8" Zerochromat refractor--I want one now!
My wife and I just got back from a trip to London with a side trip up to the Worcester area to meet an on-line friend and look through his 8" Zerochromat. Wow! What a great scope! So now what do I want? Just a "Zero".... It's a folded refractor design so although its focal ratio is f/12, the tube is just about 5 feet long. It's fairly heavy (~40 pounds), but manageable by one person. Here's the maker's web site: http://www.firefly85.com/ if you're curious (you have to look for the telescope; there's a bunch of stuff about a spotting scope that uses the same optical design). For those of you who may not have followed the controversy surrounding this design (but might be interested), it utilizes a simple objective lens with very long f-ratio and has smaller lenses later in the optical train that deal with the chromatic aberration. It's a refinement of a design from John Wall (the inventor of the Crayford focuser)--described here: http://www.cloudynights.com/item.php?item_id=2024 (you can find any number of people who express how unimpressed they are with John Wall's design in the CN forums; but there's one guy in France who's making one of these so-called hypochromats and I'm interested in how it turns out--he hasn't mounted it yet so the pictures to this point are of stuff out his window). Well, supposedly Peter Wise, the "Zero's" maker has improved on John Wall's design to the point that he claims apochromat-type performance. Well, having looked through it, I was awfully impressed. The viewing, unfortunately, was limited to terrestrial targets (can you imagine, clouds and night-time rain in England?) and we didn't have another telescope to side-by-side compare it with (a reflector would have been the gold standard). One interesting way to see how good the color correction really is involves adjusting the first of the folding mirrors so that it's slightly out of collimation. As you turn the collimation knob so that it's not quite right, the chromatic aberration becomes bright and obvious; when you turn the knob back to correct the collimation, the color just disappears while you watch. Very interesting to see. I'm sure some SLAC old-timers remember a fellow and his impressive 8" refractor (he may still be active for all I know--haven't made it to any star parties in years)--back in the mid-80's when I did make a star party once in a while, his beautiful 8" refractor that was real treat to look through. I seem to recall reading about some rather amazing views of an eclipse of one of Jupiter's moons by another in the club newsletter. I fear that the fact that I can't remember the owner's name is an indication of my age (sigh). At any rate, I'd love to have an 8" refractor. And one that was small enough to transport in our Dodge Caravan? Cool! And since I couldn't reasonably afford even the objective lens for a conventional one, I really wanted to see what one of these "Zeros" was like--so now I'm wondering how to scrape up the cash! Anyone wanna go halfsies? Thirdsies? Unfortunately, I've shot my wad for this year and I don't think my iOpteron 45 would really carry something that heavy and that long very well--so a new mount would be required too: budget busted. But, if you're headed to England, the fellow who owns the one I looked through was just delighted to have a visit--he picked us up at the bus station and fed my wife and me dinner, drove us to the B & B we'd booked for the night.... So, if you are traveling that way, let me know and I'll give you his contact info (I hesitate to post stuff like that on an email list--especially w/o checking with him first). Fun stuff--but no clear skies.... John
There have been a few folded refractors at RTMC and they work very well, to me a long focal length refractor lacks versatility.
My wife and I just got back from a trip to London with a side trip up to
the Worcester area to meet an on-line friend and look through his 8" Zerochromat. Wow! What a great scope! So now what do I want? Just a "Zero".... It's a folded refractor design so although its focal ratio is f/12, the tube is just about 5 feet long. It's fairly heavy (~40 pounds), but manageable by one person. Here's the maker's web site: http://www.firefly85.com/ if you're curious (you have to look for the telescope; there's a bunch of stuff about a spotting scope that uses the same optical design).
For those of you who may not have followed the controversy surrounding this design (but might be interested), it utilizes a simple objective lens with very long f-ratio and has smaller lenses later in the optical train that deal with the chromatic aberration. It's a refinement of a design from John Wall (the inventor of the Crayford focuser)--described here: http://www.cloudynights.com/item.php?item_id=2024 (you can find any number of people who express how unimpressed they are with John Wall's design in the CN forums; but there's one guy in France who's making one of these so-called hypochromats and I'm interested in how it turns out--he hasn't mounted it yet so the pictures to this point are of stuff out his window).
Well, supposedly Peter Wise, the "Zero's" maker has improved on John Wall's design to the point that he claims apochromat-type performance. Well, having looked through it, I was awfully impressed. The viewing, unfortunately, was limited to terrestrial targets (can you imagine, clouds and night-time rain in England?) and we didn't have another telescope to side-by-side compare it with (a reflector would have been the gold standard). One interesting way to see how good the color correction really is involves adjusting the first of the folding mirrors so that it's slightly out of collimation. As you turn the collimation knob so that it's not quite right, the chromatic aberration becomes bright and obvious; when you turn the knob back to correct the collimation, the color just disappears while you watch. Very interesting to see.
I'm sure some SLAC old-timers remember a fellow and his impressive 8" refractor (he may still be active for all I know--haven't made it to any star parties in years)--back in the mid-80's when I did make a star party once in a while, his beautiful 8" refractor that was real treat to look through. I seem to recall reading about some rather amazing views of an eclipse of one of Jupiter's moons by another in the club newsletter. I fear that the fact that I can't remember the owner's name is an indication of my age (sigh). At any rate, I'd love to have an 8" refractor. And one that was small enough to transport in our Dodge Caravan? Cool! And since I couldn't reasonably afford even the objective lens for a conventional one, I really wanted to see what one of these "Zeros" was like--so now I'm wondering how to scrape up the cash! Anyone wanna go halfsies? Thirdsies? Unfortunately, I've shot my wad for this year and I don't think my iOpteron 45 would really carry something that heavy and that long very well--so a new mount would be required too: budget busted.
But, if you're headed to England, the fellow who owns the one I looked through was just delighted to have a visit--he picked us up at the bus station and fed my wife and me dinner, drove us to the B & B we'd booked for the night.... So, if you are traveling that way, let me know and I'll give you his contact info (I hesitate to post stuff like that on an email list--especially w/o checking with him first).
Fun stuff--but no clear skies....
John
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participants (2)
-
Erik Hansen -
John M. Craig