I took a few, but let's talk about one in particular.
Lens cap in place, and covering eyepiece with my thumb Exposure 8 sec ISO 1600 Format RAW Noise reduction off.
I looked at the histogram of the PEF file in PhotoshopCS
The lightest pixel was at level 80; 99th percentile was 26.
I ran a threshold adjustment on the file with the threshold set to 128. No white pixels
I was a little surprised by this. I'll run through it again with a fresh exposure when I get a chance
At 10:14 AM +1000 4/15/05, Rob Studdert wrote:
On 13 Apr 2005 at 20:39, Alan P. Hayes wrote:
Finding dead pixels (permanently stuck off) would presumably be similar to the procedure for looking for dirt, except that you wouldn't want to stop the lens down, just OOF picture of a uniformly bright field.
I haven't hear of any "dead" pixels mainly I expect due to the fact that the TIFF/JPG files used for assessment have been subjected to a de-mosaic process.
Anyhow, I don't seem to have *any* hot pixels on the istD, and my Oly C5050 had them and my Nikon Coolpix 800 had them in spades.
I've never seen a *ist D without hot pixels, did you have NR one during the testing you undertook and were the exposures of duration less than 1/4s?
A post of mine from Feb 2004:
Subject: *ist D sensor noise survey
Hey it's a while since we had a survey...
I'm interested in making an informal survey of the noise performance of our
*ist D cameras. Anyone with access to a PC who has permission to run the little
test app at http://www.starzen.com/imaging/deadpixeltest.htm can participate.
One exposure is all that's required for the test however in order to achieve
consistency we need to make sure that each camera is set up the same. I propose
that the test shot should be made as follows:
10 seconds manual exposure (lens capped) 200ISO Daylight WB NR off Saturation setting (middle) Sharpness setting (left most) Contrast setting (left most) sRGB CS TIFF L file
The tiff file can then be opened and tested under the default settings of the DeadPixelTest application and the information file saved.
I ran the procedure above and the results were as follows:
[DeadPixelText] Version=1.0 Description= FileType=TIFF NumBadPixels=15 0=Hot,2798,135,69 1=Hot,1954,339,113 2=Hot,1809,585,64 3=Hot,726,610,112 4=Hot,726,611,192 5=Hot,726,612,112 6=Hot,2312,753,121 7=Hot,323,766,94 8=Hot,572,1365,116 9=Hot,1627,1400,64 10=Hot,2163,1958,96 11=Hot,2162,1959,113 12=Hot,2163,1959,145 13=Hot,2164,1959,112 14=Hot,2163,1960,98
The first two numbers is the pixel location and the last number is the heat, 0 being off and 255 being full on. So I have one pixel that's 3/4 on at 10 seconds.
If anyone would like to mail me their results I'll collate and publish the data
later down the track (I'll keep data sources anonymous if requested).
Cheers,
Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
-- Alan P. Hayes Meaning and Form: Writing, Editing and Document Design Pittsfield, Massachusetts
Photographs at http://www.ahayesphoto.com/americandead/index.htm
