18mm prime: Finding compositions in the dark
Escher's cousin's house -- by Joe Reifer
Full frame wide angle lens choice
I tested the Olympus Zuiko 18mm f/3.5 lens during the November full moon. The Canon 17-40/4L and 16-35/2.8L suffer from poor performance near the edges on full frame cameras. I previously tested the Olympus Zuiko 21mm f/3.5 against the Canon zooms, and the Olympus was noticeably sharper. The 21mm goes for about $300 on the used market, and works on Canon SLRs via Zuiko-EOS adapter. While inexpensive adapters are available on eBay, I highly recommend the extremely well made Cameraquest adapter.
My favorite lens on the Canon 5D is the 24-70/2.8L. There is not a better all around lens for Canon in this focal range unless you need an aperture wider than f/2.8. The Oly 21mm is not that much wider than the 24-70mm, so I decided to give the Oly 18mm a try -- all I can say is wow. This lens was tough to track down, but is a great performer at f/8, and stunning at f/11. This test on 16-9.net compares the Oly to the Contax 18mm and Canon 16-35/2.8L. Please note the Contax 18mm may not be compatible with the Canon 5D.
ISO speed for night photography
The above image was exposed for 6 minutes at f/11, ISO 320. Typical full moon exposures at ISO 100 are 3-4 minutes at f/5.6, or 8 minutes at f/8. I prefer the sharpness increase of shooting at f/8 with some lenses, but typically don't like to wait for 8 minutes between shots for both productivity reasons, and sensor noise. I usually settle on 4-6 minutes at f/8, ISO 160-200, depending on conditions. I exposed one frame at 6 minutes, f/8, ISO 160, and then another at 6 minutes, f/11, ISO 320. The ISO 320 shot predictably had much more noise than ISO 160, but is still quite useable with minor noise reduction. This test did show that my understanding of ISO 200 as the highest advisable ISO speed for night shooting is indeed correct.
Composition
I was following the moonlight around the location, looking for interesting lighting. The details on the metal gate caught my attention, and then I noticed the seating around the deflated kiddie pool in the yard. At this point I removed my camera from the tripod to play with the composition, and worked on lining up all of the geometric elements in the scene. Don't let your tripod dictate or constrict your compositional creativity. Put the camera back on the tripod after you've moved around the scene, and found the best angle.
Test Exposures
Digital SLRs are fairly linear between ISO speeds when shooting at night, which makes figuring out your exposures much easier than dealing with film reciprocity failure. After framing the shot, I switched the camera to Manual mode, ISO 1600, 10 second exposure, and fired a test frame. I checked the composition on the LCD carefully. Don't be afraid to reframe and take another test shot at this point.
The histogram looked about 1/3 stop underexposed, which is about right for protecting the highlights when shooting at night. Moving from ISO 1600 to ISO 200 is 3 stops, which brings the exposure to 80 seconds. The lens was stopped down 2 stops to f/8, which takes us to about a 5 minute exposure. An ISO adjustment to 160 brings us to 6 minutes at f/8.
I hope this inside look into these processes was helpful. There are more excellent resources on night photography on www.thenocturnes.com, including a link to a nice overview called common obstacles in night photography.