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08-03-2009, 05:01 AM   #1
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K20d - under- and/or overexposuring?

Hey.

I am wondering if you have any experience of the K20D is having any under- and/or over exposuring problems?

08-03-2009, 06:00 AM   #2
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Nope--mine doesn"t.
08-03-2009, 06:30 AM   #3
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Every camera in the world since photography was invented will under expose or over expose a shot.

It all depends on the user, understanding and expeirence.

Pentax metering leans more toward underexposure to preserve highlights, where as Canon goes the opposite to claim better high ISO's. You just have to learn your lenses and gear to understand how they will work in a given situation.
08-03-2009, 11:16 AM   #4
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Problems? No. But cameras are not mind-readers. There *will* be plenty of occasions when the camera's default chosen exposue won't be to your liking. So you learn the basics of exposure - how to anticipate when compensation will be needed - and also learn how to apply it. For example, any book on photography in the world will explain that shooting a white object or something with a bright background like the sky in it requires positive compensation; conversely shooting black object or something with a dark background requires negative compensation. It's not a "problem" - it's basic SLR photography.

08-03-2009, 11:38 AM   #5
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You are asking this question at a time in the World of Pentax that a fundamental shift in thinking is happening. For many years and many models, ending with the K10/K20, the Pentax cameras has been celebrated on these forums for slightly underexposing. "Saving Highlights" !
The Nikons and Canons were always PooPoo'd by Pentaxians because they tend to expose slightly brighter with some slight tendancy to blow highlights.

Now along comes the K7 and it is very Nikon-esque in its exposure metering. It looks to expose brighter than the K20 and its flash exposures are a lot brighter. The shots posted on the forums look very similar in exposure metering to a Nikon D80 I shoot with on occasion.

I myself prefer the old Pentax way of slightly underexposing... but many of the early adopters of the K7 have now changed the tune a little about exposure metering and are singing the praises of the brighter bias of the new pentax.

What Marc and the others are saying is absolutely true... every situation has its own set of conditions and learning the camera and knowing when and why it will need some exp comp to get the look you want is the most important thing. That advice is true for every camera.

So my answer is yes... the K20 slightly underexposes. And I maintain that for me... that is a good thing.
08-04-2009, 01:33 AM   #6
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The K10 certainly did under-expose. My K20 on the other hand gives me very close to the ideal of ETTR (expose to the right which gives you the maximum amount of data to process into your images. The brightest s-stop contains exactly 1/2 of the total amount of data captured. Even though my preview and histogram indicate a small amount of clipping when the images are opened in LR2 or ACR Bridge using ProPhotoRGB highlights will be intact. This is the way to get the best image quality. You can use Photoshop the convert the image to sRGB or Adobe RGB (whichever your printer can support).
If you print from Lightroom 2.4 you can make a print directly from the camera RAW files. I assume that LR renders the RAW data into a suitable image but you do not have to concern yourself with this. I get my most accurate prints this way and it is worth it to master the learning curve that LR provides.
BTW you also save HDD space as it is not necessary to create another set of files to print from.
08-04-2009, 06:36 AM   #7
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QuoteOriginally posted by HeG Quote
Hey.

I am wondering if you have any experience of the K20D is having any under- and/or over exposuring problems?
I had to watch my K20 like a hawk. Like my K10 and *isdD, it has a really bad habit of being all over the place for exposure.
The K-7, thankfully, seems to have this sorted out.
08-04-2009, 01:11 PM   #8
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The K10 I have to watch a lot -- tends to underexpose considerably if there is anything bright at all in the photo. To me the K20 is spot on most of the time.

08-04-2009, 07:04 PM   #9
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Cameras are inherently stupid. Their metering aims to be predictive based on a secret recipe of matrix metering values, subject distance, and focus point selection. It goes wrong... frequently. Compensation works, but your eyes are too dynamic to give you accurate points of reference regarding how much is enough.
08-04-2009, 08:52 PM   #10
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QuoteOriginally posted by photog Quote
The K10 certainly did under-expose. My K20 on the other hand gives me very close to the ideal of ETTR
ETTR might be ideal from one particular perspective - the goal of minimizing noise - but it isn't the "ideal" in any more general sense. It's usually overexposed by ordinary aesthetic and traditional photographic senses, and usually requires one to then reduce exposure in PP to get a natural-looking photo. And in any case, it definitely is not the "correct" standard exposure - it's just one way of exposing to achieve a particular effect. The international standards for "correct" exposure specify something else entirely - something in which the average is somewhat *left* of center in the histogram, and the right side of the graph may or may not come anywhere near the edge. That is to say, ETTR is not something you should be expecting the camera to be doing for you, and a camera is not underexposing if it doesn't do this. Rather, ETTR is something *you* are supposed to dial in using exposure compensation as necessary, and "correct" exposure is usually a significant amount further left than what ETTR would have.

All of this is to say, it is incorrect to accuse a camera of underexposing simply because it does not use ETTR by default - that is not what a camera is supposed to be trying to do. If you want to use ETTR, you need to learn to dial in the proper amount of compensation to make it happen yourself.
08-05-2009, 04:40 AM   #11
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Original Poster
Thanx for all answers.
If I understand it right the K20d don´t have any exposuring problem, its the user.
08-05-2009, 07:14 AM   #12
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What can confuse many people learning photography is why a camera will react the way it does when exposed to light vs what our eyes see. So assuming you have a new good quality camera (K20D) the dynamic range of the camera is about 6-7 f-stops. And the metering will default to the center of the image even in full multi matrix metering. So you point the camera at a dark object in the center of the image and the bright sky above will look too bright because the camera metered the dark object in the center more accurately. Conversly a bright object in the middle against a dark background will cause the dark area to look darker than your eyes see it.

The difference between your eyes and the camera's meter is the dynamic range. The human eye in combination with the brain's calculation ablity is able to see a range of around 24-25 f stops. The eye alone has a dynamic range of about 14-15 f stops. To put that in perspective, this is exponential. So the eye is much better at adjusting the exposure of any complex image. So it will brighten a dark area and darken a bright area in the same scene. A camera can not do that as effectively.

So you have to learn what is important in high contrasting scenes. Learn how to use the meter to get what you want accurately exposed and in some cases, ignore the rest. Software to a limit will help to recover shadow areas or bring back highlights. But that has limits. ND filters can help as well and also polarizers in some situations.

It's really just a matter of getting to know the camera and how it reacts to any situation. That comes in time and with practice.

Get Brian Peterson's book "Understanding Exposure" and you will know most of what you need to take great photos.

Last edited by Peter Zack; 08-05-2009 at 07:23 AM.
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