jayscheuerle
Post Laureate
Reged: 01/16/06
Loc: S. Philadelphia, PA
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16" mirror choices (low end)
#2408741 - 05/20/08 03:58 PM
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I've been planning on getting a 16" Lightbridge to use as a staring point for an ultralight, retaining the optics, spider, cell and focuser. These go for $1850 complete.
In our classifieds, there's a Hubble Optics Lightweight Sandwich Mirror going for $1500. At least it has some test results for this particular mirror.
In general, the 16" GSO mirrors have a good figure, but are not as smooth as high-end ones. How does this Hubble Optics one appear to stand up based on its tests? (assuming the tests are properly performed and for this particular mirror).
Thanks for any thoughts! - j
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hoof
Carpal Tunnel
Reged: 04/07/05
Loc: Redmond, WA
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2408808 - 05/20/08 04:30 PM
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Discovery sells 16" F/4.5 mirrors for $1699 according to their web page ( http://www.discoverytelescope.com/optics.html ). Their optics are top-notch, easily the equal of OMI or Galaxy or any of the other premium mirror makers. The only concern would be the time it takes to get the mirror, especially since 16" isn't one of their usual 'scope sizes (you might get a 15" mirror faster). Terry Ostahowski does the final figure on their mirrors ( http://www.ostahowskioptics.com/ ). He charges more if you buy direct from him, but that's because he not only does the entire mirror himself (Discovery does most of the work for their mirrors), but he also provides some rigorous testing data.
One upside of going with the LightBridge is that you get a secondary mirror with your primary. With Discovery, you'll pay another couple hundred. Don't forget that secondary mirror quality is just as important as the primary. I've heard a number of tales of 'scopes with bad views traced to a bad secondary.
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jayscheuerle
Post Laureate
Reged: 01/16/06
Loc: S. Philadelphia, PA
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Re: 16" mirror choices (low end)
[Re: hoof]
#2408841 - 05/20/08 04:42 PM
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Quote:
I've heard a number of tales of 'scopes with bad views traced to a bad secondary.
Ugh, yes! The secondary on my 12" Lightbridge was astigmatic (a long, laborious trace), so I'm a bit in the once bitten mode.
I hadn't realized that Discovery was so competitive, but delivery time could indeed be a concern.
Thanks!
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dave b
Post Laureate
Reged: 05/10/05
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2409188 - 05/20/08 07:32 PM
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check this post on hubble optics before you buy:
test hubble optics
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johangw
super member
Reged: 10/10/07
Loc: Netherlands/Belgium
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2409942 - 05/21/08 04:26 AM
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Quote:
Quote:
I hadn't realized that Discovery was so competitive, but delivery time could indeed be a concern.
Thanks!
Swayze has otherwize long lead times aswell... 
look here: web page
I would go for the Discovery mirror. The price/quality is unbeat-able, they prove it time after time...
johan
Edited by johangw (05/21/08 06:30 AM)
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mark cowan
Vendor (Veritas Optics)
Reged: 06/03/05
Loc: salem, OR
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Re: 16" mirror choices (low end) *DELETED*
[Re: dave b]
#2409948 - 05/21/08 04:34 AM
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DumbGuy
super member
Reged: 09/26/06
Loc: Upper Marlboro, MD
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Re: 16" mirror choices (low end)
[Re: mark cowan]
#2410031 - 05/21/08 06:56 AM
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Swayze has otherwize long lead times aswell...
I'm going into my 19th month with Swayze on a 24".
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Tom Trusock
Reged: 02/26/02
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Re: 16" mirror choices (low end)
[Re: mark cowan]
#2410327 - 05/21/08 09:58 AM
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Quote:
And if you're curious where the deleted post went that's being discussed it survives on a different thread, here .
Best,
Mark
From the CN terms of service:
Quote:
In addition, vendors/manufacturers are to refrain from commenting on their competitor’s equipment (directly or indirectly). Please restrain your comments to products you manufacture or resell.
Thanks.
T
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jayscheuerle
Post Laureate
Reged: 01/16/06
Loc: S. Philadelphia, PA
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Re: 16" mirror choices (low end)
[Re: Tom Trusock]
#2430270 - 05/30/08 09:08 PM
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Besides Mark (who doesn't appear to be taking ATM orders according to Obsidian's website) and Discovery, are there any other reputable 16" mirrors in the $2k range?
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jg3
sage
Reged: 05/27/07
Loc: near Auburn, CA
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2430473 - 05/30/08 10:40 PM
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Some other reputable but low-to-mid priced mirror makers:
www.opticwavelabs.com
www.pegasusoptics.com
www.opticalmechanics.com
www.lightholderoptics.com
Sorry, all their 16-inchers are over $2000 now.
jg3
near Auburn, CA
12.5" f/6.3 truss newt (primary from the shop now known as Optic Wave Labs)
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Bill Jensen
sage
Reged: 10/23/04
Loc: Springfield VA
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Re: 16" mirror choices (low end)
[Re: jg3]
#2430489 - 05/30/08 10:46 PM
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You may find a Meade 16 inch mirror from their old sonotube scopes. I am not sure of the accuracy of those mirrors, but I believe that some had good figures, when properly supported. You could discard the tube assembly and the mount, and perhaps get a decent mirror for a fraction of the price of a new one. It may even allow you enough $$ to have the mirror tested/tweaked, assuming it had a problem.
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sixela
Postmaster
Reged: 12/23/04
Loc: Boechout, Belgium
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2430857 - 05/31/08 04:40 AM
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Quote:
How does this Hubble Optics one appear to stand up based on its tests? (assuming the tests are properly performed and for this particular mirror).
The consensus opinion (which I will not claim is anything but an opinion) appears to be that the test protocol is such that the number don't mean much (and that mirrors with significant astigmatism can be claimed as "good"), and over at the ATM forum the few mirrors that had test data posted weren't as good as GSO mirrors (by a long stretch).
Many in even that forum, though, find it hard to resist one of these sandwich mirrors - even if you have to have it refigured, if the substrate is good the advantages of sandwich mirrors make those very tempting.
But that's still a big "if", a lot bigger than with GSO mirrors.
On the other hand, the vendor seems to be interested in improving the quality of is mirrors, so it's a "to be continued" story...
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mark cowan
Vendor (Veritas Optics)
Reged: 06/03/05
Loc: salem, OR
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Re: 16" mirror choices (low end)
[Re: jayscheuerle]
#2430981 - 05/31/08 08:14 AM
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Sent you a PM... 
Best,
Mark
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dave b
Post Laureate
Reged: 05/10/05
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Re: 16" mirror choices (low end)
[Re: Bill Jensen]
#2431382 - 05/31/08 12:40 PM
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You may find a Meade 16 inch mirror from their old sonotube scopes. I am not sure of the accuracy of those mirrors, but I believe that some had good figures, when properly supported. You could discard the tube assembly and the mount, and perhaps get a decent mirror for a fraction of the price of a new one. It may even allow you enough $$ to have the mirror tested/tweaked, assuming it had a problem.
be forewarned (and im not vendor bashing, just stating the facts), the meade 16" starfinders that the club has tested, my own included, were less than 1/2 wave. the later ones seem extra bad.
one member of this forum says he has a good one, so maybe they do exist, but personally i would not pay more than the price of a 16" mirror blank for one, unless i could startest it first.
you would not really be able to salvage the spider or focuser from it either:
http://www.scopereviews.com/page1r.html
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Bill Jensen
sage
Reged: 10/23/04
Loc: Springfield VA
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Re: 16" mirror choices (low end)
[Re: dave b]
#2431442 - 05/31/08 01:09 PM
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[
be forewarned (and im not vendor bashing, just stating the facts), the meade 16" starfinders that the club has tested, my own included, were less than 1/2 wave. the later ones seem extra bad.
one member of this forum says he has a good one, so maybe they do exist, but personally i would not pay more than the price of a 16" mirror blank for one, unless i could startest it first.
you would not really be able to salvage the spider or focuser from it either:
http://www.scopereviews.com/page1r.html
Dave, good to know. I looked through one a few years back, for perhaps a half hour while at a star party. The views did not appear to be too bad, but that was one sample out of many scopes/mirrors that Meade made. The rest of the scope, as you note, was useless. Extremely hard to move, and the focuser was junk. One such older 16 inch Meade scope is for sale nearby on CL for $600, which in my opinion is too much unless the mirror is decent, and you can drop it into a truss assembly.
For my own 8 inch scope, I had the Parks mirror re-done by Steve Swayze, and it made a noticeable difference, but it was not a bad mirror to begin with. I believe he told me when it was tested that it was a bit undercorrected, but had no astigmatism to speak of. I noticed the improvement on planetary views the most, since it now handles 400x under excellent skies.
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