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01-20-2008, 03:49 AM   #1
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Urgent problem: Inconsistency in noise level with K10D

Hello all,

I need an urgent advise & help:

I own the K10D & use it mainly for birding purposes, together with the SIGMA 135-400 APO tele lense.

Although the problen occurs with other lenses as well & even with
Pentax 75-300 lense, I'm only intersted in the Sigma 135-400 for now.

The noise level of photos produced by the camera, mainly in the 400 mm focal length,
are in most cases very very very noisy even under excellent conditions Ie. normal bright daylight, Iso 100, and shutter speed of 500. The noise is most noticeable on dark or shady areas in photo taken or on contrast sky or other backgrounds.

Of course I've read of such phenomenon once in many posts here & on other Pentax forums, but my case is even stranger:
There are times and cases, using the very same conditions & camera parameters (I don't even tend to change them ever !) as mantioned before,
and even in the worst cases (Low light, Iso 160, Shutter speed 60 & such) the noise level is strangly very minor or even unnoticeable at all !!!!

I can't seem to understand or to reproduce anything I may have done to cause
this phenomenon, since I always discover it after a day's shooting out in the wild,
producing as much as nearly 600-700 shots a day...

Did someone encountered such a phenomenon before ????
Either with Sigma or any lenses ???
Did someone encountered any Inconsistencies in the K10D performance or output ???

Please advise, since I can't even pinpoint that as a camera malfunction & claim it's repair according to warrenty terms ...

Thank you all ...

01-20-2008, 06:11 AM   #2
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Can you post some examples with exif?
01-20-2008, 06:56 AM   #3
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I agree with Alan, we need the full EXIF from your images. I'd like to see what the internal temperature of the camera was for the noisy vs clean shots.

You can get a free EXIF viewer here that will export the entire EXIF as a text file, then post it here.
01-20-2008, 07:58 AM   #4
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I've attached a couple of samples to my problem.
To eliminate the sensor over heating case,
both shots were taken on 2 consecutive days, and on both these days,
the camera took only 12 shots all together.

Both shots were taken in the same place - my back yard
& on the same lighting condition - poor light.

Both pictures were edited as such:
1. Converted from RAW to JPG
2. Brighten a bit
3. Resized to 1024 X 685 pixels

The first one is noisy as hell:


The second one is almost noise free:


I'd appreciate any suggestions you may have ...


Last edited by Cannon-S2; 01-20-2008 at 08:36 AM.
01-20-2008, 08:42 AM   #5
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Need to see the RAW files to see what the original exposure was. I briefly saw a VERY dark version of the first image, but it disappeared. It looked like it was underexposed about 3 stops. If you push an image 3 stops you can expect to see noise in the result, even at ISO 100.

One thing I did notice ... you used about the same exposure for both shots but there is sunshine in the 2nd one and not the 1st. Off the top of my head I would say the 1st shot was seriously underexposed.

Last edited by Rickster; 01-20-2008 at 08:49 AM.
01-20-2008, 08:57 AM   #6
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I agree with the previous posts that the noise you're experiencing is due to inconsistent exposure. I noticed you're using spot metering and unless you have a good bit of experience, spot metering can cause lots of problems. You can try this experiment: put the camera on spot metering and Av mode (aperture priority mode). Pick a typical scene and move the camera around just slightly while keeping an eye on the shutter speed. I would guess that you'll be surprised at how much the shutter speed will vary.

My suggestion would be to use centerweighted metering and learn how much exposure compensation you need for different situations & subjects.
01-20-2008, 10:01 AM   #7
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Thanks for your kind replies but:

1. I cannot seem to be able to upload the 10 Mbytes raw files (Each) anywhere in the internet,
that is why I've converted both to JPG & also adited them a bit...
If you can suggest where I can upload the files, even temporary,
I'd appreciate it very much.
The temporary photo you've seen momentarily, Was a trial upload,
but it failed.

2. I use the spot metering since I ususly photograph birs, which are very far away,
& mostly I crop my photos, therefore the exposed subject (The bird) occupies only
the center of the view finder, the SPOT area. The other methods of exposure
fail every time.

3. Although seem otherwise, I can assure you that light conditions during the 2 shots
were almost the same, Even more, the noise free photo used even slower
shutter speed than the noisiest one (80 instead of 125).
01-20-2008, 10:11 AM   #8
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QuoteOriginally posted by Cannon-S2 Quote
Thanks for your kind replies but:

1. I cannot seem to be able to upload the 10 Mbytes raw files (Each) anywhere in the internet,
that is why I've converted both to JPG & also adited them a bit...
If you can suggest where I can upload the files, even temporary,
I'd appreciate it very much.
The temporary photo you've seen momentarily, Was a trial upload,
but it failed.

2. I use the spot metering since I ususly photograph birs, which are very far away,
& mostly I crop my photos, therefore the exposed subject (The bird) occupies only
the center of the view finder, the SPOT area. The other methods of exposure
fail every time.

3. Although seem otherwise, I can assure you that light conditions during the 2 shots
were almost the same, Even more, the noise free photo used even slower
shutter speed than the noisiest one (80 instead of 125).
PM sent to you regarding files

01-20-2008, 10:29 AM   #9
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QuoteOriginally posted by Cannon-S2 Quote
Thanks for your kind replies but:
3. Although seem otherwise, I can assure you that light conditions during the 2 shots
were almost the same, Even more, the noise free photo used even slower
shutter speed than the noisiest one (80 instead of 125).
I noticed the noisier image was shot at 100/f8.0/ISO125 while the cleaner image was shot at 80/f7.1/ISO125 so the cleaner image already has 2/3 of a stop more light, assuming EXACTLY the same light. But I also noticed that the cleaner image shows direct sunlight while the noisier image does not have any direct sunlight so I'm assuming that even if the images were taken within seconds of each other, they were not shot under the same lighting conditions. Remember your basic exposure lessons and the fact that direct sunlight is several stop brighter than flat light and/or shade.
01-20-2008, 12:07 PM   #10
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Even a bit of banding seems to be there, and that usually indicates severely underexposed pictures. My guess is that you need to let in more light.
01-20-2008, 11:55 PM   #11
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Again, thanks all for willingness
& again, according to your given opinions/answers I must have explained it all wrong.

I'll try once more:

1. The original shots were taken in 2 consecutive days, without the camera
over stressing/heating itself (total of 12 shots all together)

2. I could not upload the original PEF files due to size limits, therefore I croped

a small area out of them (something like 15% or so), than manualy, using PSP12 brigthen them a bit (Well maybe more than a bit, but both with the same brightening values), Converted the files to JPG and uploaded them without any JPG compression at all, namely 100% save of the original crop.

This is the reason that when examining the EXIF data, both attached examples seem to have the the same time & date.

3. I know all about exposure compensation, and that it actualy means increasing ISO value, and I dont complain about that, nither about the fact that there's a certain amount of noise in pictures, I complain about the fact that since both shots were taken with the same camera, with almost idetincal lighting conditions, & almost the same in-camera settings there is such a major difference in noise level.

Furthermore the 2 attached examples, are only symptoms to a phenomenon that I can't explain nor control in real life shooting.
The noise level of output shots from camera vary so much, even in the same

shooting session (I just could't find more examples in such a short notice, therefore I've attached only these) and it drives me crazy !!!!
01-21-2008, 12:35 AM   #12
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To get to the bottom of this I suggest you do some testing in a more controlled manner than under “almost” identical light and “almost” identical settings at almost the same subject. There are to many differences in these pictures to compare the results and draw any valid conclusions imho.
01-21-2008, 06:36 AM   #13
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QuoteOriginally posted by Cannon-S2 Quote

I complain about the fact that since both shots were taken with the same camera, with almost idetincal lighting conditions, & almost the same in-camera settings there is such a major difference in noise level.

Furthermore the 2 attached examples, are only symptoms to a phenomenon that I can't explain nor control in real life shooting.
The noise level of output shots from camera vary so much, even in the same

shooting session (I just could't find more examples in such a short notice, therefore I've attached only these) and it drives me crazy !!!!
Our eyes have an average dynamic range of 10000:1 or better. They can easily adjust their gain for varying light conditions. Because the human eye can adapt to a huge difference in light you were fooled into thinking you had similar light conditions on two different days. But the evidence in your images says thats not true. To put this to bed you either have to show us the images as they came out of your camera with no editing or do as the poster above suggested, make some controlled tests. Good luck.
01-21-2008, 06:44 AM   #14
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(C&P from dpreview)

This statement makes no sense and leads me to believe you are missing some fundamental understanding of photography and exposure/light.

QuoteQuote:
> 3. Since light condition under the tree i use to photograph birds are
> poor light
> and I don't want to increase ISO value, I use the maximum exposure
> compansation instead


If you shot MANUAL mode, EC has no bearing on anything. Do you mean you used EC in PSP during post-processing? I think what happened was is you guestimated some settings out in the field that got you a somewhat dark picture. And then on the computer, you boosted them up TWO STOPS (which is quite a bit, not just "brighten a little") Going by the EXIF of the two shots, the second shot had a highter EV (I think it was 1/80 @f7.1 vs. 1/100s @f/8), so the massive 2-stop push in post revealed more noise in the first shot as it was probably darker to begin with.

So I URGENTLY suggest you pick up a book or two on the basics of exposure. Bryan Peterson's "Understanding Exposure" helped me get a handle on all this stuff.

Forget manual mode for now, and don't be afraid to bump the ISO up to 400, and shake reduction will be a great help if you still get borderline shutter speeds.
01-21-2008, 06:47 AM   #15
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As for EC=raising the ISO value, are you talking about IN CAMERA EC? Or moving the slider in PSP?

In camera exposure compensation is not raising the ISO. In Av mode, +EC keeps the shutter open twice as long, and in Tv +EC opens up the aperture a stop (keeping ISO and the other parameter constant)


Again, you are most likely WAY UNDEREXPOSING and pushing too far in post.
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