one by one: motion blur, depth of focus/f stop, shutter speed too slow. Though I have made some definite progress, I still have never been particularly happy with my results.
Up until now I hadn't considered the possible effect my UV filter might have been having on my image quality. On a whim, I decided to take 2 identical photos of the same bird, back to back, one with the filter on then off. Settings were entirely manual, so no difference there, and although I cropped the images (identically), there was no other manipulation of the files, and here were my results:
With filter:
Without filter:
Here are the same shots even more cropped:
With filter:
Without filter:
I was SHOCKED to say the least. But could this have been due to motion blur on former but not the latter? Or some other cause?
To get to the bottom of this issue, I decided to test it out on a large sample of conditions and subjects. To start, I used the rain hood on all exposures, I mounted the camera/lens setup on my tripod out of the wind, and used the 2 second shutter delay to guarantee the mount wasn't shaking. [I did leave image stabilization on, and now realize I should have shut it off, but the setup was so still I don't think it skewed my results at all.] Settings were entirely manual, and I used center point only autofocus, in each case taking care to put a singular subject right in the dead center of the field and verify that it was in focus before shooting. Here are the results.
First subject: owl box at about 25 feet from camera
Original with filter:
Original without filter:
Here are the same images, cropped equally and kept at 100% resolution jpgs (ie. not resized):
With filter:
And without filter:
Second subject: Red-tailed Hawk against backlit sky, about 250 feet from the camera:
Original with filter:
And original without filter:
Cropped with filter:
Cropped without filter:
And heavily cropped with:
Heavily cropped without:
Subject 3: Suet feeder from 30 feet
Original with filter:
Original without filter:
Cropped with filter:
Cropped without filter:
Subject 5: House Sparrow from 35 feet:
Cropped with filter:
Cropped without filter:
Heavily cropped with:
Heavily cropped without:
Subject 5: Honda Civic from 50 feet:
Cropped with filter:
Cropped without filter:
Subject 6:
Sign from 100 feet:
Cropped significantly, with filter:
Cropped significantly, without filter:
Cropped slightly with filter:
Cropped slightly without filter:
Needless to say, this seals the deal for me. This filter is clearly damaging the crispness of my images, more so at long range and with increased cropping. But since I am not trying to print or sell photos, just to document rare birds, often at range, it just isn't working for me. The filter is a Promaster 77mm UV filter, and was admittedly the cheapest option I had, something like $20-30. I bought it only to protect the actual camera lens from being struck by branches or any hard object it comes into contact with. So clearly I am going to have to find a better solution to this problem.
Cropped slightly without filter: 
Needless to say, this seals the deal for me. This filter is clearly damaging the crispness of my images, more so at long range and with increased cropping. But since I am not trying to print or sell photos, just to document rare birds, often at range, it just isn't working for me. The filter is a Promaster 77mm UV filter, and was admittedly the cheapest option I had, something like $20-30. I bought it only to protect the actual camera lens from being struck by branches or any hard object it comes into contact with. So clearly I am going to have to find a better solution to this problem. I do secure the rain sleeve in the out position at all times, and perhaps this is enough to protect the lens under most circumstances? I would really appreciate the opinions of other photographers as to whether I should try to buy a more expensive filter, or if there is some other option for protecting my lens and leaving the filter off.
2 comments:
Same issues here and the same filter. Off it comes. I'm not sacrificing the crispness of my subject matter. Only potential for reinstalling it will be where haze an UV are going to be problems. Thanks for doing the footwork!
Usig a HIGH QUALITY uv filter is a must. Given that you mention you're using a 77mm size makes it known that you're using high quality glass and a $20-$30 UV is like putting a parachute on the back of an Indy car. You've got the glass, a higher quality UV filter should help. The guys/gals over at Norman's could recommend a good one but at 77mm, I would go there ready I spend upwards of $100.
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