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01-17-2011, 06:56 PM   #1
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Back Focus and Front Focus

I've just read the archived posts regarding this issue.
Just bought a Tamron 28-75 2.8 and have read that it has BF/FF issues. I still don't completely understand the issue. (so am not sure if my copy may have them or not) Is this an issue that presents itself in close up situations, or can it happen in Landscapes?
If I use a small aperture and proper shutter speed and focus using one of the auto settings, will I see the potential problem?
Please help me understand this..
Thanks!

01-17-2011, 07:31 PM - 1 Like   #2
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It can happen any/every time you focus anywhere closer than infinity but you will notice it more on closer shots. To test it you can do a controlled test with a focus chart. Just search for "focus chart" and print one out (or you can do the battery test - I'll explain that after). Focus on the center line of the chart and view the photo on your computer to see if the front, back or center is in focus. The battery test - set up 3 batteries in a diagonal line about 2 inches apart, focus on the middle battery and again view on the computer to see which battery is in focus. Good luck.
01-17-2011, 08:10 PM   #3
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Thank you so much!!
Do I have to do the test at 45 degrees like the other posts suggest?
I like the battery idea!
Many thanks again
scott
01-17-2011, 10:45 PM   #4
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I think they say 45 degrees because if you set up the chart and shoot level to the ground it should be 45 degrees, so if you can get exactly 45 degrees then do it. I just shoot on my tripod but if you don't have one, try and shoot as level to the ground as possible. You don't have to be exactly 45, I'm sure if you are close it will still work.

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