Canon just announced the EOS 5D which is a (relatively) low-cost, full-frame digital SLR camera. Canon has made some truly great cameras in recent years, but I find Canons current lens/body line up is bothersome. A digital SLR basically puts a digital sensor in a camera body that used to hold film. The digital sensor is smaller than the film it replaces, so the imagable area is now smaller. This is generally referred as the “crop factor”. So if you have a lens for an 25mm lens from your old 35mm camera and put it on a dSLR with a crop factor of 1.5, the lens will now behave like a 37mm lens, but it’s still a 25mm. A full-frame sensor has no crop factor as the sensor size is damn close to that of film. The larger sensor size usually makes the camera much more expensive.
A crop factor can have benefits for telephoto lenses (100mm lens behaves like a 150mm lens), but wide angle lenses loose the wide angle. To help this situation, most camera and lens manufacturerers have made “digital” lenses that work better with the smaller sensor and will deliver a true wide angle. Most of these digital lenses however, won’t work on traditional film cameras or with full-frame dSLRs. The latter is what troubles me. Let’s take a look at the Canons current dSLR line-up:
| Model | Megapixels | Crop Factor | 35mm Equiv of 25mm Lens (focal length x crop) |
|---|---|---|---|
| EOS Digital Rebel | 6MP | 1.6x | 40mm |
| EOS Digital Rebel Xt | 8MP | 1.6x | 40mm |
| EOS 20D | 8MP | 1.6x | 40mm |
| EOS 5D | 12.8MP | 1.0x | 25mm |
| EOS 1D Mark II N | 8.2MP | 1.3x | 32mm |
| EOS 1Ds Mark II N | 16.7MP | 1.0x | 25mm |
Notice that the crop factor differs between cameras and how a 25mm lens behaves on the different bodies. Now, imagine yourself with a 20D along with the nicer EF-S 17-85MM f4-5.6 IS USM, as opposed to the standard kit lens. If you go out and get that fancy new $3299USD EOS 5D, guess what? That $699 17-85MM lens doesn’t work with your new body. The entire “EF-S” lens line only works on the 20D down to the Rebel. So, you’ll now need a new lens for your new full-frame dSLR.
My trusty old D70 has a crop factor of 1.5, as does the new D50, the D2x, D2h, D70s, D100, and D1x. If I upgrade or downgrade, my lenses will still work and behave the same way on any camera in their line up, even my digital lens. Nikon isn’t the only brand offers consistency across their line up, Minolta, Olympus, and Pentax does as well, I just happen to like the Nikon lenses better. but people like myself who have made an investment in digital-only lenses aren’t going to be lining up to get a new body that now needs lenses originally designed for film.
Damnhandy 