Difference between pushing b/w film and colour C41 film?

Question

I have experience in pushing b/w film in my home. However, I'm also looking to get into colour C41 processing.

I Was asking a developer about pushing colour film, they said:

"The process time cannot be altered, but 1 stop 400 - 800 would not make a huge difference so it would be fine to process this."

Also:

What about C41 Colour Negative film?

There is seldom a need to adjust C41 development because there is so much exposure latitude in the film and the subsequent printing. The manufacturers reluctantly accept that colour negative film can be pushed or pulled but do not recommend it, because the photographic results are unpredictable. The resulting prints might, for instance, have greenish shadows and pink highlights due to an image imbalance called 'crossed curves' that is very difficult to remove without careful adjustments in Photoshop.

I am pushing fuji superia xtra from 400 to 800.

Thing is I can go to another developer who can lengthen dev time, but it costs around 3-4 times as much to develop per roll, than the above quoter.

thanks

Answer 1

I halfway agree with your second opinion. You rarely need to push a negative film because of the exposure latitude. With films available up to 1600 ISO this is rarely necessary.

However:

to push a color film is actually surprisingly similar to pushing a b/w film

In my career as photographer I've pushed both, positive and negative films whenever necessary. The results with the E6 process were better than the ones from the C41 process.

Process requirements

You need to chenge the time of the first development stage only. The rest of the processing steps should not be changed at all.

With a linear machine like the colenta 30 E6 26 PRO there little options to change the development time. You can only change the speed of the machine, but this affects all chemical steps the same way. You cannot reduce the development time below a certain margin (because the fixation step will not be finished then) and your maximum increase is also only around twice the time.

I have used a Colenta 130 machine (spinning drum type) which lets you set the first development time to anything between 0 and 30 minutes. The same is possible with other "processors" like the Jomo drum or with the manual processors or with the good-ole Ilford box

Paramount to all color processing is stable temperature. As this temperature (38 degrees Celsius) is significantly higher than with B/W processing this might be a challange.

Experience with Pushing Color films

It is possible to apply the experience from b/w films to color films:

• Pushing increases grain
• It also increases contrast
• the opposite (overexpose and lower development time) can be used to reduce contrast
• it is better to push already high sensitive films further than to push a lower sensitive film to a higher ISO. For example: it is better to push 1600 ISO to 6400 ISO than to push 100 ISO to 200 ISO.

Pushing of negative films (C41 process) usually causes them to loose calibration with the automated printing processes (these are usually calibrated to color film types available on the market). This means: if you want a decent print quality, you may have to order a manual print.

Pushing of positive films (E6 process) is straightforward. Up to two F-stops is usually not a big deal. Starting from three F-stops onward you will notice the "blacks" to brighten up. I would put the limit there. There is little color-shift(*) below two F-stops. The color-shift that becomes visible above that, is towards blue or green. But this stems mainly from the "brightening" of the blacks. The black becomes dark green.

Note: The E6 process additionally allows to control the yellow-blue balance chemically by setting the PH-value in the color-developer. This can be used to reduce a color-shift caused by the pushing.

Answer 2

Push process is possible in the C-41 process This is accomplished by altering the time in the color developer. Normal time is 3 minutes 15 seconds. Push 1 f/stop increase to 3 minutes 45 seconds. Push 2 f/stops increase to 4 minutes 15 seconds. The results besides a higher ISO yield is an alteration in color balance and contrast. The color balance changes can be compensated for during the printing cycle. The resulting increased contrast is unavoidable and is a consequence of push processing.

Answer 3

Difference between pushing b/w film and colour C41 film?

The difference is that with black and white, you're dealing with one chemical process, so it's not a big deal to mess with the chemistry and get a fairly predictable result. With color, on the other hand, you've got three similar processes with different parameters proceeding at simultaneously, and in order to keep them all in balance you need to respect the parameters that are meant to stay fixed, including time and temperature. It's not that the processing duration can't be changed, it's that changing that duration won't affect all three processes the same way, so you'll throw off the color balance.

Answer 4

anyone who wants color push processing must separate between b&w and color forming stages in just one step.I mean you first push it up with a high energy b&w developer like D_19 to some minutes depending on how much up rating you need ?then fix in C_22 or c 41 fixer fallowed in complete C_41 PROCESS.of course you must use Ektachrome or maybe less effective Fujichrome reversal films