M8 Lagoon Revisited

[Garbz]

I did another attempt at the Lagoon Nebula last night. M8 was originally my first ever DSO photographed through my scope. http://www.iceinspace.com.au/forum/showthread.php?t=91441
Back then it was 17 second exposures unguided through a 6 year old DSLR. I've learnt a lot in the last few months.

Scope: Celestron C8 with f/6.3 reducer
Mount: NEQ6
Camera: Nikon D800
Subs: 2min x 40
Guided through Orion 50mm finderguider

[alpal]

You've learnt a lot.
That new image is excellent in terms of data & processing.

How much processing did you do?
e.g. did you use HDR toning?

Anyway - well done.

[Nico13]

I'd be pretty happy with that, the only comment I have, well a question really, is the C8 a new one or an older one as it looks like you have the same problem I have with my old Meade with a bit of mirror flop, the mirror tilts a little when you focus adjust and it puts one side or in your case the bottom left of the image out of focus a bit.

[Garbz]

Thanks, Quite a bit of processing in this one. I actually did use HDR. My first attempt at HDR with pixinsight, talk about difficult and counter intuitive. I couldn't actually figure out how to tone the value down so I ended up making a mask which was very grey with black stars to stop the HDR tool from overdoing it and from destroying the stars. The end result is only a slight HDR effect with the majority of detail being brought out through about 5-6 different curve transformations.

Other than that, just some saturation, minor noise reduction, background correction and slight deconvolution.



It's an older C8. I don't think it's mirror flop but rather the crop of M8 was not from the very middle of the frame. I get quite bad vignetting with my DSLR when using the entire 35mm frame. It's better with the f/6.3 focal reducer and cropping to APS-C sized sensor area, but it's still quite bad. Just as well too because DeepSkyStacker doesn't like 36megapixel images much :rolleyes:

[alpal]

I just ran it through one iteraration of HDR in photoshop
with adjustments to detail & other settings & I got this:

[Garbz]

Interestingly enough there doesn't seem to be much of an additional HDR effect in your post process. It just looks like the entire image is a bit brighter. Take a look at the attached for comparison which is just the picture downloaded here with a simple curve applied.

/EDIT: It appears yours is a bit more saturated. Was that part of the HDR tool or did you saturate as well?

/EDIT2: Never mind I my mistake. When I screenshotted photoshop it applied the wrong monitor profile, the saturation actually looks spot on when converted to the right profile. :rolleyes:

[alpal]

Yes - basically I just brightened it up to show the fainter areas.
I didn't use a mask to stop stars being saturated.

Do you think it looks better brighter?

[Nico13]

Ah yes the vignetting I also have that issue with the reducer fitted.:(

[Ross G]

Looks good Chris.

Impressed by the quality of the Nikon D800.


Ross.

[Garbz]

Hard to say, I'm in two minds about it. On the one side I think it looks more natural sort of fading into the background in the dark version, on the other side your blend makes it really stand out in the way some of the Ha shots of M8 do, as a distinct object with a distinct edge, which is something that often makes me go "wow".



Thanks, so am I. It impresses me more every day. The only thing it needs now is some free software to remote control the camera. I have several programs already but none support the D800 yet.