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01-16-2010, 07:37 PM   #1
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K-7 and below average dynamic range

hey all,

I've been looking to purchase a k-7 and via various reviews have noticed that the k-7 always seems to be rated at below average for dynamic range when compared to other cameras in the same category (semi-pro, advanced, etc). This appears especially in the highlight dynamic range where it appears lower than a k20 and from what I read is the most important.

What does this actually mean in a realistic sense?

All in all this camera appears to have everything I need and I strongly prefer this camera over the nikon d300s and even the canon 7d...but this is the one thing thats been bothering me when compaired to the other two.

Could someone enlighten me on this in layman's terms? I'd greatly appreciate it.

thank you all

01-16-2010, 08:38 PM   #2
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It's mostly a matter of getting used to your camera

All current Pentax cameras have a tendency to clip highlights a bit, even the K-X, which uses the same Sony sensor as Nikons. I worried about that with my K20D. What I found is that it's something I got used to and quickly learned to compensate for. Part of the answer is to shoot Raw, which gives you an extra EV or two of dynamic range. I honestly don't understand why someone would buy such a capable camera as the K7 and not do that, but that's my problem.

Anyway, I tend to underexpose about a 3rd of a stop, which generally covers me. I do my main lighting adjustments in ACR. Lightroom uses the same graphics engine. I've gone out on photo shoots with my photo club and have never felt limited compared to owners of other brands. One thing to remember is that the K7 has a wider dynamic range than any photo paper currently available. In that context, I just don't see a problem.

I don't know what kind of shooting you do, but one huge advantage that the high end Pentax cameras have is in auto bracketing for HDR. They allow 5 exposures at 2 full stops compensation each. All other brands with APS sensors only allow steps of one stop. I can let the camera take HDR photos when others have to fiddle with shutter speed between each stop. The next closest camera in capibility and price is the Nikon D300. It only allows 1 stop bracketing but does do 9 exposures, which gives the same total dynamic range. Beyond that you have to buy a full frame sensor camera for more than I'm willing to spend. Hope this helps.

michael mckee
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01-16-2010, 09:16 PM   #3
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Our eye/brain combination is pretty good at seeing a scene that's hard to photograph. One of the limitations is the difference between the brightest and darkest parts of a scene. This often happens in a night scene like this:



This scene in reality has a very wide range of light levels. The difference between the brightest and darkest is called the dynamic range of the scene. The dynamic range of the camera is the difference between the brightest light level and darkest level the camera can capture in one photo. We care about this in digital photography because once the camera is pushed beyond its limits, it quits recording any detail at all. You either get a spot that's totally white or totally black, and there's no way to fix it.

Ideally all digital cameras would have sensors with the dynamic range to match what we see. But they don't yet, and won't for a while. Some films were better than others but today's sensors are more capable than typical color film in the total range they can capture. Film is better in still retaining some detail right at its limits, though, while digital simply stops recording any detail. Range is often expressed in "stops" so it fits in with the other ways we measure light.

With any camera you buy, some scenes will be beyond the sensor's abilities. You'll have to make some choices about what part of the range you want to capture. Because of the way the sensor data is turned into numbers, the best way to do this is to capture a scene's highlights very close to the upper edge of the sensor limit without going over. That's why highlights are important. Also important is the camera's meter, which gives you a measurement of the light in a scene. It's not usually mentioned in testing, but in the real world, a predictable meter reading makes this dynamic range adjustment a lot easier.

Another ignored aspect of dynamic range is whether the output media can actually show the range you captured. It's not as big a problem - once the detail is captured, you can use your processing technique to fit the range into a print or whatever. But you may end up not seeing that extra stop you worried about so much.

Dynamic range is better for RAW images than JPEG because RAW data has more digital information to work with. Also, dynamic range is better at low ISOs, and really plummets at high ISOs. In some cameras, the range is better at one stop above the lowest ISO.
01-17-2010, 06:00 AM   #4
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QuoteOriginally posted by harleynitelite Quote
hey all,

I've been looking to purchase a k-7 and via various reviews have noticed that the k-7 always seems to be rated at below average for dynamic range when compared to other cameras in the same category (semi-pro, advanced, etc). This appears especially in the highlight dynamic range where it appears lower than a k20 and from what I read is the most important.

What does this actually mean in a realistic sense?
In a realistic sense, it means nothing.
In a measurbating sense, it means everything.

01-17-2010, 06:17 AM   #5
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QuoteOriginally posted by Wheatfield Quote
In a realistic sense, it means nothing.
In a measurbating sense, it means everything.
Perfectly stated.

Jason
01-17-2010, 05:08 PM   #6
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QuoteOriginally posted by Jasvox Quote
Perfectly stated.

Jason
My pleasure.
Consider that any digital camera will now do 10 or more stops of DR.
Go out sometime with a spot meter and measure the DR of some common scenes.
You might be surprised at how little DR you actually need.
An awful lot of photography fits into 6 or 7 stops.
If it didn't, slide film wouldn't work.

So what if there is better? It's all good now.
01-17-2010, 07:18 PM   #7
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As mentioned above, the difference between the lightest part of a photo and the darkest part of the photo is the dynamic range. The issue is basically if your camera can capture all the shades of light and dark. If it can't, you have to make a decision as to whether you want to "blow" the highlights or, lose some of the detail in the shadows.

All in all, APS-C cameras are pretty close as far as their ability to do these things. Some are a little better (like the Kx), but over all in most photos you won't see any significant difference. To see a big difference, you need to go up to a bigger sensor (like full frame). I have a K20 and do not feel limited at all.
01-18-2010, 12:19 AM   #8
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I don't feel limited with my K-7 at all...of course there are those out there probably losing sleep over theirs, but then again, they probably don't find themselves actually out composing quality photographs anyway...or ever will, regardless of the body and lens in their hands.

Jason

01-18-2010, 12:39 AM   #9
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QuoteOriginally posted by harleynitelite Quote
What does this actually mean in a realistic sense?
Nothing. If you ever notice that when you look at your prints (preferably A3 and bigger), please be sure to add a message to this thread, as it may be interesting. But I bet, you're not going to have to write such a message in this thread.
01-18-2010, 01:05 AM   #10
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With my K-7, it's dead easy to expose a scene where the highlights in the histogram will just barely come up to the right edge of the screen without actually touching it. Honestly, I never worry about my sensor's dynamic range, I just glance real quick at the histogram and make sure there aren't a bunch of pixels at the right or left edges of the screen. If there are, I change the shutter speed and re-shoot.

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