off axis guiding

[AlexN]

too true there. With the lumicon i had to use a parfocalising ring to hold focus, and never really had sharp focus on the guider. It was pretty damn close, but never focused.. That said, guider focus isn't of all that much importance.. Although being able to get it close easily with a focuser would have been nice.

[Hagar (Doug)]

Originally Posted by monoxide

stop tempting me with self guiding ccd's!!

seriously tho if i had a choice between upgrading to a G11 and keeping my current imaging gear or sticking with the HEQ5 and spending the same amount on a new camera id definately take the camera.

back on topic though i think ill check out the orion OAG, its less cash to outay, looks a bit more user friendly and if i dont really like it then its not a big loss.

I have been sitting watching this thread with interest since it began.
On topic, I have had a lumicon OAG and found i to be a real pain in the backside to use. A small guide scope is my choice when it comes to guiding.
Off Topic but in reply to the above quote, The most usefull item of any astrophotography set up is the mount. To forego a good mount for a camera is a sure fire recipe for disaster. The HEQ5 while a reasonable mount is really not up to the specs required for imaging with anything bigger than an ED80 and a light weight DSLR.

The other term which seems to be bandied about is the word real estate with regards to CCD imaging. The realestate spoken about must be taken in context of the imaging system used. It must be realised that every camera smaller than a full frame CCD suffers from a crop factor, the smaller the CCD the larger the crop factor and the narrower the apparent field of view you can image. In todays CCD market the ST10 has a quite small CCD and when used with long focal length scopes produces quite a narrow field of view.
When trying to image nebulas this can be quite restrictive even with some quite short focal length scopes.
I understand the QE of the ST10 to be brilliant but QE isn't everything extended exposure can and does help to pad out somewhat lower QE.

Just something to think about when looking at cameras, mounts and imaging systems in general. Nothing is clear cut and easy. Spend the time before spending the money.

[Merlin66 (Ken)]

The only difference between the self-guiding CCD camera and the OAG solution is that the camera has a built in OAG guide chip ( Usually the TC-211, the same as the original ST-4 guider.. large pixel size but quite sensitive)
The OAG, yes does take a little more work to focus, but no more than a guide scope... and when it's set up you can get as big if not bigger FOV to guide on, the choice of guide cameras (QHY5, DMK, Atik etc) and the flexibility of positioning the guide chip to suit the field. Some OAG allow you to pick off the guide star prior to the filters so there's no significant light loss to the guide star.
Even if you have solid guide rings and support, you still have focuser "droop" to contend with; at least the OAG gives you some hope...
My 2c.

[coldspace]

Originally Posted by Hagar

I have been sitting watching this thread with interest since it began.
On topic, I have had a lumicon OAG and found i to be a real pain in the backside to use. A small guide scope is my choice when it comes to guiding.
Off Topic but in reply to the above quote, The most usefull item of any astrophotography set up is the mount. To forego a good mount for a camera is a sure fire recipe for disaster. The HEQ5 while a reasonable mount is really not up to the specs required for imaging with anything bigger than an ED80 and a light weight DSLR.

The other term which seems to be bandied about is the word real estate with regards to CCD imaging. The realestate spoken about must be taken in context of the imaging system used. It must be realised that every camera smaller than a full frame CCD suffers from a crop factor, the smaller the CCD the larger the crop factor and the narrower the apparent field of view you can image. In todays CCD market the ST10 has a quite small CCD and when used with long focal length scopes produces quite a narrow field of view.
When trying to image nebulas this can be quite restrictive even with some quite short focal length scopes.
I understand the QE of the ST10 to be brilliant but QE isn't everything extended exposure can and does help to pad out somewhat lower QE.

Just something to think about when looking at cameras, mounts and imaging systems in general. Nothing is clear cut and easy. Spend the time before spending the money.

I am spending the time ATM to do lots of research on what I will end up buying next year to add to my observatory kit. This is why forums are my friend on doing research not just in my addiction in Astro stuf but my many other interests.
I am not really interested in doing large field imaging ATM as my intrest is in imaging small faint fuzzies so will need high QE and if I want to do pretty pictures then I will most likely need to use Narrow band anyway so high QE is good here.
The self guiding chip seems appealing to me ATM as its a one camera/scope system, I could then use a something like a light weight piggy backed 90mm Raptor for wider field imaging if I wished to get into it by just pulling the camera out of the 12R and plugging it into the piggybacked refractor. The AO system sounds really good as well and would suit this camera especially on a wedge mounted 12R to help a little to "sharpen up the images" from minor mount errors. Compared to what I am used to the ST10 has acres and acres of real estate.
My images that I get now are so bad I would not even bother posting them but I don't care as I like them and been not very "Tech" savy on this sort of stuff makes my learning curve so much harder but I usually always buy the right thing that suits me after lots and lots of research both on Astro toys and other things as well.
I agree, that the mount is everything, but for now my 12R suits me fine and in a couple of years maybe sell it and put a 14R on a AP1200 mount like a friend of mine uses which is so sweet.
I will be looking at all options for my next camera with all accessories under 10K and will probally buy in about 4 to 6 months after my homework has finished.
So be prepared IIS members for lots of questions coming up on user feed back on various cameras over the next several months.
Thanks Doug for your feed back ,I have taken it on with interest mate. This is exactly why I like forums when doing research, feedback from both sides of the fence.
I don't just like hearing all one side as another opinion helps you make an informed opinion before spending big bucks on toys or whatever you do in life.
Thanks again.

Regards Matt.

[Hagar (Doug)]

Matt, The post was not meant as any form of attack or similar, it was just some explanation of a few things often overlooked by many imagers when they are shopping for expensive equipment which has to do a wide variety of work in many diferent aspects of astrophotography.
Perhaps I better shut up. Lots of experts out there, just filter them well.

[coldspace]

Originally Posted by Hagar

Matt, The post was not meant as any form of attack or similar, it was just some explanation of a few things often overlooked by many imagers when they are shopping for expensive equipment which has to do a wide variety of work in many diferent aspects of astrophotography.
Perhaps I better shut up. Lots of experts out there, just filter them well.

No offence taken Doug, I appreciate the feedback and was just trying to explain my needs but sometimes I rant a bit as its hard to explain thing via a key board.
Other than a guide chip camera which as I understand only S big has what other options would you recommend?
I have seen the Starlight express cameras in action and they work well.

Regards Matt.

[Hagar (Doug)]

S Big are the only manufacturer with on board guide chips. I believe they have patented the feature. The on board chip does have it's drawbacks when you mention NB imaging. The fact that the guide chip is mounted behind the NB filters it can make it near impossible to attain a good guide star. The only way to overcome this is to either use a separate guidescope, camera or an OAG. QSI make cameras these days with quite a selection of cameras with a built in OAG or SBIG do sell a separate guide camera to use external to their cameras. This again requires something to guide image with. Other alternatives exist with cameras like the QHY range, FLI, Apogee. The list is endless and so is the selection of CCD's and cooling systems etc.
It really all depends on what scope, eg fl and the type of imaging you intend to do. Quality comes at a cost but some costs can be quite inflated.
Lots of questions to ask yourself:
What do I want to image?
What scope will I be using?
Do I want a OSC or Mono with filters?
Do I need a separate guide scope/OAG?
What sort of field of view do I want?
How much do I want to spend?

Good luck with your search.

[Merlin66 (Ken)]

Re the question of self guiding Starlight cameras.
I've had a MX7c with the STAR 2000 guide interface for almost 4 years and to be honest I couldn't get the STAR2000 to work for me... well to be fair - didn't try too hard!
In the UK, there are many imagers who still use the STAR 2000 and say it's the best thing since Vegimite ( well in their case Marmite)
The Y! AstroArt group is the best place to get information.
I use the MX7c on the spectroscope with a QHY5 as the guider.

[Bassnut (Fred)]

I have tried external guide, self guide, OAGing and Ao at long FLs.

Each of these have advantages and show stoping disadvantages.

External guide is by far the most convienient and worth pursuing to the nth degree before before even thinking about the rest IMO. But the longer the FL, say over 2m the more you are forced to consider alternatives, but the much harder they get to use.

External guide allows composition of the target anyway you want, and you always get a guide star, point and go, but flexure just gets too much of a problem with exposures over 20min at over 2m FL.

SBIG internal guide is essentially impossible through NB filters unless you have a very stable mount with very low PE (eg a PME) that can get away with guide exposures of say 30secs or more, even RGB is difficult. And finding a bright guide star can be a very frustrating excerise, making composition tricky too.

Forget AO with internal guide unless useing just a lum filter (or none). AO is generally only of value if guide exposures can be 2 secs or less, otherwise there is no advantage over normal mount correction.

With internal and OAGing, manually rotating to find a bright guide star at long FLs is a painfull excercise, very hit and miss, and you have to wait till the rig settles down after bumping it, although as Alex mentions with OAG, widefield is less of a problem and a guide star maybe available without much or any rotation.

For OAG, I decided to use an autorotator for guide star searching, and that makes a huge difference, I can nudge and expose in quick succession with no disturbance.

I tried the rotator/TCFs focuser/MOAG/AO8/filter/ST10 on a 12" LX and found a showstoping problem I didnt think was going to be that bad untill I tried it. The image train is 350mm, the LX can focus, but stars are huge blobs . I dont know why yet, but I cant see anyway to make this work unless I make the train shorter. Perhaps removing the AO8 will help, but the focuser and OAGer(MOAG) are the longest items (and many adaptors), I cant get rid of them, that would defeat OAG. The rotator cant go iether IMO.

So if anyone is considering OAG on a SCT, youd need to be very sure the back focus distance can take it. Just the OAG, filter and cam would be OK, but at long FLs, not haveing a autofocuser and autorotator would be a pain in the butt IMO.

I fitted all the above to an RCOS (minus the focuser), shaved .2" off an adaptor, and it just perfectly hits BFD, no spacers, shear luck . It all works very well, each item making the whole worth while.