Changing ISO vs Changing Film

[Alpha]

160NC responds very well to overexposure/pulling. Gives tons of density and very rich colors.

 

[Moglex]

Gotcha.

Pardon?

 

[asfixiate]

Gotcha is a form of acknowledgement. It means I understand what you said.

 

[Moglex]

Gotcha is a form of acknowledgement. It means I understand what you said.

LOL, I see.

I thought you'd made a joke that had gone right over my head.

It's been one of those days!

 

[asfixiate]

Ahh Gotcha. (jk)

 

[Helen B]

Helen, is the same true of Portra 400 NC/VC, or is this only for the 800 film? I thought I read this was true for the whole Portra family but wanted to check. I have some Portra 100 and 400 on the way for my F100. Didn't bother with any of the 800 yet.

Yes, it's all very tolerant of 'overexposure', it's just that I use Portra 800 as my versatile multi-speed sort of a film. Extra exposure helps with mismatched lighting (eg daylight film in tungsten light) as well as improving smoothness and saturation.


" 160NC responds very well to overexposure/pulling. Gives tons of density and very rich colors."

Max,

Don't you mean simply overexposure, not overexposure and pulling? I wouldn't recommend pulling negative film, because it tends not to 'give tons of density and very rich colours'.

Best,
Helen

 

[Mav]

Yes, it's all very tolerant of 'overexposure', it's just that I use Portra 800 as my versatile multi-speed sort of a film. Extra exposure helps with mismatched lighting (eg daylight film in tungsten light) as well as improving smoothness and saturation.

Neat! What about underexposure though? Like say I wanted to shoot the 160 at 320, or the 400 at 800? Can you do that without a huge drop in photo quality when needed without any special processing, or is it different for the underexposure half? I guess you'd be trading off shadow detail? Generally I seem to see people from reading around that they'll commonly shoot film at a slightly slower speed (overexpose), but usually not at a slightly faster speed (underexpose) so I think I might be missing something.

 

[Alpha]

Max,

Don't you mean simply overexposure, not overexposure and pulling? I wouldn't recommend pulling negative film, because it tends not to 'give tons of density and very rich colours'.

Best,
Helen

You're right. I was remembering backwards. I accidentally shot the 160 at 320 and pushed, not the other way around. Was a bit grainier though.

 

[Helen B]

Neat! What about underexposure though? Like say I wanted to shoot the 160 at 320, or the 400 at 800? Can you do that without a huge drop in photo quality when needed without any special processing, or is it different for the underexposure half? I guess you'd be trading off shadow detail? Generally I seem to see people from reading around that they'll commonly shoot film at a slightly slower speed (overexpose), but usually not at a slightly faster speed (underexpose) so I think I might be missing something.

That's pretty much the way I think it is - underexpose and you lose shadow detail, and what there is gets grainy, particularly in the blue-sensitive layer. Dye image film tends to be like that - graininess increases as exposure decreases, particularly near the toe. Give it a bit more exposure than box speed, and it gets smoother. Give it a lot more exposure and it gets even smoother and less contrasty - an effect that is used in fashion photography and portraiture - because the characteristic curve of colour neg film tends to round off very gradually instead of having a definite shoulder.

I push Portra 800 and Fuji NPZ (now known as Pro 800Z) a couple of stops (ie 'Push 2' processing, but I don't increase the EI by two stops: EI 1600 for Pro 800Z and EI 2000 for Portra 800) and they both look good, though the dynamic range goes down, graininess goes up a little and you do lose shadow detail of course. What is left is punchy, saturated colour (as mentioned by Alpha), quite unlike how some older colour neg films responded to push processing. I haven't pushed any of the current range of Portra 160 or 400, so can't comment.

Best,
Helen

 

[Battou]

I'm getting more and more interested in this thread, I have never understood the concept or process of pushing and pulling at all.

 

[Mav]

Before last week I had ZERO clue that there was so much under/exposure latititude on color neg films. I thought the only ISO you could shoot at was the box speed and that was it. Too brainwashed by the DSLR world.

Thanks Helen! :thumbup:

 

[Moglex]

I'm getting more and more interested in this thread, I have never understood the concept or process of pushing and pulling at all.

Pushing can be great fun.

Many, many, years ago I exposed a nearly out of date b & w film by candlelight without any meter readings at all and then processed it 'to completion'.

I got some lovely 'arty' shots of various flowers made up of the enormous grain that resulted.

 

[randerson07]

I push Portra 800 and Fuji NPZ (now known as Pro 800Z) a couple of stops (ie 'Push 2' processing, but I don't increase the EI by two stops: EI 1600 for Pro 800Z and EI 2000 for Portra 800) and they both look good, though the dynamic range goes down, graininess goes up a little and you do lose shadow detail of course. What is left is punchy, saturated colour (as mentioned by Alpha), quite unlike how some older colour neg films responded to push processing. I haven't pushed any of the current range of Portra 160 or 400, so can't comment.

Best,
Helen

So when you say pushing, you mean the lab does something different? how does that work with c41 processing since all film is developed for the same amount of time? can all labs do it?

When underexposing and not pushing the processing, how much difference is there?

This is a very interesting topic, Ive had a lab push process some Tri-X 2 stops and the prints where terrible(the only printed 13 of 24 frames) as were the scans they put on a cd for me, but the negs looked pretty good and I was able to scan them on my epson. Here are some of the scans I did
http://www.flickr.com/search/?q=push to 1600&w=82308981@N00

When pushing C41 can I expect the same type of results?

 

[Helen B]

This subject deserves more of a reply than I have time to write at the moment, but here's a brief rundown of push processing for colour film.

There are three main types of film process in current use for film used in-camera for pictorial photography and cinematography, widely known by their Kodak designations: ECN-2; C-41 and E-6.

ECN-2 is a negative process for motion picture film. It is quite similar to, but not exactly the same as, C-41.

C-41 is a negative process for still film.

E-6 is a reversal process for still and motion picture film.

Each of these processes are standardised for normal development and it is the normal development process that is used to determine the ISO speed rating or recommended EI of the film*. However it is possible to alter the time in the developer (first developer for E-6 - it has two developer stages) to push or pull the film.

Just as the normal development times is standardised, so are the pull and push times, though labs often tweak the times a little. The pull and push times are given by Kodak, for example. Typically there will be pull-1, push-1, push-2 and push-3 times.

When sending a film in to a lab that does push and pull development (they may do C-41 push but not C-41 pull) you can simply specify 'push-2' for instance, and you should get the standard time for push-2. A push-2 development may not give you a two-stop increase in usable speed**. As I mentioned above, I rate Pro 800Z at EI 1600 (a one-stop increase in EI) for push-2 development. With reversal film the correspondence is usually closer - I rate Ektachrome 200 at EI 640 for push-2, a 1-2/3 stop increase in EI.

This is not the same as it is for B&W film, where processes are not nearly as standardized. Typicaly each B&W film will be developed for different times for particular speeds: there are no standard pull and push times.

Pushing and pulling film changes the contrast - typically a push will cause an increase in contrast. This can be used as a method of basic Zone-System-type manipulation of colour film, especially with reversal film. It is not unusual to specify a small push of less than a stop to make studio images pop a little ("clean up the highlights"). Colour films are carefully designed to give their optimum colour balance with normal processing. Any change from the normal process can result in slight colour shifts because different layers behave differently when the developing time is changed. This is less of a problem if the film is digitally post-processed than if it is conventionally printed.

*There are exceptions such as Ektachrome P1600, which had its recommended EI of 1600 based on push-2 processing.

** It certainly will not give you a two stop increase in true speed - half a stop increase in true speed is a good result for push-2 processing of colour negative film. The ISO speed of colour neg is determined from the shadow exposure alone, and pushing has very little effect on shadow detail.

Enough for now.

Best,
Helen

 

[randerson07]

Awesome stuff there.

I should have specified, that by same type of results, I did in fact mean an increase in contrast. I should have figured that pushing and pulling times had to also be standardized but it didnt click till you said it.

Hmm I didnt know pushing or pulling Slide film was a practice people used, I had only read that it had much less exposure latitude than Negative films. Thats very interesting.

I really like the "make them pop a little" statement, I often find my images slightly flat. Lately Ive been over exposing film by half a stop or so because I read something on flickr about rating a couple of the films I use slightly slower. It worked really well on the cheap fuji rolls I had, but it didnt do much for the flatness it just made the colors look different.

I dont use a pro lab, and cant afford to but maybe Target can do push processing, Im in there picking up prints almost every week, hopefully i can talk her into it.

Thanks Helen.