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08-31-2008, 11:14 AM   #1
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K20D Timed Exposure Review Lag?

I'm not sure if the subject title is correct, but what I'm trying to ask is do any other K20D users out there that have done time exposures find that there is a long delay in the image being processed?

I shot an image that was 11 sec and it took 4-5 secs for the image to appear for review. When I shot with the K100D before that was one of the annoying things, it would take so long for the processing. My friends that have a XTI and D80 didn't have this problem when I was shooting with them, it would appear almost instantaneous. I thought with a higher performer like the K20D, that I wouldn't have to deal with a problem like anymore.

Maybe any previous D80 or XTI can chime and say I'm on crack and it does the same thing as the K20D.

Thanks.

08-31-2008, 11:40 AM   #2
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QuoteOriginally posted by nah Quote
I'm not sure if the subject title is correct, but what I'm trying to ask is do any other K20D users out there that have done time exposures find that there is a long delay in the image being processed?

I shot an image that was 11 sec and it took 4-5 secs for the image to appear for review.
Only 4-5 seconds? You sure it isn't exactly 11 seconds? Most DSLRs have a noise reduction mode that kicks in for long exposure in which a second picture is taken at the same shutter speed but with the shutter closed, to see where hot pixels might appear so they can be removed from the actual picture. So the camera is not actually "processing" the image during that time - it's taking another picture. On most Pentax cameras, this can be turned off via a custom menu, but apparently on the K20D it cannot (I'm guessing noise would be just be so bad they decided it wouldn't be worth even giving users the option).

QuoteQuote:
Maybe any previous D80 or XTI can chime and say I'm on crack and it does the same thing as the K20D.
I'm sure they must provide the option for this form of noise reduction, but your friends presumably had it turned off.
08-31-2008, 11:42 AM   #3
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You don't have to be a D80 or XTI user to know what the fig is going on.

Dark frame subtraction noise reduction is what's going on. The camera takes a second exposure of equal length to the first one, with the shutter closed, and subtracts the noise of the second frame from the first frame. Although it takes longer, it is a far better method than the one used on Canikons: mapping out hot pixels.

It works great for particularly long exposures (10 min. or more; though you would need 20 minutes to take one picture).

EDIT: Marc was faster than me. You can disable this function from your camera's custom menu.
08-31-2008, 01:04 PM   #4
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It can't be disabled on the K20D. That stinks.

08-31-2008, 02:31 PM   #5
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Thanks for the reply guys! I didn't quite understand what was going on, it's pretty annoying that you can't turn it off.

When I take a shot that's 4 sec shot, it's pretty instantaneous though. The time it takes to appear on the screen doesn't equal the timed exposure. I just did a 20 sec test and it was there in in roughly 10 secs. I did a 10 sec test right now and it was pretty instantaneous. I'm guessing it was to do with what is being shot.
08-31-2008, 03:46 PM   #6
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What you see on the screen is not exactly what is saved on the card when you shoot RAW. The screen shows a JPEG representation of the RAW file, so that might explain the difference. When I have a chance, I'll try with my camera to check if same thing happens.
08-31-2008, 11:29 PM   #7
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I was actually shooting jpeg for the test. I'd like to know your results after your tests.
09-02-2008, 12:37 AM   #8
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QuoteOriginally posted by flyer Quote
It can't be disabled on the K20D. That stinks.
Strange, I turned off noise reduction/etc
Maybe Im not referring to the same thing. Do you have firmware 1.01 on there?
mmm

09-02-2008, 08:25 AM   #9
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QuoteOriginally posted by marlon Quote
Strange, I turned off noise reduction/etc
Maybe Im not referring to the same thing. Do you have firmware 1.01 on there?
mmm
The NR you case turn off is "high ISO" noise reducation - the ordinary sort that is also normally done via PP. The NR you *can't* turn off on the K20D (but can on other Pentax DSLR's) is the slow shutter speed NR that works by taking a second picture with shutter closed - the "dark frame subtraction" method.

I'm surprised to hear it isn't taking exactly as long as the original exposure, but mabe they've tweaked it on the K20D to not require as long, because they didn't want to annoy users too much at the fact it couldn't be turned off? I'm also guessing if they didn't provide a way to turn it off, it's because the results would have been unusably noisy without this.
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