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Coma corrector advise for Skywatcher Explorer 200P

msacco

By msacco
in Getting Started With Imaging

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msacco

msacco

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Hey, I've read a few previous discussions about it here, but some of them are old, so I just wanted to ask and hear some thoughts.

I have a Skywatcher Explorer 200P (1000mm, F/5) I'm using for imaging along with the ASI071MC pro, and I'd like to get a coma corrector for it.
There seems to be lots of possible options so I'd like to get some suggestions.

These are the common options:
https://www.firstlightoptics.com/coma-correctors/baader-mark-iii-mpcc-coma-corrector-photographic.html
https://www.firstlightoptics.com/coma-correctors/skywatcher-f4-aplanatic-coma-corrector.html
https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

As far as I understood - the baader one is very bad and is not recommended, the f4 aplanatic should be great, and the 0.9x coma corrector also seems to be ok, though there is a huge price difference between that and the aplanatic and the question is why?
Is it because it's meant for f/4 which is harder to make? Or is it just higher quality overall? Which one would work better for me? And how flat it is actually?

I don't see any image circle or any other useful information for them, so that kinda makes it hard to understand their quality, and that kinda leaves it to people's experience to 'tell the tale'.

Though I'll be using an APS-C sensor, full frame ability would always be welcomed, of course, other suggestions that I didn't link could work as well.
Thanks for the help :)

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Pryce

Pryce

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I have the Baader one my self and I've not had any issues in testing. I never read anything bad about it before I purchased it and it also has stellar reviews on FLO.

Though he Aplanatic one should be better, but that's also reflected in the price.   Since you don't already have a CC I'm assuming you're relatively new to imaging(at least with the reflector) and in that case I don't think you'll notice the slighly lesser quality of the baader or the 0.9x compared to the aplanatic.  Though I've never compared the three, so I can't say for sure. But here's what I found in my research:
 

13 hours ago, msacco said:

And how flat it is actually?

Here's a search for the baader on astrobin.  A lot of good result using setups similar to yours
https://www.astrobin.com/search/?q=Baader MPCC Mk III

And here with the f4 Aplanatic
https://www.astrobin.com/search/?q=SkyWatcher Aplanatic Coma Corrector

And the SW 0.9x
https://www.astrobin.com/search/?q=Skywatcher 0.9x coma corector

If you zoom into the corners, you can see a slight difference in the coma, but I was looking for it, so I couldn't say if someone would notice the difference if they weren't specifically looking for it. 
But if you can afford it, the Aplanatic would seem like the better option
 

13 hours ago, msacco said:

though there is a huge price difference between that and the aplanatic and the question is why?

Here's the google definition of Aplanatic:
"An aplanatic lens is a lens that is free of both spherical and coma aberrations. Aplanatic lenses can be made by combining two or three lens elements."
In other words, the optical quality is just better.


But to sum up:
The Baader and 0.9x is fine if you're just starting out, but if you can afford the Aplanatic, go for it!

Edited by Pryce
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rnobleeddy

rnobleeddy

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I've used both a baader mpcc mark ii and mark ii with sensors up to and including aps-c and they've performed fine. I'm not the pickiest imager, but I can't see any coma remaining. I know it's used by a few people and I've not heard any particularly bad reviews, but it probably depends how much you stare at the stars in the corners!

I heard from someone I purchased a 2nd hand scope from that the aplanatic cc worked well too. 

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msacco

msacco

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1 hour ago, Pryce said:

I have the Baader one my self and I've not had any issues in testing. I never read anything bad about it before I purchased it and it also has stellar reviews on FLO.

Though he Aplanatic one should be better, but that's also reflected in the price.   Since you don't already have a CC I'm assuming you're relatively new to imaging(at least with the reflector) and in that case I don't think you'll notice the slighly lesser quality of the baader or the 0.9x compared to the aplanatic.  Though I've never compared the three, so I can't say for sure. But here's what I found in my research:
 

Here's a search for the baader on astrobin.  A lot of good result using setups similar to yours
https://www.astrobin.com/search/?q=Baader MPCC Mk III

And here with the f4 Aplanatic
https://www.astrobin.com/search/?q=SkyWatcher Aplanatic Coma Corrector

And the SW 0.9x
https://www.astrobin.com/search/?q=Skywatcher 0.9x coma corector

If you zoom into the corners, you can see a slight difference in the coma, but I was looking for it, so I couldn't say if someone would notice the difference if they weren't specifically looking for it. 
But if you can afford it, the Aplanatic would seem like the better option
 

Here's the google definition of Aplanatic:
"An aplanatic lens is a lens that is free of both spherical and coma aberrations. Aplanatic lenses can be made by combining two or three lens elements."
In other words, the optical quality is just better.


But to sum up:
The Baader and 0.9x is fine if you're just starting out, but if you can afford the Aplanatic, go for it!

Thanks! I'm not new to imaging at all tbh, I imaged with the Newtonian in the past, I also own a C8 Edge HD and a SharpStar refractor.

I did search for results in astrobin, but I don't think you can really tell how much the image is cropped, so that's why it's hard to determine that.
But that's sooooooo weird though, as I remember searching yesterday and seeing LOTS people saying that the baader is not a good choice, but now all I see are good reviews, maybe I was just too tired? I'll try to go over my previous history and see what I find there.

I don't really have a budget limit, I could afford any of them but obviously, the cheaper the better, especially considering the fact that I plan on replacing it with an Esprit 120 in the future(when prices will be back to normal, so could be months, years, or never haha).

I wonder about a comparison between the baader and the 0.9x, cause faster f ratio(even though it's not by much) is always appealing!

3 minutes ago, rnobleeddy said:

I've used both a baader mpcc mark ii and mark ii with sensors up to and including aps-c and they've performed fine. I'm not the pickiest imager, but I can't see any coma remaining. I know it's used by a few people and I've not heard any particularly bad reviews, but it probably depends how much you stare at the stars in the corners!

I heard from someone I purchased a 2nd hand scope from that the aplanatic cc worked well too. 

Thanks for the comment, I am rather picky I'd say regarding the edges, but that depends on what I use, I don't expect a Newtonian to be as flat as a quality refractor.

One more general question, there seems to be many types of baader coma correctors and it seems like there are some slight differences between them, any 'best' version out there?

Thank you both :)

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msacco

msacco

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1 hour ago, Pryce said:

Could what you read previously be about one of the older(or non MPCC versions) ?

I'm assuming there's older and other versions since this one is called Multi purpose MK III. That could make sense 😅

That's.....surely possible.

So I guess that I don't really need to go with the aplanatic, but which one is better? The 0.9x or the baader one? The slightly wider focal length and f ratio could be pretty cool...
One more thing, any relevant information regarding adapters that I need to know? My camera is M42, but I have no issues with M48 as well.

Edited by msacco
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msacco

msacco

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14 minutes ago, Stu Wilson said:

Got a skywatcher  1 that's around 5 months old for sale if interested.

I used it for my sw200p but I've since got a new ota.

 

Stu

20210217_173050.jpg

Which model is that exactly? I don't think it's the aplanatic?
Do you have the link to the product? I'm not from the UK so I wonder if shipping prices would make it worthy for me, but what is the price excluding shipping?

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msacco

msacco

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20 hours ago, Stu Wilson said:

If u do a search for skywatcher coma corrector they'll come up everywhere ie flo or rothervalley optics etc. Retail is 160 gbp or mine 115 gbp plus shipping

That would depend on the shipping costs, but I could get the 0.9x for a total of 140 gbp including shipping, so I'm not really sure it would make much of a difference.
Do you have an image taken with that coma corrector to see the corners?

Thanks.

16 hours ago, Clarkey said:

There is a comparison here that might be worth a look.

https://www.astrofotoblog.eu/?p=856

Thanks, I did see that, but the only corrector relevant for me there is the baader, so that still doesn't really give me a good enough comparison compared to the 0.9x/aplanatic, tough the explore scientific one looks amazing, but the price is a bit high for that and I'm not sure I'd want to invest so much into that.

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kotitonttu

kotitonttu

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On 18/02/2021 at 18:34, Stu Wilson said:

There u go. Image taken with qhy8l on ota sw200p

RosetteTrial080121.jpg.4bcd073e262ec11e1ff8f009651d1f1f.jpg

I ordered this a corrector a while ago. Im just stressing out do I have enough inward focus. I have sw200p with stock focuser. Whitout corrector there is something like 10mm left inward focus. Did corrector affect focus point?

 

Edited by kotitonttu
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