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The mythical 14-24mm f2.8L.Agreed
Photozone have done a review of the Sigma 12 - 24mm MkII and it's not fantastic. Problems especially at the wide end with border & corner resolution, vignetting, chromatic aberations, and barrel distortion, which don't really become acceptable until f/11 on top of all this it's as expensive as the 17 - 40mm f/4 L, and you can't use filters on the front. I have owned the MkI version of this lens and it was not commercially useable until well up the zoom range.
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The 17 - 40mm f/4 L is cheap enough for an L lens, but it's not good wide open at the wide end, and could really do with being updated, again you will have to use this lens stopped down heavily if you want decent image quality. You can use filters with it though.
No, it has 2.8, because the pupil is magnified by the front element moving relative to the pupil.
If they could make the blades open to 71mm in the same form factor, they sell it as a 70-200f/1-2.8.
Zooming a lens doesn't mechanically widen the pupil. It optically magnifies it.
http://www.dgrin.com/showpost.php?p=523730&postcount=2
There is a lot of mis-information on the Internet about how "constant aperture" zooms work, but the most lucid explanation comes from Bob Shell:
Comments from Bob Shell (January 8, 2003):
"An f-stop is the ratio between the focal length of the lens and the *apparent* size of the lens opening as viewed through the front. It must take into account the magnification factor of all lens elements in front of the diaphragm, because it is the size of the opening that the light "sees" as it passes through the lens, not the actual physical diameter of the diaphragm opening.
It is this fact that allows companies to make constant aperture zoom lenses which maintain a constant f-stop when the focal length changes, because such lenses are designed so that the magnification factor (diopter value) of all elements in front of the diaphragm changes as focal length is changed to hold the aperture value constant."
<p><strong>Canon’s patent</strong></p>
<li>When doubled, twice the lateral aberration, longitudinal aberration is 4 times greater rate of expansion, because the F-number is also double, longitudinal aberration is twice per depth of focus</li>
I read that as it, like the 2X, adds two stops. So a 2.8 lens -> 5.6, not 8.
QuoteNow that I know a bit more, I will play with shutter speeds and see if it goes away (although I lose the ability to freeze).
In the US frequencies are 60hz (cycles). In Europe and the Middle-east it is 50hz (cycles) - others from various countries can/should confirm.
The Canon version is so sharp and perfect I really doubt this can better it. Even if it is Zeiss. Might be alright for Nikon folk though!
UHS-I SD cards should be about as fast. SanDisk has a 95MB/s UHS-I SDHC cards.
You do know that the 5D MK III does not support the UHS protocol?
If you have a UHS card reader you are ok, but the article is about USB 2 in the camera body.
Because it's called Canon!!
They can put a 63 zone metering into 5D3 from their cheapest model Rebel T3 for next three years rather than using the latest one from the 1DX. In this way, they can also cut the AF point-linked spot metering feature off.(you can find this feature from all Nikon bodies)
Typical answers from Canon user:
1. Oh, that's good enough.
2. There's nothing wrong with it, it works well.
I don't give a damn whether the 5Dmk3 has a USB 2 or USB 3 port. A USB 3 card reader is a cheap one off expense (already bought one), and moving the card from the camera to the read & back again takes a few seconds (which I spend as it is), and I'd rather bitch about more important features.
Ellens is correct here in the case of SDHC class 10 cards they are approx 25Mb/s or thereabouts this is around the limit of USB2.0 so for that purpose no reason for USB3.0 as the card transfer (read) wont reach USB3.0 speeds!
however im unfamiliar with CF speeds anyone?
Because it's called Canon!!
They can put a 63 zone metering into 5D3 from their cheapest model Rebel T3 for next three years rather than using the latest one from the 1DX. In this way, they can also cut the AF point-linked spot metering feature off.(you can find this feature from all Nikon bodies)
Typical answers from Canon user:
1. Oh, that's good enough.
2. There's nothing wrong with it, it works well.