Eta Carinea and Lagoon from Mono DSLR

glend (Glen) · #1 13-04-2016, 09:27 AM

I have been working on the development of my mono DSLR for some time now and am finally getting some results that can be shared.
Below are two links, one for Eta Carinae and the other for the Lagoon Nebula, in both cases one hours worth of Ha data using the mono 450D.

http://www.astrobin.com/full/244755/0/

http://www.astrobin.com/full/244873/0/

I continue to collect OIII and SII when weather permits and will get some colour processing up for these in the future.

raymo · #2 13-04-2016, 12:24 PM

Looking good Glen, I'll be interested to see how the colour results turn out.
raymo

Atmos (Colin) · #3 13-04-2016, 05:11 PM

Looking quite good so far Glen. Being now a mono camera, have you given it the magenta cast or is that inherent of the Ha passband with your camera?

glend (Glen) · #4 13-04-2016, 06:11 PM

Quote:

Originally Posted by Atmos

Looking quite good so far Glen. Being now a mono camera, have you given it the magenta cast or is that inherent of the Ha passband with your camera?

It could be just a result of the camera settings, related to colour balance because i have not set the camera to mono. I could strip it out in Photoshop but I am leaving it for now. It will disappear when I colourise the files later.

Camelopardalis (Dunk) · #5 13-04-2016, 10:08 PM

The colour balance is just a profile included in the raw file and it requires the viewing software to support it for it to be of use...it's not enforced in any way.

The raw file is otherwise just that...it's pixel values. As it is, it's (again) software that demosaics this into a colour image, otherwise it's just a mono image.

Glen, if you're getting a colour image by default then the demosaicing is happening when you don't want it to. Look at the dcraw command line options to disable it. Doing the demosaicing on mono data is meaningless and you'll be losing valuable resolution by doing so.

glend (Glen) · #6 17-04-2016, 04:38 PM

This post had contained the first of my colour narrowband images (Eta C). There was much wrong with it including cummulative over-exposure.
I have deleted the posted image jpg and the Astrobin link until such time as I can reshoot. Much to learn.

glend (Glen) · #7 17-04-2016, 08:55 PM

Lagoon finished, this one is a bit better. I will have to have another go at Eta C processing.

Links below.

http://www.astrobin.com/245563/

http://www.astrobin.com/full/245563/0/

raymo · #8 17-04-2016, 09:36 PM

The colours are a bit strange Glen, but my goodness, you're getting there.
raymo

Camelopardalis (Dunk) · #9 17-04-2016, 10:05 PM

That's pretty interesting data Glen

Is it a case of the raw data being clipped in the highlights or does it happen when you combine them?

With narrowband, colours are what you choose them to be

glend (Glen) · #10 17-04-2016, 11:24 PM

Quote:

Originally Posted by Camelopardalis

That's pretty interesting data Glen

Is it a case of the raw data being clipped in the highlights or does it happen when you combine them?

With narrowband, colours are what you choose them to be

I am thinking that i need to go over each of the reg files before i layer them and try to get the levels right then. Although if i have burnt the centres in the lights then no amount of processing is going to get it back. These are reasonably bright targets and even in narrowband at f5.3 my 360" subs maybe too much at ISO1600. I might try to drop back to ISO800 300" subs and see how i go with that. On new ground here and there are not many (any) Mono DSLRs to compare results with. The SII data has looked the best, but usually the faintest, and has a nice bell curve, but the other two are over powered.

rustigsmed (Russell) · #11 18-04-2016, 10:06 AM

looking good glen.

I believe mono shots are a bit magenta because the camera's software need to boost the blue and red channels to counteract having twice as many green pixels.

how are you going about merging your data sets? sometimes the method of blending can result in the highlights blowing out. I would have thought you could go longer at iso 1600 - but maybe not.

anyway plenty of tinkering ahead but a great start nonetheless.

russ

Camelopardalis (Dunk) · #12 18-04-2016, 11:08 AM

Quote:

Originally Posted by glend

I am thinking that i need to go over each of the reg files before i layer them and try to get the levels right then. Although if i have burnt the centres in the lights then no amount of processing is going to get it back. These are reasonably bright targets and even in narrowband at f5.3 my 360" subs maybe too much at ISO1600. I might try to drop back to ISO800 300" subs and see how i go with that. On new ground here and there are not many (any) Mono DSLRs to compare results with. The SII data has looked the best, but usually the faintest, and has a nice bell curve, but the other two are over powered.

On OIII at least, your mono won't be much different from a modded DSLR, shy of a tiny bit of resolution. Actually the modded DSLR with its microlenses might gather a bit more light. OIII activates both blue and green pixels in the Bayer array.

I also think you're being held back by your processing tools, but that's another story altogether