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Thoughts on a small Ritchey Chretien


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Hi all

My first scope was a Celestron CPC925, but I quickly moved to DSO imaging and never got any success with the SCT (I think I have one of the dud Meade reducers). 90% of the time, I'm imaging with a Redcat or FLT110 refractor but would like a bit more reach for galaxies. I occasionally image the moon, but haven't had a go at the planets for years, so the SCT gets little to no use. I'm considering putting it back on the forks and selling it and getting a small (6 or 8 inch) Ritchey Chretien for galaxies. I'd be interested in thoughts/views on this. I have an Atik Horizon and an Atik 314L+ camera.

Thanks!

Nick

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People will tell you horror stories of owning an RC - mainly due to collimation.  Ive recently managed to collimate mine using David Davies's process & couldnt be happier with it.  Its not as scary as people will let you believe.

Your cameras would be a great match for that scope too - to be sure - check out CCD suitability on astronomy tools

Good luck

Cheers

Andy

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+1

I love my 8" RC, use it with ASI1600 and it is a good match, but you'll have to bin in software a bit, because at 0.48"/px it is over sampling by at least x2.

 

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Thank you both. The 314L+ though small is good for galaxies, and would give 0.97"/pix on an RC6 and 0.82 on a 6 which astro tools suggests is good for OK seeing or better. The Horizon would need good seeing or better (if not binning). 

Good to know you're both happy with the RCs!

Nick

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3 hours ago, chouet said:

Thank you both. The 314L+ though small is good for galaxies, and would give 0.97"/pix on an RC6 and 0.82 on a 6 which astro tools suggests is good for OK seeing or better. The Horizon would need good seeing or better (if not binning). 

Good to know you're both happy with the RCs!

Nick

Do yourself a favor and don't go below 1-1.2" regardless of what any particular tool says - all likelihood that you'll be oversampling if you go higher than that.

Don't be afraid to bin in software either - it is just a simple operation.

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2 hours ago, vlaiv said:

Do yourself a favor and don't go below 1-1.2" regardless of what any particular tool says - all likelihood that you'll be oversampling if you go higher than that.

Don't be afraid to bin in software either - it is just a simple operation.

Oh I agree, unless you are at an elevated location then you are just not going to get those results, the shocking thing is that on my Esprit 100 at 1.41" I can tell the difference between a night with good seeing and bad seeing in my images and so going below 1" at my location seems pointless to me. You would probably be looking at something like 1 in 5 nights having sufficient seeing to work at 1" let alone lower.

Adam

Edited by Adam J
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On 27/05/2020 at 11:52, Andy274 said:

People will tell you horror stories of owning an RC - mainly due to collimation.  Ive recently managed to collimate mine using David Davies's process & couldnt be happier with it.  Its not as scary as people will let you believe.

Your cameras would be a great match for that scope too - to be sure - check out CCD suitability on astronomy tools

Good luck

Cheers

Andy

can you give me a link to David Davies's process please.

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I think the one Andy is referring to is about a quarter of the way down the page here:

I am interested because a Ritchey Chretien (for imaging smaller galaxies and planetaries) may be in my future too, but worries about collimation (amongst other things) are holding me back.

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I started that other thread due to my difficulties collimating my 200mm RC.

My problem is that I'm too hasty! Once I'd settled down, read and re-read and re-watched various instructions and videos on the matter, collimation wasn't that difficult or time-consuming using a combination of a Howie Glatter and Cheshire, and I think I've got it nearly perfect now. The scope is so robust that it seems to hold collimation very well and if it needs collimating again, I'm confident that it wouldn't take me more than 10 minutes.

So the message is, once you've learnt the slightly quirky nuances of RC collimation, it's actually quite easy and you have a very sharp scope.

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