View Full Version : NEW Portra 160NC: My Results

21-Nov-2006, 21:33
Here's my results thus far:

NEW Portra 160NC, 4x5 Sheets

Film Speed:

EI:160 looks right on. I shot a bracket using EI:80 to EI:160, suspecting the film to be rated optimistically. I was wrong. Box speed works great. This is based on spot meter Zone III placement of "average dark material."

Reciprocity Data:

To 1 Sec: No Adjustment
4 Sec: +0.5 Stop
15 Sec: +1 Stop
30 Sec: +1.5 Stop
1 Min: +2 Stops
2 Min: Not Recommended

Other Observations:

The film looks nice and sharp, and with very fine grain.

I see no major color anomalies with the GMB Color Checker. The lower/softer contrast is apparent when comparisons are made.


While it appears to be a very nice looking film, it seems to suffer from reciprocity much more than it's predecessor. Why, Kodak? WHY?

22-Nov-2006, 04:06
Thanks for the information! Reciprocity usually isn't an issue for me, but I'll chime in on your quesiton: why, Kodak, WHY?

Your buddy,

Struan Gray
22-Nov-2006, 06:43
I would guess that poorer reciprocity is a result of the two-electron sensitisation in these films. Whereas each absorbed unit of light in previous films would produce one develpment center in the halide grains, the new films use energy stored temporarily in the sentising dye to create a second development center. My guess is that the two centers in close proximity give more chance for recombination - i.e. for the development centre to heal out before it can be made permenant.

Mere speculation, but - I hope - informed speculation.

I can live with reciprocity. I would be more worried if latent image keeping had also deteriorated. Anyone know?

adrian tyler
22-Nov-2006, 08:53
does these carateristics apply to portra 400nc too?

Henry Ambrose
22-Nov-2006, 12:51
Have you actually tested it with long exposures? Fuji claimed you couldn't use NPS for long exposures and they were so wrong. Might be similar with the new Kodak?

23-Nov-2006, 09:21
When I was using a lot of 160vc and 400nc for portrait work I would use the160vc at EI.100 but in my studio with my Wein flash meter I would use it at EI:50.(probably meter and metering technique used in the studio) The 400nc would be used outdoors in open shade portraits and EI:400 worked ok for me. On the older 400speed Kodak films I believe they cautioned that the 400 speed films should be rated at somethlike like 320 in open shade situations because of the lower contrast. The newer Portra films are more tolerant of underexposure than the older siblings.

23-Nov-2006, 15:57
Have you actually tested it with long exposures? Fuji claimed you couldn't use NPS for long exposures and they were so wrong. Might be similar with the new Kodak?

Yes, the reciprocity data posted is from my results. Kodak indicates that beyond 1 second, it is advised to test for your situation. The test was made in a controlled lighting situation with GMB Color Checker and Kodak/Tiffen Grey Scale. I shot as follows:

1. 1/2 sec (control exposure)
2. 1/2 sec, -1/2 Stop (reference exposure)
3. 1/2 Sec, -1 Stop (reference exposure)

4. 1 Sec
5. 2 Sec
6. 4 Sec
7. 8 Sec
8. 15 Sec
9. 30 Sec
10. 1 Min
11. 2 Min
12. 4 Min

The resulting negative were compared visually on my Just-Normlicht box, and also scanned on my Epson 4870. All scans were made in a consistent and controlled manner, and were viewed on a calibrated/profiled Apple Cinema HD 23". Although I did not use a densitometer for precise measurements, I feel that through these comparisons and cross-references I have arrived at at least a good starting point from which to address the reciprocity performance of NEW 160NC. As we all use this film, more accurate data will come to light. I just wanted to get the ball rolling, as I tend to run into longish exposures quite often.

As far as 400NC is concerned, and this is pure speculation, I'd wager that it follows suit with 160NC. Maybe try some tests along the same lines that I have?

23-Nov-2006, 16:00
Struan Gray, thanks for your input. Your theory seems plausible to me, but man am I no chemist. Puts things into perspective though, and confirms my suspicion that reciprocity performance was compromised so as to generally improve the film in other areas (which are probably most important to most of the people, most of the time).