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SBIG SG-4 autoguider dithering


Peter_Myers
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Greetings to the BYEOS collective....

I am hoping that someone here may be able to answer my question?

Recently I purchased an SBIG SG-4 autoguider  and after discussing the option to be able to dither...I was told by SBIG

"My question is 2-fold        will the SG-4 dither?    If so, can a software  program like PHD be used to dither?

No the SG-4 cannot dither.  Also it isn't really possible to use it as a computer-controlled autoguider - it wasn't designed for that - so you can't use PhD to dither with it.

 

My question ...within BYEOS software can I somehow manipulate the option to "dither" this SG-4 autoguider?

 

Look forward to any responses.

 

Thanx

 

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Well, in a sense the guide camera does matter. The SG-4 is a standalone guide camera, so does not connect with a computer. This means that PC-based apps like PHD and MetaGuide cannot be used to control guiding or implement dithering. This means that the SG-4 will not support dithering from the PC. I would say that the information that you got from SBIG is correct.

I would say that the SG-4 is not a good choice for a guide camera to use in conjunction with DSLR deep sky imaging, where dithering needs to be an integral part of the image capture process.

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6 minutes ago, astroman133 said:

Well, in a sense the guide camera does matter. The SG-4 is a standalone guide camera, so does not connect with a computer. This means that PC-based apps like PHD and MetaGuide cannot be used to control guiding or implement dithering. This means that the SG-4 will not support dithering from the PC. I would say that the information that you got from SBIG is correct.

I would say that the SG-4 is not a good choice for a guide camera to use in conjunction with DSLR deep sky imaging, where dithering needs to be an integral part of the image capture process.

Ahhhh... it does matter here then.  Thank you for pointing me in the right direction.

Regards,

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So, if this is he case....and there isn't a software program that I can mate with the SG-4

Since DSO imaging requires dithering...what type of astronomical imaging would benefit utilizing the SG-4 as an auto guider?

 

Look forward to your responses.

 

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Sorry, but I said that dithering should be an integral part if image capture with a DSLR. I use a cooled CCD camera which is cooled t0 -10 degC. At this temperature there is not any pattern noise and not much thermal noise. I can remove hot pixels during image calibration, so dithering does not provide as much benefit.

Also, the SG-4 has a USB port that can be used to display captured images, so there must be some software that can display those images. This is necessary for focusing. However the SG-4 does not support dithering via this USB connection.

I have a friend who uses BYE with a Canon 7D Mk II. He has to use aggressive dithering to avoid processing artifacts that show up as diagonal striations in his stacked images.

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Astroman

I understand now what you mean....

I can utilize the SG-4 with my CCD STT-8300 and filter wheel setup

Unfortunately if I image capture with my one shot Canon 6D.... I will require a different autoguide setup along with PHD.

Thank you for the information 

 

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Well, not so fast...

Dithering with a DSLR will produce BETTER Results.  But that doesn't mean that one simply cannot AP Image using a DSLR without Dithering.

Dithering works to force the Camera Sensor's Noise to be randomly distributed, so that the more sophisticated Stacking Routines can reduce the Noise that makes it through to the Final Image.  This Noise is more prevalent on certain Models than others (older models are poorer; newer and higher-end models are better - of course), and exacerbated by the Ambient Temperatures of Summer.  But there are other contributors - Light Pollution, Seeing, Transparency, Moon.

So...  There is nothing better than some Trial and Error Experience to state how much the Noise from your DSLR Images will impact your Results.

And...  The availability of Guided Imaging will have other Positive Impacts on your Images.

And as a thought:  You can still do "Poor-man's Dithering" - pick some fraction of the total Image Count you plan for a Night and after that fractional number of Exposures 1) Suspend the Image Plan; 2) Pause the SG-4; 3) Manually move the Scope's Framing a bit using the Mount Controls; 4) Resume the SG-4 and help it lock onto the Guide Star; 5) Resume the Image Plan for the next sequence of Exposures; repeat until you reach your intended Exposure Count or Dawn Breaks or the Sky Clouds Up.  Now when you Stack those Exposures, you will have the Noise "Dithered" to the degree of the number of times that you "Manually Dithered".

I've not done this in a long time, but it is how I Dithered when using my old NexGuide...

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