astrophotography – Dave's Place

The night sky

November was probably slightly outside the optimal season for astrophotography in the northern hemisphere but nevertheless finding myself in a dark sky area on a clear(-ish) night it would have been rude not to have a go.

This was the first time I’d tried the Nikon D800E for this type of photography but it handled well and combined with the Nikon 14-24 I was very happy with how it worked. The only problem came when I dropped and broke my torch meaning I had to use the light on my phone to check and change settings which was very fiddly with gloved fingers.

Looking at the EXIF data this was a 30 second exposure at ISO 800. Now at 14mm this should have meant that the stars did not visibly start to “trail” which causes them to appear as short dashes rather than dots in the image. This is based on the commonly used 500 Rule: 500 divided by the focal length of your lens = the longest exposure (in seconds) before stars start to trail. In theory I had 36 seconds to play with but looking closely I think 20 seconds would have been better even though I would have needed to increase ISO to 1600.

Capturing the core of the Milky Way has become the “in” thing in astrophotography in recent years, driven in no small measure by improvements in DSLR technologies and greater availability of accessibly-priced cameras to the enthusiast. One pre-requisite though is a reasonably clear sky along with an absence of light pollution. A Dark Sky site is ideal and the nearest to where I live is in the Forest of Bowland. Choosing when to make the attempt it is useful to understand a little about the geometry of the Galaxy, and I found an excellent guide at Andrew Rhode’s website. About half-way down the page is a really handy diagram which really makes it easy to understand when the best time to be out is and what time of the day/night is best. The explanations are clear and straightforward and I can recommend spending some time perusing Andrew’s site.

Astrophotography with Nikon D750

© Dave Whenham — Nikon D750 with 14-24 f2.8

I have toyed with photographing the night sky on a few occasions in the past with limited success so I am not expecting a great deal from last weeks trip. However, Lightroom on my computer proved a far better bet for processing than it’s iPad sibling and I’n reasonably pleased with how this one turned out. It’s a start as they say!

We were away for three nights and on the first night the sky was totally covered in clouds. Night two brought some breaks in the cloud and between 10pm and 11pm I was able to get out with the camera for an hour. The third night alas brought more cloud although there were the odd break so I went out anyway for the practice as much as anything – more in hope than expectation I believe the saying goes. On reading further this morning I should probably stayed up longer and gone out around midnight but thats all part of the learning process.

My previous research suggested an aperture of f2.8, a thirty seconds exposure and pushing the ISO dial upwards to ensure sufficient exposure. In the end I opted for ISO 800 knowing that the RAW files from the D750 could take being pushed a couple of stops or so in post processing. A tripod and cable release completed the set-up which shows just how little equipment is needed to make a start.

It seems to me having now compared the RAW files with the iPad edits and those done in Photoshop/Lightroom that post processing is a vital part of astrophotography. The top image was reprocessed using a black and white layer blended to control colour luminosity and the results (below) whilst very subtle at this size was subtle but still very noticeable at full screen size. The crop helps of course as everything appears to be bigger in the frame but the subtle changes to luminosity help bring out some of the detail in the lower part of the sky.

I’m going back to the same spot at the end of August, the tail end of prime “Milky Way season” here in the UK. This gives me plenty of time to research further and of course brush up my processing skills.

Starry, starry night …

Back home after a few days relaxing in the Forest of Bowland, where we sat, read, ate and took the odd snap along the way. Oh, and looked at the stars. I have never seen so many stars as I saw on the one clear night we had whilst we were there; even well known clusters such as the Plough became harder to pick out amongst such a multitude.

I was aware of the Forest’s status as a Dark Sky Site so had read up on photographing the night sky before I left home. I just need to work out how to get the most from the files which is my job for tomorrow. In the meantime, still stuffed from three man-sized breakfasts and three family-sized evening meals I have posted these few to be going on with.