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09-24-2007, 05:37 AM   #1
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K10D exposure problems - with KAF lens

Hi,
I just got my K10D, and so far really like it. However, it seems to be underexposing with any lens that I try on it - the kit, screwmount or an old K mount 50mm. I've adjusted the exposure by about a stop and it seems to help. Has anyone else experienced this with new lenses? I know about the problem with the old ones. Is there anyway to make the meter read correctly at the center position?

Thanks,
Eric

09-24-2007, 06:16 AM   #2
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QuoteOriginally posted by mudman Quote
Hi,
I just got my K10D, and so far really like it. However, it seems to be underexposing with any lens that I try on it - the kit, screwmount or an old K mount 50mm. I've adjusted the exposure by about a stop and it seems to help. Has anyone else experienced this with new lenses? I know about the problem with the old ones. Is there anyway to make the meter read correctly at the center position?

Thanks,
Eric
Quick answer, YES....
Where did you get the silly notion it should be "in the middle"???
Re: Shouldn’t the histogram be centered when shooting RAW?: Pentax SLR Talk Forum: Digital Photography Review
It should be like this (with a monotone subject). This is a digital image based on the readings off a hand held spotmeter. 105 is NOT in the middle.

Another thread w/ someone w/ the same misconception....
Please help - K100D - metering issues - am I crazy?: Pentax SLR Talk Forum: Digital Photography Review
09-24-2007, 08:24 AM   #3
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Thanks, this makes sens I guess. It just looked to me when I was looking at the histogram that the shadows weren't getting properly exposed. That link helped alot though. I've always shot film (canon elan 7ne, Pentax Spotmatic F) so getting used to digital is a bit of work.
09-24-2007, 08:24 AM   #4
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QuoteOriginally posted by mudman Quote
Hi,
I just got my K10D, and so far really like it. However, it seems to be underexposing with any lens that I try on it - the kit, screwmount or an old K mount 50mm. I've adjusted the exposure by about a stop and it seems to help. Has anyone else experienced this with new lenses? I know about the problem with the old ones. Is there anyway to make the meter read correctly at the center position?

Thanks,
Eric
It is "normal" for Pentax DSLRs. They tend to underexpose.

The only way to tackle the underexposure problem you experience is to apply +EV exposure compensation whenever you feel it is needed. Remember to check for the histogram to ensure that you have applied a proper amount of correction for each picture, too.

For more read, see:- RiceHigh's Pentax Blog: Underexposure Tendency of K10D and K100D

09-24-2007, 10:52 AM   #5
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QuoteOriginally posted by jeffkrol Quote
Quick answer, YES....
Where did you get the silly notion it should be "in the middle"???
Re: Shouldn’t the histogram be centered when shooting RAW?: Pentax SLR Talk Forum: Digital Photography Review
It should be like this (with a monotone subject). This is a digital image based on the readings off a hand held spotmeter. 105 is NOT in the middle.

Another thread w/ someone w/ the same misconception....
Please help - K100D - metering issues - am I crazy?: Pentax SLR Talk Forum: Digital Photography Review
Is one to infer that you:
A) read something with a spot meter and made a manual exposure from those settings with a K10 in manual mode or
B) read the scene with both a handheld meter and the K10 and are thus comparing the two devices in some fashion or
C) you took a reading with the K10 of the spotmeter and are somehow using it as a monotone subject?

Frankly, I can take a white towel, a gray card or the shadow under a big tree and 'place' any of the three anywhere I want on the histogram-the benefits of understanding exposure! And just as frankly: underexposure is a typical newbie mistake--oops, letting my opinions cloud my responses again...
09-24-2007, 11:07 AM   #6
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QuoteOriginally posted by jfdavis58 Quote
Is one to infer that you:

Frankly, I can take a white towel, a gray card or the shadow under a big tree and 'place' any of the three anywhere I want on the histogram-the benefits of understanding exposure! And just as frankly: underexposure is a typical newbie mistake--oops, letting my opinions cloud my responses again...
If you're referring to me, I'm not exactly a newbie, just new to digital photography. I get paid regularly for my work and I get published for it as well. In a variety of different lighting with a variety of different subjects, I was getting underexposure, and wanted to see if my camera wasn't metering correctly. Try being a little less condescending in your responses, I'm just looking for a little information.
09-24-2007, 11:33 AM   #7
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QuoteOriginally posted by mudman Quote
If you're referring to me, I'm not exactly a newbie, just new to digital photography. I get paid regularly for my work and I get published for it as well. In a variety of different lighting with a variety of different subjects, I was getting underexposure, and wanted to see if my camera wasn't metering correctly. Try being a little less condescending in your responses, I'm just looking for a little information.
Actually he was referring to me I believe and to answer the question the test was done by someone else. Basically take the Sekonic meter, decide on the exposure aperature/speed for that iso and plug it into the camera. Check histogram....
Have no idea what digital camera he used (BUT it's not a Canon w/ their "hot" metering )but it makes little difference: Most likey a Nikon as a wild guess.
Full disclosure here:
DPanswer: Digital Zone System Tutorial
"To be able to use the Zone System on a digital camera, you need to familiarise yourself with how your meter corresponds to your histogram. As a start, make a careful reading of some uniform surface, photograph it, and look at its histogram. You will see a narrow column. With most meters, this column will appear to the left of the center of the histogram.
The example on the right shows the histogram my camera produces when I photograph an uniform gray card, exposed as indicated by spot metering the card with a Sekonic L-778 meter, and processed with "neutral" settings in the RAW converter."
09-24-2007, 11:34 AM   #8
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QuoteOriginally posted by RiceHigh Quote
It is "normal" for Pentax DSLRs. They tend to underexpose.

The only way to tackle the underexposure problem you experience is to apply +EV exposure compensation whenever you feel it is needed. Remember to check for the histogram to ensure that you have applied a proper amount of correction for each picture, too.

For more read, see:- RiceHigh's Pentax Blog: Underexposure Tendency of K10D and K100D
Mudman...please ignore this drivel... it will only cause severe anger

09-24-2007, 11:54 AM   #9
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QuoteOriginally posted by mudman Quote
If you're referring to me, I'm not exactly a newbie, just new to digital photography. I get paid regularly for my work and I get published for it as well. In a variety of different lighting with a variety of different subjects, I was getting underexposure, and wanted to see if my camera wasn't metering correctly. Try being a little less condescending in your responses, I'm just looking for a little information.
I wasn't.

That's nice. Upon what are you basing tthe error in metering?

I not lowering any non-existent standard, nor assuming an air of superiority--information especially experimental results, without a basis are simply noise---we get a lot of that around here. Especially with topics such as this thread.
09-24-2007, 12:01 PM   #10
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QuoteOriginally posted by jeffkrol Quote
Actually he was referring to me I believe and to answer the question the test was done by someone else. Basically take the Sekonic meter, decide on the exposure aperature/speed for that iso and plug it into the camera. Check histogram....
Have no idea what digital camera he used (BUT it's not a Canon w/ their "hot" metering )but it makes little difference: Most likey a Nikon as a wild guess.
Full disclosure here:
DPanswer: Digital Zone System Tutorial
"To be able to use the Zone System on a digital camera, you need to familiarise yourself with how your meter corresponds to your histogram. As a start, make a careful reading of some uniform surface, photograph it, and look at its histogram. You will see a narrow column. With most meters, this column will appear to the left of the center of the histogram.
The example on the right shows the histogram my camera produces when I photograph an uniform gray card, exposed as indicated by spot metering the card with a Sekonic L-778 meter, and processed with "neutral" settings in the RAW converter."
I see; I read that post. Hmmm

It never surprises me (anymore) but it often amuses me, when those who know little (or nothing) about the zone system or those who skew (or misinterpret) the methodology expound exponentially on the topic.
09-24-2007, 12:19 PM   #11
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QuoteOriginally posted by jfdavis58 Quote
I see; I read that post. Hmmm

It never surprises me (anymore) but it often amuses me, when those who know little (or nothing) about the zone system or those who skew (or misinterpret) the methodology expound exponentially on the topic.
Please expand on this: I'm all ears.... Technically I know nothing about the zone system and most of what he writes is basic paraphrasing of others. My only point is most DSLR's, when using a grey card, it's base metering will produce a peak left of dead center (90, 105,110. ect)......if you feel that is incorrect I am also interested in your thoughts.
http://super.nova.org/DPR/ZoneSystem/DigitalZoneSystem.pdf
And jfdavis58 you ARE taking on the air of superiority BTW.... and it's not very subtle...... If you want to correct errors of actually bother yourself to teach something, please do so... nothing worse than a bunch of hmmmf-ing without helping.... that is something we can do without here or anywhere else. Of course we may not be worthy of your "teachings" nor are we paying you for them...
09-24-2007, 12:32 PM   #12
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To teach an introductory class on the Zone System would require several items: (1) about six months assuming a three session (3-4 hours each) per week schedule; (2) about $350.00US from every student; (3) access to Adams' The Negative, White"s New Zone System manual; several hundred rolls of black and white film and associated developers (it's much easier with sheet film and a large format field camera); (4) several hundred sheets of B&W paper and developers;(5) A darkroom, fully equipped, with a densitometer (transmissive and reflective); misc other stuff.

But here's some hints: a gray card ain't 50% reflective (or 28% or 22 or...) except in one light! The Zone System ain't about exposure or exposure theory.

And that begs the question: "exactly where (WHAT VALUE OR GROUP OF VALUES) does a gray card produce a peak on the histogram?" I.e. what would you expect?



QuoteOriginally posted by jeffkrol Quote
Please expand on this: I'm all ears.... Technically I know nothing about the zone system and most of what he writes is basic paraphrasing of others. My only point is most DSLR's, when using a grey card, it's base metering will produce a peak left of dead center (90, 105,110. ect)......if you feel that is incorrect I am also interested in your thoughts.
http://super.nova.org/DPR/ZoneSystem/DigitalZoneSystem.pdf
09-24-2007, 01:53 PM   #13
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QuoteOriginally posted by jfdavis58 Quote
To teach an introductory class on the Zone System would require several items: (1) about six months assuming a three session (3-4 hours each) per week schedule; (2) about $350.00US from every student; (3) access to Adams' The Negative, White"s New Zone System manual; several hundred rolls of black and white film and associated developers (it's much easier with sheet film and a large format field camera); (4) several hundred sheets of B&W paper and developers;(5) A darkroom, fully equipped, with a densitometer (transmissive and reflective); misc other stuff.

But here's some hints: a gray card ain't 50% reflective (or 28% or 22 or...) except in one light! The Zone System ain't about exposure or exposure theory.

And that begs the question: "exactly where (WHAT VALUE OR GROUP OF VALUES) does a gray card produce a peak on the histogram?" I.e. what would you expect?
Well you still peaked my interest as to where the author of the link "fell down".
You may not have to show how to do the zone system but it shouldn't take much work to comment on where he failed....or what he failed to understand.
As to grey cards ect... According to my understanding if you take a photo of a grey card (regardless of light conditions ect) you camera meter will average the exposure to peak around 110 in RGB color space, in gamma 2.2 (sRGB space in other words) but I don't believe this is what you are referring to.
simon brown - Gamma-Correct Rendering

Background to monitor calibration and gamma
And I'm sorry for ever mentioning the zone system. Again not my point nor is any wet chemisty part of the discussion. That said I will finish (actually start) to read the pdf posted (Chuck Gardner "tn explaination of why its not possible to use the Adams' zone system with digital but how range a digital camera can capture can be previsualized" ) in earlier thread that seems to imply the zone system and digital are mutually exclusive (at least according to the title.)..


Addendum: I'm going through the Gardner paper and I (think I) realize what your problem was w/ the zone article I posted. Anyways a few choice tidbits I found interesting:

"Some accused him of bullying Kodak into make 18% gray the standard for its cards when 12% is actually a more accurate value."
"Moving the metering reference point: Since it is the highlight detail which is the benchmark for correct digital
exposure it makes little sense to meter based on a 18% gray value. But since meters are calibrated to display
exposure based on the assumption a scene is the average of light and dark it is necessary to translate the meter
reading from the middle of the range to textured highlights. It's erroneous to think the meter reads Zone 5 and its
simply a matter reading the towel and adding 3 stops to get the reading for correctly reproducing the towel as Zone 8
on the print."
If you still think that you still don't get it.
"ZONES ARE NOT F- STOPS!!! It will be far less confusing if you forget you ever heard of the zone system and instead think in terms of brightest and darkest tone with detail: DS and DH.
In digital pre-visualization system the white towel becomes the benchmark DH and exposure in all subsequent test"
And my favorite:
Why is mid-tone adjustment significant in digital photography?
The inherent nature of the capture process often results in a digital image which appears to have less contrast than
when the scene was viewed by eye. Because the dynamic range of a given camera is fixed it is not possible to
expand the overall range of the capture (i.e. add more shadow detail to the captured image) but by shifting the tonal
value of the midtones closer to either the highlights or shadows it is possible to create more or less apparent contrast
and with it an illusion of more detail. For example if one takes a flat looking image, opens it in levels and does nothing
more than nudge the middle sider towards the right side (highlight end) of the tonal scale the image will appear to
have more contrast and detail. There is no actual increase in resolution, but eye is fooling into thinking there is
because our brains equate darker shadow transitions with dimension and detail............"

Last edited by jeffkrol; 09-24-2007 at 04:50 PM.
09-25-2007, 12:16 AM   #14
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Personally - I meter just like I did with slide film - for the highlights. Digital and slide film share the same basic characteristic, if you blow out the highlights then there is nothing to recover. A pixel, or set of pixels that are pure 255 is just as clear as acetate. Print film, on the other hand, the highlights are black (remember the paper is already white – if no light gets to the paper, then it is white). Expose for the highlights (which just might explain why the so called peak of the histogram is to the left in the example).

Oh – and to add some more fuel to the fire about a zone system (not to be confused with “the” zone system), try this site.

Zone System: Digital / 35mm / Medium Format!

The site needs to be updated (equipment wise) but in general, I always try to meter in such a way that what I would want as a mid tone in a B&W image dominates the metering area in the viewfinder.

PDL

Last edited by PDL; 09-25-2007 at 12:18 AM. Reason: added print film stuff.
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