The War Goes On

The camera war between Nikon and Canon, that is, as Nikon announced their next camera – the D700, a “full frame” chip camera that slots in just below the top-of-the-line D3. Aimed squarely at Canon’s full frame 5D, it looks likely to tromp it based on the specs published. 

A lot of my students ask why I’m so interested in the full frame cameras (currently Canon’s 5D and 1Ds Mark III and Nikon’s D3). A lot of it has to do with having grown up with 35 mm film and part of it has to do with some esoteric bits of optics and physics.

Most of today’s DSLR cameras use a CCD or CMOS chip that is smaller than a 35 mm piece of film. This APS-C size is about 22 mm x 15 mm, versus a piece of film’s 36 mm x 24 mm area. This is not about megapixels for me (well, it is, more on that later) but about optics. 

Because of that smaller size, most DSLR cameras have a cropping factor with all lenses. If you take the standard 50 mm lens, it projects a circle of coverage. With a full frame camera, the frame comes out pretty close to the edges of that circle. With an APS-C camera, it’s taking a rectangle out of the middle of that circle – what is essentially a cropped version of the full frame camera’s view. (A lot of folks refer to this as a magnification factor, which it most definitely is not.)

The optical quirk comes in subtly – with your focal length and aperture remaining constant, as you increase your camera to subject distance, you increase your depth of field. So, in our 50 mm example, on a full frame camera let’s say I’m focused at 10 feet and at f/5.6 – my depth of field would be about three feet. To get that same field of view with the same lens and aperture, I need to back up to about 15 feet. And as I increase my camera to subject distance, my depth of field increases, probably to around 12 feet.

That’s a huge jump and is going to make it much more difficult to separate my subject out from the background. 

“Old timers” like me will talk about a 50 not being a 50 anymore as there is a perceived and actual different in how a 50 mm lens renders images on a full frame camera versus a APS-C camera. As you move to wider lenses, this effect becomes even more exaggerated. 

So, am I ordering up a D700? No. As much as I love(d) my Nikons, which I used through all of my shooting career, I’m mostly a Canon guy now. Canon has stepped up and supported my students at a huge level over the last few years, so I walk a delicate line between my past brand loyalty and the current support Canon is providing. There are a few areas where Nikon is in the lead (this D700 and the D3 are arguably the top cameras out there and the flash system is stunningly good), but Canon has a deeper array of prime lenses that I like to use. 

And now I have to wait and see what the next “5D” will be …