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1st Adventure in Dual DSLR Imaging and please vote for the best photo version.

refractor observatory imaging/sketching contest imaging dslr astrophotography
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#1 skycamper

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Posted 12 December 2018 - 10:01 PM

 I had three friends process NGC 2023 (horsehead neb) Please find the links to the three versions at the end if you want to skip the reading!!  Then please vote by responding to the best rendition.  It would help me alot to pick one so I can frame it.   Please ignore any stacking artifacts on the edges. I'll crop those out.

 

So decided to see if I could do some dual dslr imaging. The last three nights ending on 12/6 were very clear and cold in Portland Oregon. I really figured that I had to since I am not able to get to a dark sky often because I have a wife and 2 small kids to be home for.  This was the same reason that I needed to build the observatory to maximize my time spent observing and imaging rather than breaking down and setting up constantly.  In this respect, im always able to be ready to go and with dual cameras.  It took a bit of time to get here acquiring the bits and pieces but here we are.

Id like to thank my best bud Casey Robbins for helping me build the observatory and for processing my images. I dont process images.  I like to take them and then have others show me whats in there. Its like Christmas morning everytime I get a decent image!  

 

This set up is 50lbs exactly and I put it on a NEQ6 that I bought used with a belt modification and improved Axiom wedge.  This is housed in an dome on a 8" custom pier J-bolted to 2,200 lb reinforced concrete plug.  This was not first light for the dome or pier BTW, my previous dual imaging run failed due to various problems.  . . . Therefore:

Heres what we have now:

  • Two SV105T Triplet APO's  Focal length 735mm (F7)
  • Two H-Alpha mddified Nikon DSLRs.(D5300 + D5500)
  • Two IDAS D1 LP filters, one clip and one 2" mounted.
  • An orion 60mm guider with a ASI290 mini guide camera.
  • Backyard Nikon for capture (BYN premium) you can use two cameras and Dither !!
  • A losmandy side-by-side dovetail with an ADM max guider. 
  • The two telescopes are the same field of view and the same camera sensor. Makes for easy stacking in Deep Sky Stacker!

Which leads me to the next subject!  Guiding,   at 735mm the focal length is more forgiving than my C11.  Im able to achieve a polar alignment within 1 arc min using Sharpcap 3.2.  Which I recommend.   Unfortunately due to the massive amount of gear and despite very good balance I still cannot guide the scope well in DEC.  This means I keep DEC guiding off for now or I guide in one direction and then I leave the RA aggressiveness low about 40-50 in pHD2. This give an acceptable result but I still have to discard about 5-8% of the subs due to egg shaped stars especially when the scopes have passed the meridian  I need to upgrade this mount in other words but I feel my skill level does not warrant it. I still do not use plate solving, auto focusing, pulse guiding, or filter wheels.  

 

 

Its been hard getting all the flexing out of the system, mostly from cables tugging on the guidcam I think. The USB is now moved to a Hub mounted with zip ties to the telescope on the right. The ST4 cable could be eliminated if I moved to pulse guiding.  Dont know how yet.  Both cameras go to the hub though USB, that solved some problems as did using battery grips instead of a power source with a cord.  The battery grip contains two fully charged batteries which last until 4am or about if I go that long.

 

 

Typically with one telescope on a decent night I can pull in 1.5 to 3.5 hours of data. Especially in the winter with long nights. But summer is less, 1 to 2 hours.  With the dual imaging rig it seems with only two or three imaging runs I was able to get 5 hours a night and a total of 15 hours.  I could have gone way past that but I stopped imaging at 2:15 am each night because I needed at least 3 hours of sleep to wake up at 6am for work, wife, kids, etc. yes I was a zombie for the whole week but the test was successful despite the bad guiding.

 

 

I started DSLR imaging in 2012, after all this time I dont do image processing, just some basic stretches in photoshop and such to check to see that my data is clean. Then I send it off to my buddies on Coudynights.com or Casey  for processing.

This leads me to how I stacked all that data which was difficult for someone without a lot of computer knowledge.  Deep Space Stacker has a function where you can dump into something called groups which are tabs at the bottom of the main page.  Its very simple,  I just dump all my lights, darks, dark flats into one group for one camera. So in this case it was three nights, with two cameras.  Each camera had calibration frames for each night which means 6 different groups.  DSS stacks everything and I usually ask it to stack the best 95% because I usually screen all the subs for defects. I use the recommended settings and click the box (use camera white balance). You have to be organized here because you dont want to mix up the frames from either camera otherwise youll probably have a terrible result.

 

 

I was told/suggested from an expert imager that I would not be able to stack different nights data from different cameras in DSS due to differences in sky conditions from night to night, at least without introducing weird noise problems into my data.  That, by the grace of God did not happen here.  Each camera on each night had its own set of darks, flats, and dark flats.  I did not use Bias frames at all.  Dark flats contain enough bias to be subtartced out.  But it could have easily gone the other way and I would have ended up blending three files together from the three nights.  In this case DSS was perfectly able to stack the frames.

 

 

Some things to watch out for:

When doing flats I messed up.  I've had good results by just holding up my laptop screen To the telescope to take my flats,  So that's what I did In this case,  However, I forgot to turn off my headlamp and so the red light Somehow got into my flat while I was holding the laptop up to the lens of each scope. There was this green cast on one side of the image. The green cast went away when I restacked the image without calibration frames. I doubt it could have been my darks or dark flats for that matter. These images are only from calibrated lights BTW.

 

 

Careful aiming the two scopes AND guide-scope at the same target, 

 

Having an inadequate mount.  At my skill level this mount is more than enough. Unfortunately, for what I want to do here and for how perfect I want my stars I need a premium heavy duty mount and thats a AP Mach1 for me which is still portable and can be pushed to the limit.  Does anyone think a Mach1 would have any troubles with this?  Especially when Im getting usable results with this NEQ6?

 

 

So having said all that id like to get to the results of the following data and get a vote on best rendition:

NGC 2023

221 x 180" and stacking 95% of the best subs in DSS.  Each nights camera was stacked with its own darks, flats, and flat darks, no bias was used.  DSS blends all the stacks together for you.  This resulted in an image that had an integration time of almost 11 hours.  I think you have to Control click to see the photos. 

 

Version 1  https://flic.kr/p/2dpu5wo

Version 2  https://flic.kr/p/2c73uM2

Version 3 https://flic.kr/p/2c73wUP

 

I'd really like to know what other think about dual imaging.  Especially what you think about this data from a red zone with OSC imaging with DSLR's Thanks for reading!

 

Dual imaging.jpg


Edited by skycamper, 12 December 2018 - 10:03 PM.

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#2 james7ca

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Posted 12 December 2018 - 10:22 PM

Probably version 1 but the background appears a little too dark. What I'd like to see is something between versions 1 and 3, since #3 seems a little over stretched or processed.


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#3 pedxing

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Posted 12 December 2018 - 10:23 PM

Version 3


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#4 17.5Dob

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Posted 12 December 2018 - 10:30 PM

1/2 way between 2 and 3.

2 is not quite enough and 3 is too much.


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#5 gcardona

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Posted 12 December 2018 - 10:47 PM

I think each has its own merits. I would register them and add them together and see what the result looks like.



#6 mikewayne3

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Posted 12 December 2018 - 10:51 PM

3 hands down


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#7 Traveler

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Posted 12 December 2018 - 11:04 PM

Yep, the 3th.

Nice dual by the way!


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#8 Melgabean

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Posted 12 December 2018 - 11:47 PM

See I like 2. It feels to me like a more natural color. Dual imaging, Genius!
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#9 Craig H

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Posted 13 December 2018 - 12:07 AM

V2 all the way!


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#10 Jim Waters

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Posted 13 December 2018 - 12:07 AM

Halfway between 2 and 3.


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