The Timelapse Diaries

Introduction.

For the past few years I have been interested in the genre of timelapse photography.  Of particular interest are those timelapse films which capture the transition from day to night or night to day.  These are commonly called ‘holy grail’ films, the term having originated in the days of celluloid film when they were an extraordinarily difficult thing to get right.  However, modern digital equipment and post-processing makes the whole process more accessible and over the last few years I have become reasonably adept at producing them.

Many holy grail films only feature the transition through sunset or sunrise, but I began to wonder about making a holy grail film featuring a sunset and sunrise in the same continuous film, which would also capture the beautiful night sky, so I decided to make it my project for the summer.

There were two main challenges which had to be overcome.  Firstly I would have to find a suitable location and secondly I would have to provide power to the camera (Nikon D600), the pan and tilt unit (Emotimo Spectrum ST4) and other equipment for the duration.

IMG_3435
Emotimo Spectrum ST4 with Nikon D600

Location.

The location needed a number of key attributes.  First, there had to be an uninterrupted view to the horizon.  Secondly, as the film features the night sky it would be preferable if the location was in a dark sky area of the UK.  Thirdly, it needed to have decent vehicle access as I need to get the equipment as close to the location as possible.  Finally, it would be preferable if the location was a lake or a body of water as reflections always make a film more interesting.

Based on my local knowledge and experience, and after a few reconnaissance trips I chose Llyn Conwy.  The source of the river of the same name, it sits on a plateau of peatland bog known as the Mignient high above Blaenau Ffestiniog.  Sitting at the highest point meant that there aren’t any hills or mountains overshadowing it, and the horizon is only just above the water level. It also had a small carpark at the southern end.

Astronomical Calculations.

Now I had my location I needed to work out how I was going to power the equipment, and in order to do this I needed some information concerning timings.  Consulting my favourite photographic app (Photo Pills) gave me the relevant information.

On midsummer’s eve (21st June) at Llyn Conwy sunset is at 9:45 PM and sunrise is at 4:45 AM.  Allowing an extra hour at each end of the sequence for run-in and run-out this meant that the equipment would have to run for 9 hours.  The compass bearing for sunset is 314° and the sunrise is 47°, giving an angle of 93° through which the camera was going to have to turn.  I could have the camera remain static and rely on the angle of view of the lens to cover the 93°, but the 14 mm lens on my full frame Nikon has an angle of view of 114°, leaving only 10° of angle at either edge of the frame, which I thought was too close for comfort.

The Power Conundrum.

Having sorted a location and the astronomical stuff the next problem to address was how I was going to power the equipment continuously for 9 hours.  I needed to power four pieces of equipment.  First there was my Nikon D600 DSLR, secondly there was my Emotimo Spectrum ST4 pan and tilt unit, thirdly there was a Samsung tablet which controls the cameras exposure settings, and finally I was going to need to power the lens heater.  After much experimentation I finally settled on running a 10 metre cable from the 12 volt leisure battery in my motorhome to the equipment location.  The cable is fairly large so that the voltage drop along a 10 m length is minimal, and is fitted with an inline fuse.   

Although the ST4 could run directly off a 12 Volt supply the camera required an 8 Volt supply.  The solution to this was provided by a small voltage and current step-down power supply.  This reduced the 12 volt to the required 8 volt and the amperage to the required 2 Amp hour max.  This in turn was plugged into a dummy battery pack DC coupler which replaced the standard battery in the camera.  I cobbled together a small box to house the power supply.

IMG_3290
Voltage regulator and DC dummy battery pack

So now I had a solution.  The camera, lens heater and the ST4 would be powered from 12 Volt supply from the leisure battery, and the tablet computer to control exposure would be powered from a 20 amp portable battery bank.  This only really needed to run for the two hours around sunset and sunrise when exposure changes are needed.  It could be switched off and recharged during the night when the exposure didn’t change.

The Timelapse Hypothesis.

Having got the equipment side of things sorted out I decided to carry out a full-scale test at home.  However before I could do any kind of test I needed to sort out the actual timelapse timings, so here we go.

9 hours total at a 24 second interval = 1350 frames. Say 1400.

So 1 hour = 155 frames

Starting at 20:45 (an hour before sunset);

Static time :- 200 frames = 1 hour 17minutes.  Takes us to 22:02

Moving time :- 1000 frames = 6 hours 27 minutes.  Takes us to 04:29

Static time :- 200 frames = 1 hour 17minutes.  Takes us to 05:46 (an hour after sunrise).

This means the camera will be static during sunset and sunrise.   I’ve also allowed for a 150 frame ramp at either end so the camera eases into and out of motion.  Simples!!

The Pudding Proof.

I ran the cable from the 12 volt leisure battery into the house and connected everything up. I started the sequence at 20:45 and left it to run.  Checking the images the following morning I found the last one had a time stamp of 04:15.   This equals 7 1/2 hours running time.

Now this may sound like a failure but a few factors meant it was actually ok.  The first is that, on location, for the first hour and the last hour the battery will be getting some charge from the roof solar panel.  So the battery-only running time is actually around 7 to 8 hours. Secondly I can adjust the motor settings on the ST4 so it uses less power, and I can turn off some settings on the camera as well.  Finally I can run the engine for a short period a couple of times during the night to top off the battery, but this means fitting a second voltage/current regulator to protect the equipment from any surges.

So the power diagram looks like this;

timelapse diagram

So we’re now good to go.  However as I write this it’s still 4 weeks to the shortest night and it may take a few weeks for the right conditions to come about but I’ll report back and post the results here. Watch this space!!

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