Problems when developing color photographs?

I have some aerial photographs of the same areas.
They are shoot within 15 min, the focal length, aperture stop, exposure time
etc. are fixed and therefore the same for all the photos.

The problem is that some of the images are very different in color (some
bluish other yellowish).
Is there anywhere in the developing process that cause these big
differences?

Any suggestions and ideas are appreciated.

Regards
/Morten Nielsen
Email: http://www.iter.dk/contact.aspx

In article ,
"Morten Nielsen" wrote:

I have some aerial photographs of the same areas.
They are shoot within 15 min, the focal length, aperture stop, exposure time
etc. are fixed and therefore the same for all the photos.

The problem is that some of the images are very different in color (some
bluish other yellowish).
Is there anywhere in the developing process that cause these big
differences?

Any suggestions and ideas are appreciated.

Regards
/Morten Nielsen
Email: http://www.iter.dk/contact.aspx

What type of film ? If the color shifts are over the
whole frame as opposed to part of the individual
frame of each shot I would theorize- no. But since your
description of the processing proceedures is so
limited its very hard to track down.

Since these are aerial images could it have been
that they were shot through the planes plexi windows ?,...
I could be angular defraction of the sunlight on the plexi
as the planes position changed in such a case.
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Morten Nielsen wrote:
I have some aerial photographs of the same areas.
They are shoot within 15 min, the focal length, aperture stop, exposure time
etc. are fixed and therefore the same for all the photos.

The problem is that some of the images are very different in color (some
bluish other yellowish).
Is there anywhere in the developing process that cause these big
differences?

Any suggestions and ideas are appreciated.


Aerial? How high up? I wonder if the uncorrect prints are blue and the
yellow ones are overcorrected. If that's the case then it's the printing.
Was this a good lab?

Nick

The color is adjusted whenever a print is made from a negative. Try getting
new prints made from the same negatives, and see if the same color problem
is still present.

"Morten Nielsen" wrote in message
...
I have some aerial photographs of the same areas.
They are shoot within 15 min, the focal length, aperture stop, exposure
time
etc. are fixed and therefore the same for all the photos.

The problem is that some of the images are very different in color (some
bluish other yellowish).
Is there anywhere in the developing process that cause these big
differences?

Any suggestions and ideas are appreciated.

Regards
/Morten Nielsen
Email: http://www.iter.dk/contact.aspx

What type of film ? If the color shifts are over the
whole frame as opposed to part of the individual
frame of each shot I would theorize- no. But since your
description of the processing proceedures is so
limited its very hard to track down.

YUP, It's over the whole frame. It is quite easy to remove using histogram
matching, but I just want know the reasons for the color-changes.
I have heard that if the images isn't on the same roll of film, they can
look different (can that be confirmed?).

Since these are aerial images could it have been
that they were shot through the planes plexi windows ?,...
I could be angular defraction of the sunlight on the plexi
as the planes position changed in such a case.

No the imagery is done with a special (very expensive) metric camera with
230mm negative (!) Focal length is fixed to 153mm.
Distortion and refraction errors in these cameras is almost non-existing
(thats what makes them so expensive)

The reason why I ask is that I wan't to point out the possible reasons for
differences in color, as a part of my master thesis. I haven't really been
able to find anything on the web about what can go wrong during the
developing, and I was hoping that some of the genius' here could tell me
about some of them.

Btw, the negative is scanned directly to a digital image later on, so it
doesn't happen when developing to a positive photograph.

Aerial? How high up?
750 meters.

I wonder if the uncorrect prints are blue and the
yellow ones are overcorrected. If that's the case then it's the printing.
Was this a good lab?

I would think so. It's not a normal Walmart lab, since its 230mm film.

/Morten

The color is adjusted whenever a print is made from a negative. Try
getting
new prints made from the same negatives, and see if the same color problem
is still present.

So what you mean is that when scanning the negative, the scanning can be the
source of it? I would think that the scanning is always done under the exact
same controlled conditions.

/Morten

In article ,
"Morten Nielsen" wrote:

The color is adjusted whenever a print is made from a negative. Try
getting
new prints made from the same negatives, and see if the same color problem
is still present.

So what you mean is that when scanning the negative, the scanning can be the
source of it? I would think that the scanning is always done under the exact
same controlled conditions.

/Morten

My thought now is along the same line as Michael Covington's that the issue
may be a result of the scan operator or that the scanning system is somehow
at fault.

There are two additional considerations, they are storage and the emulsion itself.

a) The emulsion could be defective,....IMOP the less likely but it could be unevenly
coated for what ever reason.

b) Storage; if the film is cold stored and thawed, my opinion is that the film
could produce uneven areas color areas as a result of uneven temperature
while in storage, like one side of the canister or magazine faces the coldest
side of the freezer, like wise in warmer conditions, sitting on the pavement
waiting to be loaded and all the while picking up temperature on the sunny side.

How old is the film?

Have you noticed any kind of pattern? In other words
are the miscolored framed evenly spaced....like every 6", 12" etc.
To me that would indicate what I said above in item (b).
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This is a provision for the mind's eye.

Morten Nielsen wrote:
Aerial? How high up?
750 meters.


2500 feet. I can't find my chart with the little notes on how high the
colour temp gets with altitude but assuming you didn't filter to correct
then the stuff should be blue. I think that's right. It sounds to me that
your scanner software is getting confused and trying to correct that blue. I
think you said in a different post the stuff is getting scanned. Of course
I'm assuming aerial film is set for the same "daylight" normal film is set
for.

Nick

b) Storage; if the film is cold stored and thawed, my opinion is that the
film
could produce uneven areas color areas as a result of uneven temperature
while in storage, like one side of the canister or magazine faces the coldest

side of the freezer, like wise in warmer conditions, sitting on the pavement
waiting to be loaded and all the while picking up temperature on the sunny
side.

How old is the film?

Have you noticed any kind of pattern? In other words
are the miscolored framed evenly spaced....like every 6", 12" etc.
To me that would indicate what I said above in item (b).

Hi

He has a point although I am not sure it temp issue. I worked on the U-2
program and at least 25% of the missions were in color.

Safe light fog is a big issue. Many of these aerial cameras are hard to load
in total darkness. An IR source with a viewer is used. It's also used in
processing. If it's too long, a red or reddish fog could get all over the
negatives. Alot of times it will have waves in it as you discribe.

Larry