Patent: Canon 17-40 f/2.8-4L

[Canon Rumors]

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Canon EF 17-40 f/2.8-4L Patent Below is a patent for a new Canon wide angle zoom concept. The variable aperture is interested, if it remained as light and compact as the current 17-40 f/4L, the additional stop of light wide open would be a nice feature.

Patent Publication No. 2010-42792

• 2012.3.1 Release Date
• 2010.8.20 filing date

Example 1

• 39.05mm – f = 17.64 focal length
• Fno = 2.64 – 4.10
• 28.99 deg – 50.80 half angle of view.
• Image height 21.64mm
• 136.70mm – 134.67 full-length lens
• BF 39.97 – 64.95mm
• Lens Construction 12 elements in 9 groups sheet
• 4 aspherical surface

Canon’s patent

• Negative lead type zoom lens of negative-positive
• Small and light lens for focusing
• Inner focus
• Focusing the use (1b in the figure) part of the first lens group
• Video support

Source: [EG]

cr

[D.Sim]

This will be... interesting...

[Flake]

The additional stop at the wide end, a nice feature?  Well only if it manages to be sharp across the frame, most if not all wide angle lenses struggle at the wide end, wide open.  It's only a nice feature because stopping down will probably be better than a straight f/4

[dilbert]

What is the field curvature?
Will it be better than the current 17-40L at 17mm?

The length is 134 to 136mm. Does that mean it will not be constant volume like the current model?

[Haydn1971]

An indication that the 16-35mm might get dropped fo a 14-24mm f2.8 perhaps ? 

[tss68nl]

Looks promising, but I'm reluctant to be happy about it.

Lets see if the current price of the 17-40 f/4L of $800 will be doubled to $1600 with the introduction of it's successor as well 

[pedro]

this will be really interesting. how much time does it take from this stage to an announcement normally?

[traveller]

I'd really prefer a 16-35 f/4 (like the new Nikkor) for landscape work, although I accept that there are a lot of people that would like a 14-24 f/2.8.  Perhaps this is Canon's attempt at a compromise to save having to develop two lenses.  I think that would be a mistake, as the two new wide angle full frame zooms that Nikon has serve two different market, just like the 24-70 f/2.8 and the 24-105 f/4 and the two 70-200s. 

[nesarajah]

not sure if if I need it that wide open at 17mm . Cant think of a reason why ?

[Positron]

not sure if if I need it that wide open at 17mm . Cant think of a reason why ?

Interior architecture, possibly, but I think the main thing is to allow you to stop it down to f/4 or f/5.6 for more sharpness? That is to say that it's not cause and effect, but rather, they may have made it good enough at f/4 that they can pull off f/2.8 without it being terrible.

this will be really interesting. how much time does it take from this stage to an announcement normally?

I have seen no trend, and it seems like no more than 1/3 of these patents ever actually become products. In many cases they have an idea, and they patent it just so they have legal ammo in case they ever do decide to bring it to market.

[tivoboy]

If this puppy comes out it will be hard for me not to sell my perfect 17-40 f/4L for this

[Gcon]

If this puppy comes out it will be hard for me not to sell my perfect 17-40 f/4L for this

The 17-40mm is far from perfect. I suggest learning to read an MFT chart as the first step, and then having a good look at the corners of your shots at f/4.

[crasher7]

Now this I like

[tivoboy]

If this puppy comes out it will be hard for me not to sell my perfect 17-40 f/4L for this

The 17-40mm is far from perfect. I suggest learning to read an MFT chart as the first step, and then having a good look at the corners of your shots at f/4.

I've done that many times, this one is just fine thank you.

[Mark D5 TEAM II]

I'm not too sure how this variable-aperture lens would work with Canon cameras with extra-precision f/2.8-sensitive sensors. You have extra precision at wide angle and then lose it while zooming in, that's a recipe for OOF shots . And I doubt this would even be parfocal in any case. There is a reason why the old 28-80 f/2.8-4L zoom lens didn't have a successor with the same variable-max aperture...