>
> Humbug for your USAF line charts. They probably existed for testing B&W
> aerial photography lenses. :-) I'm with Wayne. You won't find any
> bokeh in this test but I'll take this sort of controlled light test
> image any day <http://www.imaging-resource.com/PRODS/E3/E3hSLI0100.HTM>
>
Not very good for determining center and corner (all four) sharpness. There
is absolutely nothing there to quantify the results, just good, bad,
indifferent--all subjective interpretations.
Gary Reese's test were done by photographing a terrain map. We rode him
pretty hard over it back then, but the fact is, it probably is one of the
finer test subjects for lens resolution tests for non-quantifiable
measurements.
If you want to test for distortion, CA, bokeh, etc., then there are other
types of test subjects worthy of consideration.
The reason why I personally use USAF charts is because I can compare images
taken at different times with different lenses, cameras or even formats and
have a specific quantifiable number for comparison. It may seem like I'm a
stick-in-the-mud, but it works and it works extremely well. I have five of
them which are positioned in a X pattern so the four outer ones are closest
to the corners.
When testing digital sensors, we now have to test red on white, blue on
white, green on white, red on black, blue on black, green on black and black
on white to really get an idea of true resolution of the sensor--which is
definitely the weakest link for resolution testing. If you are doing lens
testing with digital cameras, the ONLY thing that will give you accurate
representation of quantifiable measurement is a black-white res chart of
some form because the sensor will skew results depending on colors of the
subjects in the test.
There are multiple types of charts available now, some with cycles/mm, some
with converging lines, some with soft cycles and hard cycles and the good
old standby of the USAF chart.
You keep trashing the USAF chart, but it remains the one standard by which
all others are compared and it was THE standard for decades for a good
reason. There may be better ones now, but some random mash of mish isn't
going to give you anything quantifiable or meaningful to anybody else and
unless everybody has exactly the same test setup, the results are relative.
If I tell you that a given lens tests out at 65 lines/mm center, 45 lines/mm
corner at F4.5 that means something. But if I tell you that the lens is
sharp in the center and not so sharp in the corner at F4.5 it means nothing
as this is a subjective interpretation. My sharp isn't your sharp and my
fuzzy isn't your fuzzy.
I will stick with my USAF charts, thank you very much. I don't do
subjective.
AG
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