8 replies to this topic

[harbaugh]

Looks like a break in the weather, so I am hopefully about 5 hours away from taking my first shot with the DSI Pro II.  I've watched the tutorial video at least 6 times, read the Meade "The Basics" a couple times, and also read OPT's Cookbook for Astrophotography.  Boy am I confused!  The video shows selecting a tracking star, the OPT version uses 2 stars (as in Drizzle), and the Meade manual doesn't use any.

I know enough to get set up and take exposures, but my biggest confusion is tracking.  I assume that once I get set up, aligned, and slewed to the object of my choice, that the telescope will be tracking in it's usual manner.  How do I get from that mode to having Envisage track?

When I connect the telescope to Envisage, does that automatically stop the scope's normal tracking? Does just drawing a tracking box start the tracking in Envisage, or do I have to click on a guide button?

I'm also confused about the function of the Auto Exp and Preview Buttons, or, more specifically, the "spin boxes" next to thoses buttons.  Which one is actually used to set the exposure duration?

Sorry to be so dense, but I find the documentation for all this stuff to be less than clear.

Thanks,

Bob

[Mark Sibole]

Bob,
The scope will still track as usuall.
When you select the star to guide on Envisage will only send minor commands to the scope to make small corrections for the star to stay in place.
If you are in ALT/AZ mode use 2 stars for the guiding as it will help eliminate some of the Field rotation.
If you are polar mounted on a wedge 1 star will do.
The auto exposure is just a reference so you really dont need to worry about it.
Depending on what you image you can go 3 seconds up to 60 minutes if your are aligned well.
This is where you will have to fine tune the mount if you are in polar mode.
Now for all of this to happen for guiding you need to be sure the scope is connected to your PC so the PC can send guide commands.
In Envisage select the telescope tab and add the com port number you are using EG. com 1,  com2 com3 then hit the connect button.
When this is done while using a 1 second exposure in the live mode look for a bright star and draw a box around it.When you have this hit the track here button and Envisage will calibrate the settings to it knows what way to make movements.
When the calibrate sequence is done the scope should automatically start to guide for you.

Now with all of this being said remember this procedure is if you have 2 imagers  one for imaging and 1 for tracking with a OAG or seperate guide scope.

If you have a single imager there is a different process.
If you need this process let me know.

Regards

Mark

[harbaugh]

Wow, that was quick.

Sorry, I have the simple setup, just one imager.

For the first session, I'll be in Alt-Az (besides the wedge isn't here yet).

I know that's not the greatest setup, but as least I can learn from it.

I've practiced all week and can get the scope connected and controllable in Envisage, so that's no problem.

Thanks,

Bob

[Mark Sibole]

Bob,
I try to keep up.
On your setup all you will need to do is box the 2 stars and the images will stack properly no matter the movement.
You dont have to connect to the scope.
Just select your 2 stars to help eliminate the field rotation and hit start.
Envisage will stack the images and align them for you.
That easy.

Regards

Mark

[swholden]

Mark,
You've been answering many of my questions that I too have asked.

I have a similar set up, just 1 imager.

So we won't "connect" to the scope in Envisage?

So the 2 stars that get selected are for stacking purposes only? And the scope will just continue to track as usual? Assuming you have a good scope alignment.

[wardenmsp]

I'm not a pro, so I may be in over my head here, but maybe I can share the results of my own confusion -

I've learned that there's a difference between selecting stars for stacking & derotation and selecting them for guiding.

In stacking, Envisage uses the selected stars to align frames that are taken with the camera, and the scope runs "open loop" - that is, tracking by itself, with accuracy determined by its motors and your initial alignment.

In guiding (which seems to be done typically with two cameras and a separate guide scope or an off-axis guider), the scope is part of a closed loop system and the guiding camera actually sends correction signals to the scope drive.

Do I have that right?

Bill Arden

[Mark Sibole]

You have it right Bill.

regards

Mark

[harbaugh]

Thanks Bill and Mark...this is finally starting to clear up.

So, for my simple setup (1 camera, 1 scope) I just forget about the guiding function in Envisage as the scope will guide itself?  I select two stars in Envisage just for stacking alignment.

Now I need to understand how this ties into the Image Process.  That is, when to select "Drizzle" and when to just select "Deep Sky."

Bob

[Mark Sibole]

Bob,
Just select deep sky for capture.
If you use drizzel for image capture it can take hours if not days to capture an image.
What drizzel does in capture is takes an image then moves over a few pixels and captures and stacks that image into the previous image.
This goes on untill it is complete.
To give you an example on a time frame I did a lunar image using drizzel using .0025 seconds and it took well over an hour to complete.
Imaging if you used 4 minute subs.
There isnt enough darkness for the image to complete.
Now in post processing you can use drizzel with no problems
I usually set the drizzel options something like this.
resolution 1.500 to 2.00 this gives you the total size of the image.
Extender view 1.00 or default.
Pixel fraction about 90 to 95.
If you go lower it makes the image vary grainy.

Regards

Mark