75% of the more typical times, so a correction 25% less :D
Ian
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75% of the more typical times, so a correction 25% less :D
Ian
Have you ever figured out what went wrong in the first place? Was it bellows extension? If so, then it's not a personal EI problem.
My personal EI is two-thirds stops below the box speed, because I want to be able to use Zone System scene evaluation with my meter. I set the clipping points on my Sekonic L-758DR at whole stops instead of the factory default (my points are at Zone I and II, then Zone VIII and IX). I mention that because you pointed out that's like the meter you use.
Even though I use 2/3 less than rated speed, I am counting on the fact that I know and trust that fresh film developed for a normal time in a normal developer, will get the rated speed. And that the relationship between Zone System evaluation and standards is 2/3 stop.
My adjustment is my personal EI because of the way I want to meter and the results I want to get.
Classic Zone System tests are aimed to paper and include a lot of variables that guarantee that different people will get different results... That's a "different" definition of personal EI than I am offering... But it might be what you are hearing a lot about.
You can design your own tests any way you like, there are so many ideas out there I don't want to put one above the other (A sensitometer or other step-wedge based exposure device is the absolute best and a step wedge costs less than the film you would waste in any other test. But I didn't come here to preach).
Here's a stupidly simple test:
If you know how "Sunny 16" works... If your shutter is any good, you might go outside on a nice clear sunny day and take a bunch of pictures of a subject you are interested in photographing... at different shutter speeds at f/16.
Then develop all the film.
As you work with the resulting negatives, pick one that gives you the best results with the least trouble... its corresponding shutter speed could be your personal EI.
The problem with this test is that it builds in your shutter error. But the idea shows how simple a test could be...