CCD's *With Built in Autoguiders*

[jamesFSO]

Hi all,

Does anyone know what is a good starter CCD that has a dual chip for autoguiding ?

Can't seem to find any good review on the tinternet for these, as most people seem to use 2 telescopes and 2 Cameras.

I can't do that setup, so im looking for a slightly more convienent setup.

Thanks !

JJ

[Ben Ritchie]

SBIG hold the patent on self-guiding, so only their CCDs have it.

The entry level one is the ST-2000XM/XCM (mono or one-shot colour), a ST-7XME can be had for less money but the CCD's pretty small and it's a battle to frame the target while putting a suitable guidestar on the autoguiding chip, especially if your mount needs rapid guide corrections.

[Milamber]

There's always STAR2000 from Starlight Express I suppose?

Arthur

PS - that's Simultaneous Track And Record I believe - using a single chip to do both guiding and imaging...

[centroid]

There's always STAR2000 from Starlight Express I suppose

It does work quite well. I used it quite successfully with an MX7C for some time.

It does of course doble the time taken to capture an image, but as its guiding, its no 'big deal'.

Dave

[ngc2403]

What kind of setup do you have?

i use the old ST7 for a while on a 16'' LX200. OMG never again, tiny Field of view and we never got the guiding to work. am told it's possible but hm mm it was a challenge to get the guide CCD on a star that was bright enough even in the 16''!!!!

What about off axis guiding?

that can be very good i hear but i don't know that many people who do it. there are some problems but i think i might be easier than self guiding.

ally

[jamesFSO]

My setup would either be my ED80Pro or my C9.25, but more likely the Skywatcher on my EQ6Pro mount.

I can get about a min approx with a rough/good alignment, but as you know you can do little with such a small amount of time.

Im very much a lunar imager, but it would be nice to play when we have clear skies and no/low moon.

JJ

[Milamber]

Hmm. First thing is to get a focal reducer to play with since that will effectively increase your available exposure times.

Arthur

[ngc2403]

yeah arthur is correct,

but why can't you mount the ED80 on top of the SCT as a guide scope?

[Ben Ritchie]

i use the old ST7 for a while on a 16'' LX200. OMG never again

OMG indeed, I had a hard enough time with a telescope with a quarter of the focal length!

What about off axis guiding?

that can be very good i hear but i don't know that many people who do it. there are some problems but i think i might be easier than self guiding.

At its best, self-guiding is superb - with one-shot colour and a reasonable size of CCD it's a doddle (the two go together in reality, as the ST-2000XCM is the smallest OSC CCD that SBIG do). Self-guiding through filters is harder work, especially if you need to do short guide exposures because of the mount's PE, self-guiding through an H-alpha filter takes a very high level mount indeed. With the bigger monochrome CCDs you have some flexibility in guide star choice without causing too many problems with framing, but the ST-7 was/is a pain to use...

I've also found OAGs to be fairly painful, I'm not sure i'd call it easier than self-guiding, just different. If you have a reasonable mount and anything other than a ST-7 then i'd say that (non-H-alpha) self-guiding is considerably easier.

[ngc2403]

yeah the FOV with the ST-7, ~ 9' by 6' and the guider ~2' by 1' and that was with the f/6.3 reducer!

i shudder at the thought.

I know someone else with one of those lovely Starfire telescopes and an AP 900GTO, but he is mad.

i agree that the self guide is good if you do single shot colour but narrow band imaging is tricky.

one other point about the sbig self guiding is that while it downloads the image is closes the shutter so guiding stops while the image is downloading

[ribuck]

James, i'm busy going through the learning curve of guiding as we speak and here's the advice i can give you from what i've found so far, and i can tell you it's a steep learning curve.

1) Imaging & guiding is a steep learning curve so be prepared for lots of frustration. You have to have patience, but the results will be well worth it.

2) There is no single right solution, as it all depends on your OTA and mount. E.g. if you have a newtonian then you can forget Off-Axis guiders and Focal reducers as you will never be able to bring them to focus. I know this from experience.

3) To get decent images you also have to match up the pixel size of the camera to your OTA.

3) What type of mount do you have, fork or equtorial ? if you have a fork mount then you'll need a wedge and they aren't cheap.

4) What is your budget ? I picked up a usb1.1 Starlight Xpress MX916 with the star 2000 interface for £375 second hand. This is a very good starter camera as it has very high sensativity due to it's larger pixel's which means that it's easier to guide through filters.

5) Do you want to use a single shot colour ccd or a mono with filters. Mono with filter produces a lot more detail due to being able to do a seperate luminance image. Again filters & filter wheel aren't cheap and add to the cost.

6) What software do you want to use for imaging ?

You need to think about all these factors before making the plunge. your cheapest option would be something like a single shot colour Starlight Xpress Mx7c which supports star 2000. if you shop around you can pick these up for about £250 with the star interface.

[jamesFSO]

ok, my setup is a grab and go ... it is not permanetly set up, so mounting / dismounting of 2 scopes would take time and I would need to buy rings, get a good balance etc, etc all of which is just too time cosuming when all I want to do is have fun with my scope and imaging (for the time being).

So the thought of a CCD that has a dual chip while more expensive would allow me to keep the fun in the hobby. I would

imaging that SBIG would be alot easier to use instead of autoguiders etc, etc (otherwise what is the point ?). Money isn't really a problem as long as it works well.

I do have a focal reducer. My setup is a EQ6Pro Mount with either a C.925 or a Skywatcher ED80Pro.

Im not expecting amazing results just really to do some long(ish) exposures while the Moon isn't around.

I've seen some SBIG's on Astro Buy and Sell for approx £1700, which sounds responsable.

Does anyone know anyone I can talk to about dual chip experience just to get an idea on how easy they are to setup and use ??

Thanks for your help so far

JJ

[Ben Ritchie]

Does anyone know anyone I can talk to about dual chip experience just to get an idea on how easy they are to setup and use ??

Me

[ribuck]

James,

If you can afford that sort of money then definately go with a Sbig ST-2000 or better. Sbig are pretty much the only dual chip sollution. If you want ease of use stick with a colour version.

Man i wish i has £1700 to spend on a ccd...........sigh......

Rich.

[ngc2403]

ok,

i can understand the easy of use is a big thing for you and that the self guide CCD is the best opinion however, as Ben may tell you it is not plain sailing all the time and the bigger and more expensive the CCD the easier it gets.

Alot of people think that the two scope set up is better and just think, this is the reason why SBIG have the STV which is the new ST4, which really was the first proper guide camera and what all standard guide ports are based on.

You could also ask Gordon; mackeyphotography.co.uk he used a single shot colour SBIG CCD for a long while

all the best with the set up

ally

[Ben Ritchie]

as Ben may tell you it is not plain sailing all the time

Indeed.

Assuming that the EQ6 behaves similarly to the HEQ5, i.e. it requires relatively rapid guide corrections and therefore precludes guide exposures of more than a couple of seconds, then I think I suspect that you would be disappointed in the performance of a monochrome self-guiding CCD, finding a guide star that can be imaged with 1..2s exposures through a coloured filter will require some effort.

A one-shot colour CCD would be very convenient though, and with the 80ED there would almost always be a suitable guide star in the field of view without having to go searching. The C9.25 would be harder, mainly due to the long focal length (=small field of view for the guide ccd) and the possibility of off-axis curvature.