TheSkySearchers

I surely needed to get out last night and I had a great time trying out my new Stellarview field flattened/0.80 focal reducer. I anticipated some issues with plate solving and/or focus and had none.

Guiding was good at an average 1.1 arcsec total rms error in PHD2 (good for me).

Shot 240 second lights with my Ha modded D5300 at iso 400 with an IDAS LPD-D1 filter (about three hours total integration).

I am happy with the image. Definitely pleasant enough and possibly on the bluish side, but a big improvement over my first time imaging M13.
There are some things with the image I would like to improve on next time and hopefully some of you experienced imagers might be able to help with some suggestions.

First off, I somewhat blew out the core. Apparently, 240 seconds at iso 400 is too much exposure. The histogram peaks in APT were in the first and second sectors from the left which are below recommendations in the APT manual. Perhaps 120 second lights?

The other thing is that some of the stars in the corners are slightly non- homogeneous in color. I did check the camera and there is a significant amount of flexure at the t-ring possibly causing the camera sensor not being perfectly perpendicular to the imaging train. Possibly a contributor to the corner star color?

I will tell you though, that this is the flattest image that this rig has ever produced by far! I feel like the FF is doing a great job. When I compared these light frames to light frames in other sessions (with no FF/FR), the corner stars are beautifully round and don’t look like flaring comets as before!

If you have any suggestions please comment and thanks for looking!

Jim - I like the color you have pulled out and you got a long way into the core from what I see. Some people treat globs as HDR images using shorter subs to bring out the core details and longer ones to get at all the faint outer details.

The color fringing looks a little more pronounced to me on the left side of the image than the right. Maybe that is an indicator of some tilt, as you suspect?

Bob

That's a great one Jim!

Hi Bob and I appreciate your comments/observations.

Yes, I took this target too lightly and an easy catch, but didn’t anticipate the brightness of the core. Sure does sound like an hdr approach. I will try that next time.

I just dug around in my box of “junk” and found another t-ring. It fits much tighter on the camera and has far less flex than the t-ring that I used last night. Thanks for your thoughts that this could be the cause of the corner star color issue.

I really appreciate your thoughts sir!

Great capture Jim, I bet it felt good to get out there under the stars. The frame looks very flat, good job on choosing the right equipment!

Very Nice, Jim!

That's a great M13 Jim.

The star colours are really nice. I always like that star colour difference of the two nearby stars. I'm not sure it's overexposed, the core is very dense.

And you caught the propeller very well too!

Regards

Graeme

Nice shot Jim, expanding it out the core looks very reasonable to me.

Nice capture Jim! Great star colors. That FF/FR is working nicely for you.

Very nice capture

Mac wrote: ↑Fri Jun 12, 2020 12:45 pm Great capture Jim, I bet it felt good to get out there under the stars. The frame looks very flat, good job on choosing the right equipment!

It sure did! Unfortunately, it was near 80F and the mosquitoes were pretty active.
After starting the session, I only went out to check for cable snags and watch the flip.
That ASI EAF is great! Running a focus routine within the imaging fov from inside is super!

I was really happy with the flatness of the field. BTW, removing one of the three 2” focus extensions and dropping in the FF/FR was almost in perfect focus (+/- a few mm on the focuser). Looks like I now have a F5.6 at 571mm scope! Some day, I will probably buy the Stellarview field flattener to get the 714mm back for smaller targets.

Thanks Steve!

jerrysykes wrote: ↑Fri Jun 12, 2020 12:57 pm Very Nice, Jim!

Thanks Jerry!

Graeme1858 wrote: ↑Fri Jun 12, 2020 1:10 pm That's a great M13 Jim.

The star colours are really nice. I always like that star colour difference of the two nearby stars. I'm not sure it's overexposed, the core is very dense.

And you caught the propeller very well too!

Regards

Graeme

What is the propeller? Is that NGC 6207?

I saw another much smaller galaxy closer to M13 and looked it up in SkySafari. It is IC4617 at +15 magnitude and a distance of 503 mly!!! Wow! That probably the furthest galaxy I’ve captured.

Greenman wrote: ↑Fri Jun 12, 2020 1:14 pm Nice shot Jim, expanding it out the core looks very reasonable to me.

Thank you a bunch! I appreciate your nice words!

ic_1101 wrote: ↑Fri Jun 12, 2020 2:27 pm Nice capture Jim! Great star colors. That FF/FR is working nicely for you.

Thanks Alex!

The image really looks cool on my iPad in a dark room. Like a porthole into space!

Dragonsfire wrote: ↑Fri Jun 12, 2020 3:08 pm Very nice capture

Thank you!

Juno16 wrote: ↑Fri Jun 12, 2020 3:48 pm

Graeme1858 wrote: ↑Fri Jun 12, 2020 1:10 pm That's a great M13 Jim.

The star colours are really nice. I always like that star colour difference of the two nearby stars. I'm not sure it's overexposed, the core is very dense.

And you caught the propeller very well too!

What is the propeller? Is that NGC 6207?

I saw another much smaller galaxy closer to M13 and looked it up in SkySafari. It is IC4617 at +15 magnitude and a distance of 503 mly!!! Wow! That probably the furthest galaxy I’ve captured.

Not sure what NGC6207 is. IC4617 is the faint galaxy in the background, which you also captured.

The propeller is a three spoked (it that a word?!) shape which sits off center in the core. Don't know what causes it! If you click on your image and then zoom in on the core you will see it. If nothing else it's a sign of a well defined image! If you don't see it straight away, then stare at the core for a while like those 3d pictures and it will come to you!


Regards

Graeme

I love the colours in this one and the sundry tiny galaxies - beautiful.

Ian

That's a beauty! Congrats

Kanadalainen wrote: ↑Fri Jun 12, 2020 5:39 pm I love the colours in this one and the sundry tiny galaxies - beautiful.

Ian

Thanks Ian. I wanted a second try at this one and am happy with it. Looking forward to the next attempt. Hopefully I can control the core better.

SkyHiker wrote: ↑Fri Jun 12, 2020 7:26 pm That's a beauty! Congrats

I really appreciate it Henk. Thanks!

That’s a lovely M13. I don’t think you blew out the core at all. You have good detail all the way in to the centre.

You might want to try some sharpening, to lessen the blobbiness of those bright stars in the centre. You can enhance contrast there by very careful tweaking of the curves tool. Take your time to find the brightness level for that area, and then tweak only that level, in small increments. The data looks like it will support that kind of tweaking.

KathyNS wrote: ↑Fri Jun 12, 2020 9:48 pm That’s a lovely M13. I don’t think you blew out the core at all. You have good detail all the way in to the centre.

You might want to try some sharpening, to lessen the blobbiness of those bright stars in the centre. You can enhance contrast there by very careful tweaking of the curves tool. Take your time to find the brightness level for that area, and then tweak only that level, in small increments. The data looks like it will support that kind of tweaking.

Wow, thank you Kathy!

Your M13 image is phenomenal!

I have not done any sharpening at all. Just a basic process through Startools and saving the tiff as a jpeg in PS. I will certainly try the suggestions that you mention in Photoshop.

I really appreciate your comments about the core. I feel that the "sweet spot" for my system (and equipment) is 240 seconds at iso 400. The histogram was on the low side (less than 1/4) even considering the focal reducer drops the F ration from 7 to 5.6, so I wanted to somewhat control any clipping that might occur.

Thanks again for the very helpful tips!

Hey Jim,

Love the image. I've been trying with mixed results to get more data on this one. Been fighting smoke blowing up from Mexico. Let me know if you take a run at isolating the core. So far I've been imaging at 60sec with my 294mc. I've been thinking about trying 120 or 180s but like you am worried about blowing out core. This is such a pretty object and also seems to offer a good post processing learning opportunity.

--Steve
(PS - here's what I've got so far) - about 2 hours worth of 60 second subs.

starfield wrote: ↑Fri Jun 12, 2020 11:19 pm Hey Jim,

Love the image. I've been trying with mixed results to get more data on this one. Been fighting smoke blowing up from Mexico. Let me know if you take a run at isolating the core. So far I've been imaging at 60sec with my 294mc. I've been thinking about trying 120 or 180s but like you am worried about blowing out core. This is such a pretty object and also seems to offer a good post processing learning opportunity.

--Steve
(PS - here's what I've got so far) - about 2 hours worth of 60 second subs.

Our images show a lot of resemblance! Your core is somewhat better controlled though. I remember when you posted that image. Very, very nice!

I am imaging for 240 seconds, though with a Ha modded dslr and through a IDAS LPS-D1 LP filter in Bortle 7 skies.

Got a busy weekend, but I am looking forward to trying out Kathy's processing recommendations. I just recently subscribed to PS and I am just beginning to learn. This will be a good learning exercise!

Thanks for the nice words!

Nice capture Jim! I like the colors and details. You have even resolved the core in NGC 6207 "satellite" galaxy.