Stupid questions about CEM120

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turboscrew
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Stupid questions about CEM120

#1

Post by turboscrew »


I've been bending towards getting a CEM120.
- Has there been problems with it?
- Any idea if it'll be discontinued in the near future? (Like CEM60.)
- Is the iPolar mandatory, or can it be polar-aligned in other ways (without major modifications)?
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: Stupid questions about CEM120

#2

Post by SkyHiker »


Whoa! I don't have a CEM and can't comment on it, but it looks like a very nice choice. You are right to plunk down a good deal of cash for the mount. It should be able to handle your 12" Dob reasonably well though it will still be a sail that is not easy to handle, and you need to adjust it in order to get focus.

Just comparing it with my G11S that has an AP payload capacity of 60 lbs., the CEM120 link at OPT says it has a 115 lbs. payload. Is that for visual or AP? I was looking at the CEM60 at the time but decided I wanted to stimulate the local economy instead, the G11S is mechanically also quite nice. I am not trying to sway you towards a G11, I'm having enough trouble taming the beast myself (I think I'm finally getting there! Now, to build an OnStep control system because I didn't want to pay for the Gemini II. EQStar works OK too I think.).

You will need a pier for this. Are you going to build an observatory, or just a pier in concrete?

There are many ways to polar align a mount. What I do myself is, I change DEC until the center of rotation is in the FOV of the camera (rotate 30 sec around RA at 6400 ISO and look at the center of the circular tracks). Then I take 3 second pictures and move the NCP towards that center on the camera LCD using the Alt/Az controls. I usually put a piece of tape with a pinhole in it on the LCD right on the center of the tracks so I can judge the progress by comparing the NCP location with that pinhole. I know an asterism of 10 to 12 magnitude stars near the NCP that lets me eyeball the NCP easily. This is a method that requires no computer, no extra gear except a DSLR. It takes some practice but is quite accurate. Other methods are drift alignment, use the PoleMaster or Sharpcap, etcetera.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: Stupid questions about CEM120

#3

Post by turboscrew »


SkyHiker wrote: Sat Aug 22, 2020 3:45 pm Whoa! I don't have a CEM and can't comment on it, but it looks like a very nice choice. You are right to plunk down a good deal of cash for the mount. It should be able to handle your 12" Dob reasonably well though it will still be a sail that is not easy to handle, and you need to adjust it in order to get focus.

Just comparing it with my G11S that has an AP payload capacity of 60 lbs., the CEM120 link at OPT says it has a 115 lbs. payload. Is that for visual or AP? I was looking at the CEM60 at the time but decided I wanted to stimulate the local economy instead, the G11S is mechanically also quite nice. I am not trying to sway you towards a G11, I'm having enough trouble taming the beast myself (I think I'm finally getting there! Now, to build an OnStep control system because I didn't want to pay for the Gemini II. EQStar works OK too I think.).
I was thinking that would be somewhat AP capable mount, even if not expert-level.
You will need a pier for this. Are you going to build an observatory, or just a pier in concrete?
I was planning to get a LiteRock first. That can later be upgraded to Tri-Pier or something alike.
There are many ways to polar align a mount. What I do myself is, I change DEC until the center of rotation is in the FOV of the camera (rotate 30 sec around RA at 6400 ISO and look at the center of the circular tracks). Then I take 3 second pictures and move the NCP towards that center on the camera LCD using the Alt/Az controls. I usually put a piece of tape with a pinhole in it on the LCD right on the center of the tracks so I can judge the progress by comparing the NCP location with that pinhole. I know an asterism of 10 to 12 magnitude stars near the NCP that lets me eyeball the NCP easily. This is a method that requires no computer, no extra gear except a DSLR. It takes some practice but is quite accurate. Other methods are drift alignment, use the PoleMaster or Sharpcap, etcetera.
Thanks. I was thinking of getting a polar alignment stuff later and start just with visual - maybe some occasional digiscoping.
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: Stupid questions about CEM120

#4

Post by turboscrew »


BTW, funny how restricted the European markets are. And I'm not too keen to order outside - the customs and taxes might give you a VERY nasty surprise.
And now that Britannia is also outside EU...
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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Re: Stupid questions about CEM120

#5

Post by SkyHiker »


That LiteRock with 1.75" legs? Maybe a bit small for your mount.

I once saw a portable AstroPysics pier, I was impressed with how solid it was: https://optcorp.com/products/astro-phys ... cc1f1ae4d0

And here's my tripod, it feels as solid as a pier: http://losmandy.com/hi-rez-images/fhd-ma.jpg price list at http://losmandy.com/access.html

Teleskop service also has portable piers: https://www.teleskop-express.de/shop/ad ... suchdas=OK

BTW Teleskop service also has nice affordable EQ platforms, if you just want something that lets your Vx12 track for visual.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: Stupid questions about CEM120

#6

Post by turboscrew »


SkyHiker wrote: Sat Aug 22, 2020 5:25 pm That LiteRock with 1.75" legs? Maybe a bit small for your mount.

I once saw a portable AstroPysics pier, I was impressed with how solid it was: https://optcorp.com/products/astro-phys ... cc1f1ae4d0

And here's my tripod, it feels as solid as a pier: http://losmandy.com/hi-rez-images/fhd-ma.jpg price list at http://losmandy.com/access.html

Teleskop service also has portable piers: https://www.teleskop-express.de/shop/ad ... suchdas=OK

BTW Teleskop service also has nice affordable EQ platforms, if you just want something that lets your Vx12 track for visual.
The tripod for CEM70 should be enough at first. The upgrade is probably along the lines of that Losmandy's.
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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