Portra film ISO rating?

[DLee]

I just got some 400NP back from the lab and it's pretty thin. After I had taken the film to the lab I read (in the forum here) that 4X5 Portra 400 should be opened a stop and rated at 200. I'm guessing this applies to 120 sized film as well? What about Portra 160? Should I shoot that down at 80 ISO?

Or are my shutter speeds kinda messed up?

Thanks, Dennis

Amendment: I forgot that my film is super old, that's probably the problem here.

[Corran]

IMO Portra 400 at 200 is overexposed. You'll have to test for yourself to find the best EI for your process as well as test your shutter speeds. Personally I usually shoot Portra just 1/3 stop lower than box.

[BrianShaw]

I shoot Portra at box speed and always very satisfied. Commercial processing at a respectable lab.

Also, if your Portra has letters after the numbers, it is more than a decade old. Consider that potential complication.

How are you assessing your negative densities? Using this guidance?

https://imaging.kodakalaris.com/site...portra_400.pdf


What is Portra64… have I missed the news of a new film?

[DLee]

I shoot Portra at box speed and always very satisfied. Commercial processing at a respectable lab.

Also, if your Portra has letters after the numbers, it is more than a decade old. Consider that potential complication.

How are you assessing your negative densities? Using this guidance?

https://imaging.kodakalaris.com/site...portra_400.pdf


What is Portra64… have I missed the news of a new film?

I meant 160... my bad. I'll change it up top. My film IS more than a decade old so yeah, that is more than likely the problem.

Guess I'll need to experiment a little to use all this stuff up.

Thank you Gentlemen.

[BrianShaw]

Old, like this?

[nitroplait]

You really need to know your shutter speed variations. If you have a roll film back, one test roll is usually sufficient to establish the variations.
If you don't have a roll film back, a "PhotoPlug" type of device and a smartphone will be helpful - (these are only useful for central shutters, curtain shutters requires a different way of measurement). If you are comfortable with a soldering iron, Google will direct you to instructions on how to make it from recycled parts and pennies.
Buying or making - either way will cost you less than one or two sheets of Portra film and processing.

[DLee]

Old, like this?

Exactly that! Except I have 400NC instead of VC... exposure thoughts?

[DLee]

You really need to know your shutter speed variations. If you have a roll film back, one test roll is usually sufficient to establish the variations.
If you don't have a roll film back, a "PhotoPlug" type of device and a smartphone will be helpful - (these are only useful for central shutters, curtain shutters requires a different way of measurement). If you are comfortable with a soldering iron, Google will direct you to instructions on how to make it from recycled parts and pennies.
Buying or making - either way will cost you less than one or two sheets of Portra film and processing.

Thanks Niels, are you saying my ear isn't accurate enough?

I'm pretty decent with a soldering iron, I'll see what Google has to suggest, thanks for this tip. I've got three lenses, and shutters, for this camera that are all at different states of 'hmmm, I'm not sure about that.'

Cheers, this looks like a handy tool to have.

[koraks]

Exactly that! Except I have 400NC instead of VC... exposure thoughts?

400-speed film, even Portra, that's over a decade old will certainly show decreased performance. It might work OK-ish at 200 if you're not too critical about image quality. There'll be some additional fog and a color cast that's most likely correctible with fair results.
The 160 may have fared a bit better due to its slower speed.
Storage conditions matter a lot; if this film was stored in the fridge or freezer for its entire lifetime, that would be very good news. But even then, it won't be like new, at least not the 400 film.

I shoot a lot of Superia 200 that's over a decade old (cold stored the entire time) and while I get decent prints from it, its true speed at this point is closer to 100 and it has developed quite a dense layer of fog. Like many things in life, you get what you pay for!

[jmdavis]

Thanks Niels, are you saying my ear isn't accurate enough?

I'm pretty decent with a soldering iron, I'll see what Google has to suggest, thanks for this tip. I've got three lenses, and shutters, for this camera that are all at different states of 'hmmm, I'm not sure about that.'

Cheers, this looks like a handy tool to have.

When Radio Shack was around, I built a couple of sound card shutter testers. The were within 1/3 stop of my repair guys unit. The smartphone and iPad results were dismal when I tried them a couple of years ago, as were the usb-c/ thunderbolt sound input results on my Mac laptop. On the other hand the photoplug worked just fine for me with my smart phone (Android).

It was harder for me to test my TLR's one Rolliflex 3.5 and one yashica 124 G. But I was able to get it done in a dark room using the iPad as a light table. You could always sacrifice a roll of 120 and run a series of film tests. But the issue that you may not be able to overcome is color balance on 10+ year old color film.

Unless you have a lot of this film, use it for experimentation and practice.