08-23-2016, 03:17 PM
If anybody would have an interest in absolute diameters of aperture diaphragm, we simply would not have those f-numbers. but just some diameters on each lens - which makes no sense at all.
If I have a waterhose of 2 cm inner Ø, I can fill a bucket of 10 liters in 1 minute, but a swimming pool of 1000 liters in - right - 100 minutes - okay, we don't fill an exposure as a volume but as an area, but the principle remains. The basic idea of f-numbers were not "feed a DoF calculator" or "compare different sensors or negative sizes", but "use the exposuremeter to get a proper exposed result". These DoF calculators are nothing than mumbo jumbo which will never ever lead to "really sharp results over a certain distance from point A to B" but to "less blurred information within a certain distance difference, approximately". Number games, that are.
Using mathematical formulas and operating with estimated values is nothing else than bluffing, especially because the values of the airy discs to define "enough sharpness" are not constant over the whole field of view - center, border, corners - due to optical flaws of the lens itself. While closing down aperture, after f/8 diffraction leads to less sharpness. Effectively the whole maximum sharpness of the lens gets reduced, that's the price of huge DoF. While max sharpness is possible with a focus stack, a DoF calculator gives results of 3 digits behind the comma - nonsensical and not even taking focus drift in calculation.
Also, why using a DoF calculator if even lenses of the same values in terms of FL and aperture are not equal in front of a given sensor when it comes to bokeh? What good is a wide open lens if it creates a nervous bokeh?
I never saw equivalence-comparisons between mountainbikes and racing- or BMX-bikes, between lorries and race-cars, between castles and appartments. It appears to be only a phenomenon in photography, leads to nothing and is not important or helpful. Who wants to do the same with different systems? It's always the right system to be used for a certain task an for that only equivalence leads to wrong conclusions.
If I have a waterhose of 2 cm inner Ø, I can fill a bucket of 10 liters in 1 minute, but a swimming pool of 1000 liters in - right - 100 minutes - okay, we don't fill an exposure as a volume but as an area, but the principle remains. The basic idea of f-numbers were not "feed a DoF calculator" or "compare different sensors or negative sizes", but "use the exposuremeter to get a proper exposed result". These DoF calculators are nothing than mumbo jumbo which will never ever lead to "really sharp results over a certain distance from point A to B" but to "less blurred information within a certain distance difference, approximately". Number games, that are.
Using mathematical formulas and operating with estimated values is nothing else than bluffing, especially because the values of the airy discs to define "enough sharpness" are not constant over the whole field of view - center, border, corners - due to optical flaws of the lens itself. While closing down aperture, after f/8 diffraction leads to less sharpness. Effectively the whole maximum sharpness of the lens gets reduced, that's the price of huge DoF. While max sharpness is possible with a focus stack, a DoF calculator gives results of 3 digits behind the comma - nonsensical and not even taking focus drift in calculation.
Also, why using a DoF calculator if even lenses of the same values in terms of FL and aperture are not equal in front of a given sensor when it comes to bokeh? What good is a wide open lens if it creates a nervous bokeh?
I never saw equivalence-comparisons between mountainbikes and racing- or BMX-bikes, between lorries and race-cars, between castles and appartments. It appears to be only a phenomenon in photography, leads to nothing and is not important or helpful. Who wants to do the same with different systems? It's always the right system to be used for a certain task an for that only equivalence leads to wrong conclusions.