CEM-60 likes perfect balance!

Discuss iOptron mounts.
Post Reply
User avatar
KathyNS Canada
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 2584
Joined: Thu Apr 25, 2019 11:47 am
4
Location: Nova Scotia
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

CEM-60 likes perfect balance!

#1

Post by KathyNS »


Having heard rumours that the CEM-60 prefers perfect balance to east-side-heavy, I thought I'd try it. Yeah, baby! It sure does! The last couple of nights, my guiding has been my best ever. 0.82" total RMS. My pixel scale is 1.2 as/px, so I am very happy with anything under 1.0. Dec is 0.42", almost a flat line!

Note that, on the CEM-60, you have direct control over backlash. The manual says that the gear switches should be adjusted to 1/4 turn off fully-engaged to avoid wear and bad noises. I was getting backlash at that setting, so now I adjust them to 1/8 turn off fully-engaged. I am liking the result.
Untitled.jpg
Image
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
User avatar
mbenjaminz28 Canada
Moon Ambassador
Articles: 0
Offline
Posts: 70
Joined: Fri Oct 11, 2019 12:42 pm
4
Location: Halifax
Status:
Offline

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#2

Post by mbenjaminz28 »


Yeah, my cem120 likes perfect balance as well. I tried east heavy when I first picked it up but it was obvious that perfect balance was the way to go.
William optics flt 132, WO 0.72 reducer, Sbig Aluma U694/FW8G/AO-8a, 36mm LRGB 3nm Ha Oiii Sii, Cem120 non ec, Celestron CGX, Meade 12"F8 ota, Meade 70mm astrograph, Meade 6sn, TSflat2
User avatar
JayTee United States of America
Universal Ambassador
Articles: 2
Offline
Posts: 5619
Joined: Thu Apr 25, 2019 3:23 am
4
Location: Idaho, USA
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#3

Post by JayTee »


What if you can't get perfect balance. I can only get average balance, meaning that if it is perfectly balanced on one of the Meridian it is NOT perfectly balanced on the other side of the Meridian, so I strive to get the same level of imperfection on both sides of the Meridian. AND my guiding SUCKS! The best I've been able to achieve so far is 1.7 as/px and sometimes as bad as 3.0 as/px. This number is totally unacceptable. I'm pulling my hair out trying to get that "perfect" balance but no matter what imaging gear I use (my 80mm APO or my 6" RC) I can never get it perfectly balanced on both sides of the Meridian. HELP!

JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

Image
User avatar
Juno16 United States of America
Universal Ambassador
Articles: 0
Offline
Posts: 8195
Joined: Sun May 12, 2019 3:13 pm
4
Location: Mississippi Gulf Coast
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#4

Post by Juno16 »


With my system, I only get a graph like that when something is way off!

I restart the laptop and all is well (back to rms error of 1).

That is absolutely amazing Kathy!
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
User avatar
KathyNS Canada
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 2584
Joined: Thu Apr 25, 2019 11:47 am
4
Location: Nova Scotia
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#5

Post by KathyNS »


JayTee wrote: Tue Sep 08, 2020 1:57 am What if you can't get perfect balance. I can only get average balance, meaning that if it is perfectly balanced on one of the Meridian it is NOT perfectly balanced on the other side of the Meridian, so I strive to get the same level of imperfection on both sides of the Meridian.
Balance is either perfect or it isn't. Dec balance is perfect when the centre of gravity of the saddle/dovetail/OTA/guidescope assembly is on the dec axis. RA balance is perfect when the centre of gravity of all that plus the counterweights is on the RA axis. The CofG is either in the right place or it isn't.

Balance dec first, both longitudinally and laterally. Pay close attention to the lateral balance. It is not intuitive, is often forgotten, and produces bizarre effects like seeming to be in balance in one position but not in others. Once you get it balanced, that bizarre stuff goes away. Once dec is balanced in both directions, balance RA using the counterweights. When perfectly balanced, the CofG of the entire moving assembly is exactly at the intersection of the RA and Dec axes.
Image
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
User avatar
yobbo89 Australia
Moderator
Moderator
Articles: 0
Online
Posts: 2561
Joined: Sat May 11, 2019 7:44 pm
4
Location: australia qld brisbane
Status:
Online

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#6

Post by yobbo89 »


very nice kathy, you have a nice random guide patern on the bullseye with a low error, i've interpreted this over time that tracking is going good and sky conditions is the only improvment , i'll bett you'll get tighter results on varying nights .

an example i need 0.64 ''/ but some nights i get 0.9 - 1.0 ,limited to sky conditions my fwhm will be higher but no tracking problems ie star trailing, stars are round and perfect . but the end results is a very slight blur and higher fwhm . this will make purpose for me to get colour channels on bad nights and not for the lum . have you tried using 2x2 bin for your guide camera to try and average out star movment from the distortion from bad air ?
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
Juno16 United States of America
Universal Ambassador
Articles: 0
Offline
Posts: 8195
Joined: Sun May 12, 2019 3:13 pm
4
Location: Mississippi Gulf Coast
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#7

Post by Juno16 »


KathyNS wrote: Tue Sep 08, 2020 12:20 pm

Balance dec first, both longitudinally and laterally. Pay close attention to the lateral balance. It is not intuitive, is often forgotten, and produces bizarre effects like seeming to be in balance in one position but not in others.
Kathy,

Can you briefly explain how to balance in DEC laterally?

Thanks
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
User avatar
bradleybcraig
Jupiter Ambassador
Articles: 0
Offline
Posts: 224
Joined: Tue Jul 16, 2019 10:23 am
4
Location: Charlotte, North Carolina, USA
Status:
Offline

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#8

Post by bradleybcraig »


Congrats and thanks for sharing. I am interested in you guide camera focus. I've heard slightly out of focus is ok, your's looks pretty out. Do you find better results with that too?
-Brad

Hardware: Meade 8" ACF, Mallincam CF VRC-8 & 0.75 reducer w/ Moonlite 2" CS focuser & High Res Stepper, WO Star 71 w/ Moonlite High Res Stepper,
iOptron CEM60, Modified Canon 450D, Atik 383L+ mono, Lodestar X2, 2" Atik EFW2, Astrodon 36mm 3nm NB Ha/Sii/Oiii Filters, LRGB Gen2 E-Series Tru-Balance Filters, PoleMaster
Software: SkySafari Pro, Sequence Generator Pro, PHD2, PixInsight
Astrobin: https://www.astrobin.com/users/a028964/
Flickr: https://www.flickr.com/photos/bradleycr ... roimaging/
User avatar
KathyNS Canada
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 2584
Joined: Thu Apr 25, 2019 11:47 am
4
Location: Nova Scotia
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#9

Post by KathyNS »


Juno16 wrote: Tue Sep 08, 2020 1:32 pm Kathy,

Can you briefly explain how to balance in DEC laterally?

Thanks
Start with the scope balanced in dec longitudinally, and parked in the home or zero position (i.e. counterweights down, pointing at the pole). Ensure that RA is locked, and release the lock on the dec axis.

Typically, the scope will "fall" to one side or the other. If is has thick, sludgy consumer-grade grease in the bearings, you might have to give it a shove; typically it will shove easier to one side than the other. iOptron mounts have excellent bearings and no thick grease, so my CEM-60 will move on its own if it is out of balance. Whichever side it falls towards, that is the heavier side. You should be able to guess that load is making that side heavier: focuser (Newt), diagonal (SCT or frac), finder, guide scope, etc..

If your OTA is mounted in rings, loosen them and rotate the OTA in whatever direction will move the off-centre load towards the centre. You'll have to guess how far to rotate it. Clamp down the rings and re-check the balance. Repeat until it does not pull to either side.

Note that, with a Newt, the focuser will end up above or below the tube. Either is fine. Focuser-up is good for mount clearance and is comfortable for visual use (except when looking at Polaris!), but it requires more counterweight moment to balance RA. Focuser-down requires less counterweight moment, but is very inconvenient for visual use, and has more risk of mount interference.

Mount interference is a particular issue with the CEM mounts and their large counterweight hub. Be sure to test the configuration for mount clearance. I slid my OTA forward so the camera clears the counterweight hub, and balanced longitudinally by sliding the guide camera back on its rail.


bradleybcraig wrote: Tue Sep 08, 2020 2:07 pm Congrats and thanks for sharing. I am interested in you guide camera focus. I've heard slightly out of focus is ok, your's looks pretty out. Do you find better results with that too?
The focus on the guide scope is definitely weird. I can't seem to get rid of the haloes around the stars. However, since it is working well - particularly last night - if it ain't broke, don't fix it. Fiddling with it is rather far down my list of priorities.
Image
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
User avatar
Juno16 United States of America
Universal Ambassador
Articles: 0
Offline
Posts: 8195
Joined: Sun May 12, 2019 3:13 pm
4
Location: Mississippi Gulf Coast
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#10

Post by Juno16 »


KathyNS wrote: Tue Sep 08, 2020 4:37 pm
Juno16 wrote: Tue Sep 08, 2020 1:32 pm Kathy,

Can you briefly explain how to balance in DEC laterally?

Thanks
Start with the scope balanced in dec longitudinally, and parked in the home or zero position (i.e. counterweights down, pointing at the pole). Ensure that RA is locked, and release the lock on the dec axis.

Typically, the scope will "fall" to one side or the other. If is has thick, sludgy consumer-grade grease in the bearings, you might have to give it a shove; typically it will shove easier to one side than the other. iOptron mounts have excellent bearings and no thick grease, so my CEM-60 will move on its own if it is out of balance. Whichever side it falls towards, that is the heavier side. You should be able to guess that load is making that side heavier: focuser (Newt), diagonal (SCT or frac), finder, guide scope, etc..

If your OTA is mounted in rings, loosen them and rotate the OTA in whatever direction will move the off-centre load towards the centre. You'll have to guess how far to rotate it. Clamp down the rings and re-check the balance. Repeat until it does not pull to either side.

Note that, with a Newt, the focuser will end up above or below the tube. Either is fine. Focuser-up is good for mount clearance and is comfortable for visual use (except when looking at Polaris!), but it requires more counterweight moment to balance RA. Focuser-down requires less counterweight moment, but is very inconvenient for visual use, and has more risk of mount interference.

Mount interference is a particular issue with the CEM mounts and their large counterweight hub. Be sure to test the configuration for mount clearance. I slid my OTA forward so the camera clears the counterweight hub, and balanced longitudinally by sliding the guide camera back on its rail.

I have heard about lateral balancing, but was never quite sure what it meant.

Excellent description. Thank you!
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
User avatar
KathyNS Canada
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 2584
Joined: Thu Apr 25, 2019 11:47 am
4
Location: Nova Scotia
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: CEM-60 likes perfect balance!

#11

Post by KathyNS »


yobbo89 wrote: Tue Sep 08, 2020 1:04 pm have you tried using 2x2 bin for your guide camera to try and average out star movment from the distortion from bad air ?
I am not even sure if I can bin my guide camera. I shoot 4.0 second subs for guiding, specifically to ride out poor seeing. I used to use 2 sec subs, but the guiding was all over the place on poor nights. There was a noticeable improvement when I increased to 3 and then to 4 seconds.
Image
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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 “iOptron mounts”