I'm trying to use SharpCap Live View to focus ASI224MC

Discussion of using SharpCap for Deep Sky Imaging
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reifheck
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I'm trying to use SharpCap Live View to focus ASI224MC

#1

Post by reifheck »

Hi,

I'm trying to figure out how to real-time focus my asi224mc on my Celestron Nexstar Evolution 9.25" SCT using SharpCap.

I'm trying to perform some DSO with it but I can't even see the telescope moving in the image.

Any suggestions?

Thank you,

Reif
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admin
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Re: I'm trying to use SharpCap Live View to focus ASI224MC

#2

Post by admin »

Hi,

tricky one, since the 224MC has a very small field of view when used with an SCT and the SCT has a very wide range of focus adjustments.

I would suggest starting with the moon - it's big, it's bright and if you are anywhere near it the camera will either see it or the glow around it. Get the moon in view, turn down exposure to avoid over exposure and then focus on the moon. Now you have found the right focus point and you can move the telescope to point elsewhere and turn the gain/exposure up (maybe 4s exposure, max gain) and you should start to see stars.

If the moon is not around at a convenient time, point the telescope at the furthest away terrestrial object you can get in view (tree, roof, hill in the distance, etc). Focus on that - If the target is far enough away (ideally 1km or more), the focus point will not be very far out for viewing the stars later.

Hope this helps,

Robin
reifheck
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Joined: Wed Mar 02, 2022 11:55 pm

Re: I'm trying to use SharpCap Live View to focus ASI224MC

#3

Post by reifheck »

admin wrote: Sat Jul 23, 2022 3:10 pm Hi,

tricky one, since the 224MC has a very small field of view when used with an SCT and the SCT has a very wide range of focus adjustments.

I would suggest starting with the moon - it's big, it's bright and if you are anywhere near it the camera will either see it or the glow around it. Get the moon in view, turn down exposure to avoid over exposure and then focus on the moon. Now you have found the right focus point and you can move the telescope to point elsewhere and turn the gain/exposure up (maybe 4s exposure, max gain) and you should start to see stars.

If the moon is not around at a convenient time, point the telescope at the furthest away terrestrial object you can get in view (tree, roof, hill in the distance, etc). Focus on that - If the target is far enough away (ideally 1km or more), the focus point will not be very far out for viewing the stars later.

Hope this helps,

Robin
Thank you,

I do understand all of what you responded with but the moon is not out for awhile. ;~(

I just want to be able to see the image as I am slewing the telescope.

What exposure and fps values would you suggest to be able to do this?

Thank you,

Reif
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Re: I'm trying to use SharpCap Live View to focus ASI224MC

#4

Post by admin »

Hi,

Set the exposure for about 4s, maximum gain, you should then have a good chance of seeing trails of brighter stars as the telescope moves around. FPS is really irrelevant in this case, since with 4s exposures you will get 1 frame every 4 seconds!

cheers,

Robin
reifheck
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Re: I'm trying to use SharpCap Live View to focus ASI224MC

#5

Post by reifheck »

admin wrote: Sat Jul 23, 2022 8:25 pm Hi,

Set the exposure for about 4s, maximum gain, you should then have a good chance of seeing trails of brighter stars as the telescope moves around. FPS is really irrelevant in this case, since with 4s exposures you will get 1 frame every 4 seconds!

cheers,

Robin
Thank you Robin!

That is exactly the information I was looking for :D .

Thanks again,

Reif
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