Imaging Advise

[Astro Fan]

Hello All - I am currently running a CPC 9.25 GPS Alt Az fork mounted, when set up carefully the tracking and GOTO works really well and I have taken some OK lunar images with a Toucam. I now want to upgrade to a 1/2" CCD Imager for targets like M42 - Question is - Can anybody recommend a camera thats a good allrounder and can be autoguided at a later date and will I eventually have to move to an EQ mount for longer exposures. (as usual price is an issue)

[brantuk]

Hi Astro - nice scope.

The fork mount is very good for lunar/planetary short exposure work. But if you go DSO and LE then you'll want to at least mount it on an equatorial wedge or eventually get an EQ mount.

Because stuff is moving up there you need to track with high accuracy. Fortunately the CPC's are superb at tracking. But you need the dec axis fixed for LE and only track in ra axis on a single drive motor to get the accuracy required - a wedge will facilitate this.

With the schmitt/cass there is more than one solution for guiding. Off-axis guiders use the same optics for guiding and shooting, and has the benefit of eliminating the flexure that occurs when you use a separate guide scope fixed to the main scope.

I'm only using a webcam at the moment but it's recently been modified for LE. Soon as I get some decent nights I'll be trying it out with the 800 on a wedge mount. Be interesting to compare results.

Cheers

[Astro Fan]

Thanks for the reply - a wedge or pier could be the way to go (it's cheaper than a new eq mount) the goto software has EQ tracking as an menu option so that's not a problem, I just need to spec the right ccd camera and off axis guide camera - there's quite a few to choose from old & new.

[RobH]

Brandt has said it all really.

If you haven't done any astrophotography before though, you can get reasonable results with an alt/az mount if you keep your exposures short to avoid field rotation. Deal with all the other stuff later and just get the feel of what it's about.... The time you can go for depends on where in the sky you are pointing, but no more than 30 secs max, and 20 is more realistic. You can get good results, you just have to take lots of exposures and stack them, a minimum of 50.

What kit to get depends on your budget.

If you have £700-800 for a camera, Atik 16HR's are starting to appear in the S/H market, having been replaced by the 314L.They have the same chip, and there no important differences.

I use one and won't replace it until it (or I) expire

Cheers

Rob

[Astro Fan]

Thanks Rob - The 314L seems to be the way to go, if bought new you can get a half price electric filter wheel as well. The C9.25 is to heavy for me to keep mounting/dismounting on a wedge so I guess its alt/az + shortish exposures.

Thanks Again Guy

[brantuk]

Yeah - getting the 800 onto a wedge is about my limit so I can only imagine you'd need a helping hand with the 925.

The results I've seen from the Atik's are smashing and I know they're very popular, though I don't have personal experience using one.

[NickH]

Outstanding camera the 314L, stick an F6.3 reducer on the 9.25, and get it wedged up...you'll have a nice dual purpose imaging platform then (as at F10 it's a superb planetary scope and at 6.3 will give you enough "FOV" for more deep sky objects (and will be faster too)

get a very lightweight piggyback ST80 on it as a guider too..

[Space Bat]

Hi,

I have same scope and have had success using the F6.3 reducer /corrector with a Cannon DSLR up to 60 secs no noticeable trailing and have taken exposures to 2 minutes with good effect albeit with some trailing - however these can be processed with good software to remove evidence of trailing - and a little more can be done I am sure If I knew how to use this software properly.

But as others have said - the wedge is where I will need to go if I want to get the most our of the scope astrophotography wise.

Chris

[RobH]

The trick with Alt/Az imaging is where you are pointing.

If you are due north or south, you'll get rotation very quickly, due east or west, and at a fairly low altitude you can expose for a lot longer without it being an issue.

The 314L is a brilliant camera...the same chip as the 16HR but with setpoint cooling and USB2.

It would seem a bit of a shame to limit what you can do with it by not having a wedge though.

Cheers

Rob