NBR filter - Widefiel Crux Region

JohnH · #1 24-02-2008, 04:14 PM

Another shot with th 135mm lens, I did not the the focus spot on this time....

iceman (Mike) · #2 24-02-2008, 04:35 PM

Which filter is that, John?
How long was the exposure?

JohnH · #3 24-02-2008, 04:47 PM

DGM Optics NBP filter Mike - the same one you use, I have the 2" version fitted to the front of my Zeiss 135 or Pentax 50mm lenses via 48-49 step ring. I am testing it out for use with imaging during the bright moon, so far the results are promising - but I am having difficulty getting the colours to look right. I have a CGE as well and will try that out for comparison - I hoped that will give more natural colours but so far I has not.

The shot is a stack of 6x360s at iso 800, conditions were poor, high cloud blowing through during the run.

Still using it means I can image during a full moon...so I am happy. As I mentioned the focus for this shot was off a bit and with the lens wide open that has distorted the stars a bit, especially at the lhs of the image.

iceman (Mike) · #4 24-02-2008, 04:49 PM

Thanks John - definitely interesting results. I would've expected to see more stars for exposures that long, but the moon may have had an impact.

I look forward to seeing more results and comparisons!

Geoff45 (Geoff) · #5 24-02-2008, 08:36 PM

This is a really great shot! Well Done!
Geoff

robin · #6 24-02-2008, 11:20 PM

This is an excellent shot. Fabulous star colours

JohnH · #7 25-02-2008, 06:31 PM

Quote:

Originally Posted by iceman

...more stars for exposures that long...

Quite right - I did not push too hard as I was trying to keep the cpolours under control, here is a new version. More stars but less natural colors I think...I will see if custom colour balancing will remove let a more natural colour through the moonlight...

Peter Ward · #8 25-02-2008, 07:40 PM

John,

I'm not going to be PC and say "great effort". Fact of the matter is there is no nebulosity to the right of Crux.

I suspect a gradient of some sort, so not the best there.

Focus and tracking very tidy indeed. Stick with it.

Peter

Geoff45 (Geoff) · #9 25-02-2008, 08:38 PM

Quote:

Originally Posted by JohnH

Quite right - I did not push too hard as I was trying to keep the cpolours under control, here is a new version. More stars but less natural colors I think...I will see if custom colour balancing will remove let a more natural colour through the moonlight...

The old version is much better. It does look like there is a gradient problem. Also, some of the dark detail has been chopped. See the histogram I did of your shot. All that said, I still think it's a great shot, but it could be greater.

JohnH · #10 25-02-2008, 10:04 PM

Peter, Geoff, I agree with your comments so please don't worry - I love feedback. I was experimenting with the filter. I think the colour to the S of Crux should be the orange/brown of the general star clouds in the milkyway it has come through as pinkish, overall the filter tints things pink/purple. I will attempt to correct for this using a custom colour balance in the camera as I am not having much luck correcting it in PS. Of course this filter is not really designed for imaging, the moon was full and just to make things even worse I am N of Sydney so this was shot into the city lights. Pretty stiff test for the filter really...

JohnH · #11 25-02-2008, 10:59 PM

I think this is about as good as I can get it for now, I need to collect better data as my focus was a bit off and the stars are a little bloated as a result when I push the image. The histogram still seems clipped but I am not sure why, I bracketed each color curve in PS individually to try and restore a neural color balance - it seems to have worked reasonable well.