Celeston Tracking with 5x Barlow

[zakkhogan]

Good Morning SGL

I have been imaging the planets with my celsetron 102gt, but have always had a slight issue with drifting.

I have now upgraded from a 2.5x barlow to a 5x, and obviously the drifting has now become a problem.

Is there any way of reducing the drifting? I have never played with the Tracking Rates (Sidereal, Solar and Lunar) and I always use 3 star alignment (normally 2 stars and a planet)

I have also never looked at Tracking Modes (Alt-Az, EQ North & EQ South)

The scope is on a single arm fork mount,

Full spec here

http://www.celestron.com/astronomy/telescopes/nexstar-102-gt-computerized-telescope.html

Many thanks in advanced

Craig

[Capricorn]

Simple answer: You have a focal length of 1000mm, you are putting a 5x barlow on it so acting as if 5000mm, the mount is an Alt/Az.

You are going to get drift.

Cannot think of anything that will track as accurate as you need with the set up you are trying.

How well is the scope actually set up?

Have you an accurate bubble level for the mount?

How accurate is the initial position set?

Ask this as during the alignment the scope is calculating the errors that it needs to apply. If you minimise these errors then the scope will track better as its start position is closer to the ideal and less compensation needs to be applied.

Please consider that the computer is not a i3 core with 4Gb of memory, it is a very, very simple and basic processor with close to no memory.

Is there a method of calibrating the tracking?

If so have you done it?

[zakkhogan]

Thanks,

The tri-pod has a bubble level on one leg, is this enough? should i use a spirit level on all 3 legs for a better set up ?

"How accurate is the initial position set?" not sure what you mean, i intend (next time im out) to do the 3 star alignment using the 5x barlow and get all 3 objects centered that way

i also wouldnt know how to calibrate the tracking ;(

Thanks

Criag

[sgazer]

I have an SLT mount which is similar. The initial position doesn't matter, but being level does. Just get the bubble as close to the centre as possible. 2 star or 3 any star alignment makes no difference. It only aligns on 2 stars, either specific stars or any stars, the 3rd just being used to work out what stars they are, but it's still only aligned to 2. Tracking is more accurate if you align to stars near to your observed object, so select Saturn or whatever as one of the alignment stars and something else closeby, 2 star alginment is easy, you just need to rember the name and position of 1 bright star near your planet. Any star alignment is more likely to fall over and you have to find more bright stars.

There's pretty much no way these mounts will track accurately at 5000mm focal length, in fact even an expensive EQ mount wouldn't, which is why people have to use guiding. Plus your scope is quite heavy for the mount and really pushing its weight limit. When I was imaging the sun at 600mm, I had to correct it every 30mins or so.

If you get it in the FOV for 30s at 5000mm f/l, then it's doing well.