Guiding; will it work on a smaller Eq mount?

[nightvision]

I am new to imaging; I was thinking of building a cheap guided setup. Will a guider work on a smaller Eq mount? I was thinking of getting a motorised Eq3-2 and using a guider with laptop software.

I have a SW F9 100ED scope and would put a SW ST80 on top for the guide camera.

Would this arrangement work OK for short DSLR exposures? I realise it wouldn't be as stable as a Eq5 or Eq6 but would it work for sub 1 minutes exposures on a windless night?

Thanks, Tony.

[steppenwolf]

It will work but the limitation here could be backlash and containing it - how much backlash is there on your mount and drive? The standard RA motor for the EQ3-2 is a little 'clunky' but by modifying the hand controller by soldering parallel cables onto the key pads and using an external relay box (semiconductor or actual relays) you could certainly do it.

I made a mod like this to my original non-GoTo EQ6 and it certainly made a worthwhile improvement. Details on how I did it can be found on my website here. Exactly the same principles would apply to your EQ3-2.

[nightvision]

Thanks for that Steve, I am just starting to read your brilliant book and skim reading the part on modifing the hand controller. I only have an old meade (4504-Starfinder-Autostar) goto tracking Eq mount that I know isn't suitable, I use it with my 300D only.

I can get a EQ3-2 for a good price and then thought of the hand controller with mod and then if feasible adding a guide-camera.

I am OK with electronics so no challenges there.

Tony.

[samtheeagle]

I got perfectly good results from my dual drive eq3-2 mount and homebrew autoguider, and that was with just a 50mm finder scope. My first ever test of this particular setup was a 300 second capture in the vicinity of Vega, I've still got the image as it brings back happy memories (I should get out more). This was taken with a 150PL scope on the eq3-2, so a good sized bit of kit... I'd be slightly concerned about having two full sized scopes on the eq3-2, the less load you put on it the better, hence why I used, and still use a 50mm finder.

[nightvision]

Hi Sam, you built own autoguider system?

It seems to have tracked/guided really well for such a long exposure.

What does the set-up consist of?

'just a 50mm finder scope' Do you mean you have a guide camera on the finder?

Tony.

[samtheeagle]

Yep, I have a Meade DSI affixed to a 50mm finderscope. If you search the forums for "Finder Guider" you should find quite a few posts on the subject, I'm not the only one using this technique.

The autoguider system is a simple switching mechanism, using an optoisolator, which connects to the hand controller mod you mention above to the computer. The hardware is very simple, the ASCOM driver was a bit more work See here:

http://stargazerslounge.com/diy-astronomer/105214-arduinoastrocontrol-homebrew-autoguider-mkii.html

Basically it's my own implementation of the commercial GP-USB product.

[nightvision]

Thanks for the info, I will look into it, it now seems feasible to do some basic astro imaging without triggering a divorce!

I took some shots the other night (full moon) just using the 300d and cheap goto mount, only have the 18-55 it came with, I was surprised how well DSS and PS4 pulled out Ursa Major and other stars despite bad LP and moonlight. Just the beginning I think.

[samtheeagle]

Yeah, there's no reason why you have to spend a fortune, not at first... Of course you will eventually end up spending loads, it seems to be the way this hobby goes! But in all seriousness, you can get very good results with modest quiptment. It might take a bit more effort here and there, but the important thing is to learn good technique, whatever kit you're using. Then in time you can upgrade a bit here and there, and before you know it you're broke!