Hanwell Dialyte 30" Refractor (cyber revisit)

[Macavity]

Posted this ages ago back on CN. I have no links to the Hanwell folks, just something I (cyber) revisited today!

http://www.hanwellobservatory.org.uk/

Rather impressive the 30" refractor? There's some interesting (Google searchable) stuff on "Dialyte design" too.

[Kaptain Klevtsov]

That's the Zerochromat guy that built it isn't it? Along with Peter Wise of course.

Kaptain Klevtsov

[Macavity]

Ah. Still have this LARGE single (flint glass?) biconvex 6" (only) lens that "micaculously appeared" on my Dad's back lawn, one night during World War Two! Once I dreamed of it's use in such a thing as this. But 6" achromats are (almost) "ten a penny" these days. Large lenses still have a kinda fascination tho'...

[Kaptain Klevtsov]

I know what you mean about large lenses. My chick's friend turned up a few weeks ago along with her hubby. He plonked a 9" condenser lens on the table and said "any good to you? I was going to put it in the skip." So now I have to think of something to do with it. It appears to be a matched pair of plano convex lenses mounted flat side out in a brass tube.

Any suggestions would be greatly appreciated.

Kaptain Klevtsov

[John]

I wonder if they have issues with lens "sag" with this one and if so how they have over come that ?. I think it's sagging that keeps the maximum practical size of refractors to 40 inches (the Yerkes refractor).

John