I thought I'd present a the result of a simple experiment to everyone here at PentaxForums. Enjoy.
BACKGROUND
I wanted to test what impact a UV filter would have on the resolution of a lens. When I first got my DSLR I of course got a UV filter to "protect" the lens and because the helpful sales person said I'd be crazy not to.
However I've now gotten three lenses where the hoods are solid enough and deep enough that I feel the lens is protected and I started to wonder what kind of damage the filter is doing.
I've got a DA 12-24mm f4 and it has had an Optex 77mm A1 filter on it since I got it off another forum member.
Henry's has this 77mm filter for $39, and as all Canadians know Henry's is almost always the most expensive place in Canada. So that can give you some kind of idea about the filter. For price comparison the very basic B+W UV filter is $118.
METHODOLOGY
The experiment consisted of shooting ten images with the filter on and ten with the filter off. The camera was locked down to a heavy tripod and the ballhead was secured.
The camera was set to x-sync and f8 and ISO 100, and tripped with a remote. Shake reduction was of course off. I even cleaned the filter with lens paper and before the test.
Lighting was a single strobe bounded into a silver umbrella mounted above and behind the camera.
Its freezing rain/snowing outside so I shot the fireplace, the only brick wall I have inside.
I shot RAW and created an action to load each image into photoshop and crop the centre. The automated action ensured that the conversion was the same for each image.
I then reviewed the series of 10 and chose the sharpest image for each set.
RESULTS
The image on the left is with the filter the one on the right without.
To say the least I was surprised how much of the difference there is, but I will let the results speak for themselves.
(but I think I am looking for a new filter) PART II
I repeated the test this morning with a Sigma 17-70mm Macro and a HOYA HMC Super UV(0) filter. The results are below in the attached image.
As expected (or at least hoped for) there is alot less change between images.
Last edited by omega leader; 11-27-2010 at 07:05 AM.