensation would result in anything at all being blown out.

01-15-2010, 01:10 PM	#1
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576	*EV Problems (Underexposing) w/ DA 50-135mm** I have a K20D and find in my personal opinion it underexposes by about .3. So I just adjust EV by +.3 for all my lenses except the DA* 50-135. I have to set the compensation to about +1.5 or 2.0 to get a decent exposure. I typically shoot with multi segment metering unless I have a subject backlit by the sun I will use spot. Any body else have this problem or know how to fix it? All in all my metering with the DA* 50-135 seems to be very inconsistent.

01-15-2010, 07:59 PM	#12
ma318 Senior Member Join Date: Jul 2009 Location: BC, Canada Photos: Gallery Posts: 174	Originally posted by montman Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10. One suggestion for a control test. Assuming you have another lens that can shoot at the exact same setting (focal length, aperature) as your DA* 50-135mm, do the following. 1) On a tripod take a test shot with DA* 50-135mm with matrix metering in Av mode in an environment where the lighting does not change. Note down the aperture, shutter speed, ISO, and focal length. 2) Replace the DA* 50-135mm with another lens and shoot the same scene on a tripod in manual mode with same aperture, focal length, shutter speed and ISO. If the exposure of the two photos are quite different then I guess there may be something wrong with your DA* 50-135mm. Maybe the aperture is not really what it says it should be due to aperture linkage misalignment in the lens??? Last edited by ma318; 01-15-2010 at 11:19 PM.

01-15-2010, 08:17 PM	#14
ma318 Senior Member Join Date: Jul 2009 Location: BC, Canada Photos: Gallery Posts: 174	Originally posted by montman Again my bad. I should have had the first examples use multi segment metering. ma318 Right after these shots I switched to manual. I have manly been using manual with this lens. For all the shots without the snow I was practicing shooting into the light so again bad examples to use I have found manual to work best when shooting into the light. It’s example there that worries me. Even with the first two examples if it was spotted on the sky, the sky is seems underexposed. Look at example two, even if it is not spotted on the subject, at EV+2 something in that picture should be completely overexposed but nothing is. If you spot on the sky, it will be underexposed because the sky is brighter than 18% gray. The spot meter will always try to set the exposure so that the subject you spot metered on will end up exposed to 18% gray. That's why you have to manually increase compensation probably by 1.5 to 2 stops for the sky. Here is a link on using spot metering. What is spot Metering - Spot Metering Examples Last edited by ma318; 01-15-2010 at 08:28 PM.

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01-15-2010, 02:24 PM	#2
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Can you post shots that demonstrate the problem you are seeing, with EXIF intact?

01-15-2010, 02:36 PM	#3
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Please do, this doesn't sound quite right.

01-15-2010, 02:41 PM	#4
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050	Never experienced such problems with my K20d (but with legacy glass).... Doesn't sound right as Ash said...

01-15-2010, 02:50 PM	#5
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576 Original Poster	I will try to get some shots up with the EXIF tonight. Thanks again for the help.

01-15-2010, 06:36 PM	#6
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576 Original Poster	Ex 1 1/4000 2.8 ISO 200 Aperture Priority EV 0 Spot Ex2 1/800 f2.8 ISO200 Apature Pirority EV+2 Spot Ex3 1/40 F7.1 ISO400 Apature Priority Multi Seg EV +7/10

01-15-2010, 06:56 PM	#7
flyer Veteran Member Join Date: Jan 2008 Location: Ste-Anne des Plaines, Qc., Canada Posts: 2,013	Looking at all the sky included in your pictures, I'd say it's understandable that you need that much compensation. Those aren't good pictures to illustrate your point. You should try to post pictures of the same subject, preferably with more or less balanced lighting, using your different lenses against the 50-135. Then, we could form an opinion and see if you indeed have a problem with your lens or not. On top of that you used spot metering, and metered from the sky. Try it with matrix metering, you'll get better results for that kind of pictures.

01-15-2010, 07:04 PM	#8
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576 Original Poster	Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10.

01-15-2010, 07:20 PM	#9
ma318 Senior Member Join Date: Jul 2009 Location: BC, Canada Photos: Gallery Posts: 174	Originally posted by montman Ex 1 1/4000 2.8 ISO 200 Aperture Priority EV 0 Spot When using spot metering, it may be best to put the camera in manual mode. Then aim the center spot circle in the view finder onto your subject (e.g. on the subject's face). Manually adjust either the shutter speed or aperture so that the spot meter in the view finder indicates +1EV. You need +1EV because Caucasian skin is typically 1 stop brighter than 18% grey. Then recompose and shoot. When using spot metering, you will need to manually compensate for the tone of the subject you are spot metering on - unless its tone is 18% gray. If it is lighter then 18% gray, you have to increase the compensation manually. If it is darker then 18% gray, you have to decrease the compensation manually.

01-15-2010, 07:23 PM	#10
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411	Did you try cleaning the contacts? That seems to be the answer to most things around here. I do recall my DA*'s (16-50 and 50-135) requiring a bit more + compensation than my other lenses. I seem to recall it being at least 0.5 higher. I never knew why that was the case. Yours is obviously more extreme though. flyer, I think the OP sounds like he knows what he is doing. Spot metering on the foreground subject when backlit, is exactly the recommended procedure. montman, I assume you focused, exposure locked, and then recomposed for picture 1, or did you use a different af point select, and locked metering point to the AF point?

01-15-2010, 07:58 PM	#11
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576 Original Poster	Again my bad. I should have had the first examples use multi segment metering. ma318 Right after these shots I switched to manual. I have manly been using manual with this lens. For all the shots without the snow I was practicing shooting into the light so again bad examples to use I have found manual to work best when shooting into the light. It’s example there that worries me. Even with the first two examples if it was spotted on the sky, the sky is seems underexposed. Look at example two, even if it is not spotted on the subject, at EV+2 something in that picture should be completely overexposed but nothing is.

01-15-2010, 08:10 PM	#13
montman Site Supporter Join Date: Dec 2009 Location: Kansas City Photos: Gallery Posts: 576 Original Poster	ma318- I will give that a try tommorow.

01-15-2010, 10:37 PM	#15
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by montman Granted, spot metering is a bad example to use. But look at example three. It is Multi segment metering or Matrix and is very under exposed even with a EV+7/10. No, I don't think so. The sky - which completely dominates this pictures -is being rendered somewhat brighter than 18% gray. I'd say that's pretty much exactly what would be expected when not making any effort to keep the sky from determining exposure. It would be a little darker than 18% gray without the compensation, a little brighter with. As for shot #2, if the spot was on the brightest part of the image - which it pretty much is - then no, 2 compensation would result in anything at all being blown out.