Why is portrait film rated 160?

K

Krasnaya_Zvezda

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Both Kodak and Fuji offer film rated as ISO 160, why not 150? Or 175? Why is it 160? How much difference is there between 160 and 200 (other than 40)? The 160 number seems to have some 'professional mystique'. Am I wrong? Why is that?
 
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All I know is 160 NPH is great for weddings ~ ; - )
 
160 because it's twice 80 and half of 320. :) Common ASA/ISO film speeds progress like the 1/3 f/stop divisions... 50 64 80 100 125 160 200 250 320 400 500 640 800 etc.

It IS a little curious that both companies offer a professional portrait-oriented film at ISO 160. Pros may have expressed contentment with that film speed, handy somehow for their purposes.
 
Probably has to do with the films latitude - it would be very easy to rate at either 200 or 100 and just process as normal at the lab. I've only used Portra NC 160 and the situation made me need to rate it at 200 for the exposures. Came out much better than I expected.

William
 
I had this experience for NPS, I rated it at 200 once, and the local pro lab (a very good lab) said that it wasn't even worth the push charge to process it at 200, the film at 160 has enough latitude that it would make less of a difference on the negs than would any peculiarities of my camera, the particular batch of film and so on. Just like William said above...
 
True, that's only 1/3 of a stop underexposure, negligible. We routinely make larger errors in metering... Still, color neg films are much more tolerant of overexposure than under, and I routinely set my meter to 100 for an ISO 160 film.
 
My suspicion is that this is to allow everyone to rate it at 100, thereby giving an extra 2/3 stop buffer against under-exposure. Most (all?) 160 film is shot on MF where the slight loss of sharpness will not matter and the finer grain will be welcome for big wedding blow-ups.

You might also want to take a look at 'ISO Film Speeds' in the Photo School section of www.rogerandfrances.com.

Cheers,

Roger
 
"My suspicion is that this is to allow everyone to rate it at 100, thereby giving an extra 2/3 stop buffer against under-exposure."

Yup... anyway when I use it with a photo teacher in the studio thats how we work ;) But mainly 4*5" negs here ;)
 
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