"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Lee Jay Forum Pro • Posts: 53,710
Re: You are crushing my patience.

walkaround wrote:

ljfinger wrote:
35mm was bad, but 110 was much worse!  2 1/4 x 2 1/4 (and other medium formats) was a good bit better.  Much less visible grain at the same ISO

But isn't this because of the relative enlargement sizes?

The two explanations are the same.  The bigger film is better because of statistics - more light has been captured and since signal-to-noise ratio goes with the square root of the number of photons captured, more photons equals higher SnR.

Put it another way - the equivalent way!

If you double the grain size in each direction, you'll go from (say) ISO 100 film to ISO 400 film.  Now use a piece of film twice as large, enlarge it half as much, and you'll get the same image with each format - equivalent images!  But you'll over-expose that larger film if you don't use equivalent settings, which means 2 stops lower exposure for the larger, more sensitive piece of film.

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Lee Jay
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