ah tong said:
Hi all,
Need to ask you all as i sometimes come across people "pushing or pulling" their film speed on their camera
eg. Actual B&W film speed is 3200 but rated as 1600.
1. What's the purpose?
2. When you send to develop, how do you tell the film developrs?
Thanks!
That was a common thing some of us use to do when we want to get better or at least quicker ISO sensitivity from an existing roll of film.
For example I am shooting a wedding. And for some reason my flash stop working. Say I am left with just my built-in flash which might not be strong enough for those long range shot thus I might need to use a slow shutter speed to compensate for the missing flash power and dimmer lighting. How do I compensate and still get reasonable picture for the rest of the night? That way would be to push my film to a higher ISO sensitivity to gain some "speed" So basically you push your film to get abit more sensitivity out of them.
You pull process especially when you changed film in your camera for example, accidently put in ISO 200 film but your camera setting was still set for ISO 100. So now you have shot a roll that is over-expose. So if you caught it in time and know that roll of film is over exposed, you can still save it by pulling processing. Of course in these day and age...most SLR come with auto ISO detection but reading the film's container with some connectors that line the film roll bay on your SLRs. So this error is rare. IN fact pull process is seldom practice...except made from what I rad for those duplicating slides. They do that to keep the saturation and colours if I am not wrong.
Both processing of pull or push involves spending more or less time in certain developing chemical in order to "correct" the exposure.
The problem is...when you push or pull process. You can NOT do it as and when you like within ONE ROLL of negative. ( meaning shoot some at iso 400 and then change to ISO 800 and back) You have to PUSH the whole roll or you don't push at all. You might suffer abit more grain in your picture but not alot. As far as pushing or pulling, you normally can not exceed about twice the speed of the original film ISO. (2X ISO speed) That is why you notice people using ISO 1600 which is push to ISO 3200. And push and pull processing might not work for all brand and type of film. Some has a lower rating for this and some have wider tolerant for it.
Also!..very important. Bring your roll to only photo shop that knows about Push or Pull processing. They have to specially adjust for the processing. Normal processing will ruin it.
I use to do that alot because hi-speed film cost alot more in those days in the 1980s heh. Also MARKED YOUR FILM ROLL so you don't forget! Push or pull processing a roll of normal film might also ruin it.
