Catadioptric telescopes

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A VMC200L

Last post by JayTee « Tue Dec 29, 2020 10:08 pm
Replies: 20
by notFritzArgelander » Mon May 11, 2020 4:16 am
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First post

I have troubles with astigmatism and field curvature for visual use in SCT and RC designs. The field always looks gauzy or hazy to me. I discovered...

Last post

US Hwy 491 between Monticello (Southeast) Utah and Cortez (Southwest) Colorado is one of the darkest roads in the country. I have driven it many...
20 Replies

30195 Views

Last post by JayTee
Tue Dec 29, 2020 10:08 pm
Dust and dew accumulation in a closed tube OTA

Last post by Bigzmey « Mon Nov 02, 2020 2:14 am
Replies: 3
by DEnc » Sun Oct 25, 2020 12:05 am

First post

I’m considering an 11” EdgeHD for astrophotography. Right now I often image in the California desert with a 4” achromat, where dust and dew are in...

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I am a visual observer, but I would never use fans to blow stuff inside my 9.25 Edge. I would rather let it sit for a few hours to acclimate.

The...

3 Replies

4278 Views

Last post by Bigzmey
Mon Nov 02, 2020 2:14 am
New to 10-inch Meade SCT

Last post by quigly7777 « Fri Oct 16, 2020 6:25 pm
Replies: 15
by mikemarotta » Mon May 25, 2020 1:48 pm

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I borrowed one from my local club. I read the user manual before I set the telescope on the dining room table to work with it. Aside from everything,...

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I had the 8 /203mm and liked it but traded for the 10 and it is a lot to handle. Would like a more permanent setup but a bit concerned about the...

15 Replies

11905 Views

Last post by quigly7777
Fri Oct 16, 2020 6:25 pm
Issue with my Celestron Astro Fi 5 SCT

Last post by Lady Fraktor « Sat Sep 26, 2020 8:00 pm
Replies: 11
by Oxous » Sat May 16, 2020 5:46 pm

First post

Greeting everyone,

I'm an astronomy enthusiast from Valparaíso, Chile, and recently bought myself a Celestron Astro Fi 5 SCT telescope. The first...

Last post

With the electronics of these mounts they tend to operate better on 12V DC than using a AC to DC converter as you can get voltage spikes from the...

11 Replies

9980 Views

Last post by Lady Fraktor
Sat Sep 26, 2020 8:00 pm
Improving balance of Mak on my Alt/Az mount.

Last post by helicon « Sat Sep 12, 2020 4:00 pm
Replies: 2
by John Baars » Mon Sep 07, 2020 9:16 pm

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This is what my GnG Maksutov scope looked like.

IMG_1445 (638x850).jpg

I still found a little disadvantageous that the powerful viewfinder was...

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Good modification John and should contribute to ease of use.

2 Replies

3502 Views

Last post by helicon
Sat Sep 12, 2020 4:00 pm
new scope for the farm

Last post by helicon « Wed Sep 02, 2020 3:17 pm
Replies: 15
by yobbo89 » Tue Sep 01, 2020 4:06 pm

First post

my boss kindly gave me his meade etx 90 that he has had in storage for probably about 10-15 years. i think the model is from 2005.

he isn't into...

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Nice boss. Congrats on the pick-up Rob.

15 Replies

9815 Views

Last post by helicon
Wed Sep 02, 2020 3:17 pm
Optimizing a small Maksutov.

Last post by Bigzmey « Wed Aug 12, 2020 7:03 pm
Replies: 5
by John Baars » Sat Aug 08, 2020 10:36 am

First post

There are several ways to improve the performance of a small Maksutov. The first two that I suggest make the biggest difference. There is no need to...

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Nice mods John! If we can do it, why they can't incorporate better stray light control into manufacturing process.

5 Replies

5748 Views

Last post by Bigzmey
Wed Aug 12, 2020 7:03 pm
102/127mm Mak O rings

Last post by Lady Fraktor « Sat Aug 08, 2020 2:06 pm
Replies: 7
by Ylem » Sun Apr 12, 2020 8:47 pm

First post

My 127mm Mak, of 12 years O ring has rotted out. Any ideas for replacement?
Has this happened to anyone else?

I am now starting to think this is a...

Last post

If you do want to replace the o-ring you may be able to find a o-ring making kit at a automotive shop.
I have replaced the 4mm thick o-rings in one...

7 Replies

6600 Views

Last post by Lady Fraktor
Sat Aug 08, 2020 2:06 pm
Mewlon 210 for visual use?

Last post by notFritzArgelander « Wed Jul 15, 2020 12:06 am
Replies: 7
by AntennaGuy » Mon Jul 13, 2020 2:40 am

First post

Hi All. I've been extending and updating my list of OTA options (the non-updated list is at ) for visual astronomy, and have begun to seriously...

Last post

Hmm. Interestingly, the Vixen VMC260L boasts the largest aperture area/weight ratio among any of the OTAs I've considered:
(and yes, sorry, I know...

7 Replies

6709 Views

Last post by notFritzArgelander
Wed Jul 15, 2020 12:06 am
C90. Bought another one!

Last post by Ylem « Mon Jul 13, 2020 11:53 pm
Replies: 6
by Ylem » Mon Jul 06, 2020 11:13 pm

First post

I sold my C90 not long ago, good God I missed it!!!
Had to buy another!

Such a great light weight scope, goes on my photo tripod and kicks butt!...

Last post

I never had one of the originals :(
I see a bunch on fleabay, maybe, just maybe ;)

6 Replies

5492 Views

Last post by Ylem
Mon Jul 13, 2020 11:53 pm
2" EPs with an 8" SCT?

Last post by Bigzmey « Mon Jun 29, 2020 5:06 pm
Replies: 14
by Ylem » Fri Jun 26, 2020 12:17 am

First post

I use a FR/C and have been doing so for decades.
I have never tried 2 EPs nor do I own any.
So I was curious if others here have.

My other...

Last post

Sounds logical.

So back to my C8, I think I may go shopping for a 2 er :)
It has a 37mm baffle tube, I should be able to find something to work...

14 Replies

10333 Views

Last post by Bigzmey
Mon Jun 29, 2020 5:06 pm
Maksutov + widefield telescope in one grab.

Last post by StarBru « Sat Jun 06, 2020 4:03 pm
Replies: 7
by John Baars » Mon May 04, 2020 12:25 pm

First post

If you use a 102 mm Maksutov as a grab and go telescope you will have some issues.

1. Cooling down. It generally takes a long time before a Maksutov...

Last post

Great tips on improving and making a small MAK more user-friendly, John! Great pics of the moon, too!

7 Replies

6713 Views

Last post by StarBru
Sat Jun 06, 2020 4:03 pm
Help plz :) Geting an eye shaped airy disc not circular.

Last post by jbelden « Thu May 28, 2020 4:37 am
Replies: 14
by TheButcher » Sun May 17, 2020 5:35 am

First post

Hey all,

I just installed Bobs knobs on my secondary and when I went out tonight, I kept getting this shape when I go out of focus to see if it is...

Last post

Nice, I think I might build one of these Dunkin masks. I agree that the Bob's knobs screw was tilting your secondary drastically, I honestly haven't...

14 Replies

5109 Views

Last post by jbelden
Thu May 28, 2020 4:37 am
Request pleasant discussion of med/large CATs for visual use.

Last post by notFritzArgelander « Fri May 15, 2020 4:16 am
Replies: 40
by AntennaGuy » Sat May 02, 2020 3:49 am
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First post

Hi All. I'd appreciate more input about the relative merits of commercially available Cats & Casses for visual use , emphases on DSOs but also...

Last post

If I understand you correctly , you think you can (more or less) model the optics in these subject telescopes, apparently based on published...
40 Replies

14644 Views

Last post by notFritzArgelander
Fri May 15, 2020 4:16 am
Recomendations for Dew Shield/Heater for C 11 SCT?

Last post by Bigzmey « Thu May 07, 2020 8:22 pm
Replies: 13
by TheButcher » Tue May 05, 2020 8:30 am

First post

Hey all,
I was wondering what is the best dew solution for the Celestron 11 SCT XLT? WIth out going broke, but get something that is reliable.

I see...

Last post

I have switched to home made dew shields for all my scopes. I make them from crafting foam (3-5mm) and staple or duct tape to hold the shape. Here is...

13 Replies

4888 Views

Last post by Bigzmey
Thu May 07, 2020 8:22 pm
11" SCT buying advice?

Last post by Lady Fraktor « Sun May 03, 2020 4:50 pm
Replies: 4
by TheButcher » Sun May 03, 2020 3:04 am

First post

Hey all,

I am at that stage now to get an Celestron 11 SCT. I will be mounting this on top of my Skywatcher EQ6-R (Mainly for Planetary and Lunar...

Last post

Unless it is a aplanatic version all of the standard SCTs will be the same quality.

Carbon fibre tends to expand/ contract less than aluminium and...

4 Replies

2223 Views

Last post by Lady Fraktor
Sun May 03, 2020 4:50 pm
APM MAk Cass 275mm f14 17,900 eur

Last post by notFritzArgelander « Fri May 01, 2020 4:50 pm
Replies: 2
by notFritzArgelander » Fri May 01, 2020 2:44 pm

First post

The ad is translator per:

APM Maksutov Cassegrain 275 mm f/14 Telescope; APM has 1 pc Telescopes Maksutov Cassegrain 275 mm f/14 with small C.O.,...

Last post

At first I thought this was Markus Intes Mak then realized it is a 10 , I wonder where he had this hidden!

Looks like a one off. US optical...

2 Replies

2469 Views

Last post by notFritzArgelander
Fri May 01, 2020 4:50 pm
Bresser 152/1900

Last post by Graeme1858 « Tue Apr 14, 2020 5:32 am
Replies: 11
by Mack41 » Thu Feb 20, 2020 9:10 pm

First post

Hi
Just pulled the trigger on a bresser 152/1900 mak
Got it ex display for £200 so steal really.
Anyone had any experience with bresser scopes ?

Last post

That's a right result for £200!

All you need now is a chainsaw to sort those trees out!

Regards

Graeme

11 Replies

4660 Views

Last post by Graeme1858
Tue Apr 14, 2020 5:32 am
C14

Last post by helicon « Thu Apr 09, 2020 2:29 pm
Replies: 12
by Mandrew » Mon Jan 20, 2020 6:27 am

First post

I have been using my 180mm Mak-Cass for Lunar photography, and want to go for the gusto. I am saving up foe a Celestron C14 Edge for serious work....

Last post

Great photos Avani - thanks for the share.

12 Replies

4167 Views

Last post by helicon
Thu Apr 09, 2020 2:29 pm
Temp equalization AKA cool down time for small Mak?

Last post by notFritzArgelander « Wed Apr 01, 2020 12:25 am
Replies: 9
by pakarinen » Tue Mar 17, 2020 12:44 pm

First post

Wondering if there's an average recommended cool down time for small Maks. I took out my new 90 this morning and without waiting I had a look at...

Last post

Hmm, question, how does insulating the OTA help with cool down?
Would not the insulation hold the heat in the scope?
What am I missing?

It reduces...

9 Replies

3932 Views

Last post by notFritzArgelander
Wed Apr 01, 2020 12:25 am
Rain is coming to Northern California - sorry.

Last post by Bigzmey « Mon Mar 16, 2020 4:59 pm
Replies: 9
by cmassa » Sat Mar 14, 2020 3:57 am

First post

This telescope should be good for a fair amount of rain which we really need. I managed to get the last AG Optical 12.5 Convergent telescope. It's...

Last post

It's a beauty, congrats! I think we are getting the rain which supposed to go your way. :lol:

9 Replies

3400 Views

Last post by Bigzmey
Mon Mar 16, 2020 4:59 pm
SCT Tube Damage

Last post by notFritzArgelander « Sun Mar 15, 2020 6:32 pm
Replies: 40
by Graeme1858 » Wed Feb 05, 2020 11:54 pm
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First post

I noticed my STC had some strange marks on the inside of the tube and the corrector plate and mirror had dust. I had just fitted the mounting bar for...

Last post

Well... that's dismal news. Sorry to hear that folks are being non responsive.
40 Replies

12281 Views

Last post by notFritzArgelander
Sun Mar 15, 2020 6:32 pm
As if I need a new telescope...

Last post by pakarinen « Fri Jan 24, 2020 2:05 pm
Replies: 49
by Lady Fraktor » Thu Jan 09, 2020 6:28 am
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First post

This looks interesting

Last post

For people in the USA they can be purchased through Teleskop-Service and at a slightly lower price for some reason:

Nice; but they still...
49 Replies

13939 Views

Last post by pakarinen
Fri Jan 24, 2020 2:05 pm
6-inch Mak?

Last post by John Baars « Wed Jan 22, 2020 10:10 pm
Replies: 15
by pakarinen » Sat Aug 24, 2019 6:49 pm

First post

In the random churning of my idle brain, I’ve been thinking about a 6-inch Mak. I have 80mm and 120mm ST fracs and maybe a slower Mak would be a nice...

Last post

I think it is worth considering.
While doing that you could consider the OMC140 as well. (5.5 inch)

I have the normal 1/4 P/V one, but Wolfgang...

15 Replies

7887 Views

Last post by John Baars
Wed Jan 22, 2020 10:10 pm
First (day)light SCT EdgeHD 9.25"

Last post by Bigzmey « Tue Jan 21, 2020 8:29 pm
Replies: 11
by Bigzmey » Mon Jan 20, 2020 9:51 pm

First post

I was really hoping for some clear skies this weekend, but it did not happen. Well, at least it was not raining. :D

Wanted to test my new EdgeHD...

Last post

nice images, who needs a zoom lense when ya have a 9.25 edge !

Exactly! :D

11 Replies

3540 Views

Last post by Bigzmey
Tue Jan 21, 2020 8:29 pm

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Catadioptric telescopes

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