Changing rating of film mid roll?

[yoz]

I am wanting to see if I am able to change the rating of a film throughout a roll, in different conditions, to see how photos turn out? If I am able to would I then ask the lab to just process as normal or different? It will be portra 400. Thanks

 

[Pieter12]

You can with 35mm. After you have shot at the initial rating, shoot a couple of blank frames, take the camera into a darkroom (total darkness) and snip the film near the take-up reel, unspool what is on that spindle and load it on a developing tank reel and put that in the tank. Then take the loose end that is still in the camera, trim the end and reload it in the take-up reel. Close the camera, turn on the lights and finish the roll at the new rating. Unless you have some way to measure the frames in the dark ( like a piece of film with the same number of frames as you have shot where you want to cut the film--a tricky procedure in total darkness-- it is not really practical with medium format or 35mm without removing the film from the camera midway.​

 

[MattKing]

Welcome to Photrio.
The film itself doesn't change. In particular, the sensitivity of the film to light doesn't change.
You can change how the film responds to light a very little bit by changing how the film is developed. Some people think that they can change how sensitive to light the film is by lengthening development ("pushing" the development). That isn't really what happens. A "push" development merely increases contrast, which can make the results from under-exposed film look marginally better.
Some people also like to over-expose film and then tell the lab to decrease or "pull" the development. That change in development merely reduces contrast, at the expense of colour fidelity.
If the development is changed from the standard method, the overall quality goes down.
Most labs charge extra for non-normal developing.
What is accomplished by experimenting with the speed rating of film is that you get to see how film responds to your method of metering the light. It may very well be that the way you use your meter results in a tendency to under-expose film. If so, regularly down-rating the film speed setting or dialing in extra exposure may give you better results. The same applies if you regularly over-expose your film, except in that case you would uprate the speed setting or dial out some exposure.
More commonly though, you may find that for much of your photography using the "box" speed and metering in your usual way is optimum, but under certain lighting conditions you need to adjust. That is something you learn through experience.

 

[yoz]

You can with 35mm. After you have shot at the initial rating, shoot a couple of blank frames, take the camera into a darkroom (total darkness) and snip the film near the take-up reel, unspool what is on that spindle and load it on a developing tank reel and put that in the tank. Then take the loose end that is still in the camera, trim the end and reload it in the take-up reel. Close the camera, turn on the lights and finish the roll at the new rating. Unless you have some way to measure the frames in the dark ( like a piece of film with the same number of frames as you have shot where you want to cut the film--a tricky procedure in total darkness-- it is not really practical with medium format or 35mm without removing the film from the camera midway.​

I only use a lab

 

[yoz]

Welcome to Photrio.
The film itself doesn't change. In particular, the sensitivity of the film to light doesn't change.
You can change how the film responds to light a very little bit by changing how the film is developed. Some people think that they can change how sensitive to light the film is by lengthening development ("pushing" the development). That isn't really what happens. A "push" development merely increases contrast, which can make the results from under-exposed film look marginally better.
Some people also like to over-expose film and then tell the lab to decrease or "pull" the development. That change in development merely reduces contrast, at the expense of colour fidelity.
If the development is changed from the standard method, the overall quality goes down.
Most labs charge extra for non-normal developing.
What is accomplished by experimenting with the speed rating of film is that you get to see how film responds to your method of metering the light. It may very well be that the way you use your meter results in a tendency to under-expose film. If so, regularly down-rating the film speed setting or dialing in extra exposure may give you better results. The same applies if you regularly over-expose your film, except in that case you would uprate the speed setting or dial out some exposure.
More commonly though, you may find that for much of your photography using the "box" speed and metering in your usual way is optimum, but under certain lighting conditions you need to adjust. That is something you learn through experience.

So development I will do as normal, which should still show the results in my changes? For rating i was just going to change the iso. Thanks

 

[MattKing]

So development I will do as normal, which should still show the results in my changes? For rating i was just going to change the iso. Thanks

Technically, and this is really just a matter of nomenclature, when you use a different film speed setting on your camera or meter, you are using a different Exposure Index ("EI") because the ISO speed is set when the film is manufactured.

 

[Pieter12]

I only use a lab

You would have to ask them if they can do that for you. If you want to use 2 rolls, you can carefully rewind the film into the cassette, leaving some leader exposed and note on the cassette the number of exposures taken and the ISO you used. Load a new roll and shoot at your other rating, doing the same. You now have the choice of reloading the camera with either roll and finish it at the marked rating, taking care to advance the film, shooting at your camera's fastest shutter speed and smallest aperture with the lens cap on for the number of frames you had previously shot, plus a couple for safety. Or just process your half-shot rolls. But that method does not really allow you to really change the speed mid-roll, just shoot 2 rolls at different speeds. At which point you might as well be shooting different films.

 

[Pieter12]

So development I will do as normal, which should still show the results in my changes? For rating i was just going to change the iso. Thanks

It depends on how much you intend to change the rating. A stop or two between ratings is manageable, you might want the film devloped at an ISO that falls between the two. The negs might be a bit more challenging to print.

 

[Bill Burk]

If you change from 400 to 200 or 100 at different places in the roll no real bad pictures will come out at normal processing.

If you are thinking 800 and 1600 then you are better off sticking to one high speed and tell the lab to push

 

[yoz]

It depends on how much you intend to change the rating. A stop or two between ratings is manageable, you might want the film devloped at an ISO that falls between the two. The negs might be a bit more challenging to print.

Yers 2 stops would be maximum. Thanks

 

[koraks]

A stop or two between ratings is manageable

Only if it's two stops downward, so 200 or 100 for Portra 400. Upward by 2 stops to 800 will be a sorry mess regardless.

 

[MARTIE]

My understanding is, that you are just fooling the light meter. You're doing exactly the same, on manual mode or by an exposure compensation dial, by under and over exposing the metered reading.

 

[pentaxuser]

Only if it's two stops downward, so 200 or 100 for Portra 400. Upward by 2 stops to 800 will be a sorry mess regardless.

Yes I hope yoz is still following his/her thread and has understood the point you make as it is quite crucial

pentaxuser

 

[Helge]

Welcome to Photrio.
The film itself doesn't change. In particular, the sensitivity of the film to light doesn't change.
You can change how the film responds to light a very little bit by changing how the film is developed. Some people think that they can change how sensitive to light the film is by lengthening development ("pushing" the development). That isn't really what happens. A "push" development merely increases contrast, which can make the results from under-exposed film look marginally better.
Some people also like to over-expose film and then tell the lab to decrease or "pull" the development. That change in development merely reduces contrast, at the expense of colour fidelity.
If the development is changed from the standard method, the overall quality goes down.
Most labs charge extra for non-normal developing.
What is accomplished by experimenting with the speed rating of film is that you get to see how film responds to your method of metering the light. It may very well be that the way you use your meter results in a tendency to under-expose film. If so, regularly down-rating the film speed setting or dialing in extra exposure may give you better results. The same applies if you regularly over-expose your film, except in that case you would uprate the speed setting or dial out some exposure.
More commonly though, you may find that for much of your photography using the "box" speed and metering in your usual way is optimum, but under certain lighting conditions you need to adjust. That is something you learn through experience.

Developer is an amplifier quite analogous to other amplifiers in other fields.
That is, it has an inherent amount of nonlinearity and hysteresis as part of the interaction between signal type and amplifier.
IE some frequencies and amplitudes have a difference response.

You can help the amplifier in various ways, like is the case with for example the amplifier(s) in a stereo.
There are direct analogies to techniques in audio and especially analogue tape recording.

For example: Flashing and latensification is biasing current and HX-Pro, and Dolby noise reduction is analogous to acutancy effects, unsharp masking and the effect of very sharp and contrasty lenses.

What you can’t do as effectively with developer is treating different parts of the signal differentially as effectively.
Compensating developers and development attempts to kind of do that, but can’t achieve it as effectively as is possible with a temporally linear signal as on say, tape or in a wire.

 

[abruzzi]

Its also worth pointing a few things out. You mention Portra 800. Thats a color negative film which usually (though not always) can stand a fair amount of over exposure (and a little under expusure). If you tried the same with Ektachrome or any other slide/reversal film, the results would be horrible. If you tried with B&W negative film, its somewhere in between--maybe a stop up or down from the rated speed.

Also, as Matt pointed out, under or over exposure will change the character of the film. Supposedly Fuji Pro 400H was popular with wedding photographers beacause if you shot at EI100 instead of 400, you would get a kind of pastel image that was ideal for unreal romantic scenes. Portra may give similar results. Its similar to a lot of the very high contrast TriX look that some people love. That comes from shooting a 400 speed film at 800 or 1600 and push processing. In B&W the rule of thumb is over exposure and pull processing reduces contrast, and under exposure and push processing increases contrast. With color film you also have to deal with changes in colors when you over/under expose. There is a guy on youtube that tested a few color negative films on his Pentax 67 by shooting the same scene at 10 different exposures then looking at the results. His examples are interesting, and since you don't develop or presumable optically print yourself they may be instructive for your purposes (the images, being scans, are going to auto corrected by the Fronrier or Noritsu scanner software, so the differences on the film may be different than the differences on the scan.) Unfortunately, I don't have a link to his series of videos.

 

[gone]

If you're only changing it by a stop or so, you won't see any difference probably. I'd go for more than that, and make a note of where on the roll you changed the EI and see what happens.

 

[Alan Edward Klein]

Many good labs will push and pull film for a dollar to two more per roll. Check their websites.

 

[DREW WILEY]

Just changing the film speed rating mid-roll is super easy. All you're doing is changing either your shutter speed accordingly. Trying to differentially compensate for that in development is an entirely different. Automated push and pull options, ofgten offered by commerical labs, are a bit of a miserable chore mid-roll; and gross adjustments, like for 2 whole stops, is something unrealistic. It's not like developing black and white film. Even with Portra 400, being two whole stops off box speed will come with a serious quality penalty in terms of color scale reproduction. But if you have some weird creative reason to try it on relatively inexpensive roll film, why not? I'd just do it on two completely different rolls, not change my mind mid-roll. Otherwise, you'll probably pay more for the fuss the lab has to go through, if it will do it at all, versus the modest cost of just another roll.

 

[grain elevator]

I'll assume you were not planning to alter development or even have the lab snip the roll in two and push half of the film. As has been mentioned, using two rolls of film would make more sense than that.
If you adjust the ISO on your camera meter, it changes the exposure of your film. You might as well use the exposure compensation control or use manual exposure and just alter it from the meter reading. As this is for the sake of experimentation, I'd recommend you take photos of the same scene, one as the meter recommends, one overexposed by a stop, one overexposed by two stops, and one underexposed by a stop. Maybe some more because the differences between those will be subtle with Portra. Better to have a direct comparison than different scenes. You'll be able to more clearly discern the effect of exposure.

 

[yoz]

Only if it's two stops downward, so 200 or 100 for Portra 400. Upward by 2 stops to 800 will be a sorry mess regardless.

Thanks

 

[yoz]

If you're only changing it by a stop or so, you won't see any difference probably. I'd go for more than that, and make a note of where on the roll you changed the EI and see what happens.

From what i have read anymore than 2 stops, sees colours go wonky

 

[yoz]

I'll assume you were not planning to alter development or even have the lab snip the roll in two and push half of the film. As has been mentioned, using two rolls of film would make more sense than that.
If you adjust the ISO on your camera meter, it changes the exposure of your film. You might as well use the exposure compensation control or use manual exposure and just alter it from the meter reading. As this is for the sake of experimentation, I'd recommend you take photos of the same scene, one as the meter recommends, one overexposed by a stop, one overexposed by two stops, and one underexposed by a stop. Maybe some more because the differences between those will be subtle with Portra. Better to have a direct comparison than different scenes. You'll be able to more clearly discern the effect of exposure.

Yes i am looking to do this in different scenes and lighting. Is changing the iso on the film and exposure compensation not the same?

 

[yoz]

Just changing the film speed rating mid-roll is super easy. All you're doing is changing either your shutter speed accordingly. Trying to differentially compensate for that in development is an entirely different. Automated push and pull options, ofgten offered by commerical labs, are a bit of a miserable chore mid-roll; and gross adjustments, like for 2 whole stops, is something unrealistic. It's not like developing black and white film. Even with Portra 400, being two whole stops off box speed will come with a serious quality penalty in terms of color scale reproduction. But if you have some weird creative reason to try it on relatively inexpensive roll film, why not? I'd just do it on two completely different rolls, not change my mind mid-roll. Otherwise, you'll probably pay more for the fuss the lab has to go through, if it will do it at all, versus the modest cost of just another roll.

Would this be an issue if i said to develop at box speed? What would 1 or 2 stop up or down be with shutter on portra 400? I only know the iso part

 

[grain elevator]

Yes i am looking to do this in different scenes and lighting. Is changing the iso on the film and exposure compensation not the same?

Yes it is, I was trying to say that. Good idea to try in different scenes and lighting. Then I would say you're trying out exposure compensation, that's what it's for. Framing it has "rating" makes people go to pushing and pulling...

 

[JNP]

Do you have a scanner and edit software ? You might be better doing the postproduction yourself some labs don’t deal well with dense negatives