London sunset panorama, click for a larger version

One of my favourite subjects is the City during the blue hour where electric lights balance with the sky, giving beautiful “night” time pictures with colour still in the sky and with detail in the buildings. Shoot too early, and you get daytime pictures with a tiny bit of colours in windows. Shoot too late, and you either lack detail in non-lit areas or get the lights completely blown out. But get the timing right, and you’ve got Mother Nature’s version of HDR, vastly surpassing the ones produced by Photoshop and its ilk. At least in my humble opinion.

Canary Wharf behind the Greenwich Naval Barracks

Canary Wharf behind the Greenwich Naval Barracks

There’s a brilliant view from Greenwich Park towards London, but during the summer the park closes before it’s dark, and during winter I normally work in the blue hour. So with the Christmas break giving an opportunity to be out and about, I headed to Greenwich for a shot of Canary Wharf on Christmas evening. The light was fine, and during the shooting I swung the camera around and tried a panorama of London, mostly just for the fun of it. At home in front of the computer, I could see that the image was almost there. The composition was a bit off, and a few things could be improved, but I very much liked what I saw.

So yesterday I went back to make a panorama. One of the things that had annoyed me with my first test panorama was that it was very slim and long, so I turned the camera 90 degrees into “portrait” orientation. The result is still slim and long, but at least it’s 50% taller than it would otherwise have been.

St Pauls, Tower Bridge and The City

St Pauls, Tower Bridge and The City

With the camera on tripod and levelled, I started to shoot just after sunset, and did panned series after panned series of pictures until it was completely dark. Arbitrarily I had the brightest view in the first frame and worked my way away from the sun towards the dark edge. It didn’t make much difference for the first few series where I could shoot the 12-15 images in a minute. Towards the end when I was working with 30 second exposures, a series took 10 minutes, so the sky darkened quite a bit during the series, and I wonder if it would have been smarter to start with the dark frame and work towards the light, to get less exposure difference. Guess that’s one to experiment with at some point.

Despite levelling as good as I could, the camera was tilting 0.7 degrees. It doesn’t sound like much, but it meant the final image was wonky, and I had to rotate it and trim off 5% of the height. I was expecting my levelling to not be completely perfect (note to self: insert sarky comment from my friend Mark who has witnessed my obsession with getting the tripod level) so shot with a shorter than necessary focal length, to have some pixels for cropping, and was glad that I did so.

The O2

The O2

I set the exposure manually so all shots in a series would be exposed equally (ignoring the change in ambient light), and exposed for the brightest part. Although it looks on the image as if there’s a lot of difference between the two sides of the panorama, it only measured 1/3 or 2/3 of a stop at the time. So the visual difference must be partly due to the darkening of the skies during the 10 minute pan.

Photoshop has a very neat automated panorama composition function. Give it a set of pictures and let it just get on with it, and after a few minutes it will have blended the pictures seamlessly and also smoothened any differences in exposure. I used the last fact to my benefit by selecting different white balances for the various shots, and as long as it’s a gradual change, Photoshop had no problems with it. The left side of the pano is 6000K (daylight) and the right side is 3700K (flourescent).

Detail from the Naval College in the middle ground

Detail from the Naval College in the middle ground, showing the picture was taken at 4:55

The panorama is made up of 13 images, each 145 mm focal lenght, shot 50 minutes after sunset at 30 seconds exposure f/18 iso 500. The combined size of the image is around 26,000 pixels x 4,000 pixels, or just over 100 megapixel. The overall angle of view is 73 degrees. Printed at a normal resolution of 240 ppi, it would be 16″x110″ or 40x275cm. I wonder where I can find a mount and frame at that size – not to mention the wall space!

On the far left is the Shard, 6.6 km away, then comes St Paul’s Cathedral just over 8 km away, the towers of The City 7 km away, loads of different things, Canary Wharf only 3 km away and finally the O2 again about 3 km in the distance. The green line that cuts across the image, that’s the laser designating the Greenwich meridian. It is visible up to 60 miles (100 km) away from Greenwich.

I think I’m hooked and want to explore this genre of photography in more detail! In fact, I’m already making arrangements with my friend Steve to get up early over the weekend and try for the sunrise from Alexandra Palace on the opposite side of town.

The finished panorama, click for a larger version