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Old 04-04-2009, 01:42 PM
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DSI II Pro - can you guide and image at the same time?

Title says it all I guess. To date I have only used my 30D SLR for imaging and the DSI II Pro for guiding (PHD). Thinking of putting the DSI on the ED80 and imaging with it sometimes, but got to thinking about how I'd guide while doing that.
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Old 04-04-2009, 02:22 PM
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Troy,

I might be wrong but I'd guess the only way this would work is if your guide exposure was the same as your imaging exposure. Also not sure how you make the camera available to two apps at the same time? You can use Meade's track and accumulate function in Envisage to stack on the fly but this is not guiding. What about using your toucam to guide and image with the DSI?
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Old 04-04-2009, 04:31 PM
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I'm sure I've seen CCD cams with what was referred to as "guide chips" or something. I assume it's a second chip and the cam can multitask or something. Pretty sure mine doesn't have that, but thought I'd ask anyway.

I've loaned my toucam to Dave (dpastern) so he can do some guiding while he gets some funds together.
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Old 04-04-2009, 04:41 PM
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Bassnut (Fred)
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nope, you need a seperate guide cam/scope, unless you get a OAG, but you still need still need a seperate guide cam.
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  #5  
Old 04-04-2009, 11:12 PM
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Ok, thanks Fred.
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Old 05-04-2009, 07:15 AM
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CoolhandJo (Paul)
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Fred is correct. I suggest maybe getting yourself a cheap DSI-c. you can pick them up on other forums here, or Ebay from say $100 to $300 depending. Possibly the cheapest way for you to have an alternate guideing system anyway.
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Old 05-04-2009, 07:40 AM
Karls48 (Karl)
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Actually – you can. It works –sometimes but only with some Meade mounts. This picture of Moon was taken with DSI Pro and ETX 105. Auto guiding on small white crater and doing “Drizzle”. Whole exposure took about two and half hour because Envisage was rejecting most of incoming data.
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  #8  
Old 05-04-2009, 11:20 AM
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yes you can, although Ive never done it myself. There is software out there what will fool envisage into thinking it is talking to a meade mount and will translate the lx200 comands into something that your an eq mount can understand.

http://www.skyinsight.com/wiki/index...tware_Emulator

I started looking into this myself last week, i have the same mount as you do and from what I've read it can be done.

http://www.ezystyles.com.au/autoguide.html

I think ezystyles is a member here and he seems to have everything working I'm sure if you pm'd him he could help.

Sandy
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Old 05-04-2009, 12:28 PM
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Thanks! Will look into it.
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Old 06-04-2009, 04:16 PM
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Troy,

This is off the Autostarsuite site it may help you
look here http://autostarsuite.net/forums/post/15783.aspx second last paragraph, Matt Taylor says:

"
To answer your question, the simple answer is no you can't use a single camera to image and guide at the same time. The not so simple answer is that yes the software will allow you to do it but your mount will only get a guide command between exposures, so for this to work the target will need to be bright and the exposure time will need to be very short, which makes it impracticle for DSO imaging."

let us know if you suceed as I'm looking to do the same

Geoff
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Old 06-04-2009, 04:30 PM
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I see. Thanks Geoff. If that's the case, it's all looking a bit too impractical and I'd just be better off using the Toucam I've loaned a mate for guiding and the DSI for imaging.
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Old 09-04-2009, 12:33 PM
celstark (Craig)
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I hate to burst the bubble here, but the answer is no, you cannot. A few bits of info on this:

1) When you read off a CCD you dump the charge that has built up in the "wells". It's only when dumped that it goes into the ADC and you can read it off. Pretend you have one measuring cup and you want to know how much water is in some buckets (and you can't just look at the level in them). Dump and measure... But, the charge is gone and you must start over anew.

2) What you can do is guide between frames. So, see the drift starting to happen, figure the error, send the guide command, and go again. Meade will do this as will others. SBIG was doing this long before Meade.

3) Drizzle has nothing to do with this. Drizzle is a combined alignment / stacking technique developed by Fruchter for the Hubble. Many programs will let you align with Drizzle in an effort to reconstruct a higher resolution than you have in your original frames. Drizzle needs some motion between frames and if you had perfect guiding, Drizzle would not work.

4) There are 2 schemes used to say that "yes you can" and neither get around the fundamental problem. The SBIG solution uses a separate guide CCD. They read off it while the main one still builds up charge. The Starlight Xpress SX-2000 system would use the odd lines for guiding and the even for building up the image. They'd dump the charge from every other line on the interlaced Sony CCDs. But still, they can't dump the charge for guiding and image from the same CCD wells. (They'd flip which are the image and which are the guide every few frames).

5) It doesn't matter if you're using CCD or CMOS

If anyone still thinks the Meade system does this, try the following. Go out and setup a 10 minute exposure. Or a 30 minute one for that matter. You'll show the same exact error you'd see if you didn't guide and ran a 10 minute exposure. There is just no way around the problem that the same CCD wells can't be used to guide (read the image off) and image (keep building the image up) at the same time. Alternate? Sure. But if you start to trail at 20s of exposure you'll still be limited to 20s of exposure. You'll just not have the image drift off the frame as you'll bring it back b/n frames.

Craig
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Old 15-04-2009, 01:26 PM
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g__day (Matthew)
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Is that Craig Stark of stark-labs fame (PhD and Nebulosity author) answering your question? A big hello and thanks for your contribution to astronomy from those of us who get alot from your software down under!

cheers,

Matt
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Old 29-04-2009, 01:40 PM
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Quote:
Originally Posted by celstark View Post
I hate to burst the bubble here, but the answer is no, you cannot. A few bits of info on this:

1) When you read off a CCD you dump the charge that has built up in the "wells". It's only when dumped that it goes into the ADC and you can read it off. Pretend you have one measuring cup and you want to know how much water is in some buckets (and you can't just look at the level in them). Dump and measure... But, the charge is gone and you must start over anew.

2) What you can do is guide between frames. So, see the drift starting to happen, figure the error, send the guide command, and go again. Meade will do this as will others. SBIG was doing this long before Meade.

3) Drizzle has nothing to do with this. Drizzle is a combined alignment / stacking technique developed by Fruchter for the Hubble. Many programs will let you align with Drizzle in an effort to reconstruct a higher resolution than you have in your original frames. Drizzle needs some motion between frames and if you had perfect guiding, Drizzle would not work.

4) There are 2 schemes used to say that "yes you can" and neither get around the fundamental problem. The SBIG solution uses a separate guide CCD. They read off it while the main one still builds up charge. The Starlight Xpress SX-2000 system would use the odd lines for guiding and the even for building up the image. They'd dump the charge from every other line on the interlaced Sony CCDs. But still, they can't dump the charge for guiding and image from the same CCD wells. (They'd flip which are the image and which are the guide every few frames).

5) It doesn't matter if you're using CCD or CMOS

If anyone still thinks the Meade system does this, try the following. Go out and setup a 10 minute exposure. Or a 30 minute one for that matter. You'll show the same exact error you'd see if you didn't guide and ran a 10 minute exposure. There is just no way around the problem that the same CCD wells can't be used to guide (read the image off) and image (keep building the image up) at the same time. Alternate? Sure. But if you start to trail at 20s of exposure you'll still be limited to 20s of exposure. You'll just not have the image drift off the frame as you'll bring it back b/n frames.

Craig
Sorry but you can use the same camera to guide and image at the same time. But it has to be a video camera ie Watec 120N+ (on a TVGuider) or Gstar will do it also. Have a look at Steve Massey's new book Deep Sky Video Astronomy. Ive used my Watec and TVGuider to guide and image at the same time using Virtualdub. You do need a good mount and keep the integrations at 10 sec or below.
You cant use a DSI, DSLR or LPI etc.
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Old 30-04-2009, 06:55 PM
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Further to my last post - it appears you can guide and image with a DSI. I stand corrected : See this posting of FAQ from the following web site but as usual there is a cavette.
http://www.skyinsight.com/wiki/index...pSkyImager_FAQ

Guiding, Tracking, and Guiding while imaging
From: Chuck Reese (chuckr54)
Date: Oct 6, 2005
Subject: Re: Help Track and Image at same time

Perhaps the most confusing set of terms & features with the DSI :-)


"Can Guide" means the system will guide using the GPS command set.
"Can Track" means the system will guide using the Classic command set.
Both work the same from the user perspective - there is no meaningful difference in the end result.

"Guide and Image with the same camera" does work. However, guide commands are issued *between exposures*, not *during exposures*. This is useful for keeping an object centered on the chip over an imaging session if our sidereal tracking is a bit off, or our alignment is less than perfect. It will *not* correct PE during the exposure, which is what we usually think of when we use the term "autoguiding".

The StarMate (LX200 Emulator) is reported to work just fine with all the above features using the Classic command set ("Can Track").
You do learn something every day.

Last edited by allan gould; 30-04-2009 at 07:06 PM.
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Old 30-04-2009, 09:31 PM
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Thanks for following up, Allan. I've got my Toucam back from the friend that borrowed it, so don't have an issue now. I can use the DSI exclusively for imaging.
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