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Testing quality of photographic lenses

Posted: Tue Jan 30, 2007 12:46 pm
by holsetymoon
Hi experts,

First of all, I did this topic thanks to Sciencebuddies.org
https://www.sciencebuddies.org/mentorin ... ?from=Home
It is PHOTOGRAPHY. My question for this topic is:
What focal length and f-stop will produce the best resolution?
My hypothesis is: The widest-angle (smallest focal length) lens with minimum f-stop (aperture) will produce the best resolution
Currently, I am thinking about changing the question to: What focal length and f-stop will produce the sharpest image? I know that sharpness consists of both resolution and acutance, but I don't know how to measure acutance with my experiment. My experiment is with the USAF lens test chart, I did it with four different lenses : two 35mm camera lenses and two 35mm camera zoom lenses. I load my camera with Fujicolor Pro 160C color film. I maintain the exposure so that it is not over- or under- exposed in any of my picture by changing the shutter speed. My independent variable is the f-stop (aperture).
My main question to ask you experts is:
How do I measure the line pairs per milimeter from the data I got in my experiment? Hope I made sense. Thanks for helping me.

Posted: Wed Jan 31, 2007 7:48 am
by carolinethorn
Hi Lam,

You will probably get better answers to this on the physical sciences board.

-Caroline

Re: Testing quality of photographic lenses

Posted: Wed Jan 31, 2007 11:37 am
by kmanies
I'm not sure how much help I'll be since I had to look up what acutance was. But the page I found on Google that defined acutance for me also talked about ways to increase it using a unsharp mask. Maybe if you could find a program that has a unsharp mask you could measure how much you need to change it to get a "good" image. I don't know if this is possible or what program you would need, but figured it was a start.

Check out the webpage I found:
http://www.cambridgeincolour.com/tutori ... p-mask.htm

Good luck!

Posted: Thu Feb 01, 2007 8:30 am
by holsetymoon
To carolinethorn: Thanks for the suggestion, at first I did not know which board Photography fit in so I posted here. I reposted it in the Physical Sciences board.
To kmanies: Thanks for the website you showed me. It helped me to understand acutance and sharpness better.