Jonathan's blog

This week, I decided to have a look at some statistics about photos I’ve taken with my Canon 450D. Using a little Perl magic, I extracted the EXIF data from almost 7,000 photos that I’ve taken since purchasing the camera 10 months ago.

The first graph shows the different focal lengths used in the photographs. Among my lenses, I have the ability to work between 8mm and 300mm. The three large spikes to the left are apparently where I’ve taken lots of photos with my primes, at 8mm, 50mm and 90mm. The general area of bars is my 18-55mm kit lens. Finally, the spike at the far right is the 70-300mm zoom lens, which I always seem to use at full zoom. (Incidentally, the EXIF data doesn’t record whether I used my 2× teleconverter, so some of the 300mm records should be 600mm).

What can I learn from this? Maybe that I would benefit from buying a longer zoom lens, but that’s a different story.

The graph of shutter speeds is perhaps more expected. Under “normal” conditions (where normal means outdoor daylight, or indoor flash photography) the shutter mainly gets used at decent everyday handheld speeds like 1/250 – 1/30. The sudden spike at 30″ is where I’ve used my camera for long-exposure night shots, including many of the night sky. My 450D doesn’t allow for anything longer than 30″ unless in bulb mode, where continuous drive doesn’t work.

And finally, we come to apertures. Clearly the most-used aperture setting is f/5.6. This is a sensible middling value, probably giving optimum sharpness for most of my lenses. It’s the kind of thing I’d choose in manual mode, and I bet the camera would readily choose it in semi-auto mode too.

f/1.8 is slightly more common than you might expect, and is probably from shooting in low light or where I’ve tried to maximise the depth of field.

I just spotted that my Nagios/RRD graphs of my home server are showing a strange correlation.

From these graphs, it seems that the higher the outdoor temperature, the more free memory the system has available. I’m sure this is just a coincidence, though…

Outdoor temperature

Free memory

Since getting my iPhone 3GS, I’ve been playing with a few apps. Today I tried one called Cyclemeter, which is a GPS tracker and can provide some interesting stats about your cycle rides.

I set it to track my journey to work (Speedwell – Clifton) and was quite interested by the elevation graph in particular. (N.B. this route is slightly shorter than my usual one, since the Bristol-Bath cycle path is currently closed near Lodge Causeway, so I’ve been taking a shortcut on main roads).

I’ve included some iPhone screenshots of my results:

Map of my route to work

Graphs of my route

Key points:

• I start at home, taking the roads
• At 2km, I join the Bristol-Bath cycle path at Rose Green Rd. You can see a dip in my speed where I stop and push my bike through the gate.
• Most of the cycle path is gently downhill towards the city centre
• At 5km, I reach the end of the cycle path and proceed through Old Market. It’s a bit stop-start in traffic.
• From 6km onwards, it’s a steady uphill climb (Woodland Road today, sometimes St Michael’s Hill instead) from about 85m to almost 160m above sea level!