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Something obstructing the light path!

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11 replies to this topic

#1 zakry3323

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Posted 22 February 2020 - 12:18 PM

I'm at a loss. Dust motes and vignetting I'm used to dealing with. This, though, is something that I haven't seen before, and only started showing up during my last imaging session. What the heck could it be? 

 

wrong.JPG

 

 

I haven't taken the imaging train apart yet, though I do plan to today. I looked at it last night with a flashlight and couldn't see any obstructions. The OAG was off to the side with the prism parallel to the long edge of the sensor, I don't think it's been caused by the prism or stalk. The filter wheel looked properly aligned over the sensor. 

 

I don't know if it's related, but I've also been having a reflection issue over the last several sessions. The sensor is picking up a single diffraction line when pointed South at around 35 degrees. As I track targets East, the reflection disappears. 

 

reflection1.JPG

 

25 minutes later: 

 

Noflection.JPG

 

Losing my brains over this. I feel like it should be something obvious and I'm just missing it. 

Edit: Added info (Thanks Jim!)

I was using my SVX80 with the matched FF, followed by the OAG and Astronomik filters in the filter wheel (I checked with several, this issue came up with every filter being used), then a few spacers and the ASI1600mm sensor.
 

I was using a dew heater on the objective the whole time, no other heating anywhere else. The OTA is stored outside under a 360 shroud while the weather remains nice.


Edited by zakry3323, 22 February 2020 - 12:36 PM.


#2 Jim Waters

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Posted 22 February 2020 - 12:27 PM

Would really help if you provided imaging train / equipment details...  And was anything dewing up?


Edited by Jim Waters, 22 February 2020 - 12:27 PM.

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#3 zakry3323

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Posted 22 February 2020 - 12:31 PM

Would really help if you provided imaging train details...  And was anything dewing up?

Sorry Jim! I was using my SVX80 with the matched FF, followed by the OAG and Astronomik filters in the filter wheel (I checked with several, this issue came up with every filter being used), then a few spacers and the ASI1600mm sensor.\

 

I was using a dew heater on the objective the whole time, no other heating anywhere else. The OTA is stored outside under a 360 shroud while the weather remains nice. 


Edited by zakry3323, 22 February 2020 - 12:32 PM.


#4 ngc7319_20

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Posted 22 February 2020 - 01:01 PM

The diffraction spike thing might be an electrical cable or tree branch.

 

Is this a cooled camera?  Wondering if the dark thing at lower left is dew / water in the camera.  


Edited by ngc7319_20, 22 February 2020 - 01:08 PM.

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#5 zakry3323

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Posted 22 February 2020 - 01:10 PM

The diffraction spike thing might be an electrical cable or tree branch.

 

Is this a cooled camera?  Wondering if the dark thing at lower left is dew / water in the camera.  

Good point. I'm close to some trees even at 35 degrees, but I thought I was over them. I'm going to move the entire setup tonight, so if that is the issue then it will be fixed. 

It is a cooled camera. Thank you for the heads up about this- I didn't know that this was a possibility. I will check. 



#6 CCD-Freak

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Posted 22 February 2020 - 01:14 PM

Have you looked down the scope from the objective end?  Maybe a wayward spider has taken up residence in the focuser.

 

My $.02

 

John

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Edited by CCD-Freak, 22 February 2020 - 01:17 PM.

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#7 zakry3323

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Posted 22 February 2020 - 03:02 PM

Have you looked down the scope from the objective end?  Maybe a wayward spider has taken up residence in the focuser.

 

My $.02

 

John

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Lol, thanks John! I checked it but no new friends have taken up residence :)


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#8 CCD-Freak

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Posted 22 February 2020 - 03:18 PM

I once had a spider build a web and leave an egg sack in front of my finder objective....strange things can happen.grin.gif

 

John

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Edited by CCD-Freak, 22 February 2020 - 03:21 PM.

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#9 Madratter

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Posted 22 February 2020 - 04:06 PM

The diffraction spike could easily be a tree branch.

 

Assuming you're taking the flats properly, one possibility is condensation on either the sensor, or more likely the window to the camera.


Edited by Madratter, 22 February 2020 - 04:06 PM.

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#10 zakry3323

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Posted 22 February 2020 - 05:26 PM

I once had a spider build a web and leave an egg sack in front of my finder objective....strange things can happen.grin.gif

 

John

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Wow, that's wild!



#11 zakry3323

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Posted 22 February 2020 - 06:24 PM

Yinz nailed it! Not especially visible unless you have the correct angle on it, which is probably why I didn't see it with the flashlight. 

 

IMG_20200222_165110.jpg

 

I suppose the desiccant must be old because it's on the inside of the window. I will take it apart, clean it up, and replace the desiccant tab. Thanks for your help, guess we'll see how it does in a few hours!



#12 zakry3323

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Posted 23 February 2020 - 03:43 PM

Fresh flat from last night! 
 

NoNameer.jpg

 

Looks like my worst problem is solved! Now to deal with the tilt :)


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