noctilove
10
FEB
2015

Auriga

Auriga with nikon 35mm f1.8 G lens

Imaging full constellations is something I’ve been itching to do since trying the new softon filter. So last night I set off in search of some darker skies armed with a borrowed Nikon 35mm f/1.8G lens. The constellation of Auriga was the target as it’s perfectly placed overhead at this time of year, and imaging large targets overhead is much preferred. (Trying to remove gradients from targets lower down is a real nightmare).

With an exposure time of 22 minutes, the detail visible in the shot is pretty impressive. The centre of Auriga holds two open clusters, M36 and M38, which sit beside a couple of faint nebulae; the Flaming Star nebula, and the less catchy IC410 – an area which could be an excellent target for the 180mm lens at some point.

The lens itself worked like a charm. Stopped own to f4 it’s super sharp, and the light weight makes it easy on the barn door tracker (200g vs 800g for the 180mm). I also had a pleasant surprise when it came to stacking the images as I realised I’d also caught the California nebula in the upper right of the shot!

Hoya Softon A filter for astro  imagingTo get the glowing star effect I took nine 2 minute photos without the filter, then two shots with the softon filter in place. I stacked these separately in DSS and combined them in Photoshop with the softon layer set to ‘screen’.

This side-by-side caparison of 2 minute shots of Capella demonstrates the filters effect. The medium to bright stars stand out much more, as well as their colours. The filter also dims the background stars making the constellations pop out even more.

Image details: Nikon D7000Nikkor 35mm f1.8G at f4. 18 minutes (9 x 2 minutes) at iso 800 using didymium filter, plus 4 minutes (2 x 2 minutes) at iso 800 using softon filter. Stacked with Deep Sky Stacker and Photoshop. Tracked with barn door tracker.

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  1. Slavco Reply

    Hi Nick
    Can you make a post about Deep Sky Stacker, I get the part of light files, dark files, offset etc. than stacking them, but adjusting RGB colours seems daunting.
    Also if you could include somewhere in the posts a RAW unproccessed single exposure of whatever to just see how it looks would be awesome.
    I built my star tracker, but it doesn’t give the results that I was expecting. Chances are I am doing something wrong, or the alignment is off, even though after 5 min. the object in center still is in view where it suppose to be. Perhaps the fact that I was trying at 300 mm is too much.
    Anyhow, thanks

    • Nick Reply

      Hi there – no worries, I’ll put a page up about the techniques and processes I use when I get chance. Until then there are a couple of tips which helped me that I didn’t find documented anywhere..

      The first is to make sure you adjust the levels using the slider in the upper right corner before you stack the images. It depends on your exposure, but I usually drag the middle pointer so it’s around 30-40% of the way along…

      adjust levels in deep sky stacker

      For adjusting the levels after stacking, I don’t touch the RGB levels, I just try to get the curve looking like this with saturation levels set to -4 or -5%…

      adjust levels in deep sky stacker

      I also tick ‘Use RGB background calibration’ in the recommended settings box, otherwise the colour balance can be off quite a bit.

      300mm lens should be fine, though you’re probably best starting with a smaller faster lens and some shorter exposures, at least to begin with.

      Hope this helps!
      Nick

  2. Slavco Reply

    Thanks a lot Nick

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