Would a constant aperture zoom faster than f2.8 have to be really heavy and prohibitively expensive?

[kevin_harper]

Just lookin at the Oly 4/3 f2 zooms and wondering if anyone can tell

me if it could be done for a full frame format reasonably? I'm

presuming no, cos they don't exist, at least as far as I know. But

maybe someone can inform me as to why.

[neild]

Presumably, the smaller image circles of the 4/3 Olympus lenses allow for smaller f/2 zooms. Even Olympus would need to use bigger lens elements for the same aperture zooms if they were now to cover the full frame (I presume)...

[grant g]

I think the prohibiting factor would be the size of such lenses to maintain "L" quality. Just a guesstimate, but take a 24-70/2.8 and make it roughly 40% greater in diameter from the front and roughly twice the element weight. Or it could be made a little more economically (smaller, lighter than above) and vignette more than you'd expect from an L wide open, but you'd have f/2. Better yet, a similar lens could be made in EF-S format for less than the size/weight of the 24-70. Too bad *that's* not gonna happen!

[bobatkins]

It could be done, but either you couldn't afford them or you wouldn't want them.

 

I guess something easy like a 35-70/2 would be possible and affordable, but it's not very exciting. Maybe a 35-90 would be possible, but would you pay 2x to 3x the cost of an f2.8 zoom, and if you would, how many others would? Probably not enough to make it worth producing.

 

Wideangle f2 zooms and telephoto f2 zooms would be difficult to make, large and very expensive.

[marknagel]

Bob, why would wide angles be difficult and large? I can see teles, but wouldn't it be easier with a wide. I think, a 50mm f/1 would be 50 diameter x 50mm focal length. Wouldn't a 16mm-50mm f/1 be the same size glass? I don't quite understand all the guts of a zoom, so I might be missing something completely. One day I'm going to buy a cheap zoom to take it apart to see how it ticks.

Mark

[tom_m2]

As far as I remember, Olympus lenses communicate geometric distortion and vignetting information to the body, which can then correct the image. That means that they have a lot more design freedom in their lenses, since they don't need to worry (as much) about correcting those defects optically.

 

Canon can't do that for the L lenses, since those are also used with film. And they don't seem to bother doing it for the EF-S lenses (maybe there are patent problems, although that would seem silly, given that people have been doing the same sort of corrections on the desktop for a long time).

[carl_weller]

The f2.8 zooms are already really heavy and prohibitively expensive for most people! How

much heavier/more expensive do you think they should be?

 

Every lense is a compromise between many factors including speed, weight, size, focal

length, and cost.

 

I'd love a 16-300/f.1 that was only 500 grams and cost less than a house, but the

technology doesn't yet exist to make the perfect lense at a price that people can pay for

(or at a weight they can easily carry).

 

regards,

[frank_rizzo]

Anything is possible. Do not forget that back in the 70s good ol' Kubrick had Zeiss

custom make those 0.8Fstop(around that range) lenses for motion picture cameras to

shoot Barry Lyndon.

[larry h.]

I for one would love a 35-70/2.0 lens. It shouldn't need to be too complicated, big or heavy. But I would accept all three if they turned out to be necessary.

[danield]

Kevin

 

The reason why full-frame f/1 zooms can't be made is not something someone can explain in a forum post. Optics and materials technology are subjects to study for a lifetime... The fact that you have zoom lenses at all is a marvel of technology.

 

It's like asking why the corner shop doesn't sell space travel holidays - it just not feasible.

[oceanphysics]

<i> I think, a 50mm f/1 would be 50 diameter x 50mm focal length. Wouldn't a 16mm-50mm f/1 be the same size glass?</i>

<p>

Why does a 16-35 f/2.8 take a 77mm filter when, by your math, the front element should be only 35/2.8 = 12.5 mm in diameter? Answer that and you'll understand part of why it's not feasible.

[oceanphysics]

Btw, it's not just a function of zooms. Investigate the diameter of Canon's 14mm f/2.8 lens. It's a bit larger than 5mm.

[bobatkins]

The fact that there are no superwide f2 primes is a good clue as to why there will be no f2 superwide zooms!

 

The optics (retrofocus) required for supewide lenses are complex, and making them both fast and aberration free is very difficult. That's why the give away 50/1.8 lenses and charge you an arm and a leg for a 14/2.8. The complexity of the lens isn't linear with aperture. It goes up FAST. That's why even for a 50/1.0 it's two arms and a leg.

[funkag]

Bob,

 

Is that why we're not seeing any EFS (or DC or di-II) wide primes? I keep thinking that an EFS-type 15mm 2.8 shouldn't be any more complicated than an EF 24 2.8. Or am I thinking engineering while Canon is thinking accounting?

[phil vaughan - yorkshire u]

<i>"Is that why we're not seeing any EFS (or DC or di-II) wide primes? I keep thinking that an EFS-type 15mm 2.8 shouldn't be any more complicated than an EF 24 2.8. Or am I thinking engineering while Canon is thinking accounting?"</i><p>No you're thinking (il)logically, a 14mm lens is still a 14mm lens whether it's designed for efs or not. There is a little design leeway due to the mirror box, but essentially you have the problem Bob described re retrofocussing lenses.<p>The only accounting point Canon have (for any of these lenses) is whether they could sell enough of them at a decent enough price to recoup the R&D costs.

[neild]

<i>"The fact that there are no superwide f2 primes is a good clue as to why there will be no f2 superwide zooms!"</i>

<p>

But what about the Olympus <a href="http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/zuiko/htmls/21mm.htm"><b>21mm f/2.0</b></a>?