Yesterday was the first night out with my Telescope since the 23rd May! Image capture is with a Meade SN10 LXD 55 mount using a DSI II color camera and an ATik 0.5 focal reducer. Guiding is with a DSI color through a Bresser Skylux with a focal length of 700mm. Both cameras are connected through a powered USB2 hub and I finally managed to re-name the DS1 II so that it is easily identified on the image capture screen. The guiding camera was set to black and white and there were plenty of guide stars using a 3.5 second exposure time as I was imaging M56 in Lyra, and it's easy to find as it's only a short hop from Vega.  Connection to the scope went OK, got the message on the bottom Autostar version 42G can guide, I made a tracking box round a nice star and we went into some calibration routine, after a while a circle also with a reticle appeared and was almost on top of the square with the reticle so off I went to the image capture and the least movement that I have ever had in my images and quite nice round stars.  The mist then started to close in but before shutting down for the night I went back to look at how the tracking was going and found the square reticle box still locked on the guide star but the circle reticle a good distance away to the right.  What was the significance of this?  What have I done wrong and what can I do to correct this?  Your help as always much appreciated.  Dark clear skies to you all.  Fred

The circle marks the spot where Envisage is instructed to keep the guide star. The square marks the current location of the guide star and if it's centered over the guide star is means Envisage as locked onto the star (if the guide star is faint the software will occassionally lose the guide star in which case the square may not be centered over the star). If the square and circle are centered or nearly centered over each other Envisage is guiding properly. If not, the corrections Envisage is applying may not be keeping up with the tracking error and the guide star drifts away from the guiding point. You can try re-calibrating, increasing the gain, or moving the guide star back to the guiding point using the arrow buttons on the telescope control panel. I like to start with my gain fairly high (as high as 1) until Envisage settles in on the guide star, then reduce the gain quite a bit (from 0.25 to 0.5) to keep Envisage from over-controlling the telescope.

-John

 

Hey Fred,

I too had the same problem with the guide star drifting from the target area. A simple fix corrected my problem. I had to reverse the East/West arrow keys in my AutoStart 497 controller handset. Use the up/down and left/right arrow keys in Envisage to determine which set move the guide star back toward the target. I my case the east/west (right/left) arrow keys moved the guide star up and down on the screen (my guide star was drifting away from the target toward the top of the screen). Whichever set moves it in the direction you need to go, then that is what needs to be reversed in the Autostar handset. My experience was that, no matter the gain, I used, Envisage was sending the wrong directional commands to the mount and thus, driving the guide star away.

I have found that with my mount, 70-80 gain (depending on conditions) generally is sufficient to keep the guide star target centered. Also, I have found that with my LXD75 mount and the DSI Ic as a guide scope, that .70 of a sec usually will provide a good guiding routine. My mount struggles with anything over 2 secs for guiding purposes generating good pics with tight stars. I found that I could use shorter times if I optimized the focus of the star in the guide scope (using the same focal routine I use with My SN8, (I'm using a 900 mm Orion Guide scope and both have a stock focuser). Hope this helps.

Kaos

Hi Kaos,

Thanks for that it sounds spot on to me.  Off I go to find out how to reverse the keys.  Fred.

OK guys, How do I do it?  Have been searching the net for an hour now and can find no clues. Fred

OK, just shows how stupid I am when in a flap.  Powered up the mount, sure enough the left right buttons were reversed.  Went into the menu, Setup, Telescope, Reverse Left Right, and the Handbox and Laptop buttons now move the mount in the same direction   Fred.

Hi John, I got to 90 second subs last night but the seeing was very poor and the square and circle were not always on top of each other, you could sometimes see a gap between the cross hairs.  Is this normal.  Mind you I was in the area of M15 at 23:00 UK time and it was pretty low on the horizon.  Fred.

It's not unusual at all for the guide star to wander around a bit, so that's normal. I had mine out last night doing 60 second subs, something I've only briefly experimented with before. It worked like a charm. Saving all of my uncombined images as FITS and using median combine in Autostar Image Processing did a great job cleaning up the little bit of residual tracking error. Even the image stacked in real-time looked really nice.

-John