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Old Oct 8, 2009, 1:36 AM   #1
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Default Tamron f2.8 90mm tests

As suggested, I have just taken a bracket of a flower.

All three at f8. In order of taking, first one is with no AV variation. the second minus .7 and the last + .7

To me, the minus .7 is the correct exposure. Exposures were 1/100, 1/160 and 1/60

I have also confirmed this with taking the same picture at the same time but single shot with the same variation.

Except for sizing there has been no work on the photos

I am not too concerned about this necessity of setting the AV as a standard when using this lens but am interested as to why this should be so
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Last edited by Bootneck3; Oct 8, 2009 at 1:42 AM. Reason: change burst for bracket
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Old Oct 8, 2009, 4:37 AM   #2
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Attached are the histograms of the three images you posted (which don't contain any EXIF data, btw, which would have been helpful.)

From these histograms, it's clear that the third was over exposed and that the second was underexposed.

Perhaps you could take two photos of the same subject, one with your Tamron 90/2.8 Macro, and one with your Tamron 18-250 zoomed to the same angle of view as the 90. Shoot both at f/8.0 and the same ISO. You could even use Manual Mode, pick the same shutter speed for both images, and then we could compare apples to apples, so to speak.
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Old Oct 8, 2009, 5:52 AM   #3
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Keeping the same shutter speed might not be such a good idea, as lighting conditions could change in the time it takes to change lenses. Using A Mode and setting the aperture to f/8.0 for both lenses at that focal length would make it easier to compare what you get with your two lenses.
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