Sharpcap + Sparkocam + Nikon D5300?

Using SharpCap's Polar Alignment feature
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Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Thu Dec 14, 2017 12:58 am

Hi!

I'm trying to figure out whether it's practical to use SharpCap for my polar alignment, without a guidescope. I'm using a 102mm refractor with a Nikon D5300. I understand from other sites, that Sparkocam can be used to make my DSLR appear to Sharpcap as a webcam. Is this correct?

If so, then presumably we're down to whether Sharpcap would be happy with the images available from my camera, and whether its sensitivity would be sufficient for the job. I recently had a sample image sent to astrometry.net, and its FOV came back as 1.44 x 2.17 degrees.

Is anyone doing something like this? If so, how well does it work? What about the FOV and sensitivity?

Thanks in advance!

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by admin » Thu Dec 14, 2017 7:28 am

Unfortunately I've no experience of the Sparkocam/Nikon combo, although I have seen it mentioned before.

The things you need to test out are

* Can you turn the exposure up to ~2s.
* Can you turn up the gain (ISO)
* Can you reduce the resolution (optional, but might help avoid the polar alignment being a bit slow on full DSLR resolution images)

You cn of course run the PA routine right up as far as it telling you how big your PA error is without needing a SharpCap Pro license (not sure if you need to pay for Sparkocam or not), so probably the best bet is to give it a try. Be interesting to hear if it works!

Robin

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Thu Dec 14, 2017 1:58 pm

Thanks, Robin!

It looks like Sparkocam has quite a bit of control over the camera, so perhaps yes to your questions - but what about FOV?
Is mine large enough for you to solve with?

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by admin » Thu Dec 14, 2017 10:17 pm

Yes, the FOV should be fine as it is more than 1 degree in each direction. I'm still not sure that you can get a 2s exposure on a DSLR in 'live' mode though, so I don't know that you will be able to get enough stars picked up.

cheers,

Robin

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Thu Dec 14, 2017 11:59 pm

Well, (pending a clear sky), I'll set up a test and let you know how it goes. :-)

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Fri Dec 15, 2017 4:08 pm

Robin,

So far, so good, on a daytime integration test, with a neighbor's tree as a target and trialware for both.

I am able to control the D5300's ISO, exposure, and within limits, the image size with Sparkocam and display shots manually in its preview pane. So far, a multi-second image doesn't look like a problem.

Sharpcap sees 'Sparkocam video' as an available source, and displays the still picture that is in its preview pane. Manually change the preview and Sharpcap picks up the new photo.

TBD how all this will work with Polar Alignment, but at least they're communicating. A PA test will have to wait for clearer skies, but so far I'm encouraged.

But... if all that's really needed for PA is a succession of still photos... it would be nice to skip the Sparkocam integration and just manually pick/source each image file from a directory without being too concerned about how it got there...

- Bob

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by admin » Fri Dec 15, 2017 8:59 pm

Hi Bob,

well, if you picked files from a directory then you would loose the live guidance while adjusting the alignment, which is what makes the SharpCap PA so easy... But, if that's really what you want then I'd suggest you look at PhotoPolarAlign - https://stargazerslounge.com/topic/2299 ... t-utility/ - it does just what you are talking about.

cheers,

Robin

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Sun Dec 17, 2017 5:43 pm

Robin,

It's more a case of what I have to work with, than what I want :-)

I did look up a demo on youtube to better understand what you were saying about live guidance. I also took a look at Themos's work on the thread you linked, and over at github. It does look similarly 'manual' as what I've found with Sparkocam pushing stills across a video driver, but I'd really prefer to solve this with a product, if I can.

I'd still like to see if Sharpcap could be made to do a Polar Alignment with a DSLR, even if the workflow is less smooth than your usual. My guess is that would be good news for others besides me. Right now, the only products that I know of that are doing a plate-solved polar alignment on Polaris are Sharpcap and Polemaster...

- Bob

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by devonshire » Thu Dec 21, 2017 3:45 am

Hi Robin,

I was able to give this a brief try a couple of days ago. Had to break off due to an unrelated mount issue, but I think I learned enough to give this a 'no-go'.

There wasn't a problem passing images from the D5300 to Sharpcap via Sparkocam. Yes, a little clumsy, but doable for this purpose. And Sharpcap gave a good try on solving image #1.

The limitation turned out to be not the camera, but the scope's FOV. My f6.1's field of view wasn't turning up enough stars to drive the solution, even with 30 second images. It was at that point that I had to stop. Perhaps I could have jigged around and come up with enough stars to solve #1, but what to do if stars dropped out when I rotated, or when tuning the alignment?

It's really too soon in my AP journey to start guiding, but I've picked up a 50mm/F4 guidescope with an Altair GP224C camera anyway. Guiding will wait, Polar Alignment won't. Hoping it will help with my PA for now, while I work on other AP skills.

Thanks for your help with this! I'll be back later, as a licensee.

- Bob

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Re: Sharpcap + Sparkocam + Nikon D5300?

Post by admin » Thu Dec 21, 2017 10:24 pm

Hi Bob,

did you save any captured frames? It would be interesting to run them through my test setup just to see if there is something stopping the stars from being detected properly that could be fixed in software.

You won't go far wrong with the Altair 224 and the 50mm/F4 guider though :)

cheers,

Robin

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