Can a DSLR camera be used with PHD2 to drift align?

[Geoffrey Lewis]

Hi Bruce, Andy, or anyone that knows,
I've been asked whether PHD2 could be used to drift align with a DSLR camera where the rig is being used unguided for imaging, i.e. the person does not have a guide scope or guide camera, so images unguided, but would love to use the drift align tool prior to shooting unguided subs. I don't see any DSLR camera option in the camera drop down, so is it possible and if yes, how to do it please?
Cheers,

Geof

[FERNANDO MAGALHAES]

  Geof, I was shooting this last weekend with a DSLR and a C8, and this, and the same thought came to me, too.It would be great, if possible, that PHD 2 could recognize the Canons(in my case), not only to drif align,, but to make PEC through its display.I made a drift align, by the way, good, with my Orion Starshoot autoguder and a Orion mini guidescope, but it would far more precise with the main scope in prime focus.With PEC, the same thing, I can use Nebulosity with Live view, but I changed the DSLR with the Starshoot to create PEC, but I personaly, don´t like to take out cameras, to make this adjustments, it would be more stable and confident, don´t touching my cameras and doing everything with one software.But, is it possible?PHD2 reading DSLRs drivers?At least, for this two tasks, with exposures or live view
  Fernando

[FERNANDO MAGALHAES]

Geof, and everybody, sorry by my mistakes in English.

[Bruce Feagle]

Makes perfect sense. I had the same thought a few days ago. I have the same setup, Orion mini with SSAG. I was thinking I could get a better drift alignment if I was using the longer focal length of the main telescope.

Bruce

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Bruce Feagle

Creative Monster
thecreativemonster.com

760.898.2885

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[bw_msgboard]

Hi Geof.  No, it can’t currently be done, and I think support of DSLR cameras is unlikely to happen anytime soon.  DSLRs are generally not well-suited as guide cameras, so this would be a pretty marginal return on investment.  Do you really want to be downloading images of 15-50M pixels? (top-end guide cameras have less than 1M pixels).  Beyond that, the major DSLR vendors are notoriously difficult to work with and generally provide SDKs on an as-is basis.  Adding support for a new camera in PHD2 is generally a sizable effort unless the camera is very similar to something else that is already supported.  If someone wanted to take on the job, they could certainly do it – but I certainly wouldn’t.  <g>  If your friend is even half-interested in astro-imaging, he would be much better off just getting a guide set-up and moving forward.

 

Bruce

 

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[bw_msgboard]

I don’t think I quite follow your thinking here.  It sounds like you think image scale is the limiting factor for alignment – why?  If your guider image scale is sufficient for guiding (a hard job), why isn’t it more than sufficient for drift alignment (a relatively easy job).  If you haven’t already done so, you should probably use one of the web tools to see how good is good enough on polar alignment.  If you’re trying for an error of zero, I think you’re just wasting time.  In my experience, the limiting factors are usually a) how much time you’re willing to spend on it and b) the precision afforded by the mount for making fine adjustments in both altitude and azimuth.  And if you think your image scale is too small for good guiding, that’s the problem to fix, perhaps with an OAG arrangement.

 

Bruce W.

 

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[Geoffrey Lewis]

Thanks Bruce,
No problem, I thought that it was a long shot...
He doesn't want to guide with the DSLR, but had heard that PHD2 drift alignment tool was very good, which I confirmed, so he wondered if he could access that tool without investing in a guide scope and camera. Those may follow in due course, but he is looking for a quick and reliable method to improve polar alignment. I've explained that he will have other issues than polar alignment error trying to imaging unguided, e.g. PE, but we all start somewhere, don't we....?!!
Regards,

Geof

[Bruce Feagle]

Thanks for indulging my curiosity.  :)  I was thinking by using the live view from my 7D on the scope with the longer focal length. The drift trend would reveal itself faster.

But that's flawed. The errors in the mount need to be averaged out during the drift for the trend correct? So the longer you drift after each adjustment adds to the accuracy. I have found with my CGEM that I can rough in the first few adjustments with 30-60 seconds of drift. Then the last few with 120 seconds of drift gets me as close as the accuracy of the AZ/ALT controls on the mount allow. So I love the drift tool. :)

Bruce F

[FERNANDO MAGALHAES]

  Bruce, I got your point, I think you are correct, I made a drift with my little guidescope, and it was very good, by the way, The Drift align tool is fantastic.
  So, I will make my PEC with PHD2 and my SSAG/mini guidescope.What I don´t want, I don´t know if this a silly way, is to change cameras to do something, so, if I can get, the best accuracy, that my equipment can give in this way, so, that´s it.
Thanks a lot
Fernando

[bw_msgboard]

Yes, you’ve got it.  Like everything else in guiding, every time we sample the position of the guide star, there are error-bars attached to the measurement.  So the longer you run and the more samples you take, the better we can do a fit to the data to estimate the drift rate.  As you watch the graph get updated, you can usually see it converge on a trend line that then changes very little with successive samples.

 

Have fun,

Bruce

[FERNANDO MAGALHAES]

  Bruce, I made exposures of 1s with the guidescope, both near the meridian and at east, and when the star stopped drifting, I observed it for, more or less, 4 minutes, till the "ups and downs", I judged it was "seeing".After that, I moved the camera to the main scope, to create a PEC, and recording the east/west corrections, the star didn`t move in declination.So the drift align tool is a winner.PHD 2 is a great piece of work.
  And guiding became excellent.
  Best regards
  Fernando

[bw_msgboard]

Gracias, Fernando, glad things are working well for you.

 

Bruce

 

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