questions about pushing film

[anish]

i recently posted a question about challenges in shooting landscapes

at slow shutter speeds when a breeze is present. one of the many

suggestions was to use provia (instead of velvia) and push 1 stop to

effectively gain two stops. This, in many cases, would put me into

a range of shutter speeds that would better handle the effects of

the breeze. My questions are as follows:

1. Is there much effect on sharpness with velvia and provia, pushed

one stop (at 12" x 18")?

2. This might sound dumb, but when pushing provia one stop, for

example, do i simply set the ISO setting on my camera to 200 and

fire away (or do i set it to 50)?

3. Lastly, can i shoot part of a roll pushed, and part of it not

pushed? i guess this is a processing question, can the lab process

certain slides from a roll pushed, but not all?

 

Thanks for any input.

-Anish

[stephen hazelton]

If it's a 100 speed film, you'd set the ISO setting to 200 to push it one stop. Or, you might be able to do the same thing with an exposure compensation dial or setting, if your camera has that.

 

The lab has to process the whole roll the same way- it's all pushed or none of it is, so you'd just shoot the whole roll at that speed. You might want to check with your lab before doing so to make sure this isn't a problem. If you're using the local drugstore, you may not find anyone that even knows what pushing a film is.

[berk_sirman2]

When you want to push Provia (100 ASA) by one stop you underexpose it by one stop by exposing it as if it was a 200ASA film. Just set your camera to 200 ASA. Push processing makes up for the one stop underexposure.

 

The only way to push one part of a roll and not push the other part is by processing them seperately. You can shoot the first part at 200 for example and take the film to the lab and state how many exposures you made at what speed. They may take that number of films off the roll (in the darkroom of course) and process them according to your directions. They may leave the rest of the film in the roll, you can put it back in your camera and shoot the rest in a different speed if you wish and have it processed accordingly. Note that you will have to pay double for processing, as if you were shooting two rolls of film. I think it is a better idea to shoot two rolls, it will be more cost effective. In the method I explained above the total number of frames will be less than 36 (or 24) as 1-the lab will cut one or two exposures more when they cut the half exposed film in order to make sure they do not cut any exposed frames in half 2-you will lose a few more frames as you are putting the film back in your camera for the second time.

[steve_dunn2]

<p>Just to add to what's already been said: check the datasheet and/or do your own testing to find out what speed works best for a one-stop push. It's not always exactly double the film's ISO speed. For instance, some films only gain about 2/3 of a stop of exposure from a one-stop push, so you'd rate the film at 160 - at 200 it would turn out a bit underexposed.</p>

[rowland_mowrey]

Pushing all films increases contrast and grain.

 

Pushing reversal films lowers Dmax, and pushing negative films raises Dmin.

 

The difference often is that the effects of the push are more noticeable in reversal pictures than in prints from negatives, as the changes in the negative can, in part, be minimized during printing.

 

Ron Mowrey

[r.t. dowling]

Another option is to simply use a faster film, such as Kodak E200 or Fuji 400F. These films *generally* give better results than slower films that have been pushed.

[david_henderson]

The increase in grain from a one-stop push isn't very great, but of course if you're starting from 35mm then at 18"x 12" I might expect to see some grain in prints anyway and if you can then pushing is going to make it a bit more obvious. Other than that you're unlikely to notice any effect on sharpness.

 

The advice to check with your lab to see if they handle push processing is good. That said we aren't talking unknown black art here and I'd expect any competent lab to offer this service on E6.

 

You set the film speed to double your usual rating and tell the lab; adding the fact that you want them to push one stop. With Provia there's a view that it's "real" speed isn't the 100 ISO it claims but nearer 80. If you subscribed to this you'd set the speed to 160 for a one stop push. I've just shot some rolls of Provia 100F at 100 and they look OK to me. The nuances of the real speed are something you can deal with later and it's a tweak , that's all.

 

Unlike RT, I don't much like Provia 400F, and in my view- which others might not share- Provia 100F pushed one is the best 200 ISO slide film around. Some people push it two stops but I've had bad experience with contrast in sunny conditions. If I needed a 400 speed slide film I'd rather use Provia 400 than push Provia 100 two stops, despite my misgivings about its palette.

 

Materially you have to get the whole roll pushed- or not. And you can't vary the degree of push within the roll. The lab may charge a little more for push processing. Some do, some don't.