Bulb ramping arduino intervalometer for Time lapse photography – theory, build and early experimentation.

My interest in photography has drawn me into a new world that has reignited interests in electronics and programming which I haven’t explored in decades. A number of months ago I saw some amazing time lapse videos on Vimeo and I spent quite a bit of time trying to figure them out. This has been a really interesting journey which I’ve decided to share.

If you want to learn more, I would highly recommend you check out the Timescape.org forum. I would definitely say it is the one single place where most of the heavy hitters hang out and are very willing to share their techniques. I wont take all the fun out of it and tell you all the gory details. Those can mostly be found on Timescapes and a few other sites I’ll tell you about later.

What sets so many of these time lapse sequences apart for me is the introduction of motion, the level of detail achieved through the use of DSLRs, and lastly the smooth transition from day to night or vice versa. Being able to do this turns out to be quite a technical feat, and it is very much these technical challenges that have interested me.

Briefly I’ll touch on the way these are achieved. The detail is out there on the interwebs, so I’ll leave you to find it all.

Firstly, by using DSLRs over a video camera, you are able to achieve a number of advantages, some rather insignificant, whilst other are game changers. In the same way the Canon 5D Mk II with its large sensor, exceptional low light performance and wide range of relatively affordable glass has changed independent video making, using a DSLR for time lapse brings similar advantages including very narrow depth of field (if you require). There are also other advantages specific to time lapse video. The large sensor of a DSLR has more than enough resolution to shoot HD. In fact you are able to shoot 4K video if you use the entire sensor, or alternatively you can use a small crop of the sensor and still achieve full HD video. This allows you to add pan and zoom in post production, without dropping below full HD quality. This is one of the ways in which one can give an impression of motion during post production. Another advantage is the ability to shoot in Raw and this gives you greater latitude in post production (Similar to the Red Video Cameras).

A better way to achieve motion control in time lapse is the use a dolly system which moves between exposures. There is a community of time lapse photographers out there currently making there own, and recently the fruit of much of this labour has resulted in the launch of a very affordable system from Dynamic Perception. This is built by the same guys that run an open source motion control project called OpenMoco, and you will find them on the timescapes forum too.

The last aspect of these time lapse videos that has really impressed me, has been the smooth transition of exposure from day to night and vice versa. This turns out to be quite difficult to resolve. The dynamic range typical of sunset and sunrise scenes is quite massive, and the change in exposure required to smoothly capture these transitions is also very large. Some folk have dealt with the dynamic range issue by shooting HDR timelape which I personally am not a fan of for the same reason that I am not a fan of most HDR out there: It is usually far to saturated with too much localised contrast. I prefer HDR photography which doesn’t look like HDR. I am digressing. There are many real difficulties associated with the smooth transition from day to night and amongst the time lapse photographers, getting this right is seen as the holy grail. At first one might think that you can achieve this by simply leaving your camera on aperture or shutter speed priority and, after dialing in the over or underexposure you desire, let it calculate the exposure automatically. This is what you would do if you are taking a still photo, but unfortunately it doesn’t work so well with time lapse photography. Typically the best DSLR will change exposures by a minimum of one third of a stop. As a result, when you then create a video, there are distinct jumps from one exposure level to next as the metered exposure results in a change in the exposure value. This introduces dreaded flicker into your time lapse video. Although in post production you can make two still images shot at 1/3 of a stop apart look almost the same, when you have 30 frames in each second of footage, there is a great deal of post production that is required to get rid of this flicker. There are some software solutions to that resolve this problem, the best I’ve tried is the trial version of GBdeflicker for Adobe Aftereffects.

Another workflow which I haven’t personally tried, involved shooting on manual settings and monitoring the historgram. As soon as the exposure level moves enough that you are loosing shadow details or highlights that you wish to maintain, you then adjust your exposure value accordingly and then in post production you fade these sequences into each other.

The solution I’ve most experimented with, and which has prompted me to write this post, involves using an intervalometer that ramps the shutter speed according to the ambient lighting conditions. Tom on timescapes has prototyped such a device which he calls the Little Bramper. He is currently making his second batch. I’ve got my name down to receive one of these when they are ready, but its been a rather frustrating wait. It has been so frustrating that I eventually decided to build somehting of my own. Chris Church (aka roaming drone), who is the same man, along with Jay Burlage, behind Dynamic Perceptions and Openmoco, built a system based on the TAOS TSL230R Light to frequency IC and the Arduino Microprocessor. A little while ago I decided to embark on a project to build this same system, and recently built a second one which included a few of my own changes to the software.

Having never studied electronics, and only having limited programming experience, I found this quite a challenge, which I have really enjoyed a great deal. My soldering skills have improved 1000 fold and I’ve learnt a lot. With a rather limited foundation of knowledge troubleshooting proved very challenging, but ultimately achieving some success has been very rewarding.

Chris’s original blog post as well as a few similar Arduino based bulb-ramping intervalometers proved invaluable in being able to put this little puppy together. I hope in time this functionality will be added to the firmware of current cameras or released in future models, or alternatively consumer products that are able to achieve the same results are released. I’m a bit of a tinkerer, so I am happy to cobble together my own.

Another method worth mentioning, involves aperture ramping. By using a motor to drive the aperture ring on a suitable modified manual lens, you are able to change the exposure level smoothly over time as the lighting conditions change. This has the effect of being able to maintain the same shutter speed so motion doesn’t speed up or slow down as the shutter speed decreases or speeds up respectively. You do have the effect, which might be desirable, of a changing depth of field.

ISO ramping is another alternative, as well as a combination of all three (ISO, shutter speed and aperture). How you achieve these technically is left to your imagination.

This is by no means an exhaustive guide to time lapse photography with DSLRs. There is a lot of information out there which I have found useful and informative. I am simply at the early stages of exploring the state of the art and wanted to share this with others and perhaps point people in the right direction.

I’ve decided to share the product of 3 evening of work with my little bulb ramping intervalometer. There is so much left for me to learn about video post production and I am still learning from the many mistakes I make every time I go out. From the video it might be self evident that my tripod isn’t quite stable enough (btw – bridges shake quite a lot when lorries drive over them!), I’ve forgotten to set the white balance before a few of the shots, and there are a few missing frames which result in the test pattern you see. I am otherwise happy with what is at this stage just a proof of concept bulb ramping time lapse.

In many ways shooting time lapse photography is much like the old days of photography with film. You only fully learn what mistakes you have made long after you have taken a picture. Your ability to make adjustments on the go is rather limited and experimenting takes a lot of time.

If you are looking to embark on a similar journey, be prepared to wake up early, go to bed late and spend a great deal of time doing this. Shooting a single sequence can end up taking hours, and then post production is laborious and a subject in it’s own right.

I am currently living in Johannesburg, South Africa and being in some of these locations with a bunch of gear after dark makes me a little nervous too. Last week I had the police pay me a visit while I was on a bridge over looking Park Station. They were concern about my safety and asked me why I hadn’t brought along friends.

One last point I’ll make about the Arduino: when i started writing this post I thought I would have more to say about the Arduino. I am new to it, but i believe it is an affordable platform  that is easy to get into and the end which can be achieved are limited only by your imagination. There is also lot of inspiration out there: The Arduino is the processor behind the dynamic perception stage zero dolly, I’ve seen a number of motorized panohead that use the Arduino, and I’ve seen some really interesting quadcopters and other assorted drone mounted cameras controlled by arduino setups (Think low cost aerial photography and the ultimate infinity boom!). I’ve only been citing photography/time lapse/videography example because I have a particular interest in them, but the list goes on and on.

I’ve managed to find a well priced South African supplier of an Arduino variant called the Aarduino. Anton from Karasu has also been really helpful when I’ve needed a little guidance.

Other interesting stuff that I might write about or might interest you:

USB control of camera

Cheap intervalometer/remote timer