M101 (but wheres the magenta??)

[Jockinireland]

So, got out again with the new rig but cloud rolled in after 2 hours on target - had been scheduled to get 5 or 6 hours but hey ho!

Not nearly enough time on the target but I gave it my best effort - probably overdone it a bit - I really need to learn when to stop. But I just kept looking for the magenta Ha patches but they are just not there. Camera is Ha modded and has shown the red in other images so i dont really get it. i'll try to add some Ha to it with my Ha clip in another day.

Anyway;
SW 80ED, SW 0.85FR/FF
NEQ6
Modded EOS1100D
Guided with SW Evoguide 50ED ZWO ASI120mm Mini
29 X240s ISO 800

Comments and suggestions for improvement, as always, gratefully received.

[dritter]

To take a wild guess, to pull out the Ha, maybe you need to expose longer?

Generally, Ha is really faint and when taking images of Ha nebula in our galaxy, my exposures usually range from ten to twenty minutes each, depending on the target and speed of the scope. That is with an Ha filter in place and on a CCD camera. So it's not really comparable.

With an OSC camera and no filter, going that long would probably just cause horrible saturation so very long exposures are probably not the answer you are looking for.

And in this case, the Ha is in another galaxy so I'm not sure how well my experience translates anyway. Still, if nobody has a better suggestion, maybe try exposing longer just to see. I did do an OSC version of this galaxy some time ago and used a mix of 5 and 6 minute exposures. A tiny bit of magenta showed up for me, but it's pretty faint and it looks a lot like flaring off nearby stars rather than Ha areas in the galaxy. Still, I'm no expert on this, so maybe it is Ha that I picked up.

[helicon]

Great little image considering you didn't get in the exposure times you wanted. Thanks for the share Jock!

[Jockinireland]

I had another go at processing this and tried to calm it down a bit. Looks better i think but still needs much more time on target.

Full res image is here https://astrob.in/e2q9je/0/

[Thefatkitty]

I really can't decide between the two, though the second does pull out the fainter details. Well done on both counts, David!

Nice to see you got some clear skies and all the best,

[Juno16]

Very nice David!

I know, it it hard to know when to stop. The only time I know when to stop is when I have really good data and the image kind of just snaps into place. That almost never happens!

I like your second version better. Did you process with Startools?

[Jockinireland]

Very nice David!

I know, it it hard to know when to stop. The only time I know when to stop is when I have really good data and the image kind of just snaps into place. That almost never happens!

I like your second version better. Did you process with Startools?

Hi Jim

i started in Startools but really was not getting anywhere good so went back to PS - the first is what came out of that. I was not satisfied with that so went back to startools, took some more time and care, tried more parameters and ended up with the second version which I think is better. I'm still not wholly satisfied with it but that I think is the shortage of integration time really and i wont improve it till I have more data.

Take care

David

[chartram]

Nice image David!

it looks to me like it is slightly out of focus, which could be a factor in pulling the more subtle colors out. If you do not have an autofocus, I would recommend using a Bahtinov mask with the Bahtinov Grabber or similar freeware to get all the way into the CFZ. Also, re-focus every 1.5 or 2°C as focus will change with temperature. Hope this helps!

Mike

[Larry 1969]

That's a pretty nice M101 with only 2 hours on target!
I have a pretty fast set up (F4.1 after the come corrector) and I was able to get 1:45 on this the other night and I wasn't happy with it.

Larry

[Jockinireland]

Nice image David!

it looks to me like it is slightly out of focus, which could be a factor in pulling the more subtle colors out. If you do not have an autofocus, I would recommend using a Bahtinov mask with the Bahtinov Grabber or similar freeware to get all the way into the CFZ. Also, re-focus every 1.5 or 2°C as focus will change with temperature. Hope this helps!

Mike

Hi Mike,

Thanks for this. Yes I do see what you mean. But I did use a Bahtinov and the Bahtinov tool in APT. But I really struggled to get it to settle at "in focus" - it was moving around +/- 0.02 - 0.04 or so from 2in focus" to "focus is close". I was putting it down to seeing although I was stacking a good number of images (right up to the max 40) within the Bahtinov tool. This was my very first time using the Bahtinov with this set up and I thought it would be alright.The scope had several hours out before this run started andthe temp was not really changing that night over the minimal capture period so I dont think that was a factor this time

Anyway, thanks for your observation- I'll need to work harder on focus next time.