[Astromelb]

This unit is an oil spaced doublet with a Crown element in the front and a fluorite element at the rear, as was Barry Adcock's standard practice.
The optics are uncoated, and the glass (both elements) were sourced from O'Hara.

My own personal unit I personally measured out at 1/20 wave P/V, I would expect this unit to be similar upon final assembly.

Barry's 6 inch units were quite capable. This unit (as my own) used a f11 design, and thereby a 1700mm focal length. As such it requires a strong and robust foundation. I used my unit on an ASA DDM 60 Equatorial mount, and thereby squeezed the best out of the optic, as the mount foundations for any long focal length refractor is crucial.

A larger Eq mount with a higher than standard capacity is recommended. Short focal length 6 inch units such as 1200mm can use a smaller mount, sure. But this telescope is a 1700mm focal length, and those that know longer focal length units will know that - as example - Unipol has a 4 inch Unitron with it's f1500mm, and well knows this needs a higher capacity mount than any standard 4 inch f10.

I have had three Barry Adcock refractors and can vouch for their performance and quality, although these days I have only one unit left as I have moved on to OK4 triplets, and also Carl Zeiss triplet refractors, which those that know these systems will well know why I have done this.

For a lower cost solution than the exotica level LZOS refractors the Adcock units are a very capable opportunity.