Rating Film (Specifically Tri-X)

[j._queue]

I am somewhat new to the process of developing my own film. I have been using Tri-X 400 with Diafine. During my reading here on

photo.net and other sites I see people stating that they like to rate Tri-X at other speeds (ie 800, 1250, 1600). I can't seem to get my head

around this. How do I go about rating Tri-X at, say, 1600? I am using a Nikon FE so would it be as simple as setting the film speed index

dial to 1600? Also, what are the pros and cons of doing this? If I wanted to use Tri-X 400 in a low light setting, I would not want to set the

dial to 1600 but rather 200. Since it is a 400 speed film, setting the film speed dial to 1600 is going to let in less light resulting in an

underexposed negative, right? Any help would be appreciated as I am confused.

[jpo3136b]

The short answer is, Yes, it is as simple as setting the film speed dial to another number. However, in order to do this

successfully, to carry the image all the way through the development process, you would have to adjust the

development time of the film accordingly. Typically, what you will see is that when you set the film speed higher,

effectively, you are creating metering situations that are deliberately underexposing the film by a few steps. Then, to

compensate for this, the development time will have to be extended.

 

When film is sold to you, as "400" speed film, that is usually the optimum speed for that roll, that kind, from that brand.

Depending on how the film was created, it can usually be pushed or pulled somewhat. This is not limitless; for example,

some films are usually only recommended for use as one or two speeds. Others may have a much wider latitude.

 

For example, check out this chart from Ilford. It summarizes in a one page pdf how their films can be shot at different

film speeds, and then have the development adjusted accordingly.

 

http://www.ilfordphoto.com/Webfiles/2006216122447.pdf

 

Or, the Massive Development Chart at digital truth: http://www.digitaltruth.com/devchart.html

 

There are some drawbacks. For example, one may see an increase in contrast; thus, a reduction in tonal range of the

final print. Film shot at very high speeds may need to be developed soon. Other characteristics could come out.

 

Also, some films can only be pushed so far; it's possible to under/over expose the film through Film Speed adjustment

to the point that there are no usable images on the negative.

 

The principle advantages include shooting in situations with less light; or adjusting the speed downward (say, from 1600

to 400) to improve detail or reduce developing time.

 

Using film at speeds other than those normally marketed to consumers is kind of like adjusting your own carburetor.

Chances are the factory sold you a good one to begin with, but the advanced user might want to adjust his own to

change its performance.

 

I enjoy HP5+ at 1600; PanF+ at 32. Try a roll or two like this, and I think in most cases you'll be pleasantly surprised.

Tip: I find that it is best to let pushed or pulled film sit for 24 to 48 hours of air drying before evaluating the negative.

And, review the negative with glancing light; look at it from an angle. There will be much more detail revealed than you

might initially expect just by looking at it in harsh lighting, head on. Those details, on the negative, can be brought into

your print. Good luck. J.

[lex_jenkins]

It's usually called "pushing" film: underexposure compensated for through extra development. The extra development is usually called "push processing".

 

Rating the the speed higher doesn't change the ISO, which is determined according to (not surprisingly), ISO standards. Changing the ISO on the camera or meter is just a handy way to keep track of the exposure needed to keep the push within fairly consistent limits. But it doesn't actually change the light sensitivity or "speed" of the film itself.

 

Pushing film can be a useful option for various reasons. It doesn't suit every photographer's needs or tastes.

[marek_fogiel]

Check if your Nikon has the DX readout, if yes, you have to compensate on the +- dial, otherwise you can simply set the

ISO dial to the desired speed. As far as Tri-X in Diafine, it will give you perfectly useable results exposed anywhere

between ISO 400 and 1600 on the same roll, I have even exposed it at ISO 200, and it is acceptable, although the drop in

sharpness is evident. If you use a through the lens average metering, you will probebly be best off to set the speed around

ISO 1000 in most cases. Just try it, it works well especially if you scan and can adjust the contrast in post processing.

BTW, look at this guy's site:http://figitalrevolution.com/?s=tri+x+diafine

[jim_appleyard]

Please remember, tho', that Tri-X, or any other film, has only one ISO. When you change the dial on the camera, you're not changing the ISO, but you are changing the Exposure Index (EI). Your exposure index can be anything you want, within reason. Nitpicking, but many people forget this.

[AJG]

My experience with looking at prints made by people who "push" their film has been disappointing. Grain will increase

because of the increased developing time, and shadow detail goes away. While push processing can be useful under

some circumstances, where you couldn't stop subject/camera movement without a higher ISO, it generally leads to prints

with a poor tonal range.

[j._queue]

First, thanks to everyone for all of the feedback. It is very helpful.

 

Now, according to the Massive Dev Chart Tri-X 400 will be pushed to a rating of 1600. That means that the next time I

need to shoot in a low light situation that I can set the dial to 1600 and, in theory, the photos should turn out reasonably

fine.

[vincent_peri]

"That means that the next time I need to shoot in a low light situation that I can set the dial to 1600 and, in theory, the photos should turn out reasonably fine."

 

Just be aware that you need to shoot the entire roll at one ISO setting, such as ISO 1600. You can't shoot some photos at ISO 400 and others at ISO 1600.

[bcostin]

"Just be aware that you need to shoot the entire roll at one ISO setting, such as ISO 1600. You can't shoot some

photos at ISO 400 and others at ISO 1600."

 

Actually, with Diafine you can change ISO settings at any point in the roll. It always develops to completion

after 3-5 minutes, so the EI you shoot at is about all you can vary.

 

I routinely shoot Tri-X (or Arista Premium 400) at speeds from 200-1600 on the same roll. (This is handy for

gaming the programmed exposure in a point-and-shoot with limited manual control, like my XA4.) The negatives do

begin to get thinner and more grainy as you go above EI 1000 or thereabouts but in most cases I'm hard-pressed to

tell the difference. Diafine is particuarly well suited to Tri-X, but some other films also work quite well when

used this way. Efke KB400, for example.

[j._queue]

I was actually thinking that the EI could vary on a given roll of film when using Diafine since it develops at fixed 3+3.

Thanks for pointing that out Bryan.

[jeff_phillips7]

I just finished several rolls of Tri-X exposed at 1600 asa and processed in Rodinal 1:50 @ 18min with

wonderful results - it is easy and correct to set your speed to 1600 but you might want to experiment with

one or several rolls as different developers give different results - Note I am shooting 6x6 and rodinal is not

a fine grain developer - try it out - good luck - Jeff