I've always liked the thought of having a super-thin ("pancake") lens for my Canon DSLR, for when I just want to take my camera out with as little bulk as possible. I'm not even too concerned about the focal length: I find I'm always more creative when I'm working with constraints. A wide aperture (f/2.8 or wider) would be good though.
So, does such a thing even exist and if so can anyone recommend one?
Voigtländer Ultron 40mm f/2 is available in Canon mount. Photozone review praises its build quality and dislikes its rough bokeh. There's also 20mm Color Skopar SL II, but it's almost a stop slower than what you asked for, f/3.5. Photozone review describes it as well-built, but optically a little soft and vignetted when wide open, decent from f/5.6 to f/11.
With an adapter, you could use Pentax Limited line lenses. I can personally vouch for the 40mm f/2.8. An even smaller (and cheaper, APS-C coverage) XS version of it was announced recently, but it could be awkwardly tiny to use with manual focusing on a Canon body. But that's probably somewhat true for any pancake lens. Missing any way to control aperture of an adapted lens is probably a more important factor steering away from this option.
Update: Canon now produces the EF 40mm f/2.8 STM pancake lens:
Features (quoted from Canon's product page) include:
Plenty of sample images can be found in this Flickr group.
I've secretly lusted after a Pentax body just because of the available of pancake lenses. :)
A Rebel and a 35/2 or 50/1.8 will be the smallest and lightest Canon option that retains autofocus.
Canon now makes two pancake lenses for the EOS mount. Both are just slightly wider than "normal", f/2.8, metal builds, and come with the STM focus motor. Both have reviewed quite well for sharpness and overall image quality; see the-digital-picture.com reviews for the 40/2.8 and the 24/2.8.
The EF 40mm f/2.8 STM is for full-frame cameras.
The EF-S 24mm f/2.8 STM is for crop cameras.
Voigtländer makes three pancake SL II lenses, the Color Skopar 20/3.5 and 28/2.8 and the Ultron 40/2, but these lenses, while they do communicate with the camera body to allow aperture control and metering, do not autofocus. And, of course, adapting pancake lenses, such as the Nikon or Contax/Yashica Zeiss 45/2.8 lenses, or any of Pentax's pancake offerings would be manual focus/aperture with non-reporting lenses, so not nearly as convenient to use as Canon's offerings. In addition, the CZ Tessar 45/2.8 does not have mirror clearance on a Canon 5D body.
Does the Canon 50mm F1.8 get close enough for you? Its pretty small, and only $100
