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Is this kind of unusually high noise expected for K-x at ISO 400 ?

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I think your problem is more bad light than noise.
Why are you shooting at 1/1600?
--
Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright
 
Wow, never saw output from a K-x like that but your exposure and lighting is not the greatest. I take up to 6400 and never have had a problem with it being too noisy. This one was JPG no PP:





--
Jim
 
Full exif details might provide some clue to arrive at the solution for this problem
R.Raghu
--
'The Photographer reveals the light;the light reveals the picture'--C.Rajagopal.
A picture should communicate with our heart.
Efzee-50 & Foojee F 31fd---Polaroid X-530

 
Aperture priority, camera selected that

EXIF Details

Result
File size : 1108330 Bytes
MIME type : image/jpeg
Image size : 2848 x 871
Camera make : PENTAX
Camera model : PENTAX K-x
Image timestamp : 2011:09:26 18:19:20
Image number :
Exposure time : 1/1600 s
Aperture : F5.6
Exposure bias : 0
Flash : No, compulsory
Flash bias :
Focal length : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed : 400
Exposure mode : Aperture priority
Metering mode : Center weighted average
Macro mode :
Image quality :
Exif Resolution : 2848 x 871
White balance : Auto
Thumbnail : None
Copyright : PHOTOLEET
Exif comment :
ozdean said:
I think your problem is more bad light than noise.
Why are you shooting at 1/1600?
--
Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright
Click to expand...
--
My Flickr Photostream - http://www.flickr.com/photos/photoleet
 
With an exposure range 0-255 your image hits a median of 21.

I decent exposure should be around 200 for this DR of this shot.

SO you image is approx 4 stops under exposed, The Noise is appropriate for this exposure and is actually quite good for how badly exposed the shot is.

You've hit the Noise floor for an exposure in the iso 3200 range.

The image would have been considerably improved by increasing the iso something around iso1600 would have pushed the exposure up the histogram and dragged the exposed image out of the noise floor.

This is not a camera KX or otherwise problem but a fundamental issue with the way your taking the image that would occur on any camera analogue or digital.

--
My PPG

http://www.pentaxphotogallery.com/home#section=ARTIST&subSection=1471087&subSubSection=0&language=EN
My Photo Stream
http://www.flickr.com/photos/awaldram/
 
awaldram said:
SO you image is approx 4 stops under exposed, The Noise is appropriate for this exposure and is actually quite good for how badly exposed the shot is.

You've hit the Noise floor for an exposure in the iso 3200 range.
Click to expand...
Wouldn't 4 stops from ISO400 be ISO6400?

--
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=
 
What Andrew has said is spot on, you seem to have cropped out the worst shadow part of a backlit image that has been poorly photographed with no regard to lighting and I still question why you used 1/1600s for a shot like this?
--
Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright
 
It would help us to understand why the camera chose the given exposure if you posted the complete original shot. It doesn't have to be full size, resizing to 1000px on the long side will be fine for this purpose. If the image shown is heavily backlit then the camera has chosen a suitable exposure for a bright sky, not your human subject. For backlit subjects you need to apply exposure compensation or use fill-in flash.

--
Steve

http://www.pbase.com/steephill
 
MightyMike said:
awaldram said:
SO you image is approx 4 stops under exposed, The Noise is appropriate for this exposure and is actually quite good for how badly exposed the shot is.

You've hit the Noise floor for an exposure in the iso 3200 range.
Click to expand...
Wouldn't 4 stops from ISO400 be ISO6400?
Click to expand...
Yes, and the noise looks about like that too.

Eric
--
I never saw an ugly thing in my life: for let the form of an object
be what it may - light, shade, and perspective will always make it
beautiful. - John Constable (quote)

See my Blog at: http://www.erphotoreview.com/ (bi-weekly)
Flickr Photostream: http://www.flickr.com/photos/28177041@N03/ (updated daily)
 
Do you have any functions enabled that might be boosting shadow exposure? Like the shadow fill correction or the extended dynamic range option? That is what it looks like is happening, the shadows are being boosted, but they are noisy from being so under exposed.

Eric
StDevious said:
EXIF Details

Result
File size : 1108330 Bytes
MIME type : image/jpeg
Image size : 2848 x 871
Camera make : PENTAX
Camera model : PENTAX K-x
Image timestamp : 2011:09:26 18:19:20
Image number :
Exposure time : 1/1600 s
Aperture : F5.6
Exposure bias : 0
Flash : No, compulsory
Flash bias :
Focal length : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed : 400
Exposure mode : Aperture priority
Metering mode : Center weighted average
Macro mode :
Image quality :
Exif Resolution : 2848 x 871
White balance : Auto
Thumbnail : None
Copyright : PHOTOLEET
Exif comment :
ozdean said:
I think your problem is more bad light than noise.
Why are you shooting at 1/1600?
--
Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright
Click to expand...
--
My Flickr Photostream - http://www.flickr.com/photos/photoleet
Click to expand...
--
I never saw an ugly thing in my life: for let the form of an object
be what it may - light, shade, and perspective will always make it
beautiful. - John Constable (quote)

See my Blog at: http://www.erphotoreview.com/ (bi-weekly)
Flickr Photostream: http://www.flickr.com/photos/28177041@N03/ (updated daily)
 
MightyMike said:
awaldram said:
SO you image is approx 4 stops under exposed, The Noise is appropriate for this exposure and is actually quite good for how badly exposed the shot is.

You've hit the Noise floor for an exposure in the iso 3200 range.
Click to expand...
Wouldn't 4 stops from ISO400 be ISO6400?
Click to expand...
I was giving a bit of latitude to allow for less noise from the OP amps as iso400 will have less amplification the noise floor will be lower than 6400.

I deliberately didn't use 6400 in my explanation as that would imply there is a linear correlation between underexposure and pushed shooting which there isn't.

Maybe I should have gone for 4200 or something so I didn't give the idea I can't count :)
MightyMike said:
--
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=
Click to expand...
--
My PPG

http://www.pentaxphotogallery.com/home#section=ARTIST&subSection=1471087&subSubSection=0&language=EN
My Photo Stream
http://www.flickr.com/photos/awaldram/
 
StDevious said:


Seems awfully high to me ? Have the in camera JPEG high ISO noise reduction on strong to begin at ISO 400.
Click to expand...
Turn off shadow compensation - it does not work properly in the K-x.

It is grossly noisy - it turns acceptable images into a complete waste of pixels.

See some posts of mine in here 12 months ago, where I discovered that this feature is completely useless in the K-x.

Instead, use the Pentax DCU4 software to lift shadows in processing afterwards. That seems to do a much better job without all the in-camera noise as showing here.

Also, expose to the right - get as much "brightness" into the image as possible, to avoid having to lift the shadows later. If it starts to blow out you can sometimes use the highlight adjustment tool in DCU4 to bring back some of the blown highlights.

--
Cheers

Trevor G

http://www.computerwyse.com
 
Trevor G said:
Also, expose to the right - get as much "brightness" into the image as possible, to avoid having to lift the shadows later. If it starts to blow out you can sometimes use the highlight adjustment tool in DCU4 to bring back some of the blown highlights.
Click to expand...
Meh. I can't say I agree with this. Exposing to the right on the K-x can be fairly risky. I find I have much more "Head"room by exposing for the highlights instead, since the K-x appears to have much more shadow headroom than highlight headroom. I'm used to ETTR but with the K-x I tend to get blown highlights.

I'd rather get noisy shadows than blown highlights, but to each his own. Its clearly on an image-by-image basis. (But it is a known fact that the K-x's metering blows out highlights).

http://www.dpreview.com/reviews/pentaxkx/page17.asp

The K-x has 3.2 EV worth of highlight range, while the D5000 has 4.0. The K-x has significantly higher shadow range than its competitors.

But in a low DR image (like the original post), I agree - expose to the right and pull down the exposure later. In original picture, you could have shot with a slower shutter speed and lower ISO altogether. :)
 
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