Refractor type Telescopes

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Star test 70mm F6 achromat doublet. with and without central obstruction. + green filter

Last post by realflow100 « Sat Dec 04, 2021 11:38 am
Replies: 2
by realflow100 » Wed Nov 17, 2021 5:05 pm

First post

I'm attempting to interpret the results of my star test and tried multiple strategies.
With or without a green filter. its clear one side of focus of...

Last post

I usually find the atmosphere is more of a problem than the optical quality of the telescope itself. at 70x or higher sometimes the atmosphere is...

2 Replies

3751 Views

Last post by realflow100
Sat Dec 04, 2021 11:38 am
Field flattener, Williams old one.

Last post by Altocumulus « Thu Nov 25, 2021 11:12 am
Replies: 1
by Altocumulus » Wed Nov 24, 2021 5:29 pm

First post

Does anyone have a William Optics 102GT with an old style flattener/reducer, and can post an image or two showing their setup so I can see how it all...

Last post

If the 'normal' focus distance is 277.44 mm without the FF, and the
back focus for the FF is 69.9mm.

In normal solar work the distance is assisted...

1 Replies

2546 Views

Last post by Altocumulus
Thu Nov 25, 2021 11:12 am
100th post on CN

Last post by KingNothing13 « Tue Nov 09, 2021 7:16 pm
Replies: 36
by Bigzmey » Thu Sep 26, 2019 10:43 pm
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First post

Yep, took me only 4 years to get there. More importantly the topic of the thread is

why would anyone want to drop $2K on a 4 apo for visual??? A 6...

Last post

Hey all - since we have meandered way off the original topic, we are going to go ahead and close this here.

Please feel free to open a new topic...
36 Replies

21714 Views

Last post by KingNothing13
Tue Nov 09, 2021 7:16 pm
"A good 70-mm refractor..."

Last post by mikemarotta « Wed Nov 03, 2021 10:25 am
Replies: 16
by mikemarotta » Fri Oct 29, 2021 12:20 am

First post

So, still trying to split the epsilon Lyrae companions, I decided to find out more about the range of 70-mm refractors.

Meade series 6000 Quad...

Last post

We may be extending the original work of William Rutter Dawes beyond its useful limits.

Hence it follows that the tests of separating power...

16 Replies

7535 Views

Last post by mikemarotta
Wed Nov 03, 2021 10:25 am
Recommendations for a suitable scope for the Fornax LT2 Tracker

Last post by Deserter « Sat Oct 16, 2021 12:48 pm
Replies: 5
by Deserter » Thu Oct 07, 2021 7:25 pm

First post

I'm a relative novice in the dark arts, and recently bought a Fornax LT2 tracker, which I am rather pleased with. I also have an ASAI Air pro for PA...

Last post

And in a complete about face I ordered a checked and tuned GT71. Kinda on the limit of the Fornax with this scope but I have a counterbalance arm so...

5 Replies

3382 Views

Last post by Deserter
Sat Oct 16, 2021 12:48 pm
TS achro 6" F5.9 - any owners

Last post by Bigzmey « Fri Oct 15, 2021 9:06 pm
Replies: 1
by 25585 » Wed Oct 13, 2021 12:03 pm

First post

I am tempted by the TS 6 F5.9 to replace my C8 I recently sold.

It seems quite a deluxe product compared to others, and has a Japanese Ohara...

Last post

There are a few 6 achro owners here. Celestron, SW and ES models from F5 to F8. I believe everybody are happy with what they got. :D I feel you will...

1 Replies

2197 Views

Last post by Bigzmey
Fri Oct 15, 2021 9:06 pm
Reflected and scattered light in the zenith diagonal mirror

Last post by j.gardavsky « Sat Sep 04, 2021 5:57 pm
Replies: 3
by j.gardavsky » Thu Aug 26, 2021 1:43 pm

First post

Hello all,

it eventually happens, that you buy a zenith diagonal mirror, and start wondering why the contrast of the views is not as good as...

Last post

Hello John,

fixing the scatterd light problem in the telescopes and in their accessories makes really the visible difference.
Clear skies,
JG

3 Replies

2837 Views

Last post by j.gardavsky
Sat Sep 04, 2021 5:57 pm
Scattering of light in the refractor optical tube assemblies

Last post by j.gardavsky « Sun Aug 29, 2021 10:12 am
Replies: 9
by j.gardavsky » Thu Aug 26, 2021 2:21 pm

First post

Hello all,

the question why some refractors deliver higher contrast views than the others,
is not just an object of the speculative philosophical...

Last post

You are quite right JG!
Thats why I examined all my telescopes, prisms and diagonals on light scattering and made adjustments when needed.

A nice...

9 Replies

5057 Views

Last post by j.gardavsky
Sun Aug 29, 2021 10:12 am
A 30$ svbony SV501 telescope. slight modification.

Last post by realflow100 « Mon Aug 23, 2021 7:50 pm

by realflow100 » Mon Aug 23, 2021 7:50 pm

I just purchased a new very cheap 30$ telescope (just the scope. no tripod) 70mm F6 diameter and focal ratio
i was wondering what was going on...

0 Replies

2079 Views

Last post by realflow100
Mon Aug 23, 2021 7:50 pm
Is this a good one?

Last post by Ylem « Fri Aug 20, 2021 11:34 pm
Replies: 5
by Capt. Midnight » Fri Aug 20, 2021 3:15 pm

First post

For backpacking. All objects except the sun (I’m scared😎😆).
I could go up in price if it’s worth it.

Last post

Great scope!

I have the 90 (and the 127) it's very portable, and gives very sharp views.

The 102 would be a step up from my 90, it will not...

5 Replies

3383 Views

Last post by Ylem
Fri Aug 20, 2021 11:34 pm
cheap 70mm refractor telescope F5.1 testing again

Last post by realflow100 « Fri Aug 20, 2021 3:20 pm
Replies: 10
by realflow100 » Mon Aug 16, 2021 4:24 pm

First post

still messing with this thing trying to get the sharpest image possible. and least amount of blurry edges as i can.
this seems to be the best result...

Last post

I could see the bands on jupiter quite easily Almost even some detail in the bands. I see 2-3 bands for sure. just looks like a lot of atmosphere...

10 Replies

5275 Views

Last post by realflow100
Fri Aug 20, 2021 3:20 pm
Whats the typical maximum resolution in arcseconds of a 70mm achromat/doublet refractor?

Last post by John Baars « Thu Aug 19, 2021 6:29 pm
Replies: 7
by realflow100 » Tue Aug 17, 2021 3:57 pm

First post

Whats the typical maximum resolution in arcseconds of a 70mm achromat/doublet refractor telescope?
I have a cheap one and ive been messing around...

Last post

(...)
I can see the grating in the platform a person would stand on at the top of a cell tower like a half a mile to a mile away (Not quite sure but...

7 Replies

4502 Views

Last post by John Baars
Thu Aug 19, 2021 6:29 pm
My new baby...

Last post by chris_g « Wed Aug 11, 2021 3:56 am
Replies: 23
by AstroBee » Mon Jul 26, 2021 8:20 pm
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First post

I've had an Explore Scientific ED127mm APO for a few years now and have always been very, very happy with it. I've dreamed about getting the big...

Last post

Wow, if she were mine, I'd call her Black Beauty. She certainly is that! Congrats...
23 Replies

11010 Views

Last post by chris_g
Wed Aug 11, 2021 3:56 am
Picked up this little beauty today.

Last post by Gmetric « Sat Aug 07, 2021 12:15 pm
Replies: 25
by Gmetric » Thu Jul 08, 2021 6:27 am
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First post

I have been looking for a long focal length achromatic refractor with an objective lens of around 80 to 100mm mark for a while to do some visual work...

Last post

Something I have known for quite a while since I am a refractor enthusiast ;)
With the CA chart, it is only applicable to crown/ flint refractors and...
25 Replies

11996 Views

Last post by Gmetric
Sat Aug 07, 2021 12:15 pm
is it better to correct doublet for center to edge sharpness. or for some other aberration?

Last post by realflow100 « Sun Aug 01, 2021 2:09 pm
Replies: 18
by realflow100 » Tue Jul 20, 2021 5:45 pm

First post

is it better to correct doublet for center to edge sharpness. or for some other aberration? like coma. field flatness. or chromatic aberrations?
Like...

Last post

heres a better test image showing whats going on with the focus. Nothing is really in focus even when I get as much as possible in focus.
the edges...

18 Replies

9182 Views

Last post by realflow100
Sun Aug 01, 2021 2:09 pm
Astro Tech 115 APO ED triplet (engaged impulse drive)

Last post by Bigzmey « Thu Jul 08, 2021 7:24 pm
Replies: 16
by mikemarotta » Fri May 07, 2021 12:40 am

First post

Well, they sent me an ad... And I have been wanting to upgrade... and I want something that I can carry. And I paid the rent last week. And I have...

Last post

In my experience the shakes come for the arm. It could be improved by reinforcing the arm with a block of wood, etc. I found that wrapping it with...

16 Replies

9532 Views

Last post by Bigzmey
Thu Jul 08, 2021 7:24 pm
APM 140mm ED, my next intended.

Last post by 25585 « Tue Jul 06, 2021 9:13 pm
Replies: 29
by 25585 » Wed Jun 02, 2021 6:31 pm
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First post

Been in my subconscious tempting me. :sprefac: :galleleo:

Last post

After reading the review I can imagine your subconscious temptations. The same happened to me. :shock:
It's a doublet, beware!
After reading this...
29 Replies

15028 Views

Last post by 25585
Tue Jul 06, 2021 9:13 pm
Would You Spend $100 On This Telescope?

Last post by Richard « Fri Jun 25, 2021 1:59 pm
Replies: 12
by Refractordude » Tue Jun 22, 2021 9:19 pm

First post

I could not find used prices for this telescope with GoTo on the world wide web. Before buying I will test the GoTo out in the evening. I feel if the...

Last post

Well I am sure there will be others , at one stage people were selling these STL mount in RSA for nothing , the one I tested I purchased for R600 or...

12 Replies

6126 Views

Last post by Richard
Fri Jun 25, 2021 1:59 pm
Created A Quickie For Days When Tired

Last post by dagadget « Fri Jun 25, 2021 1:02 am
Replies: 7
by Refractordude » Thu Jun 17, 2021 6:21 pm

First post

Sometimes I am to tired to bring the 150mm f/8 out back and set up the SkyTee II. It does not take long, but sometimes I am just to tired after work....

Last post

Hello Refractordude. It appears that you have solved the problem for a quick setup session. Although I have an 120ST refractor, the XLT150 refractor...

7 Replies

3676 Views

Last post by dagadget
Fri Jun 25, 2021 1:02 am
Achromatic and apochromatic doublets

Last post by dagadget « Thu Jun 24, 2021 11:38 pm
Replies: 33
by James » Mon Feb 08, 2021 2:49 pm
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First post

are all apochromatic doublets made out of ED glass and do they have the same design as achromatic ones?

Last post

Is lanthanum really worth the extra cost or is it just marketing? I'd Google, but I'm lazy. ;)
:text-thankyoublue:

Totally worth it.

I will...
33 Replies

13009 Views

Last post by dagadget
Thu Jun 24, 2021 11:38 pm
Refractor overload in 2021!

Last post by dagadget « Thu Jun 24, 2021 6:43 pm
Replies: 9
by Lady Fraktor » Sun Jan 17, 2021 6:08 pm

First post

Vic Maris of Stellarvue will be releasing a limited edition 180mm f/7 triplet this year, price has not been announced but likely comparable to...

Last post

DSC01631.JPG

Here is my current Frac in the POD

9 Replies

4771 Views

Last post by dagadget
Thu Jun 24, 2021 6:43 pm
AT70ED

Last post by pakarinen « Mon Jun 21, 2021 2:48 pm
Replies: 11
by pakarinen » Sat Jun 12, 2021 11:53 am

First post

Got an e-blast about this newly released OTA. Looks quite affordable.

Last post

There is also this one:

:think:

Of course it is out of stock, I don't like wait lists :D

I've been looking at that one for awhile, but in my...

11 Replies

2582 Views

Last post by pakarinen
Mon Jun 21, 2021 2:48 pm
Binoviewer friendly 4" Apo?

Last post by WilliamPaolini « Sat Jun 05, 2021 2:26 am
Replies: 11
by Virtus » Tue Jun 01, 2021 2:05 pm

First post

Can anyone recommend a 4 refractor that is binoviewer friendly? Ideally would be less than $1k give or take a couple hundred.

Last post

I can use my TSA-102 Apo and my APM 152 ED-Apo without an OCA binoviewing with the Baader MaxBright-II binoviewers. I will have to check my notes if...

11 Replies

2508 Views

Last post by WilliamPaolini
Sat Jun 05, 2021 2:26 am
AT-60ED, how is yours?

Last post by John Fitzgerald « Tue Jun 01, 2021 10:39 pm

by John Fitzgerald » Tue Jun 01, 2021 10:39 pm

I got this AT-60ED (FPL-53) a few weeks ago. Star testing is so-so, by my estimate, about 1/4 wave SA under corrected, a little better than that if I...

0 Replies

759 Views

Last post by John Fitzgerald
Tue Jun 01, 2021 10:39 pm
iOptron ST90?

Last post by John Fitzgerald « Mon May 31, 2021 1:27 pm
Replies: 4
by pakarinen » Mon Feb 22, 2021 2:44 pm

First post

Ummm, so this just popped up on a random Google search. $189 for a 90mm? (Single speed R&P though.) F5.6

Last post

This seems to be the same as the original Orion ST90. I had one. It was best for terrestrial viewing, although I used it stopped down a bit to...

4 Replies

1541 Views

Last post by John Fitzgerald
Mon May 31, 2021 1:27 pm

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