When people talk about developers and film speed, what are they actually talking about and what are we likely to see in a negative.
I understand that bit, but the bit I was not getting was when people refer to developers loosing or increasing film speed or have I misread itI think David has explained it pretty well. The box speed is determined by the manufacturer under very specific laboratory conditions. Your personal EI is determined based on sensitometric testing or empirically and is tailored to your personal equipment and workflow. Therefore, film speed is a moving target.
Thanks Stephen, that explains it nicely for me.Very simplistically a fine grain developer may work by solvent action and dissolve away developed specks; this may reduce the overall visible grain, but it will also reduce the amount of silver in the image, giving a less dense negative that needs more exposure to compensate. Hence a loss of "film speed".
I've always heard of certain developers being "speed increasing" developers, but, personally, I've never measured one that actually increased speed. Significantly expanding/reducing development time can affect film speed, but over my years of testing various films & developers I've never found it significant enough to be concerned with.I understand that bit, but the bit I was not getting was when people refer to developers loosing or increasing film speed or have I misread it
I've had a situation where I needed to push process 5x4 HP5 and can foresee doing it again using Pyrocat HD. The first time was successful in terms of the negative quality, tonality/shadow and highlight detail, grain etc, however even at 1600/3200 approx EI I was limited to 1/25th @ f5.5, if Tornado hadn't been an hour late it would have been 400EI and 1/100 @ f16There might be different ideas in peoples' heads when they speak of speed increase. One person might think of needing to get any kind of image at all, despite difficult circumstances, but another might be looking for "...better shadow detail."
In my mind, the first one is associated with 35mm and the second with LF. Others may have different views, of course.