old scope for autoguiding?

[Lognic04]

Hi all,
I found an old refractor, and proceeded to attach it to a clamshell, make it take 1.25 inch eyepieces in hope that i can use it as a guidescope. My problem is, focus is tricky as there is no focuser, just pull and push (as i couldnt use the included focuser after the 1.25 change) , the focal length is 700mm, and my big scope is 1000mm. So far i only have a webcam (logitech c170), how good would that be for guiding? or not bother for now? pic attached (scope is mounted on a dob box while waiting for an eq6 to pop up)
:thanx:

[billdan]

Hi Logan,

You would have to remove the lens from the webcam before you install it onto the refractor.
Then hope it is sensitive enough to pick up stars that can be guided on.

As the webcam does not have a guide port (ST4), you will have to find an ASCOM driver for it and use pulse guiding to the EQ6 (you will need the ASCOM driver for the EQ6 as well).

Personally I don't think the webcam will work, webcams operate at 15 -25 frames per second, whereas guide cams we use 1 to 3 secs per frame to beat the seeing. You may have to save up for a cheap guide cam like a ZWO or QHY.

Cheers
Bill

[jenchris]

I've used a cheap webcam on an old scope.
Works fine.
Remove the lens and fix a nose.
I've even got a 640x480 webcam someone gave me that does the job in phd2
Just a matter of getting a decent focus.

[AndrewJ]

Then look at using something like Metaguide.
It is designed to use high framerate video with internal stacking to get around seeing and dim stars. Works well with crappy webcams, as well as higher class units, even with small aperture guide scopes.

Andrew

[Lognic04]

Hi all,
just letting you know that i have already modified etc the webcam, and phd2 can tell the webcam to do long exposures up to 15 seconds.

[Lognic04]

and shouldnt phd output directly to the mount via a serial cable connected to pc?

[AndrewJ]

Gday Logan
PHD can output pulseguide data via USB to serial to the mounts rs232 port if it has a valid driver inbetween ( normally an ASCOM driver )
PHD can also output low level ST4 commands directly to the mounts ST4 port if you have a suitable USB to ST4 converter/cable. In the latter, no ASCOM driver is required for guiding, but you only get guiding.
Andrew

Andrew

[Lognic04]

Hi andrew,
My old laptop already has a serial port, infact almost all of the old format ports (serial,dial up line etc)

[AndrewJ]

Gday Logan
If you already have a serial port, you can use that with the correct ASCOM driver to allow full mount control, incl pulseguiding.
I cant remember ever seeing a true COMPort/rs232 to ST4 adapter,
but there are some parallel port to ST4 cables if you have an LPT port
( my lappie has one :-) )
These allow ST4 guiding via the LPT port and leave the com port free.

Andrew

[Lognic04]

so using direct serial is the same or not as st4?

[Lognic04]

or can you use direct st4 pc to mount for autoguiding?

[AndrewJ]

Gday Logan

Direct serial commands to the handbox are totally different to ST4.

Not sure what you mean here????
When using serial pulseguides, the PHD talks to the handbox rs232 port via the PC serial port and sends proprietary commands to start moving and stop moving. This requires an ASCOM driver inbetween.
The ST4 port on the mount uses simple switches, that when closed, start a guide operation. ( ie no ASCOM required )
The PC needs a way to select these switches properly, and hence needs a specialised USB or parallel to ST4 cable
Things like the LPT converter supplied by shoestring astronomy
http://www.store.shoestringastronomy.com/User_Manual_GPINT_PT.pdf
or the USB converter
http://www.store.shoestringastronomy.com/User_Manual_GPUSB.pdf
allow this to happen, but it can only guide, it has no other functions.

Andrew