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View Full Version here: : Yeta-nother Eta Carinae nebula


Camelopardalis
03-06-2014, 03:32 PM
Can we ever have enough of it :)

This was my first experiment with exposures of this kind of length, using my little WO Zenithstar 71mm (with reducer/flattener) and Canon 1100D on an EQ6 at SPSP. While unpacking my stuff back at home, I realised I hadn't used the spacer between scope and camera :help:

15x 20s exposures, stacked in DSS, then tweaked to enhance the colours. I'd like to try longer exposures next but not sure what I should expect from my mount :confused2:

Any tips/feedback appreciated!

cometcatcher
03-06-2014, 03:50 PM
That's very nice. With a little 71mm and reducer you could easily get 2+ minutes with good PA.

LightningNZ
03-06-2014, 04:49 PM
Very nice, very wide field you've got there. What's the final focal ratio?
-Cam

Camelopardalis
03-06-2014, 06:01 PM
Thanks guys!

I'll look forward to practicing longer exposures the next time I'm out of the City for sure :)

The scope is f/5.9 native and the reducer is 0.8x, so around f/4.7-ish. Not sure if it is altered by lacking the spacer, but I'll try some similar shots someday to see.

raymo
03-06-2014, 11:55 PM
Yes, very nice Dunk, what ISO did you use?
raymo

Camelopardalis
04-06-2014, 10:32 AM
Thanks raymo, oops I forgot to put the ISO...1600

jsmoraes
04-06-2014, 11:16 AM
if you work with Photoshop, to realce the nebula you can use the filter minimum with blend mode luminosity and 20 % or 30 % of oppacity with background selected. This will reduce the presence of stars without loss of information from the Nebula.

LightningNZ
04-06-2014, 02:49 PM
I rather like that the stars are over-emphasized. I think it gives it more of a 'visual' appearance.
-Cam

Camelopardalis
04-06-2014, 06:11 PM
Thanks chaps - I'm learning, experimenting with my processing workflow, so I'm open to any and all suggestions :) it's hard for me to grasp how things should look... natural colours and so on.

As an update to my previous comment about the spacer...I tried again last night with the spacer inline and got stretching (like warp drive) effect on stars from about 2/3 the way out getting worse towards the edge. I took some shots of the same scene as above for comparison, and I don't see that effect on my shots from SPSP...so I can only assume that without the spacer is closer to optimal :shrug:

Regulus
04-06-2014, 10:59 PM
Seriously like the colours in that version Dunk.

Can't believe u even asked: Nope!

Camelopardalis
05-06-2014, 10:34 AM
Thanks Trevor! It'll be interesting to see what happens to the colours when I can get my paws on more subs :D

I'm more of a visual guy but have a good look at it every chance I can!

Camelopardalis
06-06-2014, 01:24 PM
So...I've been playing around with different stacking and processing parameters and ended up with a...erm...different result.

I don't think I like it as much as the first, it's more yellowy-greeny and the stars are more pronounced than before :confused2:

What colours should I be aiming for? I appreciate there's a limit to the data I have.

cometcatcher
06-06-2014, 01:36 PM
Blues and reds. Unless they're comets, greens are usually not a sought after colour in astro pics, hence HLVG.

Camelopardalis
06-06-2014, 01:36 PM
I've just tried recreating the first image from the same settings and the only difference seems to be the source images...the first was direct from the raw files, the second from raw converted to tiff files in Canon DPP :confused2:

Camelopardalis
06-06-2014, 02:25 PM
Thanks Kevin, I'll stick with my first pic then as that's got less green to it. Not sure what's going on with the tiff conversion. Weird.