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08-20-2008, 01:47 AM   #1
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Noise at low ISO in k200d

I would like to ask if it is normal to experience relatively high amount of noise at low ISO settings using k200d. I was taking some pictures at 200 ISO in the mountains (kit lens + UV filter + dark and cloudy day) and I noticed that dark areas in ALL pictures (not only those underexposed) are very noisy. I shot in RAW and JPEG and both are really bad. I compared pictures with those on the web taken by the same camera + lens and same or similar settings and they're much better. Even after quite harsh noise removal situation is far from perfect (not mentioning that very soft after such processing). Interestingly my previous pictures (mostly at ISO 100) are almost noise-free. I will post samples as soon as I will come back home (+/- 9 h). My camera is only one month old and apart from noise in great condition. Could you post some suggestions and ideas how I can test my camera in case I will have to prove dealer that something is wrong with it.

ATB,

Pusiek

08-20-2008, 03:15 AM   #2
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Best to post some photo examples of the noise with EXIF data.
Most common cause - underexposure. At ISO 200, you really should not have noticeable noise unless underexposure compels your PP program to push exposure up by more than a stop to get a decent image.

On dark days with highlights that may trick the meter, try spot metering to get the exposure right the first time, then see your results.
08-20-2008, 03:43 AM   #3
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Bet your filter is the culprit

You may be seeing the results of under exposure AND the UV filter. In my film days, even though I can't remember ever touching it, I always had a UV filter on my lens for "protection." Since migrating to the DSLR, I've found that the extra glass of a filter negatively affected IQ.

Go 'filter-less' for a while to see if that helps.

Enjoy...
08-20-2008, 05:13 AM   #4
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Try pushing the EV up about 2/3 stop. My K10D (same sensor) has way less noise with this adjustment due to less underexposure.

08-20-2008, 05:01 PM   #5
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Finally I managed to upload few pictures for noise evaluation. First three are shot in jpeg (default k200d settings). Last two are RAW converted to tiff by Ligthroom 1.4 (default settings) then saved as jpeg by photoshop (max quality, baseline optimized). All are 100% crops. I have to correct the information about ISO. It was set to 400 not 200. Still, according to some reviews almost no noise supposed to be visible at 400 ISO. Tomorrow, I will try to do some tests with corrected exposure and UV filter taken off.



1/750s, f5.6, 18mm


1/350s, f5.6, 26mm


1/180s, f5.6, 55mm


1/125s, f5.6, 31mm


1/4000s, f5.6, 45mm
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08-20-2008, 05:03 PM   #6
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Sorry for doubling the pictures. I wasn't sure how the uploading system works.
08-20-2008, 06:16 PM   #7
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They look pretty normal to me - as in, that's about the amount of deep shadow noise I expect at ISO 400. The most underexposed images look the worst, and that's normal too.
08-24-2008, 11:24 AM   #8
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Thank you for all the suggestions. It is really nice to know that there is always someone on the forum willing to reply. I hope that the thread is not too old to upload additional examples and expect reply. This time no UV filter, 100% crops, first two 100 ISO, f6.7, 43 mm, s + s and last two 200 ISO, f6.7, 43 mm, s + 1 s. First one in each set is properly exposed and second is +1 EV. Pictures are overall properly exposed (the histogram is not shifted towards darker values). Again the question remains if that is a standard amount of noise. This time the post processing values are set to zero except a small amount of colour noise reduction. Same program and jpeg settings as previously.

Attached Images
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PENTAX K200D  Photo 
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08-24-2008, 01:23 PM   #9
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Despite the blur, I'm hard pressed to find the noise.
They all look OK.
Really, as long as you've not underexposed a shot and expected to boost the exposure up with your PP program to get a good picture, you should get very little noticeable noise at 100% until perhaps at ISO 500 and above.

And it's not necessarily that low-key images or shadow areas will show noise, it's more in situations where you have shadow detail that you want to 'push' to expose the image better where you'll run into obvious colour noise - even at ISO 100.
08-24-2008, 02:01 PM   #10
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Ok, Again thanks. I am just little paranoid Please forgive me I just bought my first DSLR and after using a film camera I am suspicious. My sensitive eyes have to accept what I see and take it for a standard
08-24-2008, 02:53 PM   #11
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QuoteOriginally posted by Pusiek Quote
Ok, Again thanks. I am just little paranoid Please forgive me I just bought my first DSLR and after using a film camera I am suspicious. My sensitive eyes have to accept what I see and take it for a standard
You also have to remember that with film, you probably rarely if ever blew up an image as large as a 100% crop. The very nature of digital encourages you to "pixel peep" and see things that would have been there with film if you ever looked *that* closely, but hardly anyone ever did.

Anyhow, I agree - the last set of images don't look particularly noisy to me at all. They look *underexposed*, but presumably this is the darkest area of a picture that had much brighter areas too. They also look generally devoid of detail. That would be partially due to how underexposed those areas of the picture are, and perhaps partially due to the lens used not being the sharpest glass on the block.
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