First time imaging Ha - tips/suggestions?

[Drac0]

Well I got myself a 7nm Ha filter & with MAYBE the chance of a few hours of clear sky & the full moon over the weekend I was thinking of giving it a go. But never tried it before so any tips & suggestions would be welcome.


My intended target is M20 - the Trifid Nebula. I do have a few of questions to get started.



1. Where to position the filter, close to the sensor (I have a ZWO adapter to put it right up close) or further out on the scope side of the flattener/reducer?
2. Going to also be capturing it with an OSC and combining them in post. What sort of integration time ratio should I be looking for? Say I do 4 hours OSC, how much time would be suitable for just Ha?
3. In regards to exposure time, do I keep them the same for both OSC & Ha, or should I do longer/shorter Ha subs.


That will do foe a start.


TIA!
Mark

[Startrek]

Mark,
With my experience imaging the Trifid over the past 2 years with my 2600MC OSC I found that no filter and no moon around works best in darker skies to bring out all three types of emission in this object ( Ha ,Dark and Reflection nebulosity)
My 2600MC just has an internalUV/IR cut filter as it’s protective window.
But that’s not to say don’t use the Ha filter , it all depends on your cameras ability to pick up that wavelength. Even with the Bayer matrix on my 2600MC this camera picks up quite a decent amount of Ha for an OSC

This image was captured from my South Coast Obs using my 8” f5 newt and 2600MC OSC (no filter ) on a moonless night last Winter.

From memory I think I used the following technical card -
3 minute dithered guided subs
Total integration 3 hours
Gain 0 or highest dynamic range
Camera cooled to -10C
No calibration frames although I should have taken and used them
Stacked in DSS
Processed in Startools V1.7

PS: I also used my old DSLR prior to owning the 2600MC and again used no filters , just a dark moonless night and plenty of good data, the DSLR use to produce a fair image but noting like the 2600MC , chalk and cheese

IMO try capturing data with and without the Ha filter ( can’t help you with spacing etc... ) that way you have more options in post processing

Good luck

I’m heading down the coast on Saturday for 2 weeks , hope to get some clear nights after a horrible 6 or 7 months

Cheers
Martin

[Startrek]

Mark,
I just checked the specs on your 224MC ( if that’s what your using ) and it’s more of a dedicated planetary colour camera with only a AR protective window , so using no filter probability won’t work.
Personally I’d gather data with both a luminance filter ( if you have one as it’s similar to a UV/IR cut filter ) and the Ha filter too.

Any thoughts of upgrading in the future to a cooled OSC with larger sensor ??

Cheers
Martin

[Drac0]

Hi Martin.
Great capture. I am looking forward to imaging under dark skies but you may have noticed our clear nights seem to be syncing with the coming of the full moon for some time now. I have heard you can get good Ha data even with the moon out, so going to try if it's clear.

Yeah, the 224MC is mainly a planetary camera but I do find it useful for smaller DSO compared to a DSLR, adding either the UV/IR cut or L-Pro filter depending where I am & how dark it is. I actually haven't got around to imaging with just the cut filter from here in town yet - the moon is always there. I am saving for a 533MC Pro with a sensor size in between the 224MC & DSLR then maybe a larger sensor later, after a new mount!


Cheers,
Mark

[Startrek]

Mark,
All sounds good to me
The 533MC is a great camera too
You just have to check your FOV and image scale with your scopes
If I can give you a strong recommendation for a mount upgrade ( up to 15kg AP payload ) you can’t go past the EQ6-R pro ( I’ve owned 2 off them for nearly 3 years now ). IMO the best 20kg class mount in the world under $3K
Hope we all get some clear nights

Cheers
Martin

[Drac0]

Martin,
FoV & image scale seems good with both scopes with the 533MC. And the EQ6-R Pro is my hoped for mount, though the way my saving progress is going I might need to pick up a 2nd hand HEQ5 as an interim mount otherwise I might be stuck with the EQM35 for too long. :D

Clear skies,
Mark

[Drac0]

So much for that idea, mount died tonight. RA motor won't operate correctly, I think it's the controller as I swapped the motor (and cables) with a spare I had & both do the same - no way they could both crap themselves on the same night...oh well, a lot of early nights ahead... :mad2:

[Startrek]

Sorry to hear the bad news , hope you sort things out soon
You didn’t miss anything last night , I’m down south on the coast at my Dome, seeing was poor as there was a heavy dew early so guide Star was bouncing around. Couldn’t get below 1 arc sec Ra and Dec saw toothing. At 1.00am guiding was 1.30 to 1.40 with some jumps, not good .........
Stars were round but fat
I think same scenario tonight