35 replies to this topic

[mtr1]

Here's a galaxy I haven't done before; it's small and faint but a beautiful pinwheel -- M99.  My mono cam/ LRGB filterset enabled me to get a respectable image from the Q but lots of effort was involved.  Then again this thing is about 50 million light years away so it's a little mindblowing to get any sort of image from my own little scope in my own backyard. 

 

 

Tech Stuff:  Questar 3.5" mounted on RST-135E/ ZWO ASI 533Mono /8- 10 second unguided exposures L X 80min, R, G, B X 30 min each.  Processed with PixInsight.  From my Bortle 7 yard in Westchester County, NY, 10 miles north of NYC.

 

Cheers,

Mauri

[mtr1]

I haven't finished fooling around with my Q mounted on my strainwave mount.  We've had dreadful weather for imaging (a layer of snow in my yard which refused to melt followed by generic bad weather).  We had a couple of good nights so I decided to revisit M63, the Sunflower Galaxy, just with a simple mono capture for efficiency's sake.  I had to clean up some messy gradients from a bright moon and less than pristine optics but I think I got a decent shot of the galaxy.  ZWO ASI 533 mono; 2 hours of 8-second exposures.

 

 

Clear skies, 

Mauri

[CGN36]

Wow Mauri!  The details in the "petals" of the Sunflower Galaxy are incredibly delicate and detailed.  Was this unguided on your RST-135E as before?  If so, that's fantastic.  I was under the impression that one needed to guide strainwave mounts because of their non-periodic behavior.  Or are the 8 second exposures short enough to avoid those kinds of issues?  I'm still doing the "easy" planetary high speed frame rate captures and look forward someday to taking the DSO plunge with my Questar (beyond the blurry livestack exposures I only seem capable of capturing today ;-)

[mtr1]

Thanks!  The "E" in RST-135E means this is an encoder model, which followed the initial strainwave implementations for which people complained about periodic error.  They're more expensive but track nicely.  That said guiding could still be useful for long exposures if you haven't eliminated tracking error from imperfect polar alignment.  I do have mild drift during capture which is obviated in the images by using the short (8-second) exposures.  SharpCap also recenters the mount so the target stays in frame pretty long, although for this image I did an additional manual recentering just about every half hour.  Remember the mount can handle a lot of weight for its size which I"m taking advantage of by mounting the whole Q, base and all.  This works but with the axis of the optical tube elevated from the axis of the mount, I don't think I can completely eliminate tracking error.  

 

The mono camera with no filters gets a decent amount of "signal" with the 8-second exposures, even with the f/15 Questar.  So I wasn't surprised to see the detail in the galaxy arms.  I have used BlurXterminator (which is an AI-enhanced deconvolution engine, now considered a standard step in deep sky imaging) and it makes short work of rounding up and de-bloating the stars and bringing out detail in nebular structures.  What you're not seeing in the final processed image is a lot of nasty gradients from the bright gibbous moon, and dust-donut type artifacts which I couldn't eliminate with flat frames.  Each 5-minute livestack shows the galactic details but it's kind of a noisy, smudgy mess.  Even after stacking 25 of them I only achieved a clean and pretty picture by using intermediate level processing skills with ever-more-powerful PixInsight.  I don't want to mislead anyone about deep sky imaging with the Questar -- it's feasible but if you don't already have some image capture and processing skills it's going to be inefficient and frustrating compared with using more conventional (typically faster focal ratio) gear.  If you have the skills or the desire to learn and use them, then adding a CMOS camera and shooting at Messier-level objects can be a fun way to extract more value from our small but capable Questars.     

 

Best, Mauri 

[CGN36]

Thanks for painting a realistic image of the amount of work required to tease out decent images from a scope that really was not designed from the ground up to be a DSO imaging tool.  My hat off to you, Bob Vanderbei and others who have nonetheless pulled off incredible DSO images with the Questar.  Eventually, I'll get there, but your sage advice of getting the basisc DSO image processing skills on a more forgiving instrument is how I'll start.  In the meantime, I'll continue to work on my planetary captures with the Questar frustration free ;-)

 

Regards,

Frank

[mtr1]

Ten years ago I was struggling through my first year of astro imaging with my Questar and I set up one April night to try to find M51.  Within a few weeks I succeeded with what still looks like a pretty decent image, see this link in Flickr if interested.  On my first attempt I struggled with the balance of the scope and lost my bearings in the sky pretty badly.  When I was about to give up for the night, my guide camera (piggybacked on my Q) was showing a galaxy in PHD and I rattled off a handful of 5-minute exposures through the main mirror.  Processed as best as I could manage it looked like this:  

 

 

With a bit of research I concluded that I'd missed M51 by a considerable distance, and instead I had bagged M106.  I also learned about a light leak I'd need to close off before going after other deep sky targets. 

 

Last night I used the same approach as I did for the Sunflower Galaxy above and shot 100 minutes of M106 on purpose.  I guess I have learned a few things over the past decade:

 

That's my Q3.5"; ZWO ASI 533 mono; 100 minutes of unguided 8-second exposures using my RST135-E mount. 

 

For fun, it's easy to annotate images with SharpCap, PixInsight, and other software -- this is from the script in PixInsight which I used to save me the effort of looking up the companion galaxy:

 

 

Clear skies... Mauri

[newbieskysurfer]

Amazing Capture!

[CGN36]

Thanks for sharing Mauri.  It really is wonderful knowing that our little Qs can pull out DSO images like yours in the hands of skilled experienced hands!

[mtr1]

I really wanted this to be the foundation of an LRGB image, but the forecast is for cloudy nights through the end of April (at least...)

 

Q 3.5/ZWO ASI 533 Mono/ RST-135E/ 85 min of 4-second exposures 

 

I hope your skies are clearer than mine!

Mauri

Edited by mtr1, 19 April 2025 - 05:27 PM.

[CGN36]

Worth the 10 year wait to find M51, Mauri  ;-) LOL

 

I really drawn in by the classic black and white rendering mixed with the modern imaging techniques of 2025 to capture such fine swirling details and extended delicate nebula.  All that from the dimunitive Q.  Amazing!

 

Thanks for sharing and hoping your skies clear sooner rather than later,

Frank

[newbieskysurfer]

Mauri, these galaxy images are getting better and better!