Long exposures with Kodak Portriga VC 400

I recently exposed some shots with 120 Kodak Portriga VC 400 and got an

unanticipated result -- think I understand why, but wanted to check in with the

experts here. The exposures were for 3 - 5 seconds in muted daylight indoors --

I bracketed and compensated for reciprocity failure, and generally got great

results. But there was an interesting color shift -- the pears I was shooting

were retained their reddish/orange hue, but the completely black background

against which I was shooting shifted -- to BLUE! I assume this color shift is

a result of the long exposure, but wanted to check with you all to get

confirmation. Many thanks!

yeah, sort of a reciprocity problem, sometimes you should use a color correcting filter for those kind of shots

You were using Portra film. Portriga is the name of a long discontinued Agfa black & white printing paper.

If done with automated printing, this is easily explained.

Printer software added blue to compensate for predominant yellow

in the pears. I can't imagine Portra exhibits reciprocity failure

at only 5 seconds. It would help if you posted a sample.

Jeff, yes, of course! Sorry for the mistake.

Bill -- Thanks for this tip -- will check it out.

You get color shifts or color crossovers when doing long exposures with any currently available color film. The tungsten films are not as bad, but still not as good as the old type L films, which were made SPECIFICALLY for long exposures (hence the "L"), and were all tungsten balanced.

 

In this particular case, the data sheet for New Portra states that reciprocity is not applicable in exposures longer than one second, and that individual tests should be made in the case longer exposures.

 

Also, you can't judge properly if there is any automation whatsoever in the printing process. You need to look at hand-printed examples, or possibly scan and try color correcting in the computer. If you can't color correct by using curves or levels adjustments of either RGB, CMY, or AB, then you have had a color crossover. If you can correct, then you have had a color shift, and in the future you know exactly which way the shift went.

 

Try again with a MacBeth chart if you really want to get into it.

 

Keith

Keith -- great help! Thanks

If you underexposed slightly, the black in the print would be on the toe of the negative and might end up blue due to the underexposure.

 

Check to see whether the negatives are thin or not, and what kind of detail you have in the blacks.

 

What you describe really sounds like underexposure, or perhaps as stated above, some correction factor. I suspect underexposure.

 

Of course, OTOH, overexposure with the image being on the shoulder would require that blacks be in the mid scale. If this took place, then printer compensation would blue up the blacks but for another reason.

 

Ron Mowrey

Rowland -- don't think these are under-exposed -- the pears are perfectly exposed, just PERFECT -- so that's why I think we have a reciprocity problem. Or else a printing problem.....I will take them in to an expert and see what he/she says.....

Your highlights might be exposed in a way that makes them printable, but your shadows

might be falling off the scale.

 

I've noticed that the 'NEW' Kodak Portra emulsions have very poor reciprocity

characteristics and in some instances require 4-5 STOPS exposure compensation! (Which

makes me want to kick someone at Kodak)

 

My initial tests with this 'new' emulsion (gggrrrrr!!) gave me highlight and midtones but no

shadow detail in exposures that were corrected by only one stop.

Thanks to everyone. All very helpful. I must confess that this is the first times I have ever used color film for serious work -- and I am inclined (LOL) to stick with B&W, where I have spent a decade learning about how to deal with all these problems effectively.....but I will take the negs and prints back to the lab and report back on their response.

Mr Engel, the new Portra datasheet says no compensation is required

for exposures up to 1 second. Could you please be more specific about

the tests you did and the results you got?