17 replies to this topic

[mtr1]

I just acquired an RST-135E mount and one project I've planned is a revisit of deep sky imaging with my Q 3.5".  Here's M13 from last night, a nice bright target for shaking down my technique:

 

I've written a lot about guided CCD imaging with PG2, then guided and unguided CMOS imaging with PG3.  Both work, but the go-to capability of the RST-135E will make lining up invisible targets far more efficient.  This image used 4 second exposures, livestacked in SharpCap, total integration time 50 minutes.  Also first light for a ZWO ASI 533 MC camera. 

 

There are many ways to get started in astrophotography and using a 3.5" Questar is not one of the easiest.  But astrophotography extends the reach of a scope like this way beyond the solar system, and the cameras, mounts, and software available today make imaging far more feasible than 5-10 years ago.

 

 

[trentfysty]

Great pic! Do you have a duplex? If not, how did you mount it on the RST-135E?

[mtr1]

Great pic! Do you have a duplex? If not, how did you mount it on the RST-135E?

Great question; I do not have a duplex!  I realized that the RST-135E weight capacity would allow me to mount the whole unit by using a Vixen dovetail across the base.  I've locked the Q's fork declination at 0° and I've been pleased that the RA clutch is just tight enough to stay put, at least with the camera weight I've used so far (camera is in the axial port via slip-fit adapter using a 1.25" nosepiece).  We'll see if I can get away with the weight of a filter wheel (seems likely) and maybe a PowerMate (seems less likely).  I'm still experimenting with configuration options, but so far this is working a little better than I expected.  I thought the height of the scope above the mount might create polar alignment/tracking problems but thus far it's fine.  I think this approach would work with any "beefy" equatorial mount but as you know the form factor for the RST is awesome and I can get the rig in and out of the house pretty easily, even with the Q on the mount.  No fretting about balance (other than ensuring the tripod won't tip) and my Manfrotto 55 carbon fiber tripod is handling this setup without any issues.  I'm happy I finally pulled the trigger on this mount, it's adding new life to my core set of scopes but stays within my goal of optimizing the use of portable gear. 

 

[edhuff]

Very nice setup. Hefty ZWO!

Edited by edhuff, 30 May 2023 - 03:09 PM.

[mtr1]

Here it is in daylight:

 

 

I've left some, but not all cables in place.  A 12 volt battery hangs from the tripod and powers the mount and the camera.  I always have a chair or bench adjacent to the rig to hold the computer, which connects by USB to the camera, and the mount is also connected by USB cable to the camera's hub (and therefore also to the laptop).  The hand controller is also hanging from the tripod here but also rests on the bench and comes in handy -- some steps are easier to do with the hand control, some are easier with the laptop.  Once Polar Alignment and focusing are completed at the scope, I can control the laptop (and thereby the rig) from inside the house.  My key software for a capture session is SharpCap Pro using the ASTAP plate solver, and Cartes de Ciel for target selection.  I'm also using NINA for three point polar alignment -- something I've been hoping for for years since my view to the north is blocked by trees in summer.  Plate solving is essential for efficiency and performance is spotty with the Q's high focal length and limited FOV.  I'm still sorting whether I can get it to work consistently but for now my workaround has simply been to align the mount with a small refractor -- ASTAP is fast and almost magic and the NINA algorithm is well designed.  Swapping the scopes is easy enough.  I could put an eyepiece-style camera in the EP port and use the Q finder as a guide scope and may try this in coming weeks, but that adds a camera and one more cable, mildly inconvenient.  We'll see...

[trentfysty]

 

Great question; I do not have a duplex!  I realized that the RST-135E weight capacity would allow me to mount the whole unit by using a Vixen dovetail across the base.  I've locked the Q's fork declination at 0° and I've been pleased that the RA clutch is just tight enough to stay put, at least with the camera weight I've used so far (camera is in the axial port via slip-fit adapter using a 1.25" nosepiece).  We'll see if I can get away with the weight of a filter wheel (seems likely) and maybe a PowerMate (seems less likely).  I'm still experimenting with configuration options, but so far this is working a little better than I expected.  I thought the height of the scope above the mount might create polar alignment/tracking problems but thus far it's fine.  I think this approach would work with any "beefy" equatorial mount but as you know the form factor for the RST is awesome and I can get the rig in and out of the house pretty easily, even with the Q on the mount.  No fretting about balance (other than ensuring the tripod won't tip) and my Manfrotto 55 carbon fiber tripod is handling this setup without any issues.  I'm happy I finally pulled the trigger on this mount, it's adding new life to my core set of scopes but stays within my goal of optimizing the use of portable gear. 

 

 

Very creative thinking. The RST is a fantastic mount and I never would have thought of mounting a Questar that way. Looking forward to seeing more of your pics!

[mtr1]

Here's a mildly less successful M71, I had some trouble with star halos.

 

 

33 min of 4-second exposures, Q 3.5/ZWO ASI 533 camera unguided.

 

Too much Canadian smoke for imaging tonight...

[mtr1]

On Sunday night I set out to image 10 Globular Clusters.  I only shot 5 or 6 before my batteries gave out.  I'll try to fill them in as I can.  Globulars are more similar than different, although M71 above may be the exception since it's not spherical in shape.   For this series I integrated 15 minutes per cluster so that I had enough data to add a little processing cleanup, but not so much that I'd get the depth of M13 at the start of the thread.  Q3.5"/ZWO ASI 533 MC Pro (axial port, no filter, no focal reducer).  8 second unguided exposures using the RST-135E mount as described at the top of the thread.

 

M10

[Moon-Watcher]

Fantastic image. I played with contrast and blackpoint with your image on my iPhone and got this.

 

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Edited by Moon-Watcher, 03 August 2023 - 10:43 AM.

[Mike McShan]

I love globular clusters, and your images are really quite lovely. However, than can present quite a bit of variety when you go through the different Shapley-Sawyer classes.  

 

Clear skies,

Mike

[mtr1]

Hey Mike -- thanks for the tip!  I'm always pleased to learn about exploits from the Harvard Observatory in the first half of the last century.  A lot transpired then in the understanding of the universe.  From Shapley's Wikipedia bio: "Shapley fiercely critiqued Hubble and regarded his work as junk science. However, after he received a letter from Hubble showing Hubble's observed light curve of V1...he withdrew his criticism. He reportedly told a colleague, "Here is the letter that destroyed my universe." ....Hubble's findings went on to fundamentally reshape the scientific view of the universe.

Despite having earlier argued strongly against the idea of galaxies other than our Milky Way, Shapley went on to make significant progress in the research of the distribution of galaxies, working between 1925 and 1932. In this time period, with the Harvard College Observatory, he worked to map 76,000 galaxies."

Sawyer's Bio is equally interesting -- I encourage people to check out both.  "Following the expectations and work ethic of Dr. Shapley, Hogg worked hard, long hours measuring the size and brightness of globular clusters and published several papers.[3] Hogg received her master's degree in 1928 and her doctoral degree in 1931, both from Radcliffe College, as Harvard refused to award graduate degrees in science to women at the time." 

 

So here's your payoff for the cool reference:

 

M12 (archetype for Shapley-Sawyer Class IX, "Loose towards the Center")

 

Same tech details: Q3.5/ZWO ASI 533MC Pro/15 min unguided 4 -8 second exposures, processed in PixInsight

 

I suspect Dr. Sawyer would have enjoyed the lifestyle benefit of a Questar and CMOS camera... "[Sawyer] was able to continue her observation work by bringing her sleeping daughter with her to the observatory at night in a basket. The observatory's director, Dr. J.S. Plaskett, also was supportive; he gave Helen Sawyer Hogg a research grant of $200, which she used to hire a full-time housekeeper for an entire year, providing further support for her research work." 

[Mike McShan]

Another great image, mtr1. The Questar really shines with these globulars.  I also love the biographies of the pioneering astronomers, especially the women who often had to overcome a lot of obstacles to do their research.  I learned about the Shapley-Sawyer classes when I started on the Astronomical League's globular clusters observing program (still in progress). https://www.astrolea...erving-program/

[newbieskysurfer]

Hello all, Mauri has inspired me to try DSOs with the Q. Here is a first take - not perfect with some star trails.

 

Iris Nebula (NGC 7023)- 8 second exposures unguided with a Sony mirrorless (a6600) and then cropped no darks and no flats here; 49mins and reduced quality to post here

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Edited by newbieskysurfer, 17 August 2023 - 10:04 AM.

[trentfysty]

Hello all, Mauri has inspired me to try DSOs with the Q. Here is a first take - not perfect with some star trails.

 

Iris Nebula (NGC 7023)- 8 second exposures unguided with a Sony mirrorless (a6600) and then cropped no darks and no flats here; 49mins and reduced quality to post here

That's impressive for no guiding, etc. Well done. I just purchased the .44x reducer for my Q and going to try my hand at DSO with it soon. Just need the weather to cooperate. 

[newbieskysurfer]

Thank you! this a first effort at it. I did notice stars being more round in the middle of the exposure (in the uncropped) than those at the edges. 

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Edited by newbieskysurfer, 17 August 2023 - 11:54 AM.

[98105dude]

Do my eyes deceive me, or is that a Q50?

[mtr1]

Wow, the iris is a tough target so that's a terrific start!  Give yourself a break and knock off a few globulars and brighter nebulae like M27 and M57 (filters that emphasize Ha and O3 can help with these).  I can't hit the Iris from my yard (summer leaves block my view to the north) but you have your proof of concept -- if you could manage this, you'll be able to image nearly any target that fits within the Questar's field of view.  Nice going!

Mauri

[newbieskysurfer]

Thanks much! Unfortunately, my apartment balcony only has a west to north view. don't get the benefit of the many milky way targets hence not a lot of choice around globular clusters. I think I'll try M3 next though... might even be able to guide that target given the lower declination.