I’m getting a bit tired of all the frolicking about “fast” m4/3 (micro four-thirds) or other crop sensor lenses that are so much lighter and so much more compact than their full frame equivalents, and how people are wondering what Nikon or Canon will “do about that.”
Lately, Olympus’s 40-150mm/2.8 telezoom gets a lot of attention. Let’s have a look: it weighs 1.94 pounds (880 grams) and is 6.25 inches (15.8 cm) long. For a lens that offers the focal length equivalent of an 80-300mm on full frame, that sounds pretty cool at first, especially at f/2.8… but wait.
The crop factor applies to the field of view as well. So on a m4/3 camera with its 2.0 crop factor, that lens translates to the full frame equivalent of an 80-300/5.6 lens! Yes, you get the brightness and “light gathering ability” of f/2.8 – but you’re not getting the (smaller) depth of field of an f/2.8 lens. You’re getting the full-frame equivalent DOF of an f/5.6 lens!
Depending on where your priorities lie (hello, subject isolation), this may or may not be (very) important. Yes, there’s probably thousands of people who don’t care about that, because subject isolation isn’t everything. Of course, I get it. But if you want a “true” 80-300/2.8 equivalent for a 2.0 crop sensor, it would have to be a 40-150mm/1.4 lens! Now how much would that cost, and what would its size and weight be?
Or look at it this way: my cheap-ish Nikon 70-300mm/4.5-5.6VR weighs 1.64 pounds (744 grams) and is 5.67 inches (14.4 cm) long. If I do the full math and transfer that to the m4/3 specs and crop, that’s a 35-150/2.25-2.8 lens. It both weighs less and is shorter than the Olympus lens. Hu?
The Olympus 40-150/2.8 costs $1500. The Nikon 70-300/4.5-5.6 costs $600. Yes, that’s comparing apples and oranges because the Nikon is “slow” in its light-gathering abilities* and there’s no doubt that the consumer Nikon zoom is no optical match for the Olympus. But on the other hand, it doesn’t even cost half as much as the Olympus lens!
So can we please stop this black & white thinking and the useless comparisons? Mirrorless crop sensor cameras and full frame DSLR are two different camera systems. Right? They can happily exist next to each other, and they can not be compared directly. Each has its advantages and disadvantages. Get over it.
*) but then again, larger sensors are producing better high ISO quality. Maybe not worth full two stops, but still. 😉