Cheap refractor glass any good?

Discuss making your own telescope!
Post Reply
User avatar
gregl
Milky Way Ambassador
Articles: 0
Offline
Posts: 1091
Joined: Fri Sep 06, 2019 2:30 am
4
Location: California
Status:
Offline

Cheap refractor glass any good?

#1

Post by gregl »


Are the objective lenses in the cheap refractors any good? Just thinking. As we know, the cheapo scopes sold in big box stores usually have terrible hardware: tripods, mounts, focusers, finders. But how is the front end glass? I have machine tools and can upgrade or make lots of hardware. It might be fun to chop up a cheapo refractor and make up a new focuser and mount for it. Craigslist is littered with such stuff some of which can be had for $20 or so. Keep in mind that this would be a project for fun, not to save money or time. But if the objective lenses are trash, then I'd not bother.
User avatar
Bigzmey United States of America
Moderator
Moderator
Articles: 8
Online
Posts: 7549
Joined: Sat May 11, 2019 7:55 pm
4
Location: San Diego, CA USA
Status:
Online

TSS Awards Badges

Re: Cheap refractor glass any good?

#2

Post by Bigzmey »


Yes, most of budget refractors have reasonably good objectives.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#3

Post by notFritzArgelander »


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.
Last edited by notFritzArgelander on Fri Nov 22, 2019 5:02 am, edited 1 time in total.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
Lady Fraktor Slovakia
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 9860
Joined: Mon Apr 29, 2019 9:14 pm
4
Location: Slovakia
Status:
Offline

Re: Cheap refractor glass any good?

#4

Post by Lady Fraktor »


Most of the name brand objectives are reasonable and would be a fun place to start off learning how to make your own refractor.
Some objectives as nFA pointed out are better than others so keep your eyes open for a good one.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
My day was going well until... people
Image
User avatar
gregl
Milky Way Ambassador
Articles: 0
Offline
Posts: 1091
Joined: Fri Sep 06, 2019 2:30 am
4
Location: California
Status:
Offline

Re: Cheap refractor glass any good?

#5

Post by gregl »


Thanks, folks. While the Istar objectives look great, the fun is to make something out of a piece of junk. I think I'll keep an eye on the local thrift shops, which our town seems to have many of.

Clear skies....
User avatar
DeanD Australia
Orion Spur Ambassador
Articles: 0
Offline
Posts: 653
Joined: Fri May 17, 2019 7:27 am
4
Location: Adelaide South Australia
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#6

Post by DeanD »


Even the cheap 60mm f12's have quite good optics, so you can probably pick up something that will give good views from the Thrift shop. If you make a nice tube, mount and focuser you could always upgrade the lens down the track. If you manage to find a 100mm or bigger scope to play with then you are golden with one of the iStar lenses as nFA suggests.

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
Telescopes: 12" f5 dob, Celestron CPC800, 150mmf5 Celestron achro, Tak TSA102, TV76, ETX125...
Binos: Steiner Wildlife XP 10x26, Swarovski 8x30 Habicht, Zeiss SFL 8x40, Vanguard Endeavour 10.5x45, Fuji FMTR-SX 10x50, Tak 22x60, Orion Resolux 15x70
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
User avatar
gregl
Milky Way Ambassador
Articles: 0
Offline
Posts: 1091
Joined: Fri Sep 06, 2019 2:30 am
4
Location: California
Status:
Offline

Re: Cheap refractor glass any good?

#7

Post by gregl »


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
Oohh that sounds like fun!
User avatar
yobbo89 Australia
Moderator
Moderator
Articles: 0
Offline
Posts: 2561
Joined: Sat May 11, 2019 7:44 pm
4
Location: australia qld brisbane
Status:
Offline

TSS Photo of the Day

Re: Cheap refractor glass any good?

#8

Post by yobbo89 »


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.
would you need a second rear glass element ?
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
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 .

Image
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#9

Post by notFritzArgelander »


yobbo89 wrote: Fri Nov 22, 2019 7:15 pm
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.
would you need a second rear glass element ?
No. The iStar objectives are a complete doublet.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
yobbo89 Australia
Moderator
Moderator
Articles: 0
Offline
Posts: 2561
Joined: Sat May 11, 2019 7:44 pm
4
Location: australia qld brisbane
Status:
Offline

TSS Photo of the Day

Re: Cheap refractor glass any good?

#10

Post by yobbo89 »


notFritzArgelander wrote: Fri Nov 22, 2019 7:23 pm
yobbo89 wrote: Fri Nov 22, 2019 7:15 pm
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.
would you need a second rear glass element ?
No. The iStar objectives are a complete doublet.
wow! that makes for an easy diy project, sign me up!
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
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 .

Image
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#11

Post by notFritzArgelander »


yobbo89 wrote: Fri Nov 22, 2019 7:32 pm
notFritzArgelander wrote: Fri Nov 22, 2019 7:23 pm
yobbo89 wrote: Fri Nov 22, 2019 7:15 pm

would you need a second rear glass element ?
No. The iStar objectives are a complete doublet.
wow! that makes for an easy diy project, sign me up!
I often find myself wishing my mechanical skills were better. :shrug:
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#12

Post by notFritzArgelander »


gregl wrote: Fri Nov 22, 2019 5:08 am Thanks, folks. While the Istar objectives look great, the fun is to make something out of a piece of junk. I think I'll keep an eye on the local thrift shops, which our town seems to have many of.

Clear skies....
Some brands to look for include Towa. Made in Japan is a good thing in inexpensive used refractors.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
j.gardavsky Germany
Orion Spur Ambassador
Articles: 0
Offline
Posts: 711
Joined: Mon Sep 23, 2019 1:52 pm
4
Location: Germany
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#13

Post by j.gardavsky »


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.

Another choice is to take the Cook triplets from the overhead projectors. Their typical aperture is around 100mm, the speed is fast, like F/4, but you can stretch them with a 2" Barlow.

Happy doing,
JG
6" F/5 Sky-Watcher achro, 2" BBHS Star Diagonal, 2" zenith prism, 1.25" Takahashi prism
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)
User avatar
PalomarJack
Earth Ambassador
Articles: 0
Offline
Posts: 41
Joined: Fri Nov 22, 2019 9:50 pm
4
Location: Tehachapi, Ca
Status:
Offline

Re: Cheap refractor glass any good?

#14

Post by PalomarJack »


I know you are looking to re-condition something, but there is also another source. Surplus Shed, https://www.surplusshed.com/category/Objective_Lenses . They have sizes up to 153mm / 6". I got a 90mm f/10 for a travel scope, 69.00 US. They have air spaced glass down to 50mm. One thing though, the non-Wollensak lenses may be assembled wrong, in the cell backwards or the wrong curve facing the flint. That was mine. I also adjusted the spacing for best performance. Even with all that, the prices are to die for. The Wollensak 127mm I want to build a scope around is 249.00 US. And many times they have sales of 30% - 40% off. They are also typically out of anything above 100mm, but sign up for their newsletter and when they anticipate them being in stock you can pre-order them, many times at a discount. Their 70 or 80mm glass may be just the ticket. They also have some 1 1/4" refractor tailpieces, too. One last thing, stay with the higher f/ratios with smaller lenses, I don't think the 90mm f/5.5 will perform as well as the f/10, for example.
I'm here to do two things, build something and dump some light down it.

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.
User avatar
Thefatkitty Canada
Co-Administrator
Co-Administrator
Articles: 0
Online
Posts: 4133
Joined: Sat May 11, 2019 4:20 pm
4
Location: Ontario, Canada
Status:
Online

TSS Awards Badges

TSS Photo of the Day

Re: Cheap refractor glass any good?

#15

Post by Thefatkitty »


Hi Greg,
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.
Image001.png

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 f/7 60mm (420mm length); the 'Towatron' :D
IMG1.jpg

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 achro it takes some OK pics:

Moon_Venus_2018_07_15.jpg
IMG3.jpg
Racoon_01.jpg

I'm always on the lookout for stuff like this. The iStars look tempting... ;)
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

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.

Oh yeah, and Solar Cycle 25 :D
User avatar
gregl
Milky Way Ambassador
Articles: 0
Offline
Posts: 1091
Joined: Fri Sep 06, 2019 2:30 am
4
Location: California
Status:
Offline

Re: Cheap refractor glass any good?

#16

Post by gregl »


Thanks, Fatkitty. Boy, you folks are giving me all sorts of great ideas.

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
Hi 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.
User avatar
j.gardavsky Germany
Orion Spur Ambassador
Articles: 0
Offline
Posts: 711
Joined: Mon Sep 23, 2019 1:52 pm
4
Location: Germany
Status:
Offline

TSS Awards Badges

Re: Cheap refractor glass any good?

#17

Post by j.gardavsky »


[quote Hi 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.
[/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/ca/erker/closeups.html

It is the skill of doing business to get these lenses for 10 bucks, like I've got mine,

JG
6" F/5 Sky-Watcher achro, 2" BBHS Star Diagonal, 2" zenith prism, 1.25" Takahashi prism
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)
User avatar
gregl
Milky Way Ambassador
Articles: 0
Offline
Posts: 1091
Joined: Fri Sep 06, 2019 2:30 am
4
Location: California
Status:
Offline

Re: Cheap refractor glass any good?

#18

Post by gregl »


Thanks, JG . :handgestures-salute:
Post Reply

Create an account or sign in to join the discussion

You need to be a member in order to post a reply

Create an account

Not a member? register to join our community
Members can start their own topics & subscribe to topics
It’s free and only takes a minute

Register

Sign in

Return to “ATM”