Quote Originally Posted by rydolan View Post
@MattKing, thanks, I've been meaning to join this forum for a while now!

I guess my question is more about how to understand the relationship between developing times, exposure, and the rating that one gives a particular film. I'm getting nice results using the ISO 100 rating, but I'm still interested in understanding more about how I can experiment with rating it differently to see if I can get more out of the film.
The film I use for my 120 pinhole cameras are the Arista stuff I mentioned above, and Neopan Acros. Both have very "pinhole friendly" reciprocity curves. Especially the Acros. I can shoot exposures well over 30 seconds with no adjustment for r.f.

I recently switched all of my cameras' exposure charts over to LV instead of EV. That is, instead of changing my light meter to the ISO of the film or paper I am using, I meter everything at ISO 100 and compensate for the film speed after I get the light reading. Are LV and EI the same thing?

Thanks for the info,

Ryan
Ryan:

I use LV to indicate a light value - a measure of the intensity of the light in the scene. It is film independent.

EI is a measure of the light sensitivity of the system, including factors like the film, the meter, the camera equipment, your metering technique, your preferences with respect to shadow detail (in the case of negatives) and, to a certain relatively small extent, the developer you are using.

The ISO is a measure of the light sensitivity of the film when measured under very specific, repeatable circumstances - those circumstances will most likely be at least slightly different then yours. The ISO rating allows you to compare films from different manufacturers.

When it comes to developing times, within a reasonable range, they have relatively little effect on shadow detail. They have a relatively large effect on contrast.

In the pinhole world, you are often working at light levels (at the film plane) where reciprocity fails. As a result, it is not uncommon to have the shadows record on the film with much, much less density than the highlights. The difference between the shadow density and the highlight density is much greater then when the light levels all around are much higher (at the film plane). As a result, the overall contrast of the negative may be increased. This may lead you to decrease development time, to tame that contrast. But you may prefer not to make that change.

If you experiment with different ratings, you are essentially experimenting with different ways of interpreting the information from your meter, in light of the behaviour of your system (including the film). Your goal is to get the right density in various parts of your negatives, but you are concentrating particularly on the shadow densities.

If you experiment with different development times, you are essentially adjusting the contrast between the densities which record the different parts of the scene, while concentrating particularly on the highlight densities.

Hope this helps.