What next ?

[tileys]

I have an EQ6 with a fast 8" Newt and a small refractor guidescope riding piggy back (rings not adjustable for the guidescope though). I have an EOS 400D (and 350D) for imaging (unmodded) and a shoestring tether to the mount from a laptop running EQMOD/Cartes Du Ciel/Backyard EOS.

What do you think (in your experience) would represent the best value in terms of the next purchase ? (considering the objective is DSO imaging).

1, Coma Corrector
2, CLS filter (prob a clip on)
3, Autoguide for the refractor
4, IR Mod for the camera
5, CCD (as an alternative to the EOS imager)

If money was no object I guess I'd just get all of the first 3 or 4/5 as I'm sure I will need to at some point if I get serious about this.

I am still grappling with consistently accurate polar alignment and focussing (the 400D is a bit clunky for focus as it has no live view - but, with a Bahtinov mask I am making headway there). So maybe the Autoguider would help iron out my alignment ? (of course, no substitute for a 'poorly aligned' scope).

Learnt so much from here in such a short time - thanks guys.

[ZeroID (Brent)]

I'd suggest the autoguider as your best next step although you would need some ability to adjust it as well. That will get you into longer exposures and rounder stars and will probably indicate your next purchase, coma corrector or CLS maybe.
You will still need to have good polar alignment for guiding to work well obviously but at least then you will only (hopefully) be dealing with optical and scope issues.

[tileys]

Thanks Brent - my guidescope is a 70mm so I'm hoping that will give me enough 'catchment' for a candidate guide star but hopefully I can get hold of some of those rings with the adjustable nuts - that would definitely help I think.

[glend (Glen)]

My view would be to get a good coma corrector like the Baader Mark III MPCC as it will be a good match for the Canon sensor spacing and really improve images. Re the guidescope, many are hard to aim and I hate aiming with rings - the Skywatcher or ADM guidescope mounts are a great investment as they allow good x and y axis control with simple knobs and are easy to use in the dark and your guidescope will not slide out.

[tileys]

Thanks Glen - I assumed all the coma-correctors did their thing in pretty much the same way and didn't even entertain the notion that some may be better suited to some specific image trains.

Cheers,

[ZeroID (Brent)]

Originally Posted by tileys

Thanks Brent - my guidescope is a 70mm so I'm hoping that will give me enough 'catchment' for a candidate guide star but hopefully I can get hold of some of those rings with the adjustable nuts - that would definitely help I think.

F# ?
What 'camera' and software will you use ?
I'd suggest PHD2 for the software. I'm using a Phillips SPC900 in an 80F5 SW. Once I figured out appropriate exposure\time settings it works quite well.

[tileys]

I downloaded PHD2 the other day - it's what others seem to recommend. The scope is one of those short Skywatcher 70mm/500mm(I think) - would make it an f7.14. I was thinking of getting one of those Orion Starshoot/QHY5II L equivalents to attach to it.

[kens (Ken)]

For a guidescope the most important factor is F ratio as that determines how many guide stars you see.
http://www.sbig.com/site/assets/file...ersion3_mb.pdf

What this means is that, when it comes to finding a star on the chip, what’s important is the F-number of the telescope, not the aperture, and not the focal length. An F/4 system will see four times more stars than an F/8.