After lurking on this list for ages I figure that it is about time I put something out there for review and feedback. Attached is a processed image of the Emu dark constellation. I would appreciate a critical review and advice as to what further processing may benefit (colour, contrast, detail etc) or anything that I should change in the approach.
Details are:
Canon 550D (unmodified)
20mm F1.8 USM lens @ F5
Ten subs ISO800 @ 6 minutes each
6 x dark frames
6 x bias frames
No flats (couldn't get them to work - for further discussion)
Mount = Losmandy GM8
Guiding = Synguider
Image plus for calibration, aligning and stacking
Photoshop curves adjustment for initial stretch and contrast enhancement
Some colour tweaking in levels and curves
There is some gradient present from sky glow even though I was imaging from a reasonable dark site. I tried removing these with Gradient Xterminator but was not happy with the result so left it as is.
I took some flat field frames with my 20mm lens but when I included these in the processing it introduced vignetting (odd, yes I know). This is a matter for further investigation. Anyway, I have learnt a lot about ImagePlus in the process. I found out, for example, that it was necessary to set the 'Short FL - Small stars' option in the align/combine menu due to the 20mm wide field lens.
As indicated, I would appreciate any feedback that can assist with improving the these images.
OK, I see an Emu, but the head has come off.
Photographically I think it's pretty darn good ( I am no expert on this btw). You say it is a dark nebula but you seem to have captured it well, the colours seem quite natural and the stars are nice and round without being burnt out or showing trails. Colour range is good, solid blacks at top left to bright white at major stars.
I'd say well done I'd be proud of it.
Thanks for the feedback Brent. It is good to be able to get other opinions as one tends to go a bit stare crazy looking at the same image for a long time.
R
I love a good emu, and yours is quite good. I think though it is a little under done. There seems to be plenty of data in there still that can be streched out. I had a play with the JPG and there is still a lot of hidden detail in the dark areas.
Thanks Trevor - can you briefly describe the basic approach to stretching out the additional data. Am happy for you to post any updates if it helps with improving my processing of these images.
Thanks Trevor - can you briefly describe the basic approach to stretching out the additional data. Am happy for you to post any updates if it helps with improving my processing of these images.
More just looking at photoshop levels and curves then anything, trying to increase the constrast within the dark areas. It is a subtle balancing act.
I'm no expert on wide angle shots like this, but I can
Give you one tip. If you make a small round aperture mask and attach it to the lens to blank out the shutter blades, you won't get diffraction spikes, like you have on the brighter star at the centre of the fov.
Rex, Trevor, Brett.
Thanks for your response and feedback. I have received some good recommendations from the review of my image. Thanks also Brett for the tip on the diffraction spikes as I have been puzzled as to how these have been finding their way into my wide angle images.
R
I'd be proud of it.
