Imaging dark/reflection nebulae Q's - Forums

Topic starter

Jul 29, 2023

Howdy all. I'm wondering what the best process is for imaging non-emission nebulae with narrowband, where they are in proximity to emission nebulae. Is it lots of exposure time for LRGB? LRGB for nebulae which would blow out stars and then take star subs separately? Am I off track? Be gentle, I've only taken one image so I have a LOT to learn lol.

Thx,
Sean.

Respectful Engaging

Rob

Jul 29, 2023

I haven't done this with my mono camera yet, but you don't want to expose as long as you do with narrowband (SHO) filters. It's going to depend on the quality of your sky background on how long you can expose in LRGB for. The idea is to go long enough to make sure the background noise swamps out the digital read noise of the camera, but not so long where the background noise is overwhelming the signal you're wanting to collect. For these objects, dark sky is more crucial I suspect. I've imaged a very dim dust cloud in a Bortle 4 and it was a little strange not seeing any of the target in a single exposure!

What software do you use for acquisition/imaging?
What Bortle zone are you doing this from?
What camera and telescope are you using?

Helpful Respectful Engaging

Sean Mc

Topic starter

Jul 29, 2023

Bortle 8 :/
asiar plus. Askar 65phq, asi249mm pro.

Rob

Jul 29, 2023

Ooof. I'm not sure how much success is possible from a Bortle 8 on Dark Nebula. I know you can get some of the dark dust clouds in front of the Milky Way, thanks to the plethora of background stars. I will defer to the experts and those with experience imaging these things. I've had a terrible time trying the Iris in a Bortle 6…

Well Written Respectful

Gabriel R. Santos (grsotnas)

Jul 30, 2023

To image dark nebulae well you must get darker skies and integrate a lot of broadband data. Bortle 5 minimum, Bortle 3 or darker desirable. You would then shoot at least 2 to 4 hours of LRGB. The proportion of L to RGB is endlessly debated, but in theory you could get good results faster by shhoting more L. Some advocate pure RGB as well. In any case, narrowband filters are generally avoided (unless in the special case of highlighting background emission around a dark nebula).

As for star bloat, I personally think lots of people worry too much about it. If you shoot from high LP, you will see that going to darker skies help a lot with it. And in any case, I think it should be the least concern, especially with modern CMOS sensors.

Helpful Concise

John Dziuba

IOTD Staff

Jul 30, 2023

I agree that dark sky is crucial. Otherwise the sky glow noise robs you of the fine detail and washes out the image. I only image narrowband from my B8 home site. I gave up on broadband early on. Eventually, I graduated to remote imaging from ideal dark sites which opens up the broadband world.

CS

Sean Mc

Topic starter

Jul 30, 2023

Well that sucks. Thanks for the responses! I might have access to a B2 site occasionally. I guess I’ll have to plan imaging time for when i can get there.

Well Written

Ashraf AbuSara

Jul 30, 2023 · Edited: Jul 30, 2023

For Dark / Reflection nebula you need to use broad band imaging with either LRGB with mono system, or just UV/IR/ Broadband filter with OSC. I have imaged it from my Bortle 6/ Bortle 7 back yard in LRGB with a monochrome camera. The raw data looks good but my processing needs more work. I would definitely choose a moonless night to image this. You don't want to fight light pollution and the moon when imaging this.

Bear in mind my post processing skills are quite rudimentary. Still need to learn how to use masks better, so I think a lot more can be done with this image.

https://www.astrobin.com/zn3lt8/

Helpful

pterodattilo

Aug 4, 2023

Suburban astrophotographer here.
I have a OSC camera, and I struggled with my IDAS LP for a long time, trying to integrate insane quantity of frames with not-so-good results, postprocessing was a nightmare, background is strong with considerable gradients.
I few month ago I bought an Antlia Triband RGB Ultra filter and I'm quite impressed.
The background signal of a frame taken with this new Triband RGB is three times lower than the one taken with my old IDAS LP, i.e. it removes a magnitude of light pollution more than the IDAS.

Here's my Iris Nebula with Triband filter

https://www.astrobin.com/mav6h6/

Helpful Concise

Dale Penkala

Aug 4, 2023 · Edited: Aug 4, 2023

I’m far from an expert but I shoot in Bortle 4 skies and use both UV/IR cut & L-Pro filters.

Here is my Iris attempt: https://www.astrobin.com/j1z8vv/E/?nc=&nce=
Here is my B175 & vdB-152 attempt closeup: https://www.astrobin.com/j1z8vv/E/?nc=&nce=
Here is a wider fov: https://www.astrobin.com/11u26w/B/

In all cases I shot from 180s -600s subs depending on what I wanted to do. In the case of my Iris, I should go back and reprocess as I didn’t have the same workflow as I do now.

Dale

Helpful

Joe Linington

Aug 4, 2023

Are you shooting Bin1 or Bin2 with your 294? Bin1 requires very short subs to not blast the stars away. I shoot Lums of 45s and RGB of 1m at a gain of 0 at still have a few blown out stars. Some people replace their UV/IR filter with some sort of CLS for shooting Lum under heavy pollution.

Helpful Concise

Sean Mc

Topic starter

Aug 5, 2023

Bin1 for detail? At least that’s the plan. Maybe for lum and Ha and stick with bin2 for rgb.

SavannahCarl

Sep 23, 2023

I think you possibly might mean broadband. This shot of B 142 is from Bortle 6.5 in Savannah, GA (basically in the middle of a swamp). Not the greatest picture, but it certainly can be done. This is using the ZWO 2600 MC one shot color camera, 300s subs.

Sean Mc

Topic starter

Sep 24, 2023

Wow that’s a lot of stars!