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04-10-2008, 01:47 PM   #1
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K10D underexposure + Pentax Colorado

Has anyone sent their K10D in for this? I sent mine in and they just sent it back out, I should get it on Monday....I'm dying to see if they fixed it.

04-10-2008, 04:53 PM   #2
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Sorry, got to ask

QuoteOriginally posted by jshurak Quote
Has anyone sent their K10D in for this? I sent mine in and they just sent it back out, I should get it on Monday....I'm dying to see if they fixed it.
Which one of your K10's are you talking about?
If I in any way I understand from your previous threads, you have 2 K10's that expose the same but "underexpose" by a stop????
How did you conclude that they underexpose in the first place?
I'll take a giant leap here and say that your soon to be retuned camera will expose roughly the same as when you sent it in.... MAYBE you'll gain a 1/2 stop....
04-11-2008, 06:15 AM   #3
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QuoteOriginally posted by jeffkrol Quote
Which one of your K10's are you talking about?
If I in any way I understand from your previous threads, you have 2 K10's that expose the same but "underexpose" by a stop????
How did you conclude that they underexpose in the first place?
I'll take a giant leap here and say that your soon to be retuned camera will expose roughly the same as when you sent it in.... MAYBE you'll gain a 1/2 stop....
you're correct in your understanding.


we'll see. I'm willing to take that giant leap myself. I determined that they underexposed images by viewing the histogram and the fact that I have to bump up the exposure for every image in PP. I'm going to run some tests and maybe post some results along with the corresponding histograms
04-11-2008, 06:54 AM   #4
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QuoteOriginally posted by jshurak Quote
you're correct in your understanding.


we'll see. I'm willing to take that giant leap myself. I determined that they underexposed images by viewing the histogram and the fact that I have to bump up the exposure for every image in PP. I'm going to run some tests and maybe post some results along with the corresponding histograms
If you photograph a "white wall" or any such monotone object and the peak in the histogram
is left of dead center (in a photo editor an eyedropper will report it at level 110 approx) then the meter is calibrated correctly to my understanding. Some cameras (like the D. To be honest there are D's that are higher but at the time of this old issue they were mostly in the southern hemisphere, long story ) are about a half stop under that (peak at 90, about a 1/2 stop below 110). When my D was serviced it was recalibrated and came back w/ the peak as it was when it was sent in (90ish). There are a million threads on this "issue" BTW.
Most of the confusion stems from the fact that Canon fudged their iso so as to produce a "centered" calibration point without the meter itself using f stops/shutter speeds thst were different from a hand held calibrated meter.
For that history see (pg 18-19 in particular):
http://doug.kerr.home.att.net/pumpkin/Exposure_Calibration.pdf
And if you shot negative film, your "Processor" would have automatically adjusted the development time so you would never see the true exposure.
Without user intervention or setting the camera bright/contrast ect. it is not unusual to see
some need for exposure compensation. Personally contrast is more the key then exposure adjustment. The histogram is "bunched" and opening it up (changing white point) is the easist thing to do. Just my 2 cents.
For more esoteric reading re: light meters and calibration:
http://doug.kerr.home.att.net/pumpkin/Exposure_metering_18.pdf
Meters Don't See 18% Gray by Thom Hogan
Articles by Doug Kerr


Last edited by jeffkrol; 04-11-2008 at 07:06 AM.
04-11-2008, 08:08 AM   #5
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jshurak,

Well, I'm in the same situation as you. Despite all of the discussion on "correct" metering the bottom line is that most of my pictures come out dark. This is the main reason I'm shooting in RAW now. It's easy to adjust to look the way I think it should look. I guess we were all blissfully ignorant shooting film when the processor corrected all of our underexposed photos!
I'm using Rawtherapee and tend to bump up exposure comp and brightness equally until it looks right. Then, a little histogram tweak in Paint Shop Pro and they look great.
04-11-2008, 08:21 AM   #6
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QuoteOriginally posted by Workingdog Quote
jshurak,

Well, I'm in the same situation as you. Despite all of the discussion on "correct" metering the bottom line is that most of my pictures come out dark. This is the main reason I'm shooting in RAW now. It's easy to adjust to look the way I think it should look. I guess we were all blissfully ignorant shooting film when the processor corrected all of our underexposed photos!
I'm using Rawtherapee and tend to bump up exposure comp and brightness equally until it looks right. Then, a little histogram tweak in Paint Shop Pro and they look great.
my sentiments exactly. If my camera comes back exposing exactly the same as before, I'm obviously not going to send my second body in.

If this was this situation with film and it was always handled by processors, camera manufacturers should take that into consideration and calibrate the meter appropriately.
04-11-2008, 08:45 AM   #7
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Normal or not, shots bunched to the left use alot less available levels and are more subject to banding. I just wish there was a global exposure compensation setting.
04-11-2008, 10:37 AM   #8
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QuoteOriginally posted by Geekybiker Quote
Normal or not, shots bunched to the left use alot less available levels and are more subject to banding. I just wish there was a global exposure compensation setting.
what's the difference between global exposure compensation and regular exposure compensation?

04-11-2008, 11:10 AM   #9
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in reguards to underexposure...
I have heard that it is better to underexpose rather than over expose. Something to do with "blowing" the highlights.. is this accurate?
04-11-2008, 11:12 AM   #10
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QuoteOriginally posted by jshurak Quote
what's the difference between global exposure compensation and regular exposure compensation?
Nikon did this w/ some of their new models (D300 I believe, saw the manual). Basically it's like exp comp that is applied to all metering modes ect. It's not visible and can only be turned off (or adjusted) in a menu item.
Nikon manual recommends using it at your own risk.
Basically it's like being able to calibrate the meter yourself.....
pg 277-278
Nikon D300 | User Manual Download
Small edit: Apparently you can "tune" each type of metering (spot ect.) individually so it's only semi-global
Exposure CAN be Fine Tuned! Why is this an issue?: Nikon D300/D200/D100 Forum: Digital Photography Review

Last edited by jeffkrol; 04-11-2008 at 11:54 AM.
04-11-2008, 11:47 AM   #11
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QuoteOriginally posted by madisonphotogrl Quote
in reguards to underexposure...
I have heard that it is better to underexpose rather than over expose. Something to do with "blowing" the highlights.. is this accurate?
this is true. but i thinks its better to 'properly' expose than to underexpose!

QuoteOriginally posted by jeffkrol Quote
Nikon did this w/ some of their new models (D300 I believe, saw the manual). Basically it's like exp comp that is applied to all metering modes ect. It's not visible and can only be turned off (or adjusted) in a menu item.
Nikon manual recommends using it at your own risk.
Basically it's like being able to calibrate the meter yourself.....
The K10D does this as well. I noticed this as a result from an earlier thread I started about exposure bracketing. I never turned on EV compensation on my newer body. It was exposing 'properly' so I never even thought twice about it. I shoot in 99% manual exposure mode, so the thought of EV comp never even crossed my mind. then I started auto bracketing for exposure and saw that the meter began is 0 exposure at 1 stop above the center of the meter.

I switched exposure mode to a program mode and check EV comp....sure enough it was set at +1. When I set it to 0, everything i shot, no matter the exposure mode, was 1 stop under.
04-11-2008, 12:58 PM   #12
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QuoteOriginally posted by jshurak Quote
The K10D does this as well.

I switched exposure mode to a program mode and check EV comp....sure enough it was set at +1. When I set it to 0, everything i shot, no matter the exposure mode, was 1 stop under.
Well sort of. What I am talking about is a setting so your EV comp dial is still zero'd. If you leave it at

+2/3-1 like mine normally is, you only have a range of +1 to -3 from the correct exposure insteal of the +-2 ev like you should have.
04-11-2008, 05:09 PM   #13
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QuoteOriginally posted by Geekybiker Quote
Well sort of. What I am talking about is a setting so your EV comp dial is still zero'd. If you leave it at

+2/3-1 like mine normally is, you only have a range of +1 to -3 from the correct exposure insteal of the +-2 ev like you should have.

you've got a point, but I rarely shoot outside of manual mode so it's not that big of a deal to me, but I certainly how limiting this can be in other modes.

I'm really interested to see what the exposure is like when I get the camera back on Monday. Jeff had a good point and if that is the case, sending it to Pentax was pretty much a waste of time.....I shoot in RAW, I wonder if the jpg gets corrected in camera....
04-11-2008, 09:01 PM   #14
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QuoteOriginally posted by madisonphotogrl Quote
in reguards to underexposure...
I have heard that it is better to underexpose rather than over expose. Something to do with "blowing" the highlights.. is this accurate?
That is left over from slide film days, particularly the slow ones. The best results I have come up with are using a technique called Expose To The Right (ETTR). There are several threads on the forum for you to peruse.

You want to expose to use up every available light level, because the largest gradations are in the highlights, not the shadows. Underexposed shadows are where we find digital noise. My solution to this is to turn on the "blinkies", the flashing over/under exposure warnings, and bring the exposure up to where I get one or two tiny blinks in specular highlights where I expect no detail.

I'm still working on this, but am getting good exposures by setting my camera to the "Sunny 16" exposure when I can. These are the ones that used to be printed on the little piece of paper in the film carton, then were printed on the carton, and now we don't get anymore without film. The basic exposure in bright sunlight for an "average" scene is f/16 at 1/ISO. Bright cloudy, use f/8. Cloudy use f/5.6, etc.
04-11-2008, 10:10 PM   #15
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Exposing to the right for the most tones

Here's a few very well written articles explaining exposing to the right and way you'd want to do that.

I'm new to the Pentax Digital Line, but been started shooting Raw 10 years ago with Leaf and Phase One backs on my Sinar LF.

Underexposing in digital is bad ('mm kay) Blowing the highlights in all 3 channels is bad ('mm kay)
So you'd want an exposure that is just this side of not being entirely clipped. If you are shooting raw, and using Lightroom, or another ACR shell, then you can restore the highlight detail, even if you blow one or two of the highlight channels. Of course it's best to not clip any channel in your highlight, but it can be recovered if you have info left in one or two of them.

You don't want your histogram to be in the middle or to the left, when you adjust your exposure in post, you will be left with more noise, banding, and beginning to posterize, and you're ultimately left with an image that just doesn't have the tonal information to make a decent print.

Here's a short article on the "sunny 16 rule" and exposure in general

Understanding-Exposure

Here's a short article on Histograms

Understanding Histograms


Here's an article on the "exposing to the right" theory

Expose Right


Here's one on restoring clipped highlights using a saturation mask in photoshop

Restore Those Clipped Channels

In Lightroom, there's a slider to restore highlights (again works best if there's info in 1 or 2 channels)

I'm merely posting these links and opinions, in case any of you are interested in exploring this further (proper digital exposure), everyone has to figure out what works best with their style and workflow and gives them the best results. But most of the digital photography books that deal with RAW and Photoshop books that deal with RAW goes into this as well and some with more detail. When I started in digital, I shot fabrics and clothes, and had a very bad time with noise, banding, you name it. It never occurred to me to shoot like this (I was used to shooting transparencies) But then I read a book that suggested this and what I looked at on my computer looked awful, until I made my final adjustments, then I wound up with images that had a much richer, vibrant and much extended tonal range, and finally getting rid of my worst problems. Digital sensors are much much better today, but I think it is still good to at least know about this and have it available as a tool you can use if and when you need it. I know a lot of photographers who expose like this all the time for every image, and I try to do the same myself.

I admit that my underexposed images look real nice on my screen, but I still do a lot of catalog and print work, and the difference at that point is literally night and day (especially in CMYK 4-color process, Yuk). If I was shooting for the web on the other hand, I wouldn't bother with it at all.

happy reading!
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