Baader MPCC coma corrector spacing???

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Baader MPCC coma corrector spacing???

#1

Post by UlteriorModem »


I'm about to loose my mind trying to get this spacing right.

According to Baader the required spacing is 57.5mm. I carefully measured and found a 5mm spacing ring would put me at 56.5mm within the +/- 1mm specs.

Had it at 64.5mm before due to a little misunderstanding of an additional 5mm spacer overlooked. But frankly it was better.

This was the results!? Click the image a couple of times tor a closer look.

ImageComa by Tom Whit, on Flickr

Pay no attention to the processing quality, no calibration files, and wanted to make the stars stand out.

Is it 'common' for the spacing to be slightly out of spec?
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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yobbo89 Australia
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Re: Baader MPCC coma corrector spacing???

#2

Post by yobbo89 »


Has it made the center worst? Or is that tracking, collimation problem?
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 .

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Re: Baader MPCC coma corrector spacing???

#3

Post by Gordon »


I'm assuming this is the scope you are using it on? 130mm APO triplet.
Gordon
Scopes: Explore Scientific ED80CF, Skywatcher 200 Quattro Imaging Newt, SeeStar S50 for EAA.
Mounts: Orion Atlas EQ-g mount & Skywatcher EQ5 Pro.
ZWO mini guider.
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Re: Baader MPCC coma corrector spacing???

#4

Post by UlteriorModem »


No sorry Gordon I need to update my sig. It's an 8" f4 newt. Thanks for reminding me to update my sig.

Has it made the center worst? Or is that tracking, collimation problem?

Yea the center was worse pretty sure it was collimated, I had touched it up on a star test. Unless something moved.

May be some tracking error but kinda think that was because of the oddly shaped stars. Since the OAG pick off is at the edge of the field it makes things worse.

Really should have noticed something was not right when trying to focus the guide camera some really oddly shaped stars were apparent.

Anyhow went from a 5mm to an 8mm spacer going to try tonight.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#5

Post by Gordon »


[mention]KathyNS[/mention] Has a similar scope and might be able to help.
Gordon
Scopes: Explore Scientific ED80CF, Skywatcher 200 Quattro Imaging Newt, SeeStar S50 for EAA.
Mounts: Orion Atlas EQ-g mount & Skywatcher EQ5 Pro.
ZWO mini guider.
Image cameras: ZWO ASI1600 MM Cool, ZWO ASI533mc-Pro, ZWO ASI174mm-C (for use with my Quark chromosphere), ZWO ASI120MC
Filters: LRGB, Ha 7nm, O-III 7nm, S-II 7nm
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Primary software: Cartes du Ciel, N.I.N.A, StarTools V1.4.

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Re: Baader MPCC coma corrector spacing???

#6

Post by KathyNS »


I don't see any evidence of coma. More normal processing with less contrast might show if there was coma or not.

The main aberration I see is field rotation. That indicates that your polar alignment is off.

There is something else happening, too. It seems to be worse on the right side than the left, which would indicate something out of alignment in your imaging train. Make sure all connections are rigid and symmetrical.
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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
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Re: Baader MPCC coma corrector spacing???

#7

Post by SkyHiker »


There is a known defect with some of the Baader MPCC IIIs where the lens was put in in the wrong direction. It happened to me, then also to another member in Australia whose problem was fixed once she turned it around.

It may actually be 2 lenses. I don't want to take mine apart now but the outer lens has its convex side outward (away from the camera), the inner lens has its convex side facing inward (towards the camera). AFAICT.
... 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: Baader MPCC coma corrector spacing???

#8

Post by UlteriorModem »


I realized now that I had moved and rotated the guiding camera some. Forgot to re-calibrate PHD2, so yea that probably had something to do with it :)

Ive used this CC before and it worked okay so pretty sure the elements are not backwards. It's two elements btw.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#9

Post by SkyHiker »


IMHO it has nothing to do with camera position or misalignment. There is screaming coma in every corner. The alignment isn't horrible because generally all coma tails are pointing outward. It has to be something about the distance.
... 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: Baader MPCC coma corrector spacing???

#10

Post by UlteriorModem »


Well got a chance to try things out again last night.

Took the time to fine tune the PA, remembered to calibrate PHD2, and changed the spacing out by 3mm.

Early results looked pretty good but still some Coma at the corners. Dont really know yet though. I will get to the data this afternoon.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#11

Post by bobharmony »


This is interesting. Is it the Mkiii MPCC, Tom? My recollection is that the back focus was listed as 55mm, not 57.5. If you have more recent information, I may need to make some adjustments.

Bob
Hardware: Celestron C6-N w/ Advanced GTmount, Baader MK iii CC, Orion ST-80, Canon 60D (unmodded), Nikon D5300 (modded), Orion SSAG
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Re: Baader MPCC coma corrector spacing???

#12

Post by UlteriorModem »


bobharmony wrote: Mon Nov 02, 2020 2:25 pm This is interesting. Is it the Mkiii MPCC, Tom? My recollection is that the back focus was listed as 55mm, not 57.5. If you have more recent information, I may need to make some adjustments.

Bob
It's 55.5mm with the uhhh stop ring in place. 57.5 without it. The stop ring is 2mm.

ImageBaader by Tom Whit, on Flickr
Tom

Current Equipment:
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Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#13

Post by UlteriorModem »


Okay had a chance to compile the data from last night.

It is better but still some coma and evidently some tilt as well. The stars in the upper right are pretty good. Lower Left not so much.

ImageComa 2 by Tom Whit, on Flickr

That was with the spacing at 59mm. I dont have a 6.5 mm ring so will have to grind one down.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#14

Post by JayTee »


Have you put this image through AP Lab yet to look at the "flatness".

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∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
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Re: Baader MPCC coma corrector spacing???

#15

Post by UlteriorModem »


JayTee wrote: Tue Nov 03, 2020 12:58 am Have you put this image through AP Lab yet to look at the "flatness".

JT
Nope, looked at it in Maxviewer. There is tilt there but not too bad.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#16

Post by UlteriorModem »


Okay I have freakin had it!

Spent an hour today carefully sanding down a 8mm spacer to 6.5 mm to achieve 'perfect' back focus. And it's still Excrement!

I got so pissed off I ordered a new Baader RCC-I.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#17

Post by yobbo89 »


Nice, 91mm backfocus!. I'm sick of 55mm, can't wait to see how it plays out, might ditch my skywatcher aplanatic, the tolerance spacing at f4 is just too much for the mp cc.
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 .

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Re: Baader MPCC coma corrector spacing???

#18

Post by UlteriorModem »


Yea that back focus was part of what 'sold' me.

I have however read that they are very touchy when it comes to collimation or tilt.

One thing I was unable to determine was how far into the focuser the RCC-I goes. It looks kinda long.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: Baader MPCC coma corrector spacing???

#19

Post by SkyHiker »


Rob since I will have an F/4 12" Newt and I have a Baader MPCC Mk III, I see you have one too but you are using your Skywatcher aplanatic CC? Should I start looking for something else, what is your experience with the Baader?
... 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: Baader MPCC coma corrector spacing???

#20

Post by UlteriorModem »


SkyHiker wrote: Sun Nov 01, 2020 9:01 pm There is a known defect with some of the Baader MPCC IIIs where the lens was put in in the wrong direction. It happened to me, then also to another member in Australia whose problem was fixed once she turned it around.

It may actually be 2 lenses. I don't want to take mine apart now but the outer lens has its convex side outward (away from the camera), the inner lens has its convex side facing inward (towards the camera). AFAICT.
I'm going to have to double check mine today. As evidently something is wrong.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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