My second (less embarrasing) narrow band image

[samir_ansari]

If you remember my previous attempt at a narrowband image:

http://stargazerslounge.com/imaging-deep-sky/170515-my-first-awful-narrowband-image.html

It basically looked like a clown had thrown up all over it.

BUT, I tried again last night - this time not binning my SII and OIII and finally I got some information out of them. It seemed binning 2x2 was clipping even the midrange of my OIII and SII so I was essentially working with a flat image and using the vignette to drive the colour changes!

Anyway here is my latest version which is made up of:

ED80 at F6.3 (with a focal reducer)

R - SII / 5 x 600s / no binning / with flats and darks

G - Ha / 4 x 600s / no binning / with flats and darks

B - OII / 1 x 600s / no binning / with flats and darks

L - 100% Ha / ~25% SII / ~50% OIII

It can certainly do with far more subs and longer exposure times for the SII and OIII but I think I will try another target and come back to this one some day.

[samir_ansari]

Also before packing up my gear for the night I thought I would take a quick shot at the Moon to show the scale of this target:

[Zul]

"less embarrasing"?? Thats awesome!

[Catanonia]

Very nice and a vast improvement over the 1st image you posted. Much better processing and liking the moon scale a lot.

Well done mate

[Spikey]

That's miles better Samir. You have some really nice detail emerging in your image and very nicely processed.

[kenmyers]

amazing photo and the moon looks great too.

I am new to astrphotography, as in I haven't decided what camera to get yet, but what is a narrow band image? is it a certain filter?

[samir_ansari]

Thank you all for the kind words, I tried to keep the colours a bit more on the natural side and not too over saturated, but perhaps the blue is a bit much. I think on the inside I was just so happy that I finally caught some OIII data that I just wanted to blast it up in the composite

Hey Ken, yep that's pretty much what it is. Essentially this is a colour image made up of 3 black and white images. Each image was taken with a different filter which only lets in light from a very narrow band in the spectrum - hence the name. Finally the black and white images are assigned to different colours, most narrowband images conform to this standard as a base:

SII: Red

Ha: Green

OIII: Blue

Although you can get some interesting results by mixing these up. Hope that helps!

[GordonH]

That is much better, but you will need more sub frames, a lot more. For narrow band imaging think in the region of at least 4 Hours per filter, more is better as you will be able to push the processing further without introducing noise, try to avoid the temptation of using noise reduction filters as they introduce nasty artefacts which can ruin your image

Best wishes

Gordon

[GordonH]

Just another point, I notice from your thread that you used a luminance channel made up of 100% Ha and a lesser mix of OIII and SII. The problem with this is that all you will do is enhance the already dominant Ha channel at the expense of drastically suppressing the already weak OIII and SII channels. With narrow band imaging there is no use or need for a luminance channel. Think of it this way, when doing RGB imaging and adding a luminance channel you don't make a mix of the red green and blue filtered data to make the luminance channel, you use a clear filter instead so why make a luminance channel by combining data from the other three channels, it defeats the object of imaging with narrow band filters in the first place. Unfortunately with narrow band imaging there are no short cuts in getting a good image, you have to put the imaging time in and get plenty of data

I don't mean to be critical of what is a much improved image but this is how I learnt and I've been doing narrow band imaging for 4 years now and I've found that the best results come from putting the time in at the scope

Best wishes

Gordon

[samir_ansari]

Thanks Gordon, I sincerely do appreciate yours and anyone else's criticism as learning to improve was the sole reason for me signing up to the forum in the first place.

I decided to use a combined luminance channel because my OIII and SII had virtually no information in the darker areas of the nebula and were very lacking all round because of the relatively short exposures for each. Also I didn't want to boost my Ha in a RGB image as that would leave me with far more green than I wanted.

The next time I approach this target I will certainly spend much more time on each and longer subs for the OIII and SII are definitely a must.