Cheap refractor glass any good?
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Cheap refractor glass any good?
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Re: Cheap refractor glass any good?
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
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Re: Cheap refractor glass any good?
One less expensive refractor that has IMO surprisingly good glass is the 120mm f8.33 refractor made by Synta and sold by Celestron and Meade. When I got mine it behaved badly but after I did collimation on it in my home shop it was a terrific performer. Used it in a Mars opposition (2003) and could clearly resolve the Tharsis region volcanos and Olympus Mons.
The Orion ST 80 is another one with good glass but needs mechanical upgrades. It's not available anymore but has been replaced by the CT80 which is cheaper in mechanical construction but still has (I think, someone correct me if I'm wrong) the same objective. Chromatic aberration will be an issue for high power use.
The Orion ST120 is another candidate.
BUT.... why not order a known good Fraunhofer achromatic doublet and just build around it?
http://www.istar-optical.com/achromatic.html
They have a good reputation for quality glass and you wouldn't be wasting the bathwater to save the baby. They also have lenses available with low dispersion glass.
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Re: Cheap refractor glass any good?
Some objectives as nFA pointed out are better than others so keep your eyes open for a good one.
See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
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Re: Cheap refractor glass any good?
Clear skies....
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Re: Cheap refractor glass any good?
You never know what you might find: I picked up an old 4" f18 objective in a brass cell for $5. (I would love to find out its provenance as it seems to be a 19th century build: and I found a reference that John Herschel had a 4" scope that ended up here in South Australia and then disappeared into history!!!) When I put it in a 4" down-pipe and had a play it gave images of the planets that gave my Tak TSA 102 a run for its money in terms of sharpness! One of these days I might make a tube worthy of it, but my artist daughter has stolen it for use in her artwork as a camera obscura (it can project an image inside a room that just about fills a queen-size sheet!).
Have fun, and good luck!
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Eyepieces: way too many (is that possible?), but I do like my TV 32mm plossl, 13mm Nagler T6, 27mm Panoptic and 3-6mm Nagler zoom, plus Fujiyama 18mm and 25mm orthos and Tak 7.5mm LE
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Re: Cheap refractor glass any good?
Oohh that sounds like fun!DeanD wrote: ↑Fri Nov 22, 2019 8:24 am
...
You never know what you might find: I picked up an old 4" f18 objective in a brass cell for $5. (I would love to find out its provenance as it seems to be a 19th century build: and I found a reference that John Herschel had a 4" scope that ended up here in South Australia and then disappeared into history!!!) When I put it in a 4" down-pipe and had a play it gave images of the planets that gave my Tak TSA 102 a run for its money in terms of sharpness! One of these days I might make a tube worthy of it, but my artist daughter has stolen it for use in her artwork as a camera obscura (it can project an image inside a room that just about fills a queen-size sheet!).
Have fun, and good luck!
- Dean
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Re: Cheap refractor glass any good?
would you need a second rear glass element ?notFritzArgelander wrote: ↑Fri Nov 22, 2019 4:37 am I think it is strictly a YMMV sort of thing. A lot can go wrong with glass and some of it might have to do with cutting corners poor QC etc.
One less expensive refractor that has IMO surprisingly good glass is the 120mm f8.33 refractor made by Synta and sold by Celestron and Meade. When I got mine it behaved badly but after I did collimation on it in my home shop it was a terrific performer. Used it in a Mars opposition (2003) and could clearly resolve the Tharsis region volcanos and Olympus Mons.
The Orion ST 80 is another one with good glass but needs mechanical upgrades. It's not available anymore but has been replaced by the CT80 which is cheaper in mechanical construction but still has (I think, someone correct me if I'm wrong) the same objective. Chromatic aberration will be an issue for high power use.
The Orion ST120 is another candidate.
BUT.... why not order a known good Fraunhofer achromatic doublet and just build around it?
http://www.istar-optical.com/achromatic.html
They have a good reputation for quality glass and you wouldn't be wasting the bathwater to save the baby. They also have lenses available with low dispersion glass.
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .
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Re: Cheap refractor glass any good?
No. The iStar objectives are a complete doublet.yobbo89 wrote: ↑Fri Nov 22, 2019 7:15 pmwould you need a second rear glass element ?notFritzArgelander wrote: ↑Fri Nov 22, 2019 4:37 am I think it is strictly a YMMV sort of thing. A lot can go wrong with glass and some of it might have to do with cutting corners poor QC etc.
One less expensive refractor that has IMO surprisingly good glass is the 120mm f8.33 refractor made by Synta and sold by Celestron and Meade. When I got mine it behaved badly but after I did collimation on it in my home shop it was a terrific performer. Used it in a Mars opposition (2003) and could clearly resolve the Tharsis region volcanos and Olympus Mons.
The Orion ST 80 is another one with good glass but needs mechanical upgrades. It's not available anymore but has been replaced by the CT80 which is cheaper in mechanical construction but still has (I think, someone correct me if I'm wrong) the same objective. Chromatic aberration will be an issue for high power use.
The Orion ST120 is another candidate.
BUT.... why not order a known good Fraunhofer achromatic doublet and just build around it?
http://www.istar-optical.com/achromatic.html
They have a good reputation for quality glass and you wouldn't be wasting the bathwater to save the baby. They also have lenses available with low dispersion glass.
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Re: Cheap refractor glass any good?
wow! that makes for an easy diy project, sign me up!notFritzArgelander wrote: ↑Fri Nov 22, 2019 7:23 pmNo. The iStar objectives are a complete doublet.yobbo89 wrote: ↑Fri Nov 22, 2019 7:15 pmwould you need a second rear glass element ?notFritzArgelander wrote: ↑Fri Nov 22, 2019 4:37 am I think it is strictly a YMMV sort of thing. A lot can go wrong with glass and some of it might have to do with cutting corners poor QC etc.
One less expensive refractor that has IMO surprisingly good glass is the 120mm f8.33 refractor made by Synta and sold by Celestron and Meade. When I got mine it behaved badly but after I did collimation on it in my home shop it was a terrific performer. Used it in a Mars opposition (2003) and could clearly resolve the Tharsis region volcanos and Olympus Mons.
The Orion ST 80 is another one with good glass but needs mechanical upgrades. It's not available anymore but has been replaced by the CT80 which is cheaper in mechanical construction but still has (I think, someone correct me if I'm wrong) the same objective. Chromatic aberration will be an issue for high power use.
The Orion ST120 is another candidate.
BUT.... why not order a known good Fraunhofer achromatic doublet and just build around it?
http://www.istar-optical.com/achromatic.html
They have a good reputation for quality glass and you wouldn't be wasting the bathwater to save the baby. They also have lenses available with low dispersion glass.
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .
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Re: Cheap refractor glass any good?
I often find myself wishing my mechanical skills were better. :shrug:
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Re: Cheap refractor glass any good?
Some brands to look for include Towa. Made in Japan is a good thing in inexpensive used refractors.
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Re: Cheap refractor glass any good?
you can find on the eBay or at the old photography shops the close-up lenses. Some of them are precisely made cemented doublets with AR multicoatings, I have a few from Canon and Hoya (55mm dia, 67mm dia), and have paid just peanuts.
They are miles ahead in quality if compared to what you find today in the small telescopes of similar
Another choice is to take the Cook triplets from the overhead projectors. Their typical
Happy doing,
JG
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
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Re: Cheap refractor glass any good?
8" f/6 Newtonian on a German equatorial mount, all DIY.
DIY 90mm f/10 refractor on old medium duty Edmund Scientific German equatorial mount.
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Re: Cheap refractor glass any good?
I can vouch for the old Towa glass. I have a cemented doublet 60mm that came from a Tasco 55VTE; it was like a spyglass with a click-stop focuser. I bought it and a few other old scopes at a garage sale for $10.
Sometime later I found a Celestron 60mm for $25 at a swap shop. I already have a few good classic 60mm's, but this one had a 1.25" focuser. I discover that if I took the Towa objective from the Tasco 55VTE and used it with a "normal" focuser, it made for a nice little
For a total of $35 and some time with a hacksaw and a drill, it's a fun little wide field scope. Even if it's only an
I'm always on the lookout for stuff like this. The iStars look tempting...
"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4, AZ-EQ5 and SolarQuest mounts.
Too much Towa glass/mirrors.
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H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.
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Re: Cheap refractor glass any good?
Hi JG:j.gardavsky wrote: ↑Fri Nov 22, 2019 8:13 pm Hello Gregl,
you can find on the eBay or at the old photography shops the close-up lenses. Some of them are precisely made cemented doublets with AR multicoatings, I have a few from Canon and Hoya (55mm dia, 67mm dia), and have paid just peanuts.
They are miles ahead in quality if compared to what you find today in the small telescopes of similar aperture. Their typical focus is F=500mm and shorter.
...
Happy doing,
JG
Are you referring to the c.u. lenses that screw onto a prime lens like a filter? When I was a photographer I had the usual +1 to +3 c.u. lenses and a 55 mm macro lens but I've never seen one that was a doublet. Perhaps I've missed something there.
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Re: Cheap refractor glass any good?
Are you referring to the c.u. lenses that screw onto a prime lens like a filter? When I was a photographer I had the usual +1 to +3 c.u. lenses and a 55 mm macro lens but I've never seen one that was a doublet. Perhaps I've missed something there.
[/quote]
Yes, they have the photographic filter threads, and the test of they are not a singlet, but an achromatic doublet is done when passing the beam of a green laser pointer.
With Heliopan, you can get the 2 element achromatic cloce-up lens up to 82mm,
http://www.angelfire.com/
It is the skill of doing business to get these lenses for 10 bucks, like I've got mine,
JG
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
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