Re: Hasselblad C 250 f/5.6 Superachromat on Fuji GFX
^^^
I'm not following you. The relationhips reflect the non-linearity you write about when normalized to a new standard 1.00 crop factor in each case.
I think your point was (to simplify a bit) that a .6 crop factor difference in one direction is not the same as a .6 crop factor difference in the other direction when the starting point is the same. (E.g. the relationship between a 1.6 crop factor and a .4 crop factor isn't "equal.") That makes sense.
But when you reference the starting point as 1.00 crop (for example always resetting the larger of the compared formats to a crop factor of 1.00) and calculate the second case from there, you are looking at a percentage description, which is non-linear.
Right?
Or are you agreeing that the crop factors descriptions are accurate but that calculating depth-of-field must be done using something other than crop factor?
If two things have a 1:1.6 relationship and two other things have a 1: 1.6 relationship, how is non-linearity going to change the result? Serious question.
I'm also perplexed as to why you keep bringing teleconverter magnification factors into this. They do a rather different thing than what we are looking at when we speak of crop factors. (They take an image circle of a given size and essentially expand it by 1.4x or by 2x. That process does produce the 1 and 2 stop light loss that you keep coming back to, but that is for a different reason.)
Finally, what would your spreadsheet/chart look like, and what calculations would you build into it? (Mine simply uses the standard method of calculating diagonals from width and height measurements, uses that to calculate relative crop factors, then sets the 1.00 crop value wherever you want to set it among the various formats.)
Dan
May 12, 2018 at 05:38 PM
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