On Wednesday, 29 July 2015 05:39:12 UTC+2, RichA wrote:

I think the tests on the page are legit. It's pretty hard to make a mistake in set-up that shows a zonal error. Also, it's good to have people with no axe to grind doing this. His test of the 130mm Vixen showed a fantastic result while he doesn't spare other vaunted makers of scopes.

I agree, but would enjoy hearing one of our resident optical expert's opinions on Rohr's work. If anything, I feel Rohr is helping to expose the variability of optical surfaces from some/many recognised sources.

This is a market where the buyer is [almost] powerless to test the manufacturer's claimed figures for accuracy and correction of the "problem" aberrations. The owner may well do star tests but, due to the level of interpretation required, not to mention the variability of seeing conditions, the majority are unlikely to be able to put firm figures on what they see.

There is a strong degree of "HiFi" sales hype in the optical instrument market. Every maker claims to make the best but nobody [other than Rohr] is making a habit of publicly exposing the blatant hype. Unfortunately the "double blind" tests, with which disciplined experts undermine almost 100% of HiFi manufacturer's claims as completely false, are not easily arranged with optical instruments. Only the expensive tools and [hopefully] the expertise of Rohr can remove the subjective "product loyalty" elements from the manufacturer's sales hype.

We all know that rare night of wonderful seeing when our normally "fuzzy" instruments suddenly reveal planetary detail we never [previously] knew existed. Only then can we truly appraise our optics by pushing them to their theoretical limits and stay up all night.

For the rest of the time being merely "diffraction limited" is arguably good enough. But what if those rare nights never present themselves in our continually fuzzy instruments? What then? The local consumer protection office is extremely unlikely to be able to help.