At work I am using a D90 with a AFS Nikkor 17-35 ED lens on a copystand with Osram Dulux L 36w/865 Cool Daylight (6500K) bulbs. If I take a series of shots of pages from a book I get a 'colour cast' either across the whole frame or a strip to left or right. In between these shots there may be a perfect one! I have tried combinations of my personal D70 and 18-70ED and the kit above and get the same problems whichever set up is used. The bulbs are new as I was getting a brown cast with the old ones. When I swapped out the cast went green. Tried pre WB, grey cards and colour temp. HELP!!! ANY THOUGHTS??
>Hello >Thank you for that. I only just joined so will do my profile >asap :0) The bulbs are compact flourecent, Shutter speed = >1/200 1/250 ISO 250. Let me know if you need anything else. >Thanks again
Shoot at a slower shutter speed, 1/60 or less.
I suspect you're getting into the shutter speed v. 60-Hz issue.
I hate when people ask me what I see myself doing in 5 years...... I don't have 2020 vision!
That's amazing! Thank you so much - Makes sense. Just done a quick test and problem appears to be solved. Will do some more in depth tests to optimise. Thank you once again - could hug you but better hadn't :0)
If you want to virtually eliminate the flicker issue, just upgrade your old magnetic ballast fixture to the more energy efficient electronic ballasts.
As noted, magnetic ballasts resonate at line frequency (50/60 hz depending where you live). Electronic ballasts on the other hand cycle between 10,000 to 40,000 hz depending on the design making them virtually flicker free.
I agree with Ken: you have discovered the 60 Hertz sine wave of the bulb's power source versus a faster shutter speed problem. As Ken suggests, anything slower than 1/60 second will cure that problem.
If you are still seeing the green cast that occurs with most fluorescent bulbs/tubes, try the fluorescent WB in the camera. Any residual color correction can be easily handled in Photoshop, assuming you are shooting in RAW mode.
Thanks Ken, for joining the discussion.
HBB in Phoenix, Arizona Nikonian Team Member
Photography is a journey with no conceivable destination.
Hello Everyone Thank you for all your input. The CFL I am using are I would have thought 'modern'. The problems have disappeared - actullay managed to digitise a full voume this morning - hooray. There doesn't appear to be a colour cast, but I have a grey card to hand if one sneaks in. Yes, I am shooting in RAW + basic then converting to TIFF in ViewNX. Can't keep RAW files - decree from IT department saving their storage space haha. Thanks again to everyone :0)