Bloated SCT stars - tips for processing?

Heather,
This is a hobby that really benefits from OCD.   Everything counts and it's the sum of the parts that make up the final result.  Here are some things that can contribute to less than perfect results.  

1) Optical quality.  First, the base optics need to be of high quality and second they need to be well aligned.   Using a reducer can work but in general, reducers are likely to produce poor results at the edge of the field.   My recommendation is always to start without a reducer to get everything dialed in.  That reduces the number of variables when you need to figure out why things aren't as sharp as they should be.  The other thing that affect optical quality is component spacing.  Have you confirmed that the sensor in your camera is properly positioned with respect to the specified back working distance?  Finally, it doesn't take much misalignment to seriously degrade optical performance.  Be VERY careful to make sure the secondary is properly aligned.  A misaligned secondary will produce coma and I don't see much coma so that may not be an issue with your system.

2)  The number one thing that causes poor imaging is a focus error.  Using a B-mask is a great way to focus and if you are using it properly, you should be getting pinpoint stars.  Zoom way in on the pattern and very carefully center it to insure perfect focus.  Thermal drift can cause your scope to change focus significantly so it's important to check focus frequently.  Your images looks mostly out of focus to me.

3) Guiding errors can cause enlarged stars.  Your stars should be circularly symmetric over the field and clearly that's not the case so you've most likely got a guiding related error.  Polar alignment can cause this sort of problem with longer exposures.  Mechanical vibration can also cause elongated stars so make sure that the scope is mounted on a solid surface.

With the short exposures that you are using, you should definitely see pretty sharp stars in the background when everything is properly adjusted and the guiding is good.  Keep in mind that really poor seeing can also cause soft star images but even on an average night an 8" telescope should be able to deliver sharper images than what you are showing here.

John

8 sec is too short for any good images. If you are going to go with the AZ mount you will need a rotator such as the pegasus so you can get 1-3 min exposures. If polar aligning is not a big obstacle, then look for a wedge for your mount. that would be cheaper and arguably better. I see a number of them on cloudy nights. I like the AZ mounts on a wedge because there is no meridian flip.
And like others said, you need good focusing. Best would be to use an electronic focuser such as the ZWO. This is an expensive hobby you have chosen…

Good luck, I think you will be pleasantly surprised.

I'm also completely new to this hobby and using a comparable setup: NexStar Evo 6 and a Canon R7.
I also purchased the wedge for longer exposures, and the SSAG.

The SSAG does an incredible job at correcting tracking issues.
It really helps to have good stars. So definitely give it a go!

I also recently considered back-focus, and added a spacer to my imaging train.
This helps correct stars on the edges. You may want to check if yours is appropriate.

BlurXTerminator from RC Astro is also really good for post-processing: https://www.rc-astro.com/software/bxt/
It's a PixInsight plugin. If you don't use PixInsight, maybe there's other similar software.

@Jean-David Gadina  I would LOVE to get a SSAG, but it’s a bit out of the budget right now. I also confirmed that my back focus is dead on with the reducer, t-adapter and camera.

For the post-processing steps, try doing a background extraction first (with GraXPert or DBE/ABE), and then run BlurXterminator with 'Correct Only' selected. That always helps my star bloat, especially with my 8". Then I run SPCC followed by a full BlurXterminator again to sharpen stars and non-stellar. There are a number of experts who I've picked this process up from and it really works wonders. 

Hope it helps.

I’m using a 60mm guide scope with a Svbony sv305 pro and PHD2 to run the autoguiding.  Tonight was actually my first night with the wedge and autoguiding setup. Prior to this I was just tracking in sidereal with the NexStar alt/az mount. This kept my subs limited to 8 seconds before the stars started to trail. Things didn’t work out great tonight unfortunately. I was battling clouds and wind and couldn’t get auto-guiding to run for more than 3 minutes before it would lose the star. Had to eventually accept the fact that I can’t control Mother Earth and that there will be more clear nights eventually.

Here’s Orion before I got the reducer. 

The stars all show severe coma, especially on the right side. Most likely your collimation is way off. That would explain the lack of sharpness with the reducer.

Victor Van Puyenbroeck:

Here’s Orion before I got the reducer. 

The stars all show severe coma, especially on the right side. Most likely your collimation is way off. That would explain the lack of sharpness with the reducer.

That was before I added the reducer and before I learned how to collimate. I had the telescope for about 2 weeks when I took it.

Arnie:
Since you are using Photoshop, one thing you can do to rescue the data you already have is to use the Spherize filter. Use the elliptical marquee tool to draw a small selection circle around a bloated star. Then go to Filter -> Distort -> Spherize. Move the slider all the way to -100. Voila! A smaller star. Repeat as many times as you need to or until your patience runs out. This should be one of the last things you do, as the image needs to be converted to 8 bits for this filter  to work (at least in my older version of Photoshop - newer versions may allow this filter to work on 16 bit images).

Arnie

StarShrink from Russ Cromann is cheap and does this automatically…for all the stars.

Software tools can fix a lot of defects in an image but it’s always better to fix the optical-mechanical issues before resorting to software fixes.

John