Kodak 160 vs 400 Usable Dynamic Range (Stops)

Hi.
Ive always photographed with the Kodak Portra 160, starting with the NC and VC versions. I just read somewhere (not sure where) that the ISO 400 has a larger Dmax range and better Highlight latitude. Can anyone with experience tell me if that's true, and how much of a differens in real usage this would make?

I shoot a lot of indoor Large format, and the range between indoor and outdoor (window) can be up to maybe 4-5 full steps. This works with the 160, exposing for the dark parts indoors and pulling back the outdoor a bit in the computer after scanning (Imacon). Would the 400 handle this better?

thanks

ScandiPhoto said:

4-5 full steps

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That's not a whole lot to be honest. Well within the range of any color negative film.
Perhaps there's something with definitions going on here, though. Both the indoor and the outdoor parts of the scene have a brightness range. What's the total range between deepest shadow you need to register and the brightest highlight where you want differentiation?

Overall, you can expect a little more usable DR from Portra 400 due to crossover behavior, although when scanning and digitally post processing this is fairly easy to correct for, rendering the practical difference very limited. Have a look at the overlayed curves of 160 (red) and 400 (black):

Before crossover on the red channel sets in, you can expect some 8 stops of DR on 160, but 400 does take more overexposure - in fact, the point where serious crossover happens isn't visible on the Kodak charts.
Always take these curves with a grain of salt as datasheet curves are generally not 100% accurate and they of course also depend on how the film is processed (quality of chemistry, temp. control etc.), but they do give a general impression.

Thank you. Some scenarios are of course more extreme, but like you write, looks like a negligible difference.

They are similar enough that Kodak could get away with consolidating them into a single 400 version. I don't want to give them ideas (although I'm sure they already have had the idea themselves).

For that kind of scenario, supplementary lighting and/or reflectors are a traditional approach worth considering to balance the indoor and outdoor more effectively.

loccdor said:

They are similar enough that Kodak could get away with consolidating them into a single 400 version

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Please note that to get the curves to overlap, I shifted them. This compensates for the very real and significant difference in emulsion speed. The 400 film really is faster.
What the curves also don't show is more subtle effects like saturation. With digital post processing, such differences aren't very relevant, but when optical printing, they are. So also from that angle the can be a perfectly viable reason for keeping both products around.
And of course, the question for Kodak & co is ultimately "does it sell", and as long as it does, it's a good idea to keep it around.

loccdor said:

They are similar enough that Kodak could get away with consolidating them into a single 400 version. I don't want to give them ideas (although I'm sure they already have had the idea themselves).

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This idea of using fast film as default, is very much of a phenomenon caused by young people used to digital photography trying film. Yes. I do get that the box speeds of 160 and 400 color negatives are well within the dynamic range of both films, but there are differences in characteristics of different film stocks. Much depends on the way film is used. For instance, digital post processing gives more room for exposure than traditional analog printing does. In the heyday of film, 100 ASA color negative was pretty much the standard for a consumer film sold in every grocery store. 160 ASA was very common for professional film well before Kodak started producing Portra line of films.

koraks said:

Please note that to get the curves to overlap, I shifted them. This compensates for the very real and significant difference in emulsion speed. The 400 film really is faster.
What the curves also don't show is more subtle effects like saturation. With digital post processing, such differences aren't very relevant, but when optical printing, they are. So also from that angle the can be a perfectly viable reason for keeping both products around.
And of course, the question for Kodak & co is ultimately "does it sell", and as long as it does, it's a good idea to keep it around.

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When speaking about modern color negative film, Porta 160 is my absolute favorite. should I need to choose just one. This is of course due to the fact, it behaves very similarly to Vericolor III, I used extensively in the late 80´s and early 90´s.Portra 160 is based on these films, while the 400 ISO version is based on Vision series movie film technology, although it is of course a genuine C-41 film. But it has been designed from scratch for primarily digital post processing, while the 160 version has a connection to older stocks from the days when digital post was not available.

I really wish they'd bring back Portra 160VC and Portra 400UC. But Im aware everyone would just tell me to jack up the saturation. Why then do we have Ektar 100/ other then the grain factor?

As I remember the Portra NC was the nicest film for darkroom printing. Very saturated and calm. But it could not handle mixed light, halogen turned out way to red, hence the VC.

Dont misunderstand me, I really like the 160, and its my standard film since long. I just stumbled on this claim somewhere about the better Dmax.

Faster films for the sake of speed makes no sense when shooting architecture. My indoor times varies depending on project, but often around 11/2 sec + 2 stops for POL or CF and so on.

Samu said:

But it has been designed from scratch for primarily digital post processing, while the 160 version has a connection to older stocks from the days when digital post was not available.

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I didn't know this. Interesting.

ScandiPhoto said:

I didn't know this.

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Neither do I and quite frankly I don't think it's true. Neither do I think the 'based on Vision film technology' statement is correct. As to the latter, I've previously commented on the nature of technological overlap between product ranges in this specific context, and my assessment on that matter was confirmed by someone from Kodak. A search should turn it up; it's not too long ago.

I'd take those allegations with a grain of salt.