This month’s* picture of the month is an exercise in long/timed exposure: to take a picture like this you’ll need to do a little planning and a little math, and have a little extra equipment on hand. In my case, my subject was a picture of Dunwoody, GA taken from inside a hotel room and at night. Read on for more information about how you can create a picture under these conditions!
- Set-up: Set your camera on your tripod, attach your cable release, and compose and focus your shot.
- Take two meter readings: one at your strongest light point (in my case the light on the parking garage), and one at mid-tone (in my case the lighted buildings in the background). You might also take a reading at your lowest light point — which I did not do for this photo because of…reasons…
- Use your meter readings to find your f-stop value:
- Multiply your f-stop readings and take the square root of the result.
- Average out your exposure value readings (e.g., [EV(A)+EV(B)]/2) and convert that new exposure value to an f-stop value (using your meter, or a chart like this).
- Use your f-stop/time scale to get the correct exposure time and corresponding f-stop.
- Deal with Reciprocity Failure: If you take the image using the computed factor values, your image will be under-exposed. The trouble is, once your exposure time passes about 1 second, the inverse ratio between light intensity and time duration of exposure becomes increasingly inaccurate. To escape the problem you can cheat and download a reciprocity calculator from your app store, use a reciprocity correction chart, or do a little math. [Side note from the editor: when asked about his favourite source for reciprocity correction charts, Robbie said it was in his head. Please do not try to dissect his brain to get it out.]
- Take the picture: Set the aperture and corrected time, set your shutter to bulb, re-focus, put your mirror up, and take the shot with your cable release. Time the shot and release your cable release to close the shutter.
- Bracket your shot using ±1 second.
*Editor’s Note: Robbie actually did prepare this picture for July. Unfortunately, his ne’er-do-well editor got a little lazy and/or distracted…