Request pleasant discussion of med/large CATs for visual use.

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AntennaGuy United States of America
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Re: Request pleasant discussion of med/large CATs for visual use.

#21

Post by AntennaGuy »


Lady Fraktor wrote: Sun May 03, 2020 3:34 am What about this for a telescope?
https://teleskop-austria.at/SWRMAK300
Thank you. I'll add it to my list of possibilities, although they don't seem to be offering it for sale in the USA yet.
Speaking of telescopes not being offered for sale in the USA, do you happen to know anything about ToscanOptics?
See https://www.toscanoptics.com/
E.g., https://www.toscanoptics.com/cassegrain ... ham-11-f12
(The photos of telescopes of different sizes are actually all the same photos, it appears. So maybe they haven't actually built one of each yet?)
They also list some others that stir curiosity.
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Request pleasant discussion of med/large CATs for visual use.

#22

Post by Lady Fraktor »


I have not heard of them but it is not surprising, there are many of these smaller optics shops in EU that produce amazing quality but in very limited yearly numbers such as FrT and
Astro Optik Manufaktur as examples.
I will take a look on some of the different EU forums later and see if I can find any mention.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#23

Post by Lady Fraktor »


If you do not mind buying used I would seriously keep an eye open for anything made by Valery Deryuzhin (Aries Instruments Ukraine)
Incredible instruments to say the least and they occasionally appear on the used market.
http://trafyx.com/bao/ariesmk10.html
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#24

Post by notFritzArgelander »


notFritzArgelander wrote: Sun May 03, 2020 3:23 am
AntennaGuy wrote: Sun May 03, 2020 2:47 am Hmm. At f/12 in a classical Cassegrain, there will be more coma. Will need to learn more about that. (Evidently, avoiding coma is the main reason that other large classical Cassegrains have higher focal ratios.)
Comparing the spot diagrams of a 200mm Newtonian with f10 and f15 200 mm Classical Cassegrain designs in R&V I find that the f10 CC is worse and the f15 CC is better. Coma can be ignored in an f12 Newtonian. I wouldn't worry about it.
notFritzArgelander wrote: Sun May 03, 2020 3:27 am
AntennaGuy wrote: Sun May 03, 2020 3:24 am Thank you very much for that analysis!!
I can run a model of an f12 M=4 CC design on the computer where I have my optical design SW. I have my work tools on a different machine.
I'm going to have to beg off for some additional time to do an analysis of a CC 10" f12 M=3. Since I last ran my optics design software I updated the operating system from Windows 7 to Windows 10 and I can't get any of them to run. Both ATMOS and MODAS are out of commission.

https://www.astro-physics.info/index.ht ... os/atmos89
http://www.myoptics.at/modas/

Hopefully it's just user error and rust.....
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#25

Post by Bigzmey »


I was seriously considering VMC, but at the end went with Edge HD for the following reasons:

1) weight. SCT and VMC are two lighter designs and my desert trips involve a lot of scope handling (up down stairs, in out the car, on off the mount).

2) familiarity with SCT design. I logged many hours with plain 8" SCT and like how it performs on my targets whether it faint galaxy, or tight double. Edge HD been a better version of familiar design felt like a safe choice.

3) because I am an avid double star observer I prefer vane-less design.

4) based on my experience with variety of scopes I prefer my scopes in F7-F10 range (not too slow and not too fast :)). I feel that most of premium EP lines are designed for this range to.

5) you read negative comments about other designs on forums. Some of it is real, some not, but since I don't have hands-on experience with VMC, it felt a more riskier investment.

6) cost. While I was looking for my next scope a used 9.25" came for sale from a trusty seller for an attractive price.

At the end I took delivery of 9.25" Edge HD and very happy with it. It feels like a better made version of plain SCT with sharper optics. As for the field curvature, you need to look for it but it is still there. :) It likely comes from EPs or could be even my eyeglasses, or eye. :lol: But it is mild and in no way distractive.

For all my high end scope purchases I always tried before buy. Either looking through scopes at the star parties, or purchasing used smaller versions. This strategy has prevented me from some costly mistakes. If I ever consider VMC again I will get a smaller one to try and get familiar with the design first.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#26

Post by AntennaGuy »


Bigzmey wrote: Wed May 06, 2020 6:58 pm I was seriously considering VMC, but at the end went with Edge HD for the following reasons...
Thank you for providing that perspective.
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
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Re: Request pleasant discussion of med/large CATs for visual use.

#27

Post by notFritzArgelander »


Very valid points you make here. I have a few comments.
Bigzmey wrote: Wed May 06, 2020 6:58 pm I was seriously considering VMC, but at the end went with Edge HD for the following reasons:

1) weight. SCT and VMC are two lighter designs and my desert trips involve a lot of scope handling (up down stairs, in out the car, on off the mount).

2) familiarity with SCT design. I logged many hours with plain 8" SCT and like how it performs on my targets whether it faint galaxy, or tight double. Edge HD been a better version of familiar design felt like a safe choice.
I really love the Edge optics and much prefer it to the SCT counterpart. Refractor like is not an exaggeration.
3) because I am an avid double star observer I prefer vane-less design.
An excellent point. The support vanes in different apertures of the VMC line differ too. The VMC110L has curved vane supports so there are no diffraction spikes. The VMC200L has straight vanes and so spikes.

There are criticisms on reviews of the VMC series that the vanes are thick. That is fair. But it is also complex and quantifiable. A support vane can be regarded is an inverse slit and a treatment of the dependence of the diffraction pattern can be found at the usual place

https://www.telescope-optics.net/spider.htm

I had an 8" f4 and it will be interesting to see how the VMC200L performs spike-wise. Weather is looking good in a few days.... :) Too windy tonight.
4) based on my experience with variety of scopes I prefer my scopes in F7-F10 range (not too slow and not too fast :)). I feel that most of premium EP lines are designed for this range to.
The VMC200L is f9.75, VMC260L is f11.5 and the VMC330L is f13. So eyepieces designed for f7-f10 should be just fine. I'd like to see a 65mm eyepiece for the VMC330. So one can find those at Russel Optics and the Masuyama line.
5) you read negative comments about other designs on forums. Some of it is real, some not, but since I don't have hands-on experience with VMC, it felt a more riskier investment.
I was skeptical of the negative reviews of the VMC line and decided to do some risk reduction by getting a little one first, the VMC110L. This was a mistake that hasn't put me off the idea of the VMC line. Don't get me wrong. I love the VMC110L as a grab and go scope. It just isn't comparable to the larger scopes in the line.

*It's made in China and the difference in quality control is apparent. The VMC200L is exquisitely made.
*Curved support vanes so diffraction pattern is nonexistent, there is more scattered light but not unacceptably so. We'll see what first light brings.
*The Chinese manufacturer glues the collimation screws which have to be unglued before optimization can happen. That is not the case with the larger VMCs.

So your logic that the choice for you was riskier is good. I should likely have gone directly to the VMC200L from the get go. :)
6) cost. While I was looking for my next scope a used 9.25" came for sale from a trusty seller for an attractive price.

At the end I took delivery of 9.25" Edge HD and very happy with it. It feels like a better made version of plain SCT with sharper optics. As for the field curvature, you need to look for it but it is still there. :) It likely comes from EPs or could be even my eyeglasses, or eye. :lol: But it is mild and in no way distractive.

For all my high end scope purchases I always tried before buy. Either looking through scopes at the star parties, or purchasing used smaller versions. This strategy has prevented me from some costly mistakes. If I ever consider VMC again I will get a smaller one to try and get familiar with the design first.
Agreed.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#28

Post by Bigzmey »


Thanks nFA! Some of the facts you have mentioned have eluded me. Our discussion illustrates that any design has strengths and weaknesses, same applies for EPs. The trick is to find the scope which are you most compatible with.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#29

Post by notFritzArgelander »


OH! I forgot to mention the purely operational reason why the VMC is attractive. It's the dew. Where I was living in VA high humidity was frequent and the 9.25 Edge was a dew magnet. I had an Astrozap heated dew shield and still had to run with a portable hair dryer. My MK66 had the same problems even with a Kendrick heater for the Intes dew shield. Never had a lick of dew on the VMC110L.

Now I'm in the drier conditions in the West it probably wouldn't be a problem. Ironic, no? Anyway I'll likely be traveling to dewier climes so it might make sense to consider the possibilities.....
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#30

Post by notFritzArgelander »


Bigzmey wrote: Thu May 07, 2020 5:24 am Thanks nFA! Some of the facts you have mentioned have eluded me. Our discussion illustrates that any design has strengths and weaknesses, same applies for EPs. The trick is to find the scope which are you most compatible with.
In the end that is why "try before buy" is always best. Isn't having a civil back and forth about this a relief?
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#31

Post by Lola Bruce »


I rented the Vixen and liked it, way better than a C11 I had. While weighing options I won a auction on a Takahashi 250s with corrector. The Takahashi is considerably better once cooled. Mine did not have fans but the new ones come with temperature controlled fans. I added fans to mine and it cut the cool down with up to 30 degree deltas to well under an hour. I am casually viewing at about 30 minutes, critical average about 45-50 minutes. Also no mirror shift with the 250. Dr. D I believe had a good write up on the Tak 250 but not the 250CRS (CRS is corrected no coma). The new ones are named Takahashi 250 CRS. Make sure it comes with the rings they are pricey separately.
Bruce
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Re: Request pleasant discussion of med/large CATs for visual use.

#32

Post by Bigzmey »


notFritzArgelander wrote: Thu May 07, 2020 5:27 am OH! I forgot to mention the purely operational reason why the VMC is attractive. It's the dew. Where I was living in VA high humidity was frequent and the 9.25 Edge was a dew magnet. I had an Astrozap heated dew shield and still had to run with a portable hair dryer. My MK66 had the same problems even with a Kendrick heater for the Intes dew shield. Never had a lick of dew on the VMC110L.

Now I'm in the drier conditions in the West it probably wouldn't be a problem. Ironic, no? Anyway I'll likely be traveling to dewier climes so it might make sense to consider the possibilities.....
Yes, dewing ad slow equilibration time are always concern for the closed tube designs. In our drier climate long dew shield seems to be sufficient most of the time, and it seems that for 8" and 9.25" ~couple of hours is enough for equlibration. For larger scopes and larger/faster drop in temperature it may not be the case.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#33

Post by notFritzArgelander »


Lola Bruce wrote: Thu May 07, 2020 3:54 pm I rented the Vixen and liked it, way better than a C11 I had. While weighing options I won a auction on a Takahashi 250s with corrector. The Takahashi is considerably better once cooled. Mine did not have fans but the new ones come with temperature controlled fans. I added fans to mine and it cut the cool down with up to 30 degree deltas to well under an hour. I am casually viewing at about 30 minutes, critical average about 45-50 minutes. Also no mirror shift with the 250. Dr. D I believe had a good write up on the Tak 250 but not the 250CRS (CRS is corrected no coma). The new ones are named Takahashi 250 CRS. Make sure it comes with the rings they are pricey separately.
Bruce
Interesting that you could rent the Vixen. How and where did that work? The Tak indeed has a formidable reputation.....
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#34

Post by Lola Bruce »


Woodland Hills Telescope and Camera. I have spent a good amount at their store, that may have something to do with it.

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Re: Request pleasant discussion of med/large CATs for visual use.

#35

Post by notFritzArgelander »


Well a first light from the VMC200L is reported here: viewtopic.php?f=6&t=9872

It is definitely easier on my eyes than a plain SCT. I can't evaluate it with regard to an Edge though for reasons given in the report. I think I'll need to get out of town to a dark site to make a call.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#36

Post by AntennaGuy »


notFritzArgelander wrote: Sun May 10, 2020 9:25 pm Well a first light from the VMC200L is reported here: viewtopic.php?f=6&t=9872

It is definitely easier on my eyes than a plain SCT. I can't evaluate it with regard to an Edge though for reasons given in the report. I think I'll need to get out of town to a dark site to make a call.
Thank you!
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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Re: Request pleasant discussion of med/large CATs for visual use.

#37

Post by notFritzArgelander »


notFritzArgelander wrote: Sun May 03, 2020 3:27 am
AntennaGuy wrote: Sun May 03, 2020 3:24 am Thank you very much for that analysis!!
I can run a model of an f12 M=4 CC design on the computer where I have my optical design SW. I have my work tools on a different machine.
notFritzArgelander wrote: Sun May 03, 2020 6:36 pm
notFritzArgelander wrote: Sun May 03, 2020 3:23 am
AntennaGuy wrote: Sun May 03, 2020 2:47 am Hmm. At f/12 in a classical Cassegrain, there will be more coma. Will need to learn more about that. (Evidently, avoiding coma is the main reason that other large classical Cassegrains have higher focal ratios.)
Comparing the spot diagrams of a 200mm Newtonian with f10 and f15 200 mm Classical Cassegrain designs in R&V I find that the f10 CC is worse and the f15 CC is better. Coma can be ignored in an f12 Newtonian. I wouldn't worry about it.
notFritzArgelander wrote: Sun May 03, 2020 3:27 am
AntennaGuy wrote: Sun May 03, 2020 3:24 am Thank you very much for that analysis!!
I can run a model of an f12 M=4 CC design on the computer where I have my optical design SW. I have my work tools on a different machine.
I'm going to have to beg off for some additional time to do an analysis of a CC 10" f12 M=3. Since I last ran my optics design software I updated the operating system from Windows 7 to Windows 10 and I can't get any of them to run. Both ATMOS and MODAS are out of commission.

https://www.astro-physics.info/index.ht ... os/atmos89
http://www.myoptics.at/modas/

Hopefully it's just user error and rust.....
Well it turns out that running MODAS was just rust. I've got it going. HOWEVER apparently my version of ATMOS was merely a demo and I'd need to shell out 400 shimollians to get it to run again. Not going to happen.

I'd suggest that a comparison of a CC 10" f12 M4 be run against Rutten and Venrooij designs for both an 8" f10 SCT and the aplanat but scaled up to 10" aperture, if there is still interest in that exercise.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#38

Post by AntennaGuy »


notFritzArgelander wrote: Thu May 14, 2020 4:34 am I'd suggest that a comparison of a CC 10" f12 M4 be run against Rutten and Venrooij designs for both an 8" f10 SCT and the aplanat but scaled up to 10" aperture, if there is still interest in that exercise.
If I understand you correctly, you think you can (more or less) model the optics in these subject telescopes, apparently based on published example/textbook designs that can reasonably substitute for the (presumably proprietary) actual designs (i.e., the manufacturer's designs for purposes of production) of these telescopes? Is that right?
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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Re: Request pleasant discussion of med/large CATs for visual use.

#39

Post by notFritzArgelander »


AntennaGuy wrote: Thu May 14, 2020 7:49 pm
notFritzArgelander wrote: Thu May 14, 2020 4:34 am I'd suggest that a comparison of a CC 10" f12 M4 be run against Rutten and Venrooij designs for both an 8" f10 SCT and the aplanat but scaled up to 10" aperture, if there is still interest in that exercise.
If I understand you correctly, you think you can (more or less) model the optics in these subject telescopes, apparently based on published example/textbook designs that can reasonably substitute for the (presumably proprietary) actual designs (i.e., the manufacturer's designs for purposes of production) of these telescopes? Is that right?
That's not how I would put the nature of the exercise. If you prefer something that has a flat field to it, the classical Cassegrain might not be as flat as you might like. A comparison with a generic SCT might be interesting. The degree to which the designs are proprietary seems to be small in terms of performance. There seems to be no difference in performance between Meade and Celestron performance in design apart from debatable quality control issues. Anyway the point would be to something more reliable than comparing textbook designs at an aperture that is irrelevant.

I withdraw the suggestion of computing an aplanat SCT. I looked in detail at what I had as a basis for the layout and I don't think it's close enough. There are too many degrees of freedom in the optics in the baffle tube. But the design of a CC is fixed. So is the design for a visually optimized SCT. There not much proprietary there that the performance would be far off at least at f10. I don't propose doing an f8.
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
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Re: Request pleasant discussion of med/large CATs for visual use.

#40

Post by AntennaGuy »


notFritzArgelander wrote: Thu May 14, 2020 10:26 pm
AntennaGuy wrote: Thu May 14, 2020 7:49 pm
notFritzArgelander wrote: Thu May 14, 2020 4:34 am I'd suggest that a comparison of a CC 10" f12 M4 be run against Rutten and Venrooij designs for both an 8" f10 SCT and the aplanat but scaled up to 10" aperture, if there is still interest in that exercise.
If I understand you correctly, you think you can (more or less) model the optics in these subject telescopes, apparently based on published example/textbook designs that can reasonably substitute for the (presumably proprietary) actual designs (i.e., the manufacturer's designs for purposes of production) of these telescopes? Is that right?
That's not how I would put the nature of the exercise. If you prefer something that has a flat field to it, the classical Cassegrain might not be as flat as you might like. A comparison with a generic SCT might be interesting. The degree to which the designs are proprietary seems to be small in terms of performance. There seems to be no difference in performance between Meade and Celestron performance in design apart from debatable quality control issues. Anyway the point would be to something more reliable than comparing textbook designs at an aperture that is irrelevant.

I withdraw the suggestion of computing an aplanat SCT. I looked in detail at what I had as a basis for the layout and I don't think it's close enough. There are too many degrees of freedom in the optics in the baffle tube. But the design of a CC is fixed. So is the design for a visually optimized SCT. There not much proprietary there that the performance would be far off at least at f10. I don't propose doing an f8.
Thanks for that explanation. I would certainly be interested, and likewise appreciate your generosity in doing/providing such computations!
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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