Autoguiding help :/

Bendy777 (Australia) · #1 12-01-2013, 05:43 PM

Hi All,

Well! I'm very excited, I have bought my first scope (skywatcher ED80) and my first mount is coming tomorrow (Skywatcher HEQ5 GoTo Equatorial) and the camera I'll be using for imaging is a Canon Eos 600D, I've bought all the T-ring adapter stuff. Next on my list is a power supply and dew buster. Now that you know my gear, here is my question!

Can I use the GoTo system's tracking to act as a make shift autoguiding impliment? If so how long of an exposure can I get away with at the 600mm focal length of my OTA? I've heard that you wouldn't want to stay open for more than 20seconds..... another has said 2minutes... others say it depends on how good my polar aligning is... I'm so confused! thoughts? feedback? opinions? should I just try and master manual guiding? thanks

graham.hobart (Graham stevens) · #2 12-01-2013, 06:17 PM

Hello mate. If you are really accurately polar aligned and the scope/ camera etc is balanced and there is no wind, I still would say you will be limited to approx 30 sec max exposures. That will still give you lots of sky if you use free programmes like Deep Sky Stacker to stack your (preferably) RAW canon frames and stick to bright objects.
Eventually though the rotation of the images will nerf your nads, so most folks end up using a guide cam. Doesn't have to be expensive. And a lot of the guide software is free. Webcams can do it.
Of course you can polar align really well then manual guide. Then buddy, you can do anything with your rig!!
My first astro shots were on a fork mount (not an equatorial), of some planets and a comet. I was so inordinately pleased with them I have not looked back since.
Good luck matey!
Graham.

alistairsam · #3 12-01-2013, 06:19 PM

Hi
Congrats on the new scope and mount.
As far as I'm aware, you can't use the tracking as autoguiding. both are different.
you can however get good unguided exposures if your polar alignment is good. that is the first major requirement.
Before you start, I'd suggest marking your N/S using the solar noon method. you hang a string and at a specific time during noon, dependent on your location, the shadow cast by the string will be precisely n/s.
if you then position your tripod legs exactly perpendicular to this, you should be fairly close.
this is a good starting point. Else you can use a compass, calculate for magentic deviation for your site and position your tripod.
I find the solar noon method a lot more accurate.
your elevation on the mount needs to be as close as possible to your latitude. use a digital gauge on your counterweight bar as a start.
then do a two or three star alignment using your hand controller, and try 30 sec exposures. if your PA is off, you'll get field rotation or star trails quite soon. if it is good, then you should be able to get 30s to 1min exposures without trails. It depends on a number of things.
Also read up the articles in the "Projects and Articles" section on the left. that should give you enough information to start.
once you get the hang of things, you can look at adding autoguiding which will require either a seperate guide scope or an off-axis guider, and a guide camera.
Let us know how you go.
Cheers

alistairsam · #4 12-01-2013, 06:28 PM

These are good reading materials for polar alignment. Don't worry about drift alignment just yet if it sounds confusing.

http://www.iceinspace.com.au/63-498-0-0-1-0.html
http://www.iceinspace.com.au/63-466-0-0-1-0.html
http://www.iceinspace.com.au/63-405-0-0-1-0.html

My suggestion would be to get a rough polar alignment first, a two or three star alignment, then a 30sec exposure of M42 or eta carina to see how you go.
remember to align your finder to the main scope first.
you could either do it during the day by pointing at a far away object, or at a bright star. use an eyepiece and center a bright star, then look through your finder and adjust the finder till the star is in its centre.
this is useful if you keep your camera in the scope and need to do the 3 star alignment, where you can use your aligned finder to center and sync during the alignment process.

oh and don't follow the elevation scale on your mount to get to 37 or 38deg. they're usually off by a degree or two. use a digital angle gauge, or your phone's software.

Bendy777 (Australia) · #5 13-01-2013, 01:05 AM

wow! thanks so much guys! so much to think over and proccess! I really really appreciate it, what can be said for manual guiding? is it rediculously hard? the finder scope that came with my ed80 is less than appealing... not sure on the specs... it's just the kit one... I think the PA is the scariest part for me... and also lining the finder scope up perfectly with the OTA freaks me out too haha :/

alistairsam · #6 13-01-2013, 01:16 AM

Hi,
Don't worry too much about getting it accurate at the beginning. you'll get the hang of it.
Same with polar alignment. my suggestion would be to try and understand what you're doing when polar aligning, that is pointing the RA axis as close to the south celestial pole as possible.
try and understand the RA and Dec concepts if possible.
Use stellarium or any other software or planisphere to help identify what's where or to find objects.
Even the finder alignment is easy if you use bright objects like jupiter.
just get it tracking at sidereal once you have a target.

as for manual guiding, you'll basically have to stare through the finder and watch for the star drifting as your camera will be in the main scope.
If it drifts, you press the east or west button at 1x to get the star centered again. But I wouldn't even attempt it. not worth the trouble.

Eggmoon (Geoff) · #7 13-01-2013, 01:38 PM

I have had one go doing a polar alignment and refining it by doing "Drift Alignment", using a wedge on my LX90, and it didn't go too badly if I say so myself. Obviously, more practice is needed.

But I have been starting to look into auotguiding too, and and overwhelemed by the amount of information out there... off axis... guide scope... the differing cameras... ones that use PC's and stand alone... *sigh*

But, for now, just need to put some more time into getting my drift alignment sorted... that should keep me busy a while.

Bendy777 (Australia) · #8 13-01-2013, 01:46 PM

thanks so much man! really appreciate you sharing your wisdom!

Bendy777 (Australia) · #9 13-01-2013, 01:50 PM

Quote:

Originally Posted by Eggmoon

I have had one go doing a polar alignment and refining it by doing "Drift Alignment", using a wedge on my LX90, and it didn't go too badly if I say so myself. Obviously, more practice is needed.

But I have been starting to look into auotguiding too, and and overwhelemed by the amount of information out there... off axis... guide scope... the differing cameras... ones that use PC's and stand alone... *sigh*

But, for now, just need to put some more time into getting my drift alignment sorted... that should keep me busy a while.

yeah man! totally overwhelming hey! I would have just gone ahead and bought the orion mini 50mm autoguiding package for $399 but yeah... finances prevented direct action hahaha

Poita (Peter) · #10 23-01-2013, 01:35 PM

Manual guiding is a piece of cake, just tedious. You could use a cheap OAG if your finder is rubbish.

pluto (Hugh) · #11 23-01-2013, 02:36 PM

Hi Bendy,
I Also have a SW ED80 and a SW EQ5 GOTO. I use a 2x barlow and a 12mm illumintaed reticule to drift align and when I'm done I can reliably get 45-60 second exposures though I've had good 90 second exposures a couple of times.
An autoguider is basically a camera (and scope) that watches a star and corrects the movement of the mount if the star starts to drift.
I'm planning on getting an autoguider setup soon and I'm looking at this: http://www.bintel.com.au/Astrophotog...oductview.aspx
with something like this: https://www.astrofactors.com/planeta...der/qhy5v.html