ST-4 Autoguider

Hi Guys, I bought an ST-4 a bit ago. Never used it and honestly don't know how. I was wondering what the difference is between an auto guider and an imager? Does an auto guider take images or is just for guiding a scope while an image is being taken by another camera? Thanks, Joe

Hi Joe, The ST4 was (and IS) an absolutely WONDERFUL auto-guider. Requires no PC, completely self-contained. But to adapt it to your guide scope (or off-axis as I did) requires a little practice and know-how: The CCD chip is TINY by today's standards, so you need to pre-select your guide star with either a surrogate parfocal eyepiece or equivalent flip-mirror. And when you insert the guide head need to (roughly) clock it to the RA/DEC directions. The beauty is the "calibrate" set up. You just hit that (per directions) and it will calibrate itself, sensing the directions and magnitudes of +/- Dec and +/- RA. It will say it's happy and you then just hit "track" and it locks onto your guide star like a bulldog. You also need to know some basic electronics: The ouptputs are DPDT solenoids and I think NO/NC contacts which you wire up depending on how your scope is set up. I amended a cheap Edmunds geared-down 12V reversible DC motor to my homebuilt DEC tangent arm and a commercial frequency controller to my RA (Byers 11 3/8). After some fiddling - it was tracking my 650-lb newtonian flawlessly for many thousands of hours of use at 2000mm EFL. All that said - you of course need a decent mount with good, smooth, reliable drives and decent polar alignment. I consequently collected hundreds of multi-hour exposures on film (yeah-way back then) with sub arc-sec tracking better than I could do "by hand" and I was in bed sleeping! All that said, i believe there are mounts and "idiot-proof" plug 'n play guiders today that would be WAY easier to use but maybe quite pricey once you get everything you would need. I'm old-fashioned (and now just plain OLD) so still prefer to build my own stuff and understand how and why it all works...or doesn't. I recently got a fine 36-inch PM that will fit in my dome!...ALL I need do is build the scope - Yikes! It will replace my very nice little 29-incher... The ST-4 can indeed collect images...but was never really meant for that because the chip is miniscule. Tom Dey

Hi Joe,

I have an ST-4 and still use it as an autoguider with my DSLR. As others have said, the chip is quite small, but it does work great.

You can use the ST-4 for imaging, I started my CCD imaging this way. But there are 2 problems. Firstly is the small chip. This means it works best on small objects such as galaxies. The second is that it is only an 8-bit chip, and so will not show as much as more modern and more sensitive chips.

When using the ST-4 as an imager, you will need to connect it to a computer. you will also need software to control it. SBIG does have software as a free download for the ST-4 on their website. You can use either the dedicated ST-4 software (although this is DOS!!) or I think that CCDOps is available as a free download.

One warning though.... once you start CCD imaging, you will quickly become hooked and want bigger and better CCD's!!!

Hope this helps.

Maurice