Push me, pull you

Despite the dread, you really have to do little. (See what I did there?)

So, pushing film means underexposing it, or exposing it as though it had a higher ISO, which is the same thing. To compensate we give it more development.

When we pull film we overexpose it then give it less development to compensate.

Why would you bother? Well sometimes pushing the film is the only way to get the picture. The side effect of giving it more development is that the contrast can be increased. This means you can also push the film when you want to deliberately increase the contrast. Ted Vieira shoots 400ISO black and white film at 1600 and loves it.

Similarly, you might pull the film to reduce contrast.

But what does increase or decrease development mean? By how much? Let me consult the notebook of photographic lore.

Clever book

Pushing film
1 stop, increase development time 50%
2 stops, increase development time 80%

Pulling film
1 stop, decrease development time 30%
2 stops, decrease development time 50%

The book of all cleverness also gives a formula to calculate the development time to use if you are pulling film. Take the normal development time and halve it. Take the times increase in exposure (eg 2 stops is 4 times increase, so use the figure 4) and take the reciprocal of this number (so 4 becomes 1/4). Multiply this reciprocal number by the halved value of development time. Add this number to half the normal development time.

So, imagine I pulled the film 1 stop (2x increase in exposure). Normal development time is 10 mins. Half the dev time is 5 mins; multiply by 1/2 = 2.5 mins. Add this to half the dev time of 5 mins and the new development time is 7.5 minutes. The quick reference above says cut development by 30%, so it’s a fairly good match.

Or you could start with a degree in maths. Or you could look up your film and developer combination on the Massive Dev Chart. But it your special brand of madness is not there, try the suggestions above.

But why on earth would you pull film? Well the Zoners will tell you that it is to increase the number of tones captured on the film, so expanding a high-contrast scene to show more of the intermediate tones between black and white. The book of photographic cleverness says that you can match the amount you pull the film to the tonal range of the scene like this:

‘Nomal’ range 125:1 – normal exposure and development.
250:1 – overexpose 1/3 stop, cut development 10%
500:1 – overexpose 1/2 stop, cut development 20%
1000:1 – overexpose 1 stop, cut development 30%
up to 4000:1 – overexpose 2 stops, cut development 50%

Beware though, this leads to the Dark Zone.

What I have come round to is pushing the film so that I can use better cameras settings in poor light, then using Rodinal at 1:100 to do semi-stand development.

The Enid
Even FP4 can be pushed, if it is all you have to hand. This was pushed two stops by the simple +80% development time method.

Author: fupduckphoto

Still wishing I knew what was going on.

One thought on “Push me, pull you”

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