I got this recently from David Astro. Great service and fast shipping as always. While the accessory will WORK with the Baader Zooms, Mark III and Mark IV types, I found two things not convenient using this Barlow. Hence the four stars - generally, I love Baader stuff, and 99% of the Baader line is both a phenomenal value and exceptional quality!
1) First off: the adapter(s): the Barlow IMO, should have been able to mate onto the unit directly, in lieu of an extension tube. This adds some complexity to the arrangement, and makes the zoom stick out when used in 1.25" mode. It also runs the risk of an issue with some diagonals as well.
2) the back-focus requirement: while it is entirely normal to have this situation with almost ANY Barlow, I was surprised at HOW MUCH I required, given this was desgned for the specific Baader Hyperion Zoom! I was hoping (I guess unfoundedly) that the Barlow would only draw back focus minimally, or be almost parfocal with the zoom itself. This would have been amazing, if it were the case, but not so to be found here! :(
So, as such, I have to emply an extenderring to run 2" mode on the EP - not a huge deal, but a sort of pain, when going up to the zoom.
IMO, I wish these companies in general would aim for not only functionality but FORM as well. THINK about WHAT one is doing with this. It seems the main tenet here was to use for AP and not visual, so hence the T2 adapter inclusion in the kit.
On the other hand, this is a superb Barlow and in all fairness to the above comments, I think it acts almost invisibly in the light train, and fulfills Baader's reputation of being another superb accessory. I just wish these companies would stop just thinking AP, and remember visual as well more... :(
DHennig, Edmonton AB Canada