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buckeyestargazer
Carpal Tunnel
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Reged: 01/12/08

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Evaluating Bias/Dark Frames and Camera Power Suppl new
      #5705428 - 02/28/13 02:12 PM

I'm curious if there is a way to evaluate bias frames (or darks too) that shows changes in background or irregularities etc if there is a change in the voltage supplied to the camera.

Normally I power my camera and filter wheel with separate power supplies. But in an effort to streamline cables I'd like to power the camera and filter wheel from the same power supply using a splitter. I've been told by the manufacturer (Atik) that this should be no problem as long as the power supply has enough amps to cover the components draw. In the case of my Atik camera (max 2amps) and filter wheel (very low amps), a regulated 2.5amp power supply should be fine.

So I took some bias frames with the camera drawing a lot of power and the filter wheel disconnected, and some bias frames with the filter connected and rotating (of course, the filer wheel will never be rotating during exposures in actual practice!).

Is there a way to quantitatively measure the bias frames with and without the FW attached that would show any differences induced by sharing a power supply?

I really have no clue what I'm talking about here so if this is all a ridiculous question I apologize in advance!

Edited by buckeyestargazer (02/28/13 05:15 PM)


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: buckeyestargazer]
      #5705904 - 02/28/13 06:17 PM

The simplest way to evaluate bias or dark frames for noise is to take two images and subtract them. What's left is the noise.

You could try the different power supplies and see if there's a difference in noise or subtract an image using one power supply from one using the other and see it there's a difference.

What you're trying to do is the same as with any other scientific experiment, change the thing you are measuring while keeping everything else the same.

Chris


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wolfman_4_ever
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Reged: 07/15/11

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Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: cn register 5]
      #5705925 - 02/28/13 06:32 PM

I doubt you would see any changes.. most power supply noise is transferred through an analog signal such as a video camera.. The a/d converter should dump any analog noise.

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buckeyestargazer
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Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: wolfman_4_ever]
      #5705946 - 02/28/13 06:41 PM

Quote:

I doubt you would see any changes.. most power supply noise is transferred through an analog signal such as a video camera.. The a/d converter should dump any analog noise.




Good to know, thanks.


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Mike7Mak
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Reged: 12/07/11

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Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: wolfman_4_ever]
      #5705959 - 02/28/13 06:48 PM

Quote:

I doubt you would see any changes.. most power supply noise is transferred through an analog signal such as a video camera.. The a/d converter should dump any analog noise.



Yeah, I wouldn't count on that. I've had cheap switching power supplies cause severe noise patterns in my DSIs, and my Atik occasionally picks up interference from the microfocuser.


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astrovienna
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Reged: 12/04/06

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Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: cn register 5]
      #5707153 - 03/01/13 01:10 PM

Quote:

The simplest way to evaluate bias or dark frames for noise is to take two images and subtract them. What's left is the noise.

You could try the different power supplies and see if there's a difference in noise or subtract an image using one power supply from one using the other and see it there's a difference.

What you're trying to do is the same as with any other scientific experiment, change the thing you are measuring while keeping everything else the same.

Chris




This is the way I would go. Craig Stark's writeup has pretty thorough instructions for how to do this. I learned a lot about my camera when I did this.

Kevin


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: Evaluating Bias/Dark Frames and Camera Power Suppl [Re: astrovienna]
      #5708026 - 03/02/13 12:31 AM

Ground issue more than likely... who knows..

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buckeyestargazer
Carpal Tunnel
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Reged: 01/12/08

Loc: IN, USA
Re: Evaluating Bias/Dark Frames and Camera Power Suppl new [Re: astrovienna]
      #5708363 - 03/02/13 09:04 AM

Quote:

This is the way I would go. Craig Stark's writeup has pretty thorough instructions for how to do this. I learned a lot about my camera when I did this.

Kevin




Thanks Kevin, that's good info and what I was looking for.


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