how accurate do i need to be

[rowan46]

I am one of those poor unfortunate people who have almost no view in the back garden and no front garden to speak of consequently I have to travel to see the sky. I have a nexstar5 with a wedge tripod, power tank, laptop, neximage camera, gps and a compass. My question is how accurate does my north alignment have to be to get any imaging done. I can't seem to get drift alignment or is it okay to just point it roughly north (polaris or magnetic) and let the electronics sort it. thanks

[michaelmorris]

It depends what type of imaging you want to do. If it's planetary imaging, then all you need to do is make sure the target stays on the chip. Your image will be better if the tracking is bang on, but polar alignment tends to be a (relatively) minor issue with planetary imaging (with your neximage camera). For deep sky imaging, unless your doing really wide field stuff) having a good polar alignment is absolutely essential.

[astromerlin]

Imaging does require accurate alignment, When I first started imaging about a year ago I started with Saturn as it was high in the sky at that time. I found that I was constantly adjusting to keep it centered. Where I need to setup I cant actually see Polaris through the polar scope so I roughly set the tripod to somewhere near the right direction I then tried to do the drift method by focusing on a star midway between zenith and the horizon.

The one thing I learned which helps out alot to getting it right is to turn the imaging cam in the EP holder so that when you move the telescope up or down the image on the screen moves in the same direction, the same for east and west.

If the star drifts up or down an adjustment is needed in altitude, if the star moves east or west then an adjustment is needed in azmuith. Eventually by trial and lots of error I managed to get it pretty spot on after a few minutes.

I hope I've explained this correctly, i'm sure someone will help clarify.

I'm not sure if this trick might help as i'm not sure what a wedge tripod looks like but if you favourate viewing spot is on grass or soft ground, once I got my tripod aligned correctly I obtained 3 short pieces of 2" stainless tubing about 3" long and once I'd finished my imaging session I hammered the pieces of tubing into the ground so that they were flush with the soil. This enables me to set the tripod in the same spot every time.

Maybe a bit OTT if not in your own garden but perhaps some less permanent way of marking the ground to make your setup easier the next time you setup.