Image of the day

Captured by
Shane Yarnall

LDN 1622

My Account

New to Astromart?

Register an account...

Need Help?

Autoguiding question

Started by fblue, 10/24/2007 01:20AM
Posted 10/24/2007 01:20AM | Edited 10/24/2007 04:12PM Opening Post
I have been reading some papers on autoguiding and have some questions for those that are doing it.
I have read today in a paper, that it is better to reduce signal to noise by reducing aggressive movement and making the minimum distance required for instigating a movement larger, rather than making the exposure rate longer. It was stated that by decreasing the time between movements and undershooting the correction and requiring a larger movement to begin a movement, will result in less chasing of conditions and less oscillation in the PE wave.
So, I am wondering what kind of setting you are using.
1) aggression (percentage ie 10 = 100 MaximDL or 100=100 PHD and others)
2) minimum distance ( .xx arc sec or .xx pixel)
3) actual rate in seconds for guiding ( 1.0 sec or 4.0 sec ect.)
4) PEC = on or off
5) DEC compensation on or off

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 10/24/2007 04:01AM #1
Floyd,
I am sure I am no standard... Here is what I do....
1. K3CCD Tools 30ms/arc sec (That's how it's set in K3CCDTools). BTW G11 is set at a guide rate of 0.5 siderial.
2. Min distance .6 - 1.0 RA, .8 - 1.2 Arc sec. Depending on seeing.
3. Rate for guiding (Correction rate?) depends on guide star 1.5 sec to 2.5 sec - exposure time is of course less.
4. PEC off (I have done PEC on did not see much difference but I may have judged too quickly)
5. DEC guiding on.


Jim Thommes

Mak-Newt 152 mm
C8
Megrez II APO
Zenithstar 66 mm APO
G11/Gemini
ST8300M
Artemis285 Camera
Canon 350D DSLR

http://jthommes.com/Astro/
Posted 10/24/2007 07:40AM | Edited 10/24/2007 08:05AM #2
Hi Floyd,

Interesting concept. It kind of matches my experience. I use an Sbig camera selfguided and a Tak NJP mount - no PEC but then the NJP has something like 3.5 arc sec PE which is amazingly good.

I use .1 min 1 sec max moves, .5X guiding speed, no backlash compensation, 1-2 second guide exposures if I can get a guide star bright enough, sometimes longer up to 5 seconds.

I just did a big write up of my know-how gained so far on this subject on another group. I can email it to you if you want.

The big 3 basics of autoguiding are:

1. Polar alignment
2. Balance
3. Focus

In that order of importance.

Other issues of which software settings to use are of less importance but good to know.

If the big 3 are done right autoguiding falls in your lap. If they are done poorly then
expect to spend a lot of time fiddling with everything to your general frustration!!

Cheers,

Greg.