Couldn't find any situations where I could get longer than about .2 seconds exposure at f/22 with the ISO set to 1600. I found that if I exposed at 3 stops under normal exposure, the camera's sensitivity ran seriously to the blue channel at that point, but the entire field went bluish, no green-magenta banding.
The blue-channel predominance was much less at ISO 100. Let Pentax take care of it. Something's weird with your camera. Godfrey On Jan 31, 2007, at 4:44 PM, David Weiss wrote: > Good idea, but I just went outside and reproduced the colors outside. > > I went outside and tested the k10d with a fa50f1.4. I shot a > brickwall, > natural tone jpegs. This was to correct some potential problems as > posed by the list yesterday, that is, problems caused by light going > through window material and shooting of a white object. > > First I tested at different speeds, in groups of three, normal, 1 stop > under, 2 stops under. Let the lens open up to f4 or f4.5 and varied > the > shutter speed. > > Pic's 1-3: 1/8 sec, f4, 100 speed. normal exposure. > Underexposed by slowing the shutter by 1 and 2 stops. No color > shifts. > > Pic's 4-6: Repeated of above, except start at 1/15s, f4, 400 > speed. No shifting for any of the 3. > > Pic's 7-9: Similar test at 800 speed. No problems. > > Pic's 10-12: Repeat for 1/30s, f4.5, 1600 speed. Looks okay. > > Then I decided to try things that were near what I did yesterday. > That > is, high sensitivity, long exposure (greater than 1/4s) and small f > stops (f22). > > > Pic's 13-15: Repeat situation above starting at .5s, f22, 1600 > speed. There it is again, green and magenta. Specially so in > the first (normal exposure) and the 1 stop under exposure. > > Pic's 16-18: 1 sec f22, 800 speed. Same problem as above for > first two pictures especially, but not as strongly as the one's > at 1600. > > Then I decided to see if long exposure and small f stops will produce > the color shifting at other sensitivities. > > > Pic's 19: 2 sec, f22, 400 speed. Still there, but not > strongly. > > Pic 20: 4 sec, f22, still there, although getting to the point > where it is difficult to tell. > > Pic 21: 2 sec, f22, 200 speed. Still there. Very Faint. > > > > So, my conclusions for MY CAMERA (do not know about other k10d's): > > 1. Color shift will be produced at any sensitivity, during > underexposure or normal exposure, if both the shutter speed is long > and > the f stop is small. > > 2. At conditions as described in number 1, color shifting is > maximized > at higher sensitivity and a stop of underexposure. Normal > exposures at > lower sensitivities minimize the effect. > > 3. Camera is capable of images without any color shifting at all > light > sensitivities, even with underexposure if conditions in number 1 > are not > met. > > > I am beginning to think it is just a limit of the technology. I would > bet that others could reproduce this result. On the other hand, I am > surprised that someone else has not bumped into this problem. I am > convinced that it is not the light source or lens. Could just be the > unusual conditions or just my camera. Cannot say unless some > others are > willing to give it a go. > > Godfrey (or anyone else), if you are willing, could you try a long > exposure, small f stop at a high sensitivity? > > I posted 6 of these on flickr. 10,11,12 look fine (shot as described > above), 13,14,15 show the shifting (shot as described above). If > someone would like me to post any others, I could do that. > > > http://www.flickr.com/photos/[EMAIL PROTECTED]/? > savedsettings=375990192#photo375990192 > > > > Contacted pentaxusa - they could not access the flickr pictures. > Suggested I send the camera back in. Ick. > > I am still interested in any speculation and possible attempts of > others > to duplicate this. > > Thanks for your time and patience, > > > > Dave > > > > > x > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
