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Old 04-07-2021, 11:51 AM
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rustigsmed (Russell)
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image assistance

hi team,

i am working through lots of issues with my system but (very) slowly making some progress (although my mount has other ideas).

can someone advise what they think is wrong with this image?

https://www.flickr.com/photos/803366...40481/sizes/o/

it is a refractor with reducer/flattener - is it the spacing being slightly off? is it too far out or in?

thanks

Russ
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Old 04-07-2021, 05:41 PM
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vlazg (George)
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Looks like spacing Russel but I canít tell you which way
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Old 04-07-2021, 09:23 PM
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DiscoDuck (Paul)
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Post #4 here https://www.cloudynights.com/topic/6...eld-flattener/ would indicate you're too close maybe. Not sure.
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Old 05-07-2021, 09:18 AM
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Quote:
Originally Posted by rustigsmed View Post
hi team,

i am working through lots of issues with my system but (very) slowly making some progress (although my mount has other ideas).

can someone advise what they think is wrong with this image?

https://www.flickr.com/photos/803366...40481/sizes/o/

it is a refractor with reducer/flattener - is it the spacing being slightly off? is it too far out or in?

thanks

Russ
My guess is guiding. Every star seems to be a double star, which can indicate a temporary guide movement then back.
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Old 05-07-2021, 02:37 PM
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Nikolas (Nik)
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your backspace is a little too close, if it recommended at 55mm then take it to 56, this fixed my issue
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Old 06-07-2021, 11:23 AM
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rustigsmed (Russell)
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thanks everyone for the input - looks like slightly too close - i much prefer that to too far away, hopefully will get another crack at it toward the end of the week.

thanks again - much obliged.
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Old 07-07-2021, 08:16 AM
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Originally Posted by rustigsmed View Post
thanks everyone for the input - looks like slightly too close - i much prefer that to too far away, hopefully will get another crack at it toward the end of the week.

thanks again - much obliged.
It looks to me as quite a bit off not just a bit. Perhaps 5-10mm.

This is a 130mm F5.53 or so isn't it? So its not that different to my AP130.

A 1mm spacer difference with that (the Quad TCC is very sensitive to spacing) made a noticeable improvement but it wasn't anywhere near as distorted in the corners as that.

Roland Christen has a procedure for setting spacing on flatteners.

You focus the central stars. Then you focus a corner star and note if you had to rack in the focuser or rack it out to focus it.

If you had to rack in you needed to decrease the spacing. If you needed to rack out you needed to increase the spacing.

Keep in mind reducers may not do corner stars well on a full frame sensor unless they are very high quality and at least 3 inches in diameter preferably 3.5+.

Even then some corner stars may not be perfect. That has been my experience with various reducers. Very few correct a full frame sensor and they are usually pricey.

Straight flatteners are way easier to get right and they are more forgiving and generally speaking do a better job.

Greg.

Greg.
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Old 07-07-2021, 09:31 AM
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rustigsmed (Russell)
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Quote:
Originally Posted by gregbradley View Post
It looks to me as quite a bit off not just a bit. Perhaps 5-10mm.

This is a 130mm F5.53 or so isn't it? So its not that different to my AP130.

A 1mm spacer difference with that (the Quad TCC is very sensitive to spacing) made a noticeable improvement but it wasn't anywhere near as distorted in the corners as that.

Roland Christen has a procedure for setting spacing on flatteners.

You focus the central stars. Then you focus a corner star and note if you had to rack in the focuser or rack it out to focus it.

If you had to rack in you needed to decrease the spacing. If you needed to rack out you needed to increase the spacing.

Keep in mind reducers may not do corner stars well on a full frame sensor unless they are very high quality and at least 3 inches in diameter preferably 3.5+.

Even then some corner stars may not be perfect. That has been my experience with various reducers. Very few correct a full frame sensor and they are usually pricey.

Straight flatteners are way easier to get right and they are more forgiving and generally speaking do a better job.

Greg.

Greg.

thanks very much for the info Greg so i may be quite a distance off yet - i will definitely try that method out to double check there is too much spacing. that will then verify the diagrams linked from cloudy nights.

here is the link to the corrector https://www.teleskop-express.de/shop...ollformat.html - the telescope native is 130mm f7, it is meant to do full frame.

the thread on the corrector is raised a tad making it a bit confusing if the imaging system is meant to screw all the way down or not. the image linked it was screwed all the way down.

Cheers

Russell
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Old 07-07-2021, 10:12 AM
AdamJL
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Hi Russell

Where are you going to get the spacers from? I need to get some for my setup as well
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Old 07-07-2021, 10:32 AM
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rustigsmed (Russell)
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Hi Russell

Where are you going to get the spacers from? I need to get some for my setup as well
Hi Adam,

I got the zwo filter wheel and zwo OAG - in the pic attached i think i used the middle option however the adapters were not sturdy enough so I got into contact with Joshua Bunn on this forum who machines adapters/parts. He came up with a solution which is more rigid than the zwo part.

If you are using the 2600 most of the spacers should have come with the camera see second attachment although I found that 0mm adapter useless but you may not need it if there is an M48 thread you are attaching to.

Cheers
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