sony 70-400 vs tamron 200-500

Hi,

first I'd like to ask you a question whether your test shots were taken off a tripod?

If not, I'd say the exposure times in both sets with 1/250s in the first and 1/160s in the second would be a stretch towards too long exposure times for hand held shooting with such large and heavy lenses - particulary when you want to test and compare their optical performance. You're shooting with a A580 which has an OVF - and this means a mirror moving. This could have added vibration. Repeating, if you want to compare the optical performance of lenses it makes only sense when you avoid everything in the shooting process which has a great influence on the result - such as shake. Still considering that you took the test shots handheld, your results could be indicative only in a sense that you may be able to hold the Tamron steadier than the Sony - which may be of course the case due to their difference in weight.

For handheld shooting with a long tele (zoom) I can repeat only the hint to go for shutterspeeds of round 1/(2 x FL)s which means about half of the exposure time which was known from film times. Longer times may work but today's high MP sensors provide such rich details (since supported also by the lens mounted) that even slight camera shake and/or focussing errors get noticeable.

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Cheers, Michael Fritzen