"Rating" a stock

shadowcaste · Nov 27, 2006

Hi,

What does it mean to "rate" a stock? Like shooting 500T stock and rating it at 400?

Is it just a matter of setting your meter to 400, or is there some sort of special instruction for the lab?

David Mullen ASC · Nov 28, 2006

What you tell the lab is a separate issue.

You may rate the stock at something different than the manufacturer's suggested rating, for whatever reason. For example, you may want to rate a 500 ASA stock at 400 ASA to slightly overexpose it.

Normally you would still just tell the lab "PROCESS NORMAL." Then the processed negative would end up 1/3 of a stop more dense (overexposed) than if you had rated the stock at 500 ASA. You then would probably correct that slight overexposure when making a print (by printing "down", aka using a higher set of printer light numbers) or darkening it in the telecine transfer. It helps, if you aren't there for the transfer, to shoot a grey scale or card at the rating you have chosen so that the colorist will attempt to make the card look "normal" in brightness and color, and thus correct for the extra density of the negative.

But you may tell at lab to PUSH or PULL PROCESS the negative by "x" number of stops. And you may have exposed the film to compensate for this, like rating a 500 ASA stock at 1000 ASA and then asking the lab to PUSH ONE-STOP and thus compensate for the underexposure by increasing the neg density through extended development, thus hopefully ending up with a normal density.

You could even rate a 500 ASA stock at 800 ASA, for example, which is a 2/3 stop underexposure, and then ask the lab to push one-stop and have a final negative that is 1/3 of a stop denser than normal.

The lab doesn't really care which color neg stock you give it or how you exposed it -- it all goes into the same ECN2 process. The only thing that they care about is whether you want them to process normal, or pull or push the process (or special processing like skip-bleach.)

Any final adjustments to scene density after that would probably be done in making the workprint or in the telecine transfer.

PanavisionT2 · Apr 5, 2007

David, what are you thoughts on overexposing a stop and then having the lab pull the processing by one stop? Does it really help with giving the frame extra clarity?

David Mullen ASC · Apr 5, 2007

Overexposing and pulling one-stop would:

Decrease contrast
Make colors more pastel
Decrease graininess

I don't know if it gives the image more "clarity" - the lower contrast tends to make the image feel softer, but with finer-grain.

PanavisionT2 · Apr 6, 2007

That's what I meant by clarity, finer grain.

Can you describe the intensity of the color towards the pastel feel? Are we looking at a 5%, 10%, 20% shift in color? I'm sure it doesn't go easter candy pastel but how big a shift is it? Can I compensate the color loss by adding more color while I'm shooting with gels or is it affected by color temperature?

Also, because the contrast is lowered, are you able to get more detail in the shadows?

David Mullen ASC · Apr 7, 2007

Yes, more shadow detail. It looks a little like you've switched to a low-con stock like Expression 500T or Fuji 400T, although not in terms of graininess, just the softer colors and contrast.

There is a connection between black level, contrast, and color saturation, which is why low-con stocks have softer colors.

The effect from a one-stop overexpose and pull is not dramatic in terms of making the colors softer.

Before 200T stock became available, Michael Balhaus shot Coppola's "Dracula" on 500T stock overexposed and pull-processed.

Recently, Chris Doyle pull-processed Fuji stock for "Lady in the Water" and "The White Countess."

HuangXY · Apr 13, 2007

hi,
i am not good at english, what is the low-con stock?
and i want to knowm, is there anything bad to push or pull? for example, am I going to have less detail in the bright part of the frame when overexplosure and pull.
and what is the "skip-bleach"process?? Does it mean leave the silver on the stock in different levels, like ENR process?
thanx in advance

David Mullen ASC · Apr 14, 2007

"Low-con" just means a lower contrast stock, which has a slightly wider exposure range. Usually the colors and blacks are a little softer, less snappy.

A one-stop underexposure and push, or a one-stop overexposure and pull, is not going to be that detrimental to detail because the film can handle it. More extreme under and overexposure risks losing detail at the top or bottom of the exposure range.

"Skip-bleach" or "bleach-bypass" means exactly that, skipping the bleach step the normally converts developed silver back into silver halide so it can be removed in the fixer and wash steps, leaving only color dye clouds. So it tends to be a process that leaves all the silver in, although some labs offer a halfway version.

ENR is for print stock only; it involves adding extra b&w developer tanks into the processing line to permanently develop a certain percentage of the silver so that the rest can be removed, so it is more adjustable in strength than a simple skip-bleach process.