Quote:
Originally Posted by TrevorW
How would a 2x go on a 300mm zoom Sigma lens I have for the Pentax
Cheers
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From what I've read Trevor, the 2x is a gamble on anything but the high end Canon lenses (300mm f2.8L for example) - sweet spot is the 1.4x extender.
But (there's always a "but" in astro-imaging), Photozone reviews states that IQ is degraded significantly in the 100-300mm f4 Sigma Zoom and 1.4x Extender combo - shame, as the 100-300mm Sigma zoom gets a 9.5/10 sans extender.
http://www.photozone.de/canon-eos/32...report--review
