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What's the next EF-S Lens?
- Thread starter oldboy
- Start date
skyliner
Forum Enthusiast
Unfortunately, this is what I fear may happen.
I'd like to see a fast wide prime, ideally 15/2.0 (which I would probably buy), a fisheye (which I might buy), or a 18-200 IS (which I wouldn't buy, but would like to see for the sake of all those who won't shut up about Canon's lack of such a lens), but I suspect the actual offering will be something lame.
One thing that makes that seem somewhat unlikely is that there's not a lot of room for such a lens in the lineup, with the 17-55 and 17-85 EF-S lenses. We've seen how much more expensive a lens gets when it gains IS, and I'm not sure Canon would be able to price an IS kit lens low enough to sell it given the price of the 17-85. Also, if the current kit lens were to be discontinued with the introduction of an IS version, it would raise the price of all the entry-level kits (which I doubt Canon would be foolish enough to do). A kit lens priced around $100 seems necessary for that reason, but that just leads back to the question of how much demand there would be for a slow 18-55 IS given the existence of the 17-85...
You don't want to defish a 180° diagonal fisheye as a matter of general practice. The 10-17 is better because it can reasonably be defished at the longer focal lengths, and still give you a slightly wider image than from a 10mm rectilinear, but the main reason for a fisheye is to keep the fisheye projection.
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Lee Jay
(see profile for equipment)
Steen Bay
Veteran Member
Maybe to offer a small and lightweight tele..
Lemming51
Forum Pro
nestled right between the 17-55 f/2.8 and 17-85 f/4-5.6
Making a lens longer than 44mm an EF-s won't make it smaller than making it an EF. Such lenses don't need close back focus distance and so don't benefit from the EF-s mount.
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Lee Jay
(see profile for equipment)
Steen Bay
Veteran Member
Well, let's imagine a EF-S 70-300/2,8 IS. Wouldn't that be smaller than a EF 70-300/2,8 IS because of the smaller image-circle?
Nope...same size (well, there would be a very tiny reduction).
300/2.8 = 107mm - entrance pupil size regardless of image circle size.
That entire front section on the left would still be the same, and the overall length would be the same. Some of those tiny elements on the right could get very slightly smaller. Overall, no real change in size.
Notice that there was plenty of room for them to move the rear element closer to the sensor, even with the EF mount, and they didn't. That's because there's no real advantage to doing so on a telephoto lens.
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Lee Jay
(see profile for equipment)
Steen Bay
Veteran Member
I seriously doubt that! The front element on the EF-S lens could have a 1,6x smaller diameter, and still collect enough light for the 1,6x smaller image-circle!Nope...same size (well, there would be a very tiny reduction).
300/2.8 = 107mm - entrance pupil size regardless of image circle size.
That entire front section on the left would still be the same, and
the overall length would be the same. Some of those tiny elements on
the right could get very slightly smaller. Overall, no real change
in size.
Notice that there was plenty of room for them to move the rear
element closer to the sensor, even with the EF mount, and they
didn't. That's because there's no real advantage to doing so on a
telephoto lens.
This is a fundamental misunderstanding of optics. Even if there is only a single pixel at the center of the sensor, you still need a 107mm aperture for a 300mm, f2.8 lens to illuminate that one pixel. Each and every pixel looks through the entire lens aperture. It doesn't matter how big the sensor is, a 300mm, f2.8 lens has to be at least 107mm in diameter at the front.
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Lee Jay
(see profile for equipment)
Lemming51
Forum Pro
Lens opening diameter and focal length define the maximum aperture ratio. 200 f/2.8 must have an objective lens diameter of 71.5mm or greater, whether it is projecting an image circle to cover 35mm film frame (24mm x 36mm), 1.6x (15mm x 22.5mm), 4"x5" sheet film, or a tiny 1/4" digicam sensor (2.7mm x 3.6mm).
Look at the size and weight of Olympus's 4/3 lenses.
Steen Bay
Veteran Member
You may be right, but still I don't think it makes any sense! Aperture must be 107mm yes, but I'm talking about the front-element, and the image-circle must have some influence on the overall size of the lens!
ed rader
Veteran Member
i think canon thinks the 70-300 IS has completed the trio.
ed rader
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ed rader
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The aperture can't be bigger than the front element!
The image circle is a vignette. With a tiny sensor you could create a lens with tons of vignetting, but you'd still need that big front element, and the big elements behind it.
The size of the image circle has a big effect on the size of wide-angle lenses, especially retro-focus lenses. It has almost no influence on the size of long lenses.
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Lee Jay
(see profile for equipment)
marc baumser
Senior Member
24mm equivelent Tilt shift on a crop body would be nice
Doubtful though
Marc
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All shots are 30D unless otherwise noted
http://www.pbase.com/mbaumser
01-20-09 :-D
Doubtful though
Marc
--
All shots are 30D unless otherwise noted
http://www.pbase.com/mbaumser
01-20-09 :-D
Indeed, for 200mm 2.8 one needs at least 72mm front lens.
For those that think a 1.6 crop needs less: keep in mind that your 200mm behaves in fact as a 320mm (1.6x200). So if you really want a smaller lens, lets say a 200mm EF-s lens that actually gives images with 200mm equivalent on 35mm sensor size (which would be 200/1.6=125mm), you can indeed make a much smaller lens. In fact the size of a hypothetical 125mm 2.8 EF lens. With a minimum front elementy of 125mm/2.8=45mm.
Such lens would give you the same view/magnification as a 5D with a 200mm 2.8 EF lens.
For those that think a 1.6 crop needs less: keep in mind that your 200mm behaves in fact as a 320mm (1.6x200). So if you really want a smaller lens, lets say a 200mm EF-s lens that actually gives images with 200mm equivalent on 35mm sensor size (which would be 200/1.6=125mm), you can indeed make a much smaller lens. In fact the size of a hypothetical 125mm 2.8 EF lens. With a minimum front elementy of 125mm/2.8=45mm.
Such lens would give you the same view/magnification as a 5D with a 200mm 2.8 EF lens.
Steen Bay
Veteran Member
OK. Guess I'll have to accept that
But with less total light captured because of the smaller entrance pupil.
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Lee Jay
(see profile for equipment)
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