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Equipment Discussions >> Video and Electronically Assisted Astronomy

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dragon86
member


Reged: 10/25/10

Loc: Erie, Pa.
Blurry photo
      #5527756 - 11/19/12 11:31 AM Attachment (46 downloads)

Any ideas on what could be causing the blurriness on the right side of this photo? There was no dew on the corrector plate or the focal reducer or camera chip. I am using a Mallincam Extreme.

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YetAnotherHobby
sage
*****

Reged: 09/02/09

Loc: Central CT
Re: Blurry photo new [Re: dragon86]
      #5527860 - 11/19/12 12:35 PM Attachment (26 downloads)

Is that a series of stacked images?

I am a complete newbie with image processing, but I noticed something like that in a moon image I took. I had already aligned, stacked, tuned the .avi, and did not notice the blurring to the left side of the photo (attached) until later. Seems to be an artifict of Registax - when I reprocessed the file the blurrines was gone.

Geoff

Edited by YetAnotherHobby (11/19/12 12:36 PM)


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Dwight J
scholastic sledgehammer
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Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: Blurry photo new [Re: dragon86]
      #5527875 - 11/19/12 12:45 PM

Hi Don: cause likely d/t camera not square in focuser. It doesn't take much at the fast focal ratios used by astrovideographers (I just invented a word) for any misalignment to show up on the frame. Just make sure the camera is all the way into the focuser. If it is and you still get this then the camera chip could be slightly tilted. I find the single set screw focuser to have this issue often - forcing the camera barrel to go cockeyed in the focuser tube when tightened.

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John59
sage


Reged: 11/06/11

Loc: Round Rock,TX
Re: Blurry photo new [Re: dragon86]
      #5527891 - 11/19/12 12:54 PM Attachment (32 downloads)

I get the same thing on my C11 using the .5 reducer. See the below photo. It is the reducer showing the curvature of the C11 or possibly the reducer itself. Not really sure, but I stopped using it and placed Celestron's 6.5 reducer and corrector (field flatten) inline and the issue went away.

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dragon86
member


Reged: 10/25/10

Loc: Erie, Pa.
Re: Blurry photo new [Re: John59]
      #5527994 - 11/19/12 01:35 PM Attachment (33 downloads)

First of all this is live snapshot-no processing. Two screws hold the camera in and I am using the mfr5 focal reducer I have used the camera before without any problems. Do you think that this(see photo) of my mirror could be the cause?

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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Blurry photo new [Re: dragon86]
      #5529149 - 11/19/12 11:49 PM

The optical axis is displaced upward and a little to the left. This results in the asymmetric pattern in the comatic aberration. You could re-collimate until the pattern becomes symmetrical about the field center.

By the way, the amount of coma seems excessive for the MFR-5 on an SCT; are you using any additional spacers?


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dragon86
member


Reged: 10/25/10

Loc: Erie, Pa.
Re: Blurry photo new [Re: GlennLeDrew]
      #5529563 - 11/20/12 08:13 AM

Glenn,
I am using a 5mm spacer between the camera and the MFR-5. Not sure I understand about re-collimating. If the collimation looks good through an eyepiece wouldn't I be adjusting the telescope to make the camera view better then have to go back for visual?


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Blurry photo new [Re: dragon86]
      #5529756 - 11/20/12 10:22 AM

That the pattern of aberration is asymmetric tells you that the need for collimating is there--for imaging purposes. In this case it may be due to a factor evident in my VSS+; the CCD is not precisely centered with respect to the camera's mount. Re-collimate with camera in place, adjusting until the comatic blurs all point to the field center, and are of similar form in all four corners.

The addition of the spacer quite likely is worsening the coma/field curvature. If an improvement in off-axis stars results from its removal, I'd recommend dispensing with it; the difference in image scale and working f/ratio is not to great as to miss badly.


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