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 Post subject: collimation
 Post Posted: Wed Sep 13, 2017 10:48 pm 
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Joined: Wed Sep 13, 2017 5:30 pm
Posts: 9
Location: Scottsdale, AZ
I picked up an ASI071 during the sale, and in its first use the last couple nights I encountered two problems: trouble reaching focus and poor collimation. You can see whaat I'm referring to in the attached jpg. There may be other issues. If you notice anything else, just shout it out.

The scope is an EdgeHD 11 with a hyperstar on a CGX-L. Until now, my imaging camera has been an EOS, which has a perfect record.

With a little more extension, I can fix the focus problem, but I need some advice on collimation. The manual identifies three sets of push pull screws, but doesn't label them. Which is which? Which direction do I turn them to make adjustments? I hate trial and error. How come these cameras aren't adjusted in China? I really think it should be in better shape straight out of the box.


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vega non 1s 0g 100 dss.jpg
vega non 1s 0g 100 dss.jpg [ 1.59 MiB | Viewed 405 times ]
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 Post subject: Re: collimation
 Post Posted: Thu Sep 14, 2017 6:13 am 
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Joined: Mon Aug 01, 2016 3:51 pm
Posts: 102
That doesn't look like collimation /tilt issue.
Just sort out the hyperstar-camera distance (it's quite critical), and you're fine.


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 Post subject: Re: collimation
 Post Posted: Fri Sep 15, 2017 6:49 pm 
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Joined: Wed Sep 13, 2017 5:30 pm
Posts: 9
Location: Scottsdale, AZ
einari, thanks for the reply. I'm at the correct backfocus now, but I'm still seeing some artifacts in the corners I don't like. Whats the best way to get rid of them?

Also, I'm now seeing another, separate artifact, circled in the second attachment. I've checked the glass for lint/dirt and don't find any. Does the glass come out with a spanner? I would have to drop it at my camera shop for sensor cleaning. This almost isn't worth it.


Attachments:
IC6490 artifact.jpg
IC6490 artifact.jpg [ 740.87 KiB | Viewed 374 times ]
1396 10s 200g 40o flat sh ps.jpg
1396 10s 200g 40o flat sh ps.jpg [ 559.51 KiB | Viewed 380 times ]
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 Post subject: Re: collimation
 Post Posted: Sat Sep 16, 2017 6:45 am 
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Joined: Mon Aug 01, 2016 3:51 pm
Posts: 102
So you have exactly this?
Backfocus (from mounting thread to focal plane): 59.7mm
Anyway I just noticed this of Hyperstar
Maximum Usable Sensor Size: 27mm Diagonal (APS Format)
And ASI071 has 28. 4mm diagonal so your edge might not be perfect.

That latter is dust mote.
You just have to take flats to get rid of it.


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 Post subject: Re: collimation
 Post Posted: Sat Sep 16, 2017 2:54 pm 
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Joined: Wed Sep 13, 2017 5:30 pm
Posts: 9
Location: Scottsdale, AZ
Yes, I get some vignetting. Not a problem.

So how do I get rid of the "dust mote" permanently? Or is that not possible?
Should I not expect that the camera as supplied would be completely clean?
Who would buy this thing from me should I decide to sell it at some point?


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 Post subject: Re: collimation
 Post Posted: Sat Sep 16, 2017 5:06 pm 
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Joined: Wed Sep 13, 2017 5:48 pm
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To get rid of the dust mote try using a bulb blower first, before you touch the glass over the sensor. I use an 8x jewelers eye loop to check for dust on my camera. You would not believe how much stuff is on there that you cannot see by naked eye. Sometimes a very small particle of dust can show up very prominently.


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 Post subject: Re: collimation
 Post Posted: Sun Sep 17, 2017 3:10 pm 
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Joined: Mon Aug 01, 2016 3:51 pm
Posts: 102
What John said.
So quite normal to have them.
You can clean them but sooner or later (sooner likely) they reappear.
So that's one good reason to take flats.
Btw, here's a tool to find out where they lie:
http://www.ccdware.com/resources/dust.cfm


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 Post subject: Re: collimation
 Post Posted: Fri Oct 13, 2017 8:41 pm 
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Joined: Wed Sep 13, 2017 5:30 pm
Posts: 9
Location: Scottsdale, AZ
Sent it back to the supplier, and they agreed it needed to be exchanged. The replacement
camera is working just fine. Never hurts to ask I guess.


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