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Tuesday, 21 August 2007


That's just sexy. Olympus's new lenses definately have a few wonderful things going for them, this one seems to only continue that trend.

I really disagree with you, Mike, when you list the "equivalent" focal lengths. The lens is NOT a 300mm f/2, it's a 150mm f/2. It's not a 600mm f/2.8, it's a 300mm f/2.8. No change in sensor size is ever going to make it a 600mm f/2.8.

Your readership is smarter than you're giving them credit for. We don't need the math done for us, so please list the true focal lengths.

I guess it's the human instinct to want what one cannot have, but I would happily sacrifice some of the telephoto power of my DSLR in exchange for a wider wide end. Unless you're an active nature or sports photographer, ultra-telephotos aren't especially useful except for the wow factor they deliver and they generally make poor lenses for everyday use.

Added to that, long reach is now easily and cheaply available in either cropped or 'full-frame' format while even the budget options in the ultra-wide category represent a significant investment and the choices are few. Even the widest lenses for APS-C available are not as wide as the widest that was sold for 35mm. There were at least two 12mm lenses that covered a 24x36 frame but current the widest option for digital is 10mm, offering a 15mm equivalent focal length.--Matthew

Well, Mike (H.), of course you´re right about the consistent focal length. The message about practical use is given by the viewing angles - those are equivalent to the numbers Michael mentiones. The challenge for Oly-E-lenses is to deliver about double the resolution of a 35mm-lens-camera-combo, same print size required. IMO they are doing quite well in that regard and are worth a look.
Hans-Jürgen Hertz-Eichenrode

This fall, Olympus will have a 70-300 zoom (140-600 equivalent.) 1:4.0-5.6

It's an affordable, light weight lens that will match the kit lenses that come with the e-410/510.

I have to get one!

Dear MH,

I disagree. I'm smarter than the average bear, but I don't have all the blasted sensor sizes memorized. There's too effin' many of them! I like to know BOTH real and 35mm-equiv focal length (for the camera the lens is designed for).

Which gets listed first is a matter of taste, and I do think Mike could do a little better job of calling out which kind of f.l. he's presenting. But fundamentally, I'm on his side.

pax / Ctein

I *pretend* that my Olympus Zuiko 135mm f2.8 is actually a 270mm f2.8...

Cropped sensors offer more depth of field than full-frame. Oly's sensor being half-sized, you should add a stop to their f-number when considering DOF. So their 150mm f/2 lens has the FOV of a 300mm lens and the DOF of an f/2.8 lens.

At least, that's my understanding. I may be wrong.

The only people it makes any kind of sense to give "equivalent focal length" are those who used to use film 35mm cameras. For everybody else - and that is either rapidly becoming, or already is a majority - it's just confusing. And even those people didn't use to give "equivalent focal lengths" when talking about lenses for medium or large format, right? So why suddenly do it now?

I agree that what we _should_ be talking about is probably diagonal angle of view - that's a much more direct measure of reach. And I wish we could start doing so. It would make all comparisons simple and direct between cameras and formats; it would also remove the inherent confusion between rectilinear and fisheye lenses, which get different angle of coverage with the same focal length. And in fact, we're already using angle of coverage with FE lenses; why not all others?

But the focal length is a property of the lens and is not dependent on what size (or kind) of sensor you put on the back focal plane, and treating it like it is just makes everything confusing.

If you want to talk about coverage, use the angles; in fact, please do - it'd be interesting to see if there is traction enough to actually change how we talk about this.

At Matthew Allen: Olympus has your ultra wide angle needs covered as well, with a 7-14 f4 (14-28 equivalent FOV) wide angle lens. And it's a very good lens. It comes at a price, but Olympus has stated it's going to bring out a consumer ultra wide angle next year. So we're in for a treat.

At Janne: it's not "suddenly"... I remember an old article by Mike Johnston "introducing" mm-e.

I don't understand where is the problem: "mm-e" isn't "mm". I think we all know what Mike was talking about.

Re: "Cropped sensors offer more depth of field than full-frame. Oly's sensor being half-sized, you should add a stop to their f-number when considering DOF. So their 150mm f/2 lens has the FOV of a 300mm lens and the DOF of an f/2.8 lens."

I think you'll find you have to DOUBLE a 4/3rds aperture to find it's 35mm equivalent DOF.

So the 90-250/f2.8 talked about acts like a 180-500mm lens with the DOF of f5.6 but with the light gathering ability of f2.8. [on the 35mm format]

I hope that clarifies! :-)

I'm a 4/3rds owner... love the system-wide lens and flashes...love the build quality and maintenance free package... love the system-wide image quality of the 35mm-like images.

I just wishd I had £3½ grand for the above lens! :-(

I don't think it's accurate to say "no one cares" about the FOV vs focal length provided by smaller sensors. But it's old news, so you don't see a lot of talk about it. Look back in the press and online forums of a few years back when the masses were making the film-to-digital switch and you'll see a lot of talk about it.

It's also not the case that there is no downside to the smaller sensors. They're noisier, for one thing. Since high-ISO shooting is common in sports photography below the pro or D1 college level, whether for available-light gym shooting or night field sports with flash, the poorer noise performance of smaller sensors does matter to me.

All of which is not to say the Oly 90-250mm f/2.8 is not an intriguing piece of kit!

This is not a "lens spec review manufacturing marketing sales contract professional imatest lens review site".

That is to say, Caveat emptor. I am used to and fine with the numbers as presented here as usual by Mike.

"Cropped sensors offer more depth of field than full-frame."
Maybe I'm getting old and not remembering things clearly, but I wasn't aware that sensor size had anything to do with depth of field. In the old days I don't remember using a smaller format film camera increasing the depth of field at least not when the same f-stop and focal length were used on both cameras. Am I crazy or just wrong?

I thought DOF was controlled by focal length of the lens, f-stop used, point of focus and also tilt and swing on cameras with those features. I'm serious, have I missed an important part of the equation all this time?


Rob Griffin,
Actually, you're right. A 35mm camera with a 300mm lens at f8 will produce exactly the same DOF as an 8x10 camera with a 300mm lens at f/8 from the same standpoint. It's just that the 35mm camera uses such a radically smaller portion of the frame that the perspective as a whole "seems" compressed and the DOF "seems" less. It's a visual thing, not a technical thing.


Re: DOF. The other factor effecting DOF is that you use different lenses on different formats for the same perspective. So yes, a 300 is a 300, but a 300mm is a "normal" lens on 8x10, whereas a 50mm is a "normal" lens on 35mm FF format. _That_ will definately lead you to different DOF. :-)

I honestly suggest we do not derail this discussion and focus on better part of this story (Oly introduces competitive, long tele for critter shooters) and read more about DOF at http://www.vanwalree.com/optics/dof.html

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