A D50 is most definitely *not* a professional camera, or anywhere near
it.   As a pro he should be aiming considerably higher, D200, Canon 30D
minimums.

Colin D.

Gray_Wolf skrev:

Probably a light or exposure setup that changes without he notices.

D 50 - unless defect - is fully up to the job

If he's shooting RAW he won't have to worry about the colour temperature
as he can change this with software, but from the sounds of it he might
have a faulty camera. Best to send it in.

Have him check if he has the white balance set to Auto.  I've had this
happen on my D50 a couple of times when I've shot a number of frames in
succession of the same subject.  For some reason the camera decides that the
lighting on frame 4 of 9 needs the white balance to be different.  If he
sets the white balance to either a fixed setting, or better yet, use the
preset and measure with a grey card he shouldn't see any shift.  Also, if he
shoots in RAW instead of JPEG, he'll be able to adjust the white
balance/color temperature to whatever he needs regardless of what the camera
selects.

Kyle.

If your friend is shooting with sudio strobes with modeling lights he
may not be waiting long enough for the strobes to recycle, a problem
with cheaper strobe units. So if he is shooting automatic the camera
will expose for the modeling lights. With this scenario some pictures
will be much warmer than others. With many digital cameras the auto
white balance will work from 4000 degrees K to 7000 degrees K. Modeling
light are significantly below 4000K.
Just someting to watch out for, have seen it happen on film and
digital.

Tom

Randall hasn't been around lately, so I will play Randall for this one
time and one time only.

I don't have a problem with the camera he's using, but I think there
are at least two other problems.

First, if he's a pro photographer is a studio setting, why doesn't he
just go grab a back-up body and use it.  Nobody should be relying on 1
body for professional work because somethimes they break or go screwy.

Second, a person acting as a pro should have a reasonable amount of
technical savy and knowledge of his equipment.  Why is he asking YOU
and having YOU post to a ng.  For any of about two dozen people in this
ng, I am certain that if you put them in that studio with that camera,
they would figure out what piece of equipment is causing the problem in
about half an hour (or less).  Given a bit more time, they would
probably be able to figure out a work-around that would work fine until
the camera or whatever gets fixed.  For example, has your friend turned
off auto-white balance?  Has he custom white-balanced?  Has he gone to
manual mode?  Is he independently metering the light?  Has he checked
ALL the batteries in ALL the equipment?  What equipment has he swapped
out?  Does it happen in all modes including RAW?  Has he checked the
EXIF data to see if there are any differences?  Has he set up a
still-life scene and shot a couple of hundred images and see if they
vary?  I think any professional, semi-pro, or advanced amature would
have went right down this list before he/she even thought of asking for
help.  What has your friend done other than complain to you?

What does he mean by "color balance"?  Is it white balance or color
tempurature?  It is saturation or image density?  Can he post a session
with good photos and bad photos?

I do not want to sound condensending, but if he has checked things out
you should say what he has done and what the results are.  If he
hasn't, then ....

Good luck with it.

Pat.

(How did I do as Randall's temporary fill-in?)

Tell "your friend" not to set white balance to automatic in that kind of
setting.  The camera will end up varying it from one shot to the next.
Since your lighting is controlled and consistent, you don't need or want
automatic white balance.  I mean, he doesn't.  If they're studio strobes
you could set it to 5600k or 5400k, and fix up any slight difference in
the raw conversion.  I mean, he could.

According to Gray_Wolf  <G_Wolf@nospam.com>:

    With auto white balance turned on (the default), small changes
in what colors are present in the metering areas can affect the white
balance in *any* sufficiently advanced digital camera.  (Some old ones
may not have any way to change the white balance, so this does not
apply there.)

    For consistent white balance with the D50 (or others) in the
studio, I would suggest either to manually select one of the white
balance choices from the menu, or better, meter from an 18% gray card to
set a custom white balance under the studio lighting, and select that
custom white balance for all of your shots.

    The auto white balance makes some assumptions about what
percentage of the image area is typical background (white walls, green
grass, blue sky), and what percentage is the actual subject.  It tries
to guess a white balance from this information, and (as in portraits,
where the subject can be a very large percentage of the image area) it
is easy for the clothing, or even an over-rouged cheek, to shift the
white balance from shot to shot as you go from pose to pose -- even with
the same subject.  If he is running from individual to individual, each
with their own clothing color choices, it becomes even more extreme, of
course.

    So -- manually selecting a white balance which is close to what
he is using will help, or (if possible) using the 18% gray card to
select a custom color balance based on the lighting, and *not* on the
subject will give a stable balance from shot to shot -- unless the power
line voltage is drifting up and down, and the lighting is incandescent,
in which case the auto white balance might be the best bet after all.

    Good Luck,
        DoN.