Rating for Kodak Portra 400 and 160 4x5 using “digiroid” method or light meter.

[NickB]

Picking up my Toyo 4x5 field camera for the first time in years to shoot some personal / portfolio / art work. An opportunity popped up to shot at a particular location with particular subjects next week, so I won’t have time to run any tests, so I’m wondering if I can get some thoughts and opinions on the best ISO ratings for these two films, Kodak Portra 400 and 160. I’ll be shooting on medium wide lenses, at medium distance with minimal shift/tilt so there won’t be much need for exposure adjustment due to camera movements. Subjects will be well lit, mix of natural ambient light with some strobe, outside of a house with people placed around the house.
All my stored stock of Polaroid and Fuji FPC100 are gone or so outdated as to be useful for experimental use only so I’ll be using a solid Sekonic incidence meter and / or my Canon 5D IV or Fuji XT-3 as “digiroids” to measure exposure.

Thanks!

[BrianShaw]

400 and 160, respectively.

[NickB]

Hey Brian, I should have said, the reason I asked was back in the day when I shot a good amount of Portra, we’d often rate 160 at 125 or even less, exposure checked with Polaroid single use then Fuji FPC100. I tried for a while to use digital cameras as digiroids, but the ISO ratings were way off back then. And color neg film is intrinsically harder to test and rate, especially now we don’t have labs next to our studios to run ladder exposure tests. That’s why I was asking, not trying to be funny or obtuse, just trying to see how people are rating these films and what tools they’re using to calculate exposures.

Cheers!

[agregov]

Portra films have quite a bit of latitude. Hard to blow out your highlights with that film if you overexpose. You could certainly shoot at box speed and see good results. My preference is to shoot Portra 400 at 200 and 160 at 100. I am more accurate with shadow detail that way.

[Kiwi7475]

Are you going to send to a lab for processing? If so I’d do box speed. In reality so as long as you use box speed or up to 1 stop slower you will be fine unless you’re pushing a huge dynamic range.

Typically I will give either Portra 1 stop more light but I also trim the sky with an ND filter to make sure it’s like within 2.5 stops over the exposure time. But that’s calibrated to my own developing process. If you are sending to a lab, either, as I said above, stay at box speed, or 1/2 up to 1 stop slower and you’ll be fine. Just don’t underexpose!

[Alan9940]

Never shot Portra 160, but I do use Portra 400 rated at 200. Portra 400 can handle quite a bit of overexposure and still produce useable prints.

[NickB]

Thanks all! I'll evaluate the scene I'm shooting obviously, but I'm after a wide dynamic range, lots of details in the shadows. I'm not shooting landscapes so the sky won't be an issue, so I'll go for somewhere in the 125-100 range for the 160, 200-250 for the 400. Going to be interesting deciding whether to trust my faithful Sekonic meter or the histogram on my 5D IV or XT-3 for the exposure. I'm shooting with talent, so not really feasible to do N +/- runs.

Do any of the US based color shooters here have a lab they particularly like for high rez color neg scans? It looks like the service bureau I used to use, who had color neg film scanning dialed in, are no longer in business.

Thanks!

[BrianShaw]

Your description of the scene does not sound very challenging if I understood correctly and you are using some fill flash. A incident and flash metering will likely verify your scene balance much better easier than equivalent pictures.