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A Redcat 51 comes this way... Next steps

astrophotography imaging
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#1 rcerkon

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Posted 16 January 2021 - 08:45 PM

Finally bought a Redcat 51 to dabble in Deep Sky Astrophotography. Now I'm looking for a little help developing a workflow & field craft. I've done single long exposure wide field stuff with camera & lens for a few years with reasonable success, but now it is time to step out of my comfort zone & try something new.

 

Most pressing is taking multiple images that can be stacked and post processed. How to expose? Under? Loose shadow detail. Over? Blow out highlights. There has got to be a sweet spot. What is it? How to set it up?

 

Next thing is software. I have LR/PS & Topaz(noise reduction). What Astro specific software should I consider for stacking/post processing? I have a Mac & Linux machine to run that on.

 

My imaging gear is pretty basic. Fujifilm XT-2, astro/full-spectrum modified; iOpton Star Tracker Pro; the tripod that was recommend for it at time of purchase and of course the Redcat 51. The tracker/tripod set up is pretty minimal but should be ok for starting out. I'll probably add a counterweight before long.

 

When I started wide field stuff I used a book from Alan Dyer (https://www.amazings...NightscapesBook) that walked though everything in a way that resonated with me. Maybe there is a similar book for deep sky stuff?

 

TIA for the help.

--

Rod C


Edited by rcerkon, 16 January 2021 - 11:06 PM.


#2 readkonrad

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Posted 17 January 2021 - 12:18 AM

I have a very similar set up: Redcat51, Nikon d5300, and a Star Adventurer Mini.

 

With regards to exposure, the limiting factor for us is the accuracy and quality of our trackers. Neither of our mounts can be guided (to my knowledge anyways) and no guiding means a very accurate polar alignment is required to get even 30s exposures without star trailing using the Redcat51 (because of the RedCat's longer 250mm focal length as compared to the 35mm/50mm/135mm lenses that are mainly used in the Nightscapes book - great nightscapes book btw). If I really nail my polar alignment I can sometimes get 60s subs without trailing, but most nights I'm only able to go 45 or 30 seconds with the Redcat. Given this time limitation on each exposure, ISO is the only other setting to really play with, I'm sure someone will chime in with the settings that are best for your camera. From there, just shoot as many frames as possible, and don't forget darks, bias, and flats. They are even more important in deep sky than with nightscapes.

 

Book-wise, The Deep-Sky Imaging Primer by Charles Bracken is recommended by almost everyone. I have it and it's very good. 

 

Software-wise, I use Astro Pixel Processor and a little LR/PS. APP is somewhere in the middle of the free options like Deep Sky Stacker and the gold standard of PixInsight. One great thing is both APP and PI have 30+ day free trials of the full versions.  I used some of the free software as I was first getting started, and once I felt I had enough "good" data to work with, I downloaded the free trials to see what I liked using best, I went with APP as PI was just too much of a beast for me for now.

 

One tip with the Redcat, the bahtinov mask is great for focusing but I quickly learned to give the scope some cool down time. There is a noticeable shift in focus between first taking it out and 30 mins later, much more than the camera lens I was using prior to the Redcat. And this was just from my unheated garage to an autumn evening. Hope that can save you a night of crappy focus! 

 

Have fun! 


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#3 rcerkon

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Posted 18 January 2021 - 06:37 AM

Thanks readkonrad, you nailed it, just the info I was hoping for. The Bracken book looks like just what I was hoping to find. And good tip on the cool down. I had forgotten about that, I had a Dob for a while it too needed that.

 

One question: Are you using a finder scope of any kind? After I'm past easier targets, Moon, M42...etc. Getting things aimed seems like it will be a bit of a challenge. I'm thinking a Telerad or WO Reddot Finder might be the way to go.



#4 acommonsoul

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Posted 18 January 2021 - 10:47 AM

Thanks readkonrad, you nailed it, just the info I was hoping for. The Bracken book looks like just what I was hoping to find. And good tip on the cool down. I had forgotten about that, I had a Dob for a while it too needed that.

 

One question: Are you using a finder scope of any kind? After I'm past easier targets, Moon, M42...etc. Getting things aimed seems like it will be a bit of a challenge. I'm thinking a Telerad or WO Reddot Finder might be the way to go.

Plate Solving will be the best way to go for finding targets without a GoTo mount. I have a Redcat 51 and was using it on a SkyGuider Pro. I would use my laptop and Astro Photography Tool to control my Canon T3i. Platesolving is essentially taking a picture of the sky, then the computer runs it through a star database to find where the picture is pointing. It can then show you on Stellarium exactly where you are pointed. I would do this over and over, making adjustments until it was pointed just where I want it.


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#5 AstroVagabond

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Posted 18 January 2021 - 10:59 AM

If you have the budget for the QHY Polemaster you should give consideration to doing a purchase. Also as was mentioned plate solving is very helpful. I use PlateSolve 2 through Astro Photography Tool. You can load three plate solvers through Astro Photography Tool. 


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#6 readkonrad

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Posted 18 January 2021 - 11:43 AM

Plate solving would be the way to go for sure. I’m just using a red dot finder mounted in the hot shoe of the DSLR and “manually plate solving” with high iso test images (don’t forget to turn the iso back down once you find your target!!). It works well enough for the brighter stuff but can take a little star hopping to find fainter objects.

#7 rcerkon

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Posted 18 January 2021 - 12:58 PM

If you have the budget for the QHY Polemaster you should give consideration to doing a purchase.

A cool thing for the future. I don't think my tracker can be interfaced/controlled by such a device. That said, as I ramp up on Deep Sky AP, I can see that a better mount/tracker are a high priority.

 

So many things, so little time, even less money! :-)

 

--R
 



#8 rcerkon

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Posted 20 January 2021 - 07:27 PM

Thanks to all for giving me a shove in the right direction, much appreciated. First results here: https://www.flickr.c...157717949943591 I think the results are pretty good, and they're pretty good because of you.

"a journey of a thousand miles begins with a single step", Laozi Onward!

--R

PS: getting your first decent image(s) is rather intoxicating isn't it? :-)

Edited by rcerkon, 20 January 2021 - 11:07 PM.

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#9 acommonsoul

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Posted 20 January 2021 - 07:39 PM

Looking good. Nice M42

#10 AstroVagabond

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Posted 25 January 2021 - 12:16 PM

A cool thing for the future. I don't think my tracker can be interfaced/controlled by such a device. That said, as I ramp up on Deep Sky AP, I can see that a better mount/tracker are a high priority.

 

So many things, so little time, even less money! :-)

 

--R
 

The QHY Polemaster does not control the mount. It's just an aid to get a mount aligned properly to the north celestial pole using Polaris in the process if you are in the Northern Hemisphere.

 

Here is a demo video I made if you are interested otherwise ignore. smile.gif

 

https://youtu.be/AIeJUyBCGeI

 

~ Bill



#11 rcerkon

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Posted 26 January 2021 - 09:17 AM

The QHY Polemaster does not control the mount. It's just an aid to get a mount aligned properly to the north celestial pole using Polaris in the process if you are in the Northern Hemisphere.

 

Here is a demo video I made if you are interested otherwise ignore. smile.gif

 

https://youtu.be/AIeJUyBCGeI

 

~ Bill

 

Thanks Bill, I'll keep this in mind as I move forward. Lot's of cloudy nights lately so I haven't been able to get out and practice. But what little I have done has got me leaning toward a better mount. Too early to tell for sure. The QHY Polemaster has one attractive feature, no more kneeling down to peer through an optical Polarscope. :-)

 

--Rod



#12 joeytroy

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Posted 26 January 2021 - 10:22 AM

Rod,

 

Check out the following site. He is a Mac head and has a list of all his software and what he uses, he also has a RedCat as well.

 

https://www.macobser...ronomy-software

 

I too love my RedCat and if your interested you can check out my website and see all the upgrades I have taken over the past 3 months. Right now I am waiting for some clear skies (maybe tonight) so I can take advantage of my new ASI533 astro camera.

 

https://joeytroy.com/astro-setup/

 

Best of luck!


Edited by joeytroy, 26 January 2021 - 10:23 AM.



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