Hi all
Just wondering what the best way might be to be able to judge how long an exposure I could take before amp glow got the better of me. Given that summer is coming on, I've done a few dark tests on the D40 at ISO400 and ambient temperature of 22 degrees C. I've taken frames from 1 to 15 minutes long at one minute intervals and can't see hugely appreciable difference in glow - but a few noisy pixels start to creep in after 9 minutes. What's an acceptable limit - knowing that much of the glow is able to be processed out. There doesn't seem to be much anyway.
How do you guys achieve this test? Is 15 minutes too short for a meaningful test? Should I push the next set up to ISO1600 or even 3200 if I'm going to shoot most at 400 or 800?
Cheers
Chris
All images have noise reduction set to "off". "Mode 3" has been used (camera turned off prior to median NR taking place automatically) such that the frame is flushed & written to storage before the NR algorithms can remove noisy pixels. More or less a true RAW in Nikon parlance.
A higher resolution version can be found here:
http://www.omaroo.net/index.php?set_...view_album.php
It seems that this forum alters the images on upload for some reason - and the glow doesn't appear as prevalent as it should - not that it's really bad. Here are direct links to the full images:
http://www.omaroo.net/albums/album47/1_min.jpg
http://www.omaroo.net/albums/album47/2_min.jpg
http://www.omaroo.net/albums/album47/3_min.jpg
http://www.omaroo.net/albums/album47/4_min.jpg
http://www.omaroo.net/albums/album47/5_min.jpg
http://www.omaroo.net/albums/album47/6_min.jpg
http://www.omaroo.net/albums/album47/7_min.jpg
http://www.omaroo.net/albums/album47/8_min.jpg
http://www.omaroo.net/albums/album47/9_min.jpg
http://www.omaroo.net/albums/album47/10_min.jpg
http://www.omaroo.net/albums/album47/11_min.jpg
http://www.omaroo.net/albums/album47/12_min.jpg
http://www.omaroo.net/albums/album47/13_min.jpg
http://www.omaroo.net/albums/album47/14_min.jpg
http://www.omaroo.net/albums/album47/15_min.jpg
Dark frames - 1-8 minutes