Picked up a 1.4x teleconverter the other day to use with my Sony 70-400. Tested it out and it works fine. Will need good light obviously, but the images are clear and sharp, so I'm pleased so far.
One question I'm curious about; that lens, when mounted on my A77II (aps-c format) is the equivilant of a 105-600 lens in regards to focal length (at 1.5 crop factor).
Is the 1.5 factor figured in before the 1.4x of the teleconverer, or after?
When I looked at the exif from images captured with the lens and teleconverter in use it showed a focal length of 540. This makes sense (400 x 1.4),
A 400 lens at 540 (400 x 1.4 teleconverter) x 1.5 crop would be an equivalent length of 810.
If you do the math a bit differently it works out to length of 840 (400 lens x 1.5 crop = 600, then times 1.4 teleconverter = 840).
So, do I have the equivalent focal length of 810 or 840 with this combination?
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