PDA

View Full Version here: : Rho, Antares and Scorpius with the Polarie


iceman
01-05-2013, 07:16 AM
This is a single 2 minute exposure with the Canon 5D Mk 2, 50mm lens @ f/2.0, ISO3200. Tracked using the Polarie.

Quite happy with how this turned out for a single exposure. Processed for contrast and saturation, which is obviously my taste at the moment :)

Worth looking at the large, had to reduce the small version to 600px to get it under 200kb.
- Large (http://www.mikesalway.com.au/download/410)

There's some abberations at f/2.0 still, I cropped a little off the left to get rid of some warped stars but they're still evident throughout. The lens would need to be stopped down much more to completely clean them up.

Comments welcome, thanks for looking.

multiweb
01-05-2013, 08:59 AM
Some good details on axis but your color balance is off. Red is clipped as well. You'll have to stop that lens way down too. Looks a bit like a whirlpool. Nice saturation though. :thumbsup:

gregbradley
01-05-2013, 11:56 AM
Yes nice and bright with lots of detail. Coma is a problem and blown highlights.

Its a rare lens that works wide open in astro in my experience so far. Only a couple have done it, most need a couple of stops stopped down at least. I think we get away with a lot at 14mm but 50mm is less forgiving. Also 14mm is receiving more of the available light energy in the sky, 50mm a smaller slice.

Stopped down (that looks like it needs F4 to F5.6), longer exposure, lower ISO seems the best approach. Perhaps 5 minute exposures at ISO1600 F5.6 would be the go. Working out the ideal setting for lenses is a bit time consuming.

Greg.

IanP
01-05-2013, 02:14 PM
It’s a very nice try, although I’m not an enthusiast of using DSLRs beyond ISO1600 in theses situations.
To get “something” around Antares the shadows are pushed to aggressive.
I put it through PixInsight AutoStrech – and here it is (200k limit) …

:thumbsup:

jase
01-05-2013, 04:05 PM
Woaahhh Mike! Where'd I put my sun glasses?! Absolute stonkin FOV, huge. Just a single exposure - WOW, very cool! The coma has provided a 3D effect whereby the stars on the left and right of the image appear closer than those in the middle. You might be on to something there. ;) Thanks for the view - enjoyed it :thumbsup:

dvj
02-05-2013, 04:48 AM
Interesting. Lots of light there.

What do you guys recommend for a fisheye lens for something like the 5D MKII? I want to put it in the shed to operate remotely. Looking for really good quality star images.

j

gregbradley
02-05-2013, 05:09 AM
Samyang (Rokinon in the US) 8mm is good.

Greg.

iceman
02-05-2013, 07:30 AM
Thanks for the comments. Certainly not a technically great image, but I had fun pushing the Polarie and the lens wide open.

If I was going to do it seriously, then as others have suggested, it would need to be more accurately aligned, with longer exposures and lower ISO at a lower f/stop.

Ross G
03-05-2013, 07:36 AM
Does show the amazing potential of the Canon 5d/ 50mm combination with sensitivitiy and FOV.

Good luck.

Ross.