Full Frame - Marketing Gimmick or Not?

Now that I have a Canon 5d full-frame camera, I'm wondering whether I just got caught up in a marketing push by Canon (and now Nikon) or whether there is something really magical about a full-frame camera. Here's why: if you wanted to buy a camera system plus three lenses that covered everything from wide angle, the cost of full-frame is pretty steep. Let's compare (using prices from B&H):

• APS-C package
• Canon 40D with 28-135 IS lens $1,500
• Canon 10-22 EF-S lens $690
• Canon 70-300 IS lens $549
• TOTAL: $2,739
• FF package
• Canon 5D with 24-105 L lens $3,330
• Canon 17-40 L lens $679
• Canon 70-300 DO lens $1,100
• TOTAL: $5,109

Why did I choose somewhat lesser quality lenses for the APS-C package? The smaller sensor uses the centre of the lens, so sharpness out to the corners is less critical than with the full-frame sensor. My experience with a 10d and now a 20d is that you get almost identical performance with cheaper lenses and a smaller sensor.

As you can see, full-frame comes at quite a penalty in cost. In fact, it is nearly double the cost of an equivalent APS-C system. Is the difference worth it or is it marketing hype that has driven me to buy an expensive full-frame system?

Here's an article by Ken Rockwell that goes into a lot of detail on the full-frame advantage. Ken describes why he likes his Canon 5d and how it compares to his Nikon APS-C cameras. Here are the salient points:

• Sharpness: It isn't just the number of megapixels that determines how sharp an image is. When you look at a photo, the sharpness (assuming you've taken it in focus) depends on the resolving power of the lens as well as the resolving power of the camera. Modern APS-C cameras are capable of pretty good resolving power (measured by how many black and white alternating lines you can distinguish in a millimeter) and rival full-frame. However, lenses are not necessarily up to the task. Theoretically, if you had a perfect lens, capable of outresolving any camera, the APS-C 40d sensor would actually outresolve the 5d's sensor (the 5d has around 8 megapixels within the APS-C sensor coverage area, where the 40d has 10 megapixels). But, lenses aren't perfect and the sensor actually passes the limitation of the lens. The 5d produces sharper images because it spreads its pixels out over a wider area. Think about a photo of a picket fence. Let's say that a lens can resolve 40 fence posts per millimeter. In a full-sized sensor, this works out to 40x35 = 1,400 fence posts in the photo. For an APS-C-sized sensor, the lens is only capable of showing 40x22 = 880 fence posts in the photo. Regardless of how well the two sensors resolve the fence posts, the APS-C camera starts off with fewer to begin with. Assuming the sensors can out-resolve the lens, you'll have a much sharper photo from the full-frame image.
• Noise: Big pixels are reputed to produce less noise that smaller pixels. It makes sense that a larger pixel will catch more photons of light, requiring less amplification than smaller pixels. Noise is a by-product of amplification. Now, it is true that Camera manufacturers are working hard to produce less noise in their circuitry and are working hard to put faster processors in their cameras so that sophisticated noise reduction programming can be applied, but why not start with less noise to begin with? Now, I'm not a big expert on camera noise, but the folks who produce Noise Ninja are and they develop noise profiles on most DSLR cameras. I thought I'd run a couple of 1600 ISO photos through Noise Ninja, one from my 20d and another from my 5d to see what the default noise profile was for each one. The result was a noise reduction level of 32 for the 20d and 23 for the 5d. I'm not sure if these numbers are linear or not, but there is a significant difference in values between the two cameras. I'm not sure where the 40d would come in, but I suspect that it would be comparable to the 20d if you turn off the noise post-processing in the Digic III processor.
• Colour differentiation: As a corollary to the lower noise argument, if the pixels are producing less noise, it should be easier for the camera's processor to detect the true colour of a the light being received by a pixel as opposed to muddying it in response to random coloured noise.
• Ability to use wider angle lenses: There is a limit to how wide an angle you can build into a lens and I would speculate that Canon's 10-22 AF-S lens is probably pushing it. This lens delivers a similar angle of view to a 16-35 mm lens on a full-frame camera. Canon makes a 14 mm lens that delivers a wider angle of view than possible with an APS-C camera.
• Brighter, larger viewfinder: My 5d has a much larger, brighter viewfinder than the 20d and it is such a pleasure to use!
  

So, there are advantages to full-frame, but do any of them really matter when all you want to do is take beautiful photographs? In reality, the one that smacks you in the head is the brighter, larger viewfinder. It makes it easier to compose an image because all the elements in it are larger. Pretty elementary really. The ability to buy a 14mm lens doesn't turn my crank -- 17 mm is fine. I really haven't seen the colour improvement yet, but I've only had the camera for a couple of days. Sharpness and lower noise will be important when I create larger prints, but right now my printer limits me to 13 inches wide anyway.

So is it hype or reality? I'm still waffling. Maybe the differences will become more apparent as I use the 5d more, but right now I think the premium is probably too high. I'm sure it is tough to build large sensors in the quality needed. Probably a high percentage of sensors get turfed at the assembly line due to flaws. But, does that justify spending twice the amount of money on a full-frame system. I'm not sure it does.