Cheers Chris
I've already taken the plunge and now own this great lens.
AF is lightening fast on terrestrial and stellar subjects.
I have found that wide open, the focusing has to be spot on to avoid CA on stars.
May have to try stopping down with my external aperture masks to stop that - although f5.6 is probably as slow as I'd like for astro work.
Also my Hutech IDAS LPS2 filter seems to be playing around with the focus point for red light as I have heaps of red stars in my Tarantula subs below (all single subs)...and all gone when filter is removed.
Left hand image - 10mins with IDAS LPS2 filter
Right hand image - 5mins without filter
Last image is a crop of the first image showing the small red stars.
All comments and ideas gratefully accepted.
I wish I hadn't picked the Tarantula as my first light test subject!
Cheers
Doug