Posted by Leann Greene on October 4, 2006 at 2:14 AM
I need some help on this. I have a Tamron 200-400mm LD tele zoom that for wildlife I have shot just bare glass but to use it in landscape I bought a Kenko CPL UV set . When I attached the filters my images all come out blurry even with just one or the other filter on it. Next step was to try a Cokin P polarizing filter in the filter holder-I was thinking maybe the screw in filters were too close to the glass or something. Well, same thing-blurry images. I focus manually and it always seems fine in the view finder but the shot doesn't come out. Anyone experience this before and what if anything did you do to reslove it?
Posted by Kent Staubus on October 4, 2006 at 8:39 AM
Here's my guess. The polarizer is making your viewfinder darker and you are having trouble seeing the fine details when you manually focus. Try focussing first, then adding the polarizer and see if that helps. When I want to check a lens or camera focus system, I take photos of a brick wall.
Leann, try comparing with AF, evenly-lit detailed subject (brick walls make great test subjects) and with no direct sunlight to avoid flare. If the results are consistent then you know it's not the lens or filters.
If the issue is manual focus accuracy I suggest focusing without the filter (to allow more light into the finder) and adding the filter later.
Another reasons might be flare from sunlight reflecting off the lens and bouncing back into it from the filter.
Guy
Posted by Kent Staubus on October 5, 2006 at 12:12 AM
Guy has a point. The uncoated filters can produce some flare when a direct light source shines directly onto them (such as the sun.) This can take away some sharpness. Another thing I've thought of is that your lens is already f5.6 at 250mm and longer. This is the edge of what AF can do for many cameras. The polarizer will eat up about two more stops of light, making it the equiv. of an f11 lens. That's pretty dark. My Nikon F100 has no trouble focussing and metering my Nikon 80-400mm f5.6 lens, but sometimes hunts a lot when I use a polarizer and my subject is dark or has little contrast. I'm still thinking you're having trouble seeing well enough to focus sharply though. Since the polarizer sits so close to the lens, I really doubt there could be anything specifically wrong with the polarizer itself other than the darkness.
Kent in SD
Posted by Leann Greene on October 5, 2006 at 4:54 AM
Kent ,Guy
Thank you very much -I will do the comparative test shots and if it's my focusing I will only mope for a few days that my eyes let me down:-)
Posted by Leann Greene on October 5, 2006 at 6:00 AM
Kent ,Guy
Thank you very much -I will do the comparative test shots and if it's my focusing I will only mope for a few days that my eyes let me down:-)
Discussion
5 repliesKent in SD
If the issue is manual focus accuracy I suggest focusing without the filter (to allow more light into the finder) and adding the filter later.
Another reasons might be flare from sunlight reflecting off the lens and bouncing back into it from the filter.
Guy
Kent in SD
Thank you very much -I will do the comparative test shots and if it's my focusing I will only mope for a few days that my eyes let me down:-)
Thank you very much -I will do the comparative test shots and if it's my focusing I will only mope for a few days that my eyes let me down:-)