Hi John E,

I'm not entirely sure if its right for me to share this with you, nor if you will fully appreciate it. But here is a mathematical relationship that I charted of Aperture, ISO and shutter speed. As you may know, in my other thread, there has been a heated argument going on about using math for photography. Hope it doesn't start here!

Plug the formula into an excel sheet and start calculating away! Although you will have a much more fruitful experience discovering these for yourself. (Spoiler alert!)

You need to understand the variables I guess, especially step change.

I shall leave you to figure first. If you find that you don't understand it, but really want to do it the math way, I can further explain a little.

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