decisions decisions....

[Dan13]

Hi, Im after some advice as im a bit torn on what to do. I currently image with a 130pds and a HEQ5 pro. My imaging is starting to come along and im in love with the hobby. To better my imaging i would like to resolve the coma im getting in my images at the far edges.

Now theres countless threads on how bad the SW CC is and to go with the Baader one etc, believe me its all ive done the last few days  

My issue is that although the 130pds is a fantastic scope and i adore it, im not sure i want to pay £140 for a part for it when the entire OTA cost only £170 itself. Im wandering would i benefit from using the money and say buy a 72ed or an 80ed refractor and keep the 130 for visual??

Am i being silly and should i just get the CC or should i go the refractor route, or another route if theres any other suggestions?

many thanks for any help it would be greatly appreciated.

 

Dan 

[jambouk]

For most short tube refractors you’d need a field flattener which probably costs as much as a coma corrector...

James

[andrew s]

Might you need a field flattner for the refractor ? Do you want a drop in aperture? 

Regards Andrew 

 

[Dan13]

Just now, jambouk said:

For most short tube refractors you’d need a field flattener which probably costs as much as a coma corrector...

James

Just been looking at that James, thinking to 130pds may still be the best bet. Im not opposed to upgrading further to say a William optics zenith or something alike but im really not sure its going to give me a world of difference in results and fell im being impulsive

[Dan13]

1 minute ago, andrew s said:

Might you need a field flattner for the refractor ? Do you want a drop in aperture? 

Regards Andrew 

 

i would yep, i guess it was really do i spend on the 130pds or buy and spend on a refractor, will my results be that different that i seen the monetary gain from it. think im being impulsive , that tied in with the dilemma of a coma corrector has just stumped me....

[jambouk]

I find refractors easier to work with personally, than reflectors, so if someone was starting afresh I’d say go for a refractor. But I suspect there is little difference. A short tube refractor will probably have a shorter focal length and wider field of view, which if adding in a reduced/flattener on top will give an even wider FoV - if this is important. Horses for courses.

 

[andrew s]

Ok toss a coin, heads refractor tailes coma corrector. Don't  go with the result but your emotional response to it.

Regards Andrew 

[Dan13]

4 minutes ago, jambouk said:

I find refractors easier to work with personally, than reflectors, so if someone was starting afresh I’d say go for a refractor. But I suspect there is little difference. A short tube refractor will probably have a shorter focal length and wider field of view, which if adding in a reduced/flattener on top will give an even wider FoV - if this is important. Horses for courses.

 

Food for thought appreciate it. Im sure if there was a plug and play CC for the 130pds id just get that but where i read you need to "cut this" "cut that" and weird reflections after installation etc its just really put me off..

[Dan13]

4 minutes ago, andrew s said:

Ok toss a coin, heads refractor tailes coma corrector. Don't  go with the result but your emotional response to it.

Regards Andrew 

good idea!!

[jambouk]

I’m not sure what you’ve read about cutting things... I would have thought you stuff the corrector in and it either helps reduce coma or it doesn’t. Show us one of your images with coma.

[Peter Drew]

A coma corrector could be used on subsequent telescopes, a one off purchase.     🙂

[Dan13]

9 minutes ago, jambouk said:

I’m not sure what you’ve read about cutting things... I would have thought you stuff the corrector in and it either helps reduce coma or it doesn’t. Show us one of your images with coma.

The SW CC apparently needs you to cut a few mm off the focuser tube so it doesn't protrude into the mirrors view..

this is a single light frame at 240 secs of M51- converted to PNG from CR2

[Dan13]

7 minutes ago, Peter Drew said:

A coma corrector could be used on subsequent telescopes, a one off purchase.     🙂

thats a very valid point

[jambouk]

Impressive aberration; I can see why you want to get a corrector. Maybe put a wanted advert on astrobuysellUK and see if you can get one for £80.

[vlaiv]

I think that you are looking at it the wrong way: Scope might cost £170 for visual - but it costs £310 for AP (CC price included).

Evostar 72 costs £270 for visual, but £455 for AP - you need to add the price of field flattener.

There are scopes that you can use "as is" - without additional optics - and yes, you can get one cheap - but it is another level of imaging in terms of resolution and imaging process  - something like this:

https://www.firstlightoptics.com/ioptron-telescopes/ioptron-photron-6-ritchey-chretien-telescope.html

Then there are scopes that are not as cheap - and don't need additional optics, but still keep you in the "ballpark" of 130PDS - something like this:

https://explorescientificusa.com/products/152-maksutov-newtonian

[Dan13]

7 minutes ago, jambouk said:

Impressive aberration; I can see why you want to get a corrector. Maybe put a wanted advert on astrobuysellUK and see if you can get one for £80.

it is indeed isnt it. Ive done just that and im currently speaking to a chap now ref one. he advises that the SW one no longer reducers to x.09 and is just plug and play. I've just checked this on rother valley and they say the same...so maybe after all this time SW actually took note of all the backlash they got for it and took the reducing part away from the CC?

[Dan13]

5 minutes ago, vlaiv said:

I think that you are looking at it the wrong way: Scope might cost £170 for visual - but it costs £310 for AP (CC price included).

Evostar 72 costs £270 for visual, but £455 for AP - you need to add the price of field flattener.

There are scopes that you can use "as is" - without additional optics - and yes, you can get one cheap - but it is another level of imaging in terms of resolution and imaging process  - something like this:

https://www.firstlightoptics.com/ioptron-telescopes/ioptron-photron-6-ritchey-chretien-telescope.html

Then there are scopes that are not as cheap - and don't need additional optics, but still keep you in the "ballpark" of 130PDS - something like this:

https://explorescientificusa.com/products/152-maksutov-newtonian

Thank you Vlaiv, i agree with you and i think now im being very impulsive due to not finding what i wanted!  im going to stick with the 130pds and grab the CC im in talks with now. many thanks

[CCD-Freak]

I just looked up that scope.....The 130 pds scope will need a coma corrector if your sensor is large.  I have the SW coma corrector which I like better than the MPCC with my 8" F3.8.

The thing that will give you the most grief while imaging is the mount.  Get the best one you  can afford. 

 

John Love
CCD-Freak
WD5IKX

Edited May 19, 2020 by CCD-Freak