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Guiding camera as secondary imager simultaneously?

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#1 MrPink201



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Posted 31 July 2021 - 02:35 AM

I think the title says it all…

This just occurred to me…

Does anyone use their guiding setup for data acquisition at the same time as its being used as a guider. Is this a common practice I haven’t heard of or is it a waste of time? What possible software could be used? PHD2, BYN, FireCapture?

For example:
Let’s say I got -
A ZWO MC on a120mm guide scope on
A Nikon D7000 on a 8SE(reducer prolly) on
Running PHD2 (or Firecatpure?) & BYNikon

Could I get the ZWO to capture and send to PHD2 (or FireCapture or ?) (or to the mount) and still save those images as captured data somewhere.
Essentially giving me to sets of data. A wide view and my main
8SE? Could I use filters on the ZWO for an RGB?
Or is this just all a dumb combo? And just use the ZWO with filters(Which I haven’t gotten into yet)(well, a little) on the 8SE unguided until I buy a new guide scope?

Also, anyone ever do Prime Focus stuff with an extension and an eyepiece on a DSLR? Or is that like Old School? I’ve attempted it a few times with varying results.

Thanks for you time reading that mess. Any advice, suggestions, etc. is greatly appreciated!!!!

Clear Skies!

#2 rhart426


    Ranger 4

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Posted 31 July 2021 - 05:55 AM

You could save your guide camera images as a second set of data; most don't because they are very short and it would be difficult to extract meaningful data from them.  Also, most guiding setups aren't designed with that in mind so the images often suffer to our eye in order to be more appealing to the guiding algorithms.


The ZWO MC, without further information, sounds like a RGB camera already.  If it's not, using filters will reduce its efficiency as a guide camera since filters block signal.


I wouldn't say either is a dumb combo, I like your energy!  It would be challenging and probably not worth the effort or the cost to your images, but if you have everything lying around it can't hurt to experiment.


Prime focus photography with an eyepiece is still a thing, you can get good results on bright stuff like the moon or planets; deep sky stuff would be more challenging.

#3 bobzeq25



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Posted 31 July 2021 - 02:49 PM

Advice.  I've been doing this for over 5 years.  Check out my astrobin.


Waste of time.  Trying to make one camera do double duty is both difficult and futile.  Guiding and imaging are two very different things.


This is a DSO imaging forum.  DSO imagers don't use eyepiece projection, they're a planetary/lunar thing, where the target is blindingly bright.  For DSOs (much dimmer, even so called "bright" DSOs are only bright in comparison to other DSOs) the loss of signal to noise ratio _far_ outweighs any theoretical gain in resolution.


I don't want to discourage creativity.  But, honestly, when you're starting out, doing what everyone does makes a lot of sense.  It's hard enough to learn imaging DSOs using the standard methods.  Creative ideas are overwhelmingly likely to just make a hard task harder.


Honest.  <smile>  It's not a close call.

Edited by bobzeq25, 31 July 2021 - 02:57 PM.

#4 Ken Sturrock

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Posted 31 July 2021 - 03:44 PM

Aside from the above, there are two historical examples of dual-purposing a camera:


Some of the old Starlight Xpress cameras would alternate read-out lines. Essentially, it would guide with half the chip and image with the other half and then swap lines. The good news was that it could guide on the same object you were imaging (like a comet). The bad news was that imaging took twice as long because you'd long-duration expose only half the chip at a time.


The original "self-guiding" SBIGs used two chips that were mounted next to each other. It was easy to setup and worked pretty well, unless you used filters because the (typically) less sensitive and shorter exposing guide chip was forced to look through the same filters as the imaging chip. It also stopped guiding while you downloaded the imaging side of the camera (due to some shared circuitry) which could cause problems if your mount was prone to wander.


Since digital cameras have become ubiquitous, camera sensors are cheap enough that the current solution is to dedicate a camera to guiding.

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