So we've all seen those wonderful timelapse sequences of flowers opening, but I'd never tried one myself. Until now. The two weeks I spent with the Voices From Oxford team working on timelapses encouraged me to have a go, and this blog post describes how I set about the task.

Now December in England is probably not the best time of year for any sort of flower photography; certainly there is nothing in my gardens or the nearby countryside that has anything to offer. But the local supermarket has a cut flower section, and that's where I found my ideal subject - oriental lilies. They are ideal because they have large, elegant and colourful flowers and, more importantly, they are in bud when you buy them and open reasonably quickly.

As you know, the basic idea of a timelapse is to take a series of photos at predetermined intervals, then assemble them into a video so that the action is dramatically increased in speed; in this timelapse, three days is condensed into 30 seconds. The challenge, then is to ensure that every frame (and there are over 800 of them in this sequence) is identical except for the imperceptible movement of the opening petals themselves.

First, let's look at the video, then discuss the challenges.

Challenge #1 - the flower. Not really much of a challenge - I just put the cut stem into water in a vase with a little flower food, and clamped the stem so that it can't move. The background is a sheet of black paper.

Challenge #2 - the camera. Obviously, the camera is on a solid tripod. Rather less obviously, if the tripod is on a typical wooden floor, you really don't want to be standing near the camera when shooting, because wooden floors have a tiny amount of flexibility in them, which is amplified up the tripod leg and can throw the image off by a few pixels. The other relevant camera issue is the battery: it's simply not going to last for the several days that the camera is shooting. So to fix this challenge I found a cheap mains adapter on eBay that allows me to run the camera for ever. Ah yes, and we need a card that's big enough to hold all the images. 32GB is fine.

Challenge #3 - the lens. Modern lenses have an automatic diaphragm, which means that when you look through the viewfinder the diaphragm is fully open, and only closes to the taking aperture during the actual exposure. Normally this is a Good Thing; you see a bright image that's easy to compose and focus. But diaphragms are mechanical, and all mechanical things operate within a tolerance: I can't guarantee that the diaphragm will close to exactly the same position for shot after shot, and even tiny variations will affect the exposure. So I decided to use my 35 year old Olympus 135mm macro lens on the camera (Canon 30D). Now why would I do that, you ask, when I have the fabulous Canon macro lens? Well, it's because I have a coupler that allows me to fit the Olympus mount onto the Canon body, but the way the linkage in the coupler works means that the lens' diaphragm is always stopped down to the taking aperture. Normally this is a Bad Thing, but for timelapse it's ideal, because the diaphragm never moves and I can guarantee consistency from shot to shot.

Here is the camera and lens, showing the coupler. The three cables coming from the camera are the interval timer, mains adapter for the camera, and flash sync lead.

Challenge #4 - the lighting. This is possibly the biggest challenge. I don't want the ebb and flow of daylight interfering, so the whole setup is in a darkened room. I could have used a continuous lighting source but chose to use my Bowens studio flash fitted with a beauty dish for a soft, consistent output. The flash is fired by a cable to the x-sync socket on the 30D. Incidentally, that's another vote for the 30D rather than my 5D Mkiii, which sadly has no such socket. And being mains-powered, the flash will run for ever.

Challenge #5 - the timing interval. As you can imagine, I'm not going to stand by the camera for several days, firing the shutter every few minutes. I use the Canon interval timer, and the choice of a two-minute interval was a "best guess", based on the notion that an hour of real time becomes about a second of video. It turned out to be about right.

Challenge #6 - post-production. Adobe Lightroom is the tool of choice here. Import all the (RAW) photos, and select the ones that show the interesting bits. Apply a bit of tweaking to the colour and sharpness, crop to the 16:9 ratio required for the video, and sync settings across all the images. In the "Slideshow" tab, select the desired frame rate (15, 24 or 30 frames per second) and click "Output video".