28-70mm f2.0 - can it be?

http://www.dpreview.co​m …/07101701olympu​szuiko.asp

"No other manufacturer can offer a 28-70 equiv. lens at f/2.0 but the 14-35 f/2.0 is just that" this quote must be straight from Olympus, and has been parroted by dpreview.

So lets check out this theory. Hop on over to http://www.dofmaster.c​om/dofjs.html . At 28mm F2.8, from 10ft to subject my 5D has 7.31ft DOF. At 14mm(28 equiv.), F2.0 the E510 has...... wait for it.......11.8ft DOF.

For the E510 to get the same DOF as my 5D, it would need a f1.4 14-35mm. Oh, I'm starting to see a ratio here. Huh! 2X crop needs 2X aperture opening to achieve the same DOF.

Now I'm going to stop here. This is a test.
Olympus feels justified in saying this..

So what am I missing? What makes them feel like they can say this?

Because aperture is not a measure of depth of field, and has nothing to do with format (of course, neither does focal length), it's a measure of the ratio of focal length to the size of the light opening, and thus the amount of light hitting the sensor. Their lens is an f/2.0 zoom...it lets in twice the light of any f/2.8 lens. Therefore, they've made the only 28-70 (35mm equiv FOV) f/2.0 zoom.

They, of course, have not made a 28-70 f/2...they've made a 14-35 f/2. Still..I'd love an 18-50 f/2 zoom.

there is still merit in the lens, even though not from the DoF.

the merit is that it allows more light. an f/2 is an f/2 regardless of focal length and sensor size. it will allow you to take photos with one stop less light than the f/2.8 zoom out there.

and if the DoF is wider, that's great, in fact, it is even better considering how difficult it is to focus and frame something with razor thin DoF.

on the flip side, as you mentioned, is that it cannot achieve the same thin DoF if thin DoF is desired.

A zoom faster than f/2.8 would be absolutely tits...especially something in the 24/28-70 range. Can't imagine the weight though.

jmpsmash wrote in post #4141086
the merit is that it allows more light. an f/2 is an f/2 regardless of focal length and sensor size. it will allow you to take photos with one stop less light than the f/2.8 zoom out there.

Of course, the smaller sensor of the Oly will lead to more high-iso noise. I bet the E510 shooting at ISO800 and f/2 would produce a similar image as a 40D at ISO1600 and f/2.8.

Olympus saying they've made a 28-70mm f/2 lens is like Canon saying they've made an IS 36-432mm f/2.7-3.5. Which technically Canon has, it's the lens on the S2/S3/S5.

angryhampster wrote in post #4141197
A zoom faster than f/2.8 would be absolutely tits...especially something in the 24/28-70 range. Can't imagine the weight though.

Ding!!! or the price...

Yeah well, no one else has a 14-35mm zoom @ f/2 either so IMHO Olympus can do feild goal dances all they want!