Best way to gel light for portra

Im purchasing some color 4x5 film just to make few portraits. What I have: Graflex with no flash sync and two redheads 1000w and 2 artificial silk diffusion.
You already see the problem.
Insted of losing 2 stops of viewfinder brightness, i want to buy some gels.
My lights are 3200k but once you diffuse them they go around 2900k(digital results).
Lee full ctb converts from 3200k to 5700k
So in my case that would mean from 2900k to 5400k. But are 5400k ideal?
For the same money I can buy non full but 3/4 ctb and have slighyly more light output and warmer color circa 5200k.
Which one is more correct in your experience for best result. Intend to print on ra4 paper.
Thanks

That’s a classic approach. Haven’t done it in many years yet recall using the Rosco equivalent and not being disappointed. I always wished I had a color temperature meter, though, to avoid guessing and experimenting. The printing had automatic corrections and I can’t recall details of what might have been included.

BrianShaw said:

That’s a classic approach. Haven’t done it in many years yet recall using the Rosco equivalent and not being disappointed. I always wished I had a color temperature meter, though, to avoid guessing and experimenting. The printing had automatic corrections and I can’t recall details of what might have been included.

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My problem is that even if I had color temperature meter I cant find data on “ideal” value for portra. I dont even have a camera smaller than 4x5, and I just cant afford to waste a box of film on testing….

Ales' said:

My lights are 3200k but once you diffuse them they go around 2900k(digital results).
Lee full ctb converts from 3200k to 5700k
So in my case that would mean from 2900k to 5400k. But are 5400k ideal?
For the same money I can buy non full but 3/4 ctb and have slighyly more light output and warmer color circa 5200k.
Which one is more correct in your experience for best result. Intend to print on ra4 paper.

Click to expand...

Hi, it's been probably 20 years past, but I'm from an outfit that had done pretty extensive testing on Portra 160 in a studio environment using professional-grade electronic flash.

The lighting that we used was somewhere between 5000K and 5500K in CCT, which was sorta typical of pro grade studio electronic flash. It largely varied depending on the specific flash tubes. I get this from a fair amount of actual measurements, using primarily a spectrophotometer with software to calculate CCT.

I really doubt that you'll have any problems with Portra anywhere in that general color temp range. Although I would personally probably go with the "full" ccb correction. The fact that you are using a color neg film and hand-balancing the results means you have a lot of leeway to make moderate corrections.

As a note I've also measured more than a handful of shoe-mount flash units. For some reason they've run higher color temps, typically around 6000K to 6500K. And I think there's been quite a lot of professional shooting done with similar units. So my presumption is that those can also produce high-quality results on Portra film, although I don't have any really serious experience in that area.

FWIW in the past I've been involved (through my employer) in a handful of film/paper trade trials with Kodak. Seeing how serious their testing was (Prior to the bankruptcy) is where I get my confidence that they would make sure that Portra films would also give perfectly acceptable results with the higher-color-temp hot-shoe units.

Ales' said:

My problem is that even if I had color temperature meter I cant find data on “ideal” value for portra. I dont even have a camera smaller than 4x5, and I just cant afford to waste a box of film on testing….

Click to expand...

I'm sure you've reviewed the data sheets for Portra 160 and 400. While they don't give an exact and specific value for "daylight balanced", they give many examples of how to balance various lighting scenarios. Portra isn't real fussy so getting "in the ballpark" is generally good enough for most photographers. Portra is well-known to be a very versatile film. The cost of sheet film makes experimentation very expensive and undesireable, to say the least, but if you follow the Kodak datasheet guidance there shouldn't be any experimentation required. Kodak knows of what they write.

Unfiltered daylight with sun or electronic flash - 5000-5500K - is what Portra films are optimized for.

Mr Bill said:

...

As a note I've also measured more than a handful of shoe-mount flash units. For some reason they've run higher color temps, typically around 6000K to 6500K. And I think there's been quite a lot of professional shooting done with similar units. So my presumption is that those can also produce high-quality results, although I don't have any really serious experience in that area.

Click to expand...

I use a slight warming filter with Portra and on-camera strobe. Often a Tiffen 812.