starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: mustgobigger]
#5710992 - 03/03/13 04:55 PM
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It is always fun to read comments from people who have never used the equipment they are commenting on. Wonder if any new scientific discoveries would ever even been thought of if enough people were critical like that. We might still be reading by candle light.
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terraclarke
Pooh-Bah
Reged: 05/29/12
Loc: Over the river and thru the wo...
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Re: Unitron 131-C
[Re: starman876]
#5711110 - 03/03/13 05:54 PM
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Hence the smoke.......... And mirrors comment 
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: xavier]
#5711137 - 03/03/13 06:08 PM
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Thanks! xavier 
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DAVIDG
Post Laureate
Reged: 12/02/04
Loc: Hockessin, De
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Re: Unitron 131-C
[Re: Dave M]
#5711183 - 03/03/13 06:33 PM
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The resolution won't be effected by the mirrors only the brightness of the image. With fresh standard Al coatings, reflectivity is about 88% so with two mirrors your down to 77%. If you use a star diagonal it's thru put is also around 90% so your down to 70%. It is the same when you use a Cassegrain with a star diagonal as well.
The mirrors are small so to have them enhanced coated won't cost that much. What is more critical is the flatness, especially for the mirror directly behind the objective. They both should be good to 1/10 wave for the best performance. I would test them before replacing them and/or recoating them. It's an easy test and you can get a good understanding of the surface flatness by using a small optical flat of known quality. Surplus Shed has small flats that are good 1/20 wave and also a couple at 1/10 wave that under $20.
- Dave
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Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
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Re: Unitron 131-C
[Re: starman876]
#5711373 - 03/03/13 08:13 PM
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Quote:
It is always fun to read comments from people who have never used the equipment they are commenting on. Wonder if any new scientific discoveries would ever even been thought of if enough people were critical like that. We might still be reading by candle light.
Using Classic telescopes is the realm of astronomers who are both dreamers and doers, who often research rare items that they may never see in person, and then buy and use what they can both find and afford. Whether that is true is a fair question, so I've started a thread asking about people's motivations.
In my case, I have never seen a Unitron 131-C, yet according to DavidG's post, my speculations based on the physics were spot-on. I think they were also misunderstood. If the actual brightness MustGoBigger measures shows that he has both the necessary resolution of a 75mm objective and better light throughput than a 60mm or 55mm, that will speak to the excellent quality of his scope's mirrors, not to a flaw in optical theory.
I'm a Nerd. I love physics. I do not feel that others are obliged to share my interest, but can say that what makes a Nerd a Nerd is not an elitism based on understanding calculations, but an aesthetic and egalitarian response to the wonderful truths those calculations reveal. I'll further posit that scientific discoveries are never made by people who restrict their thoughts to realms they know. They are made by those who see what they know appear in something new, and leverage that to discover further qualities in the new. If we'd rather read by candle light, we should invent a world where people restrict themselves to ever manipulating only what they already know, a dull world indeed.
Because most of us will never see most of the wonderful telescopes discussed in this forum, I hope we'll encourage the dreamers to dream, to ask, to speculate wisely, and those who know from experience to confirm the expanding knowledge. If, for fear of being razzed or any other reason, people were afraid to post about equipment they have never seen, Classic Telescopes would become a sparse forum indeed.
I've occasionally seen, but never driven, a Ferrari. May I be forgiven for saying I think it's a wonderful car? The Unitron 131-C fascinates me, despite that I've never seen or used one. If ever I see one for sale at a price I could afford, I'll buy it -- and then I'll post about it for my fellow dreamers, and invite them to my star parties to try it. A welcoming attitude expands everyone's knowledge.
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: Joe Cepleur]
#5711439 - 03/03/13 08:41 PM
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: starman876]
#5711540 - 03/03/13 09:40 PM
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Let me guess, plain, buttered, carmel and cheese.. 
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: Dave M]
#5711577 - 03/03/13 09:54 PM
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: starman876]
#5711579 - 03/03/13 09:55 PM Attachment (19 downloads)
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pics of 131C box made from spotting scope boxes
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: starman876]
#5711585 - 03/03/13 09:59 PM Attachment (16 downloads)
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pic 2
I did not cut the wood for the cradle to hold the scope in place, but for now it functions and protects the scope. I have the original boxes with the other 131C's I have so I have a good model. Nor sure if I will leave the extra handle on the box.
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mustgobigger
Post Laureate
Reged: 06/12/07
Loc: Michigan
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Re: Unitron 131-C
[Re: starman876]
#5711617 - 03/03/13 10:14 PM
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Well with the sharp images I am getting
I will not mess with mine.
Even if its not as bright as a Refractor
Straight through...all users would
Most likely use a diagonal so they
Cancell each other out and anything
Compared would lose same percentage.
I can't speak for other 131's but
I have viewed side by side
With a 142 unitron
And will never touch mirrors or
alignment on 131.
If optics were just ok I might try
To put better flats in...
Can't argue with physics but
I just don't see 30% difference.
also some 75mmon unitron
were known to have iffy optics...
More than a few threads over the years
Of buyers getting duds.
Also having mine on a 1421 mount
Doesn't hurt as its quite stable.
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: starman876]
#5711640 - 03/03/13 10:25 PM
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Thanks for posting those images Johann, thats a nice idea and it looks great, something i could consider doing if i ever run across another box like i have.
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: mustgobigger]
#5711641 - 03/03/13 10:25 PM
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here here
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: Dave M]
#5711644 - 03/03/13 10:27 PM
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you never know who might have those spotting scope boxes laying around 
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snork
super member
Reged: 01/27/12
Loc: NE Ohio
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Re: Unitron 131-C
[Re: starman876]
#5711657 - 03/03/13 10:34 PM
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That's a great looking scope Dave! Nice find. Frying pans weren't flying??
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: snork]
#5711673 - 03/03/13 10:43 PM
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That's a great looking scope Dave! Nice find. Frying pans weren't flying??
No, but you can bet i have a equal or greater expenditure in my future.
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: starman876]
#5711712 - 03/03/13 11:11 PM
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Hmm!, do i get a couple guesses 
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starman876
Carpal Tunnel
Reged: 04/28/08
Loc: VA
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Re: Unitron 131-C
[Re: Dave M]
#5711723 - 03/03/13 11:19 PM
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Nope. I do not allow that.
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Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
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Re: Unitron 131-C
[Re: Dave M]
#5711987 - 03/04/13 06:47 AM
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Quote:
Quote:
That's a great looking scope Dave! Nice find. Frying pans weren't flying??
No, but you can bet i have a equal or greater expenditure in my future.
You're buying a 4" Unitron for your wife?!
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Dave M
Postmaster
Reged: 08/03/04
Loc: N.E.Ohio
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Re: Unitron 131-C
[Re: Joe Cepleur]
#5712218 - 03/04/13 10:19 AM
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I wish thast`s what it was
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