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Jim Smith

Electronic Finder First Light

16 posts in this topic

Inspired by reading various posts on CN and SL I thought I would start using an electronic finder. I'm fed up wasting too much time trying to work out where my scope is pointing.

The finder consists of a Lodestar x2 mono, a 5mm cs to c-mount adaptor, a c-mount to Canon EOS adapter and a Samyang 85mm f/1.4 lens. I don't have any means of securely attaching it to my C6 yet, so I just plonked it on top, pointing vaguely in the direction of Ophiucus.

According to astrometry.net the image I captured below is 4.23 x 3.35 deg. I think that should work well. I notice some blurriness around red stars. Is this caused by the lens's difficulty focusing red/IR? Would an IR cut filter help?

The image below is a stack of 22 @ 0.5 seconds with the lens set to f/1.4. The image in focus and framing mode (unstacked) is noisier. Sorry, I forgot to save one of those.

Somewhere2_2017.7.17_00.18.04.png

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That looks like a perfect combination for an electronic finder, wide enough FOV to get target even if gotos are not very good, sensitive to pick up fainter objects. Do you have a spare Lodestar for EAA on the main scope or do you need to switch the Lodestar out of the finder?

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8 minutes ago, RobertI said:

Do you have a spare Lodestar for EAA on the main scope or do you need to switch the Lodestar out of the finder?

I have an Ultrastar mono on the way. I suppose the Lodestar will be the finder and the Ultrastar will be the main scope camera...or perhaps the other way round? I will experiment.

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4 hours ago, Jim Smith said:

I have an Ultrastar mono on the way. I suppose the Lodestar will be the finder and the Ultrastar will be the main scope camera...or perhaps the other way round? I will experiment.

Lucky you! Look forward to seeing your results.

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I've used an Orion 50mm Guidescope and my ZWO ASI185MC as my e-Finder.  I get about 2.5°x1.5°.   I've since switched to plate solving with Astrotortilla.   Now, I only use the 50mm guidescope to polar align and for guiding on longer exposures, or as a wide field imager.   Astrotortilla puts it in the middle of the field of view almost every time.

 

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That's the second time someone has suggested Astrotortilla to me. Perhaps I'll need to take a serious look. I'm a bit concerned about how easy it might be to get it working with SkySafari and Starlight Live on my Mac. I think, for now, I'll get used to using my new e-finder and see how I go.

One question...Roughly how long does it take for Astrotortilla to take an image, do the plate solving, slew the scope and check where its now pointing? (If that's what it does!)

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I hadn't considered that you were on a Mac so I don't know if Astrotortilla works or not on a Mac, but I'll put this up in case anyone else is considering it.  

Exposure time is typically 5 to 10 seconds.  The plate solve can vary depending on what part of the sky you're looking at and how many indexes you have installed (the more installed the slower it is).  I usually get a solve in under 30 seconds and the slew is usually just a minor correction.  It usually only has to slew once, though it will check again and slew again if needed (I've never had it slew twice).  Once you get a solve, you can look in the log to see which Index it solved with.  You can then move any indexes that don't solve out of the directory to speed it up.  I haven't done that yet.  You'll probably need different indexes for different camera/scope setups and the parameters have to change with each setup.  I created a cheat sheet for my setup and store it on the ComputeStick for quick reference.  You can also set up profiles once you're sure what you need in AT which will allow you to quickly change parameters on the fly.

I use APT with the Lodestar/Ultrastar and connect Astrotortilla to APT.  Other than starting it up and connecting to the camera, I just run APT minimized.   One thing to make sure of is that Starlight Live and AT are not collecting at the same time as they can interfere with each other if they both request the camera at the same time.  It doesn't always happen but when it does, I usually have to reseat the camera's USB connection.  I usually pause SLL and then take an image to plate solve. 

I used this site to set it up:

http://www.lightvortexastronomy.com/tutorial-setting-up-and-using-astrotortilla-for-plate-solving.html

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Thanks for the information.

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A surprise clear night gave me the opportunity to try my e-finder in tandem with my main scope. The finder camera is a Lodestar x2m and the main camera is an Ultrastar mono. I ran two instances of Starlight Live on my Macbook.

I stopped down the e-finder's 85mm f/1.4 lens to f/2.4 and found that the star bloat was much improved. The loss of speed doesn't seem to be an issue as the Lodestar is very sensitive.

After aligning the two systems, I took these two shots of my target, M57. The finder image is 1 second, unstacked. The main image is 10x5 seconds mean stacked. It seems to be working pretty well so far...

M57_2017.7.23_01.01.38.png

Image_2017.7.23_00.53.36.png

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Looks like it's working very well indeed, the finder is picking up plenty at 1 second including M57

IMG_0841.JPG

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On 19/07/2017 at 19:11, Robrj said:

I hadn't considered that you were on a Mac so I don't know if Astrotortilla works or not on a Mac, but I'll put this up in case anyone else is considering it.  

Exposure time is typically 5 to 10 seconds.  The plate solve can vary depending on what part of the sky you're looking at and how many indexes you have installed (the more installed the slower it is).  I usually get a solve in under 30 seconds and the slew is usually just a minor correction.  It usually only has to slew once, though it will check again and slew again if needed (I've never had it slew twice).  Once you get a solve, you can look in the log to see which Index it solved with.  You can then move any indexes that don't solve out of the directory to speed it up.  I haven't done that yet.  You'll probably need different indexes for different camera/scope setups and the parameters have to change with each setup.  I created a cheat sheet for my setup and store it on the ComputeStick for quick reference.  You can also set up profiles once you're sure what you need in AT which will allow you to quickly change parameters on the fly.

I use APT with the Lodestar/Ultrastar and connect Astrotortilla to APT.  Other than starting it up and connecting to the camera, I just run APT minimized.   One thing to make sure of is that Starlight Live and AT are not collecting at the same time as they can interfere with each other if they both request the camera at the same time.  It doesn't always happen but when it does, I usually have to reseat the camera's USB connection.  I usually pause SLL and then take an image to plate solve. 

I used this site to set it up:

http://www.lightvortexastronomy.com/tutorial-setting-up-and-using-astrotortilla-for-plate-solving.html

  Alternative for Mac is THESKYX which has "plate solving" (Goto/blind etc) but not sure which edition its in - In Theskyx plate solving  its called (WHY ??) "Imaging Linking" and "Closed Loop Slews" - haven't used it myself but many love it (each to their own)

Dont know why Astrotortilla isn't on Mac - you need Unix to run it on Windows (CGYWIN) and Mac is Unix based.

 

 
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On 7/23/2017 at 08:59, stash_old said:

Dont know why Astrotortilla isn't on Mac - you need Unix to run it on Windows (CGYWIN) and Mac is Unix based.

 

 

I think it only uses CGYWIN to access the astrometry files.   I believe it can be installed and run without CYGWIN, it just won't be able to solve anything without it.  The actual interface is written in Python with win32all extension.  There's been little development activity on it.  My guess is the developer doesn't have a Mac.

https://sourceforge.net/p/astrotortilla/code/HEAD/tree/branches/newgui/

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On July 23, 2017 at 04:09, Jim Smith said:

A surprise clear night gave me the opportunity to try my e-finder in tandem with my main scope. The finder camera is a Lodestar x2m and the main camera is an Ultrastar mono. I ran two instances of Starlight Live on my Macbook.

I stopped down the e-finder's 85mm f/1.4 lens to f/2.4 and found that the star bloat was much improved. The loss of speed doesn't seem to be an issue as the Lodestar is very sensitive.

Hi Jim,

Very nice!  Did you have very good seeing, or are you able to focus and get tight stars/sharp images like this all the time?  I find my Lodestar X2C gives bloated stars, and getting sharp focus has been elusive, even with a mask.... I'm not sure, maybe it's my technique, or perhaps my location (I'm on the west coast at sea level)....

Also: how did you run multiple instances of Starlight Live on your Mac?

Cheers,

-Greg

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4 minutes ago, arkosg said:

Hi Jim,

Very nice!  Did you have very good seeing, or are you able to focus and get tight stars/sharp images like this all the time?  I find my Lodestar X2C gives bloated stars, and getting sharp focus has been elusive, even with a mask.... I'm not sure, maybe it's my technique, or perhaps my location (I'm on the west coast at sea level)....

Also: how did you run multiple instances of Starlight Live on your Mac?

Cheers,

-Greg

Hi Greg,

This is all a bit new to me, so these are not expert answers! The seeing was, I think, better than average, but remember that the X2M image is wide field so may not be so susceptible to poor atmospheric conditions. The X2M image was made using a camera lens which I focused by turning it to the infinity setting and then fine-tuning it to get the smallest stars on the screen. I have a UV/IR filter on the lens which might help to remove less well focused IR. I'm not sure if your X2C is as sensitive to IR though.

The Lodestar/C6 I focused with a Bahtinov mask.

Two instances of StarLight Live? I've only done this once so far, but here's what worked... I had the Ultrastar USB cable plugged in and then started SLL. It connected OK. I then plugged in the Lodestar USB cable and started another instance of SLL using AppleScript in a .app file as below.

do shell script "open -n -a starlightlive --args -exclusive-sx-pid 0x0507 -prepend-title-text Lodestar

This then connected to the Lodestar OK. I did lose the camera connection once or twice, but I just repeated the same procedure. 

But, as I said, I've only had this working for one session so far so I'm not sure how reliable it will be.

Hope that helps, Jim

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7 hours ago, Jim Smith said:

Hi Greg,

This is all a bit new to me, so these are not expert answers! The seeing was, I think, better than average, but remember that the X2M image is wide field so may not be so susceptible to poor atmospheric conditions. The X2M image was made using a camera lens which I focused by turning it to the infinity setting and then fine-tuning it to get the smallest stars on the screen. I have a UV/IR filter on the lens which might help to remove less well focused IR. I'm not sure if your X2C is as sensitive to IR though.

The Lodestar/C6 I focused with a Bahtinov mask.

Two instances of StarLight Live? I've only done this once so far, but here's what worked... I had the Ultrastar USB cable plugged in and then started SLL. It connected OK. I then plugged in the Lodestar USB cable and started another instance of SLL using AppleScript in a .app file as below.

do shell script "open -n -a starlightlive --args -exclusive-sx-pid 0x0507 -prepend-title-text Lodestar

This then connected to the Lodestar OK. I did lose the camera connection once or twice, but I just repeated the same procedure. 

But, as I said, I've only had this working for one session so far so I'm not sure how reliable it will be.

Hope that helps, Jim

Thanks Jim!  That's very useful and helpful... keep posting, especially those Mac tips!  :-)

Clear skies,

Greg

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For Windows users, you can do a similar thing by putting the command in a batch  file.  It makes a clickable icon.   Create a text file on the desktop, insert the command you want to launch, then save the file. Change the extension from .txt to .bat. 

This assumes Starlight Live is on the C: drive  in Program Files:

C:\Program Files\StarlightLive\StarlightLive.exe -exclusive-sx-pid 0x0507 -prepend-title-text Lodestar

If you had an Ultrastar as well, you could also add another line for an Ultrastar in the same batch/script file using it's PID and it will launch both.  PID for an Ultrastar is 525.

 

Here is a guide I did for a drag and drop way to load a previously captured .fits file instead of having to type it in at a terminal prompt. 

 

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