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02-10-2013, 08:27 PM   #1
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Dreaming awake: 24-70 f/1.4 lens?

Of course there are none in existence, but just wondering, how big can it get?

1. Estimate size for: APS-C
2. Estimate size for: 35-mil

or, is there any zoom lens out there with a constant aperture greater than f2.8?
I'm not planning to buy one, just wondering if it is even "possible to build" lol

02-10-2013, 08:31 PM   #2
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The science behind building very fast constant aperture zoom lenses amazes me. I would think it's possible to build a zoom lens with a .9 constant if someone wanted to. But how big would it be? How many elements/groups would it be? And, of course, how much would it be? I would love to know.....
02-10-2013, 08:34 PM   #3
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Given the formula that A = F/D - where A is aperture, F is focal length, and D is diameter of aperture hole, at F1.4 and 70mm, the wide open aperture must measure 50mm across. Given the 70mm f2.8 is 25mm across, a wild guess is that the front element could be twice the size of a 24-70 F2.8 - and most 24-70 f2.8 have 77mm filter sizes already so... it'll be big?

That's assuming the glass must maintain the same ratio to cast an image through a 50mm wide aperture.
02-11-2013, 01:13 AM   #4
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Olympus build a couple of 4/3 format f/2 zooms with prices in top end Canikon pro lens territory:

ZUIKO DIGITAL ED 35-100mm F2.0 | Digital SLR | Olympus Imaging Asia
Olympus 14-35mm f/2.0 ED SWD Zuiko Zoom Lens for Olympus 261011


You should try looking at cinema lenses if you want ultra fast zooms (that cost as much as a house).

T/1.9 probably puts this 17-112 somewhere around f/1.7 or so but it only covers a 2/3" video sensor and it would need a pretty funky adapter because it is designed for a 3 chip broadcast camera: Zeiss DigiZoom 17-112mm T1.9 1531-502 B&H Photo Video


Since it is a super 35mm film lens this Fujinon should cover APS-C at somewhere around f/1.8: Fujinon 18-85mm T2.0 Premier PL Zoom Lens HK4.7X18-F B&H Photo

02-11-2013, 02:17 AM   #5
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QuoteOriginally posted by Steinback Quote
Olympus build a couple of 4/3 format f/2 zooms with prices in top end Canikon pro lens territory:

ZUIKO DIGITAL ED 35-100mm F2.0 | Digital SLR | Olympus Imaging Asia
Olympus 14-35mm f/2.0 ED SWD Zuiko Zoom Lens for Olympus 261011


You should try looking at cinema lenses if you want ultra fast zooms (that cost as much as a house).

T/1.9 probably puts this 17-112 somewhere around f/1.7 or so but it only covers a 2/3" video sensor and it would need a pretty funky adapter because it is designed for a 3 chip broadcast camera: Zeiss DigiZoom 17-112mm T1.9 1531-502 B&H Photo Video


Since it is a super 35mm film lens this Fujinon should cover APS-C at somewhere around f/1.8: Fujinon 18-85mm T2.0 Premier PL Zoom Lens HK4.7X18-F B&H Photo
The Olys are not comparable due to the 4/3 format and the 2x crop factor, which was supposed to be the attraction to create a smaller lens. However, we know that the numeric performance doesn't standardize well when going up against APSc and FF.

Not to mention, they were a couple thousand a piece. And the people that bought in are extremely angry right now because those lenses are essentially worthless and losing value by the day.

If people were willing to pay and to carry such a huge zoom lens around, it would be made, but no one would be. Studios, sure, but until some better carrying options come along, we're not going to have people in the field using such lenses.
02-11-2013, 02:50 AM   #6
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I just put the Oly lenses out there as samples of zooms faster than f/2.8. I certainly wouldn't buy one.

F/1.2 and f/1.4 zoom lenses are available, they're just attached to things like super 8 movie cameras and C mount surveillance cameras with small image circles.

That Fujinon I linked at 15 pounds and more than a foot long starts to give some idea of what an ultra fast APS-C zoom might look like, and I agree that it isn't practical as a consumer lens.
02-11-2013, 03:00 AM   #7
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QuoteOriginally posted by Steinback Quote
That Fujinon I linked at 15 pounds and more than a foot long starts to give some idea of what an ultra fast APS-C zoom might look like, and I agree that it isn't practical as a consumer lens.
Hmm but wait, "Super 35" is a 35-mil film format right?
02-11-2013, 06:56 AM   #8
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QuoteOriginally posted by Alizarine Quote
Hmm but wait, "Super 35" is a 35-mil film format right?

Right. It's 24.89 x 18.66mm,
just a little bit bigger than covering
Pentax APS-C with shake reduction.

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