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The Demise of the Great Refractor

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#26 rwiederrich

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Posted 19 November 2012 - 07:44 PM

Unfortunately large refractors are a thing of the past in professional astronomy. I personally love the look of these classic instruments although they are not very practical to use. Below the image of the 65cm Zeiss refracotr of the National observatory of Japan. It is unused and serves only as backdrop of the museum housed in the dome. :(

There are some special application scopes as the mentioned solar telescope but they are rare these days.

best regards
Chris


Super thing that large refractors are NOT things of the past in amateur astronomy. I also love their look and to me they are very practical in their use. :jump:

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#27 Sky Muse

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Posted 19 November 2012 - 09:53 PM

I suppose it's forgivable, as "Alvin" is the common spelling.

Similarly, I got that all my life, and still do..."Allen" here and "Allen" there, on most occasions when someone took my name for this, that or the other...

Lady: "Sir, what's your name?"
Me: "Alan."

I'd even spell it for them, but to no avail, and yes, I doubted their credibility, too.

Cheers,

Alan
 

#28 chboss

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Posted 19 November 2012 - 10:00 PM

Super thing that large refractors are NOT things of the past in amateur astronomy. I also love their look and to me they are very practical in their use. :jump:


I agree, however for objects near the horizon I see some "practical" dificulties with your setup. ;)

best regards
Chris
 

#29 Sky Muse

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Posted 19 November 2012 - 10:13 PM

That's because refractors look like a telescope, the original design, instead of a "cannon", or a howitzer, or as someone else recently suggested...

...a "water heater"...

:rofl2:

...and here I have two "water heaters"...:thinking:

By the way, yours is quintessential.

Regards,

Alan
 

#30 wiseone

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Posted 20 November 2012 - 03:52 AM

It is possible to make an excellent refractor larger than 40 inches! John Wall has made a 30 inch with a singlet objective and corrector lenses downstream of the cross-over point. After having seen John's wonderful design, I was moved to improve on it by using OSLO. John is old school, and used traditional optical design techniques to produce an outstanding telescope. OSLO gives you a design can that can be used up to 40 inches or more. The resultant configuration is hugely better than a traditional doublet, with a tiny weight of optics, and at a much lower cost.
I re-designed the optics for the 28 inch Greenwich refractor to fit inside the existing tube, as the current optics are not in good shape. The conservators put a brake on this, even though externally, there would be no change. :tonofbricks:
 

#31 Crayfordjon

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Posted 20 November 2012 - 10:51 AM

Peter is right I am old school in that I make all my own optics. I made a thirty inch retrofocally corrected dialyte of my own design, the OG is green float glass which nowdays is very transparent and suitable for such work.I achieved good colour correction with this scope after researching the design for a number of years. It is not a Schupmann, that scope is a catadioptric refractor, the retro uses a totally different design concept. Peter took my ideas and thoroughly analyzed it in OSLO coming up with a Apochromatic version and has since branched out into many ramifications of the idea. It is now the largest refractor in the UK.
 

#32 Crayfordjon

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Posted 20 November 2012 - 10:52 AM

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#33 Crayfordjon

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Posted 20 November 2012 - 10:53 AM

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#34 Crayfordjon

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Posted 20 November 2012 - 10:54 AM

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#35 Crayfordjon

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Posted 20 November 2012 - 10:57 AM

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#36 rwiederrich

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Posted 20 November 2012 - 11:13 AM

Super thing that large refractors are NOT things of the past in amateur astronomy. I also love their look and to me they are very practical in their use. :jump:


I agree, however for objects near the horizon I see some "practical" dificulties with your setup. ;)

best regards
Chris


Really..how is that exactly?
 

#37 wiseone

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Posted 20 November 2012 - 11:18 AM

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#38 Ziggy943

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Posted 20 November 2012 - 12:04 PM

I suppose it's forgivable, as "Alvin" is the common spelling.

Similarly, I got that all my life, and still do..."Allen" here and "Allen" there, on most occasions when someone took my name for this, that or the other...

Lady: "Sir, what's your name?"
Me: "Alan."

I'd even spell it for them, but to no avail, and yes, I doubted their credibility, too.

Cheers,

Alan


The difference here is that it is an extensive research paper, not a casual comment. Even so, we wouldn't misspell George Washington.
 

#39 Sky Muse

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Posted 20 November 2012 - 12:49 PM

Still, I've read of many "George"s, but only of one "Alvan".
 

#40 jrbarnett

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Posted 20 November 2012 - 02:00 PM

Me too. Alvan was Shobal's son. :lol:

Regards,

Jim
 






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