# Patent: Canon EF 16-40mm f/4



## Canon Rumors Guy (Dec 23, 2015)

```
<p>A <a href="http://egami.blog.so-net.ne.jp/2015-12-23" target="_blank">patent for a 16-40mm f/4</a> has appeared. This could be a sign that the EF 17-40mm f/4L may be on its way out. We have been told that there was a possibility that the EF 16-35 f/2.8L II replacement could be wider, maybe the information was the EF 17-40 f/4L replacement instead.</p>
<p>Patent Publication No. 2015-206976 (Google Translated)</p>
<ul>
<li>Published 2015.11.19</li>
<li>Filing date 2014.4.23</li>
<li>Zoom ratio 2.36</li>
<li>Focal length 16.48 24.40 38.90</li>
<li>F-number 4.12 4.12 4.12</li>
<li>Half angle (in degrees) 52.70 41.56 29.08</li>
<li>Image height 21.64</li>
<li>Overall length of the lens 177.74 162.40 159.73</li>
<li>BF 38.00 45.51 63.40</li>
</ul>
<p>One thing that stick out to us about this patent is the size of the lens and the fact that it’s not an internal zoom design like the current EF 17-40mm f/4L, the ‘new’ lens is also looks to be larger. Canon has increased the size of a lens recently with the EF 35mm f/1.4L II. The original was 3.4″ inches long and the new one comes in at just over 4.1″ (Canon spec), though it <a href="http://www.the-digital-picture.com/Reviews/Canon-EF-35mm-f-1.4-L-II-USM-Lens.aspx" target="_blank">measures at 4.43″ according to TDP</a>.</p>
<p>There has been a flurry of patent activity on optical formulas lately. We could be in for another good year of new lenses releases.</p>
<p><em>Note: We removed the “L” from our original post, we put it there out of habit. The patent makes no mention of a red ring.</em></p>
<span id="pty_trigger"></span>
```


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## Sabaki (Dec 23, 2015)

*Re: Patent: Canon EF 16-40mm f/4L*

I'm wondering if the extra millimeters on the wide side is an indication that Canon has gained massive confidence in designing and manufacturing wide angle lenses.

17-40 becomes 16-40 and let's be conservative and say the next flagship turns out to be a 15-35mm.

I'd love 15mm on the wide side but I'm not technically inclined enough to understand whether that means a bulbous front element too.


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## bseitz234 (Dec 23, 2015)

*Re: Patent: Canon EF 16-40mm f/4L*

I had kind of assumed the 16-35 f/4 IS L had been the replacement for the 17-40, and they were just being slow to discontinue the latter (kind of like they did with 5d2 and 5d3, not that bodies and lenses are the same...) I'd think this would make for a very crowded ultrawide-L-zoom lineup:
11-24 f/4
16-35 f/2.8 (v2 and/or v3 or whatever is rumored)
16-35 f/4 IS
16-40 f/4 

Seems like a lot of overlap... and with the 16-35 already being so sharp and cheap, any 16-40 would have to be a lot cheaper to make any sort of sense... and then we're probably talking cheaper than any other L lens, right?


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## Vivid Color (Dec 23, 2015)

*Re: Patent: Canon EF 16-40mm f/4L*



bseitz234 said:


> I had kind of assumed the 16-35 f/4 IS L had been the replacement for the 17-40, and they were just being slow to discontinue the latter (kind of like they did with 5d2 and 5d3, not that bodies and lenses are the same...) I'd think this would make for a very crowded ultrawide-L-zoom lineup:
> 11-24 f/4
> 16-35 f/2.8 (v2 and/or v3 or whatever is rumored)
> 16-35 f/4 IS
> ...



I agree that this lens would join a crowded field. The only way it makes sense to me is if it were a non-L lens, perhaps with STM.


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## infared (Dec 23, 2015)

*Re: Patent: Canon EF 16-40mm f/4L*



bseitz234 said:


> I had kind of assumed the 16-35 f/4 IS L had been the replacement for the 17-40, and they were just being slow to discontinue the latter (kind of like they did with 5d2 and 5d3, not that bodies and lenses are the same...) I'd think this would make for a very crowded ultrawide-L-zoom lineup:
> 11-24 f/4
> 16-35 f/2.8 (v2 and/or v3 or whatever is rumored)
> 16-35 f/4 IS
> ...



I am scratching my head a little on that, too. A 16-40mm f/4 would have to be super reasonably priced to make sense...if even that makes sense with the 16-35mm f/4L IS lens on the market. ....hmmmmm......


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## insanitybeard (Dec 23, 2015)

*Re: Patent: Canon EF 16-40mm f/4L*



bseitz234 said:


> I had kind of assumed the 16-35 f/4 IS L had been the replacement for the 17-40, and they were just being slow to discontinue the latter



Likewise, that's why I replaced my 17-40 with the 16-35 IS! As you say, it seems like there would be a lot of overlap, and why release a 16-40 f4 when the 16-35 IS is as good as it is and has already dropped in price to a level where it's not that much more than the old 17-40? Ok, 5mm on the long end can make a bit of a difference but other than that surely they're too similar to justify manufacturing and marketing both?


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## Talley (Dec 23, 2015)

Guys... 

This will be a MSRP of $799 and be an L lens.

This will be for people who don't want/need IS in an ultrawide and alot don't because they are exclusive to tripods. This is a cheaper alternative. Street pricing will fall around 650ish.


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## Canon Rumors Guy (Dec 23, 2015)

Canon loves overlap 

24-70 f/2.8L II
24-70 f/4L IS
24-105 f/4L IS
24-105 f/3.5-5.6 IS STM


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## Sabaki (Dec 23, 2015)

Canon Rumors said:


> Canon loves overlap
> 
> 24-70 f/2.8L II
> 24-70 f/4L IS
> ...


I get the feeling you enjoyed this post ;D


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## bseitz234 (Dec 23, 2015)

Canon Rumors said:


> Canon loves overlap
> 
> 24-70 f/2.8L II
> 24-70 f/4L IS
> ...



but then, has anyone _really_ understood the 24-70 f/4L IS?


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## Canon Rumors Guy (Dec 23, 2015)

I've also updated the post to show that this new lens design doesn't appear to be an internal style zoom (if i remember correctly, it zooms externally within the barrel) like the current EF 17-40 f/4L.


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## Mancubus (Dec 23, 2015)

Another one of those overlapping range for a dark no-is lens patent that i couldnt care less about.

Come on, i want to see replacements for 50 and 85mm primes, or an affordable super telephoto zoom like nikon just did. Not more of these damn wide zooms, my 16-35 f4IS is already pretty much all i wanted except for the aperture.


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## Zv (Dec 23, 2015)

The 17-40L is already a good budget FF lens why replace it? It's a pretty decent lens and I don't think it needs replaced especially since the 16-35 f/4L IS already exists. Part of the appeal of the 17-40L is its small size and weight. This talk of making a longer lens without internal zoom is the exact opposite of that aspect. 

What might work is a FF STM version of the EF-S 10-18 without IS and with variable aperture that's made of plastic and comes in at around $499 tops. A counterpart for the 24-105 non L? But who would buy that over the 17-40L? 

I don't see this one materializing.


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## PureClassA (Dec 23, 2015)

Canon Rumors said:


> Canon loves overlap
> 
> 24-70 f/2.8L II
> 24-70 f/4L IS
> ...



Still dont get it. An $800 L wide thats the same focal range and aperture as their $1199 L lens they just made?! No, doesn't make sense unless they release it LOWER priced than the current version at $699.


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## unfocused (Dec 23, 2015)

Zv said:


> The 17-40L is already a good budget FF lens why replace it? It's a pretty decent lens and I don't think it needs replaced especially since the 16-35 f/4L IS already exists. Part of the appeal of the 17-40L is its small size and weight. This talk of making a longer lens without internal zoom is the exact opposite of that aspect...
> 
> ...I don't see this one materializing.



I agree. This looks like one of those patents that gets filed just because they want to protect their options.


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## Luds34 (Dec 23, 2015)

Canon Rumors said:


> I've also updated the post to show that this new lens design doesn't appear to be an internal style zoom (if i remember correctly, it zooms externally within the barrel) like the current EF 17-40 f/4L.



As the 16-35 f/4 IS as well if I recall. Which isn't a bad design, especially if one seals it with a front filter. Then it is virtually the same as a completely sealed, internally zooming lens.


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## StudentOfLight (Dec 23, 2015)

With the success of the 16-35/4 IS and 17-40/4 presumably discontinued, Canon might need a new fighting grade ultrawide full frame zoom. My guess is Canon EF 16-40mm f/4 STM. (So this could be non-L, non-IS, non-weather sealed) 

So entry-level, single-lens-kit:
6D with 24-105 STM

Potential entry-level, two-lens-kit:
6D with "16-40 STM" + "55-200 STM"

Potential entry-level, three-lens-kit:
6D with "16-40 STM" + 50 STM + "55-200 STM"


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## quiquae (Dec 23, 2015)

Hmmm. Look at that graph. The astigmatism on the wide end doesn't look so hot, does it?

One way this _could_ be useful is as the kit zoom for 7D2. In case you haven't noticed yet, there is still no weather-sealed APS-C standard zoom to go with the weather-sealed 7D2! Canon does sell the 24-70F4L as a kit zoom with the 7D2, but 24mm is just not wide enough on APS-C for all-around use. 16-40 would be a much more reasonable range, though still a bit short; it'd still be more convenient than the best choice we have today, which is 16-35F4L.

Other than that, though...nah, I don't see much point either.


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## jeffa4444 (Dec 23, 2015)

As a "for profit" company Canon must think this lens will sell along side the other lenses that begin at 16mm. Owning the EF 17-40mm f4L and the EF 16-35mm f4I IS lenses the newer latter lens is far superior optically & mechanically and the 17-40mm is not worthy of the L designation at 17mm any longer it needs replacing.


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## Zv (Dec 23, 2015)

jeffa4444 said:


> As a "for profit" company Canon must think this lens will sell along side the other lenses that begin at 16mm. Owning the EF 17-40mm f4L and the EF 16-35mm f4I IS lenses the newer latter lens is far superior optically & mechanically and the 17-40mm is not worthy of the L designation at 17mm any longer it needs replacing.



I wouldn't go as far as saying it doesn't deserve the red ring. Build quality is superb, AF is fast and accurate and it's a workhorse that's served me very well over the years. There could be some copy variation; mine is pretty decent stopped down. 

16-35 f/4L IS rocks though so it's gotta go! And hopefully I sell it before a replacement actually does materialize!


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## The Supplanter (Dec 23, 2015)

quiquae said:


> Hmmm. Look at that graph. The astigmatism on the wide end doesn't look so hot, does it?
> 
> One way this _could_ be useful is as the kit zoom for 7D2. In case you haven't noticed yet, there is still no weather-sealed APS-C standard zoom to go with the weather-sealed 7D2! Canon does sell the 24-70F4L as a kit zoom with the 7D2, but 24mm is just not wide enough on APS-C for all-around use. 16-40 would be a much more reasonable range, though still a bit short; it'd still be more convenient than the best choice we have today, which is 16-35F4L.
> 
> Other than that, though...nah, I don't see much point either.



I'm not sure it will be marketed as an APS-C kit lens as it is an EF patent. But I like your idea!

This lens just doesn't make sense to me. I have to believe others in that this is a patent to protect their ideas.


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## ahsanford (Dec 23, 2015)

Fascinating development with this patent. Per my attached chart, the gap Canon has is at the ground floor price point for UWA zooms, not the mid-level.

*One would think a 'de-L-ification' of this particular lens would be in order. * That would allow Canon to pull some features like constant max aperture and USM -- just like they did with the 24-105 f/3.5-5.6 IS STM -- to keep the costs down.

But the choice to go with constant max aperture might imply a 17-40L II (in spirit, technically this would be a 16-40L I) is more likely where they are headed. 

But I noticed the L was yanked from the CR Admins in the patent announcement: has Canon ever offered a non-L constant max aperture zoom?

- A


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## mclaren777 (Dec 23, 2015)

I just wish we knew something concrete about the replacement for the 16-35mm f/2.8 II because I'm tempted to buy a 14mm f/2.8 II now, but I don't want to regret my purchase if Canon makes a 14-24mm f/2.8 or something equally tantalizing.

Grrr!!


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## infared (Dec 23, 2015)

I never liked the 17-40mm LOL!!!..I got one from B&H...and the short zoom "throw" on the wide end was just something I could not deal with, (its sooooo abrupt)..plus the lens was just was not that sharp. I sent it right back...got the 16-35mm f/2.8L II (far from great..but better) and then when the 16-35mm f/4L IS came out...I ditched the 16-35mm f/2.8 and bought one. THEN I finally had a sharp, light reasonably priced UW zoom. .. That is REALLY a great lens. I am still in shock that Canon introduced it at such a reasonable price point. 
I definitely don't see the need for another 17-40mm unless, like everyone says, it's dirt cheap.


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## ahsanford (Dec 23, 2015)

mclaren777 said:


> I just wish we knew something concrete about the replacement for the 16-35mm f/2.8 II because I'm tempted to buy a 14mm f/2.8 II now, but I don't want to regret my purchase if Canon makes a 14-24mm f/2.8 or something equally tantalizing.
> 
> Grrr!!



All conventional wisdom and rumors to date point to a 16-35 f/2.8L III coming as the next L UWA zoom. That's a staple professional lens and the current one is miles behind the 16-35 f/4L IS and 11-24 f/4L for IQ. It makes sense to go with that next.

That Canon should change that staple event/sports lens for a 14-24 f/2.8L would likely eliminate front filtering. Further, Canon already epically scratched the 'wider rectilinear zoom than 16mm' itch with the 11-24, so I don't see them going there again anytime soon. 

I am no expert at new product development predictions, but I see Canon being conservative here and simply making a new, sharper 16-35 f/2.8 and calling it good.

- A


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## NancyP (Dec 23, 2015)

STM kit zoom.


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## ahsanford (Dec 23, 2015)

NancyP said:


> STM kit zoom.



Kit = crop, you mean?

The FL range makes sense, but why go EF on a crop kit zoom? That's something a _smart_ person (planning for the future) might do. Canon doesn't want us to plan for the future -- they want us to buy more stuff! :

- A


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## unfocused (Dec 23, 2015)

NancyP said:


> STM kit zoom.



I don't read Japanese, but this is pretty easy to understand on the original source: "embodiment1: EF 16-40mm f/4 *USM*" (emphasis added)


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## The Supplanter (Dec 23, 2015)

ahsanford said:


> Kit = crop, you mean?
> 
> The FL range makes sense, but why go EF on a crop kit zoom? That's something a _smart_ person (planning for the future) might do. Canon doesn't want us to plan for the future -- they want us to buy more stuff! :
> 
> - A



You're right. This makes sense with the 7DII, but Canon won't market it as such.


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## rs (Dec 23, 2015)

ahsanford said:


> has Canon ever offered a non-L constant max aperture zoom?
> 
> - A



Here are the non L EF constant aperture zooms I'm aware of:

EF 100-300/5.6 (1987)
EF 70-210/5.6 (1987)
EF 100-200/4.5 (1988)
EF-S 17-55/2.8 (2006)

If you ignore the EF-S zoom (which isn't L for obvious reasons), nothing L since 1988.


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## ahsanford (Dec 23, 2015)

rs said:


> ahsanford said:
> 
> 
> > has Canon ever offered a non-L constant max aperture zoom?
> ...



[Hand to face] How on earth did I forget the 17-55? (Talk about a lens that needs a refresh!)

Thanks,
A


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## RGF (Dec 23, 2015)

mclaren777 said:


> I just wish we knew something concrete about the replacement for the 16-35mm f/2.8 II because I'm tempted to buy a 14mm f/2.8 II now, but I don't want to regret my purchase if Canon makes a 14-24mm f/2.8 or something equally tantalizing.
> 
> Grrr!!



Like to see the 14 F2.8 replaced with faster (and better for astro photography) version. Perhaps F2.0 or even F1.4 (not likely but F2.0 might be possible).


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## RGF (Dec 23, 2015)

ahsanford said:


> Fascinating development with this patent. Per my attached chart, the gap Canon has is at the ground floor price point for UWA zooms, not the mid-level.
> 
> *One would think a 'de-L-ification' of this particular lens would be in order. * That would allow Canon to pull some features like constant max aperture and USM -- just like they did with the 24-105 f/3.5-5.6 IS STM -- to keep the costs down.
> 
> ...



wonder what the 70-200 F2.8 IS III would be delivery? 

You don't have specialty lenses on this. 45 and 90 TS-E need to replaced as does the 180 macro.

It would nice if Canon partnered with Zeiss to allow them to make their lenses AF and co-brand them Super-L or perhaps Z versions with a different colored ring (not red and not gold - perhaps platinum colored)


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## neuroanatomist (Dec 23, 2015)

RGF said:


> It would nice if Canon partnered with Zeiss to allow them to make their lenses AF and co-brand them Super-L or perhaps Z versions with a different colored ring (not red and not gold - perhaps platinum colored)



Platinum wouldn't work, looks too close to silver. Way back in 1999 when Canon added one to the EF 75-300mm f/4-5.6 III USM, they stated, "_The front part of the zoom ring now sports a silver ring for a luxury touch._" Wouldn't want anyone confusing a 'Zeiss Uber-L' lens with an old $200 consumer zoom or any of the more recent EF-S lenses which also have that 'luxury touch'.


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## Wizardly (Dec 23, 2015)

Working example 1:
FL: 16.48 / 23.6 / 33.95 mm (16-35mm nominal)
Fno: 2.9 (f/2.8 nominal)
Half angle: 52.7 / 42.51 / 32.51°
Image Height: 21.64 mm (135-format)
Length: 177.02 / 161.56 / 156.44 mm
BF: 38 / 44.49 / 56.64 mm

Lens contracts and retracts slightly as it zooms in. 16-35mm f/2.8 lens seems redundant, but interesting if this is non-L.

Working example 2:
FL: 16.48 / 24.15 / 33.95 mm (16-35mm nominal)
Fno: 4.10 (f/4 nominal)
Half angle: 52.70 / 41.86 / 32.51°
Image height: 21.64 mm (135-format)
Lens Length: 173.42 / 158.56 / 156.35 mm
BF: 38 / 46.50 / 56.92 mm

Lens contracts but extends slightly.

Working example 3:
FL: 16.48 / 23.60 / 33.95 mm (16-35mm nominal)
Fno: 2.89 / 2.88 / 2.90 (f/2.8 nominal)
Half Angle: 52.70 / 42.51 / 32.51°
Image height: 21.64mm
Length: 177.06 / 161.89 / 158.29mm
BF: 38 / 45.63 / 60.17 mm

Lens contracts as it zooms in.

Working example 4:
FL: 16.48 / 24.40 / 38.90 (16-40mm nominal)
Fno: 4.12 (f/4 nominal)
Half angle: 52.70 / 41.56 / 29.08°
Image height: 21.64 mm
Lens length: 177.74 / 162.40/ 159.73 mm
BF: 38 / 45.51 / 63.40 mm

Lens contracts as it zooms in.

All of the examples have 2 aspherical elements.


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## neuroanatomist (Dec 23, 2015)

Wizardly said:


> Length: 177.06 / 161.89 / 158.29mm
> BF: 38 / 45.63 / 60.17 mm
> 
> Lens contracts as it zooms in.



If you're thinking a reverse zoom like the original 24-70/2.8 L (and its predecessor), unlikely. The lenses will almost certainly not change length, per se. The design specs for the current 16-35 II and 17-40 would look similar – there's in inner barrel in those lenses which retracts with zooming, but the outer barrel is fixed. That inner barrel is why those L lenses require a front filter to complete the weather/dust sealing.


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## ahsanford (Dec 23, 2015)

neuroanatomist said:


> Wizardly said:
> 
> 
> > Length: 177.06 / 161.89 / 158.29mm
> ...



+1. 

With ultrawides, the FL range is sufficiently small that there isn't a major space-in-your-bag savings for a telescoping internal barrel that clears the outer barrel (like virtually all 24-something zooms).

So just like Neuro said, zooming should be contained in the outer housing -- for naked lens shooters who don't filters for whatever reason, that's clearly better than a 24-something dust ingress situation.

- A


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## Wizardly (Dec 23, 2015)

neuroanatomist said:


> Wizardly said:
> 
> 
> > Length: 177.06 / 161.89 / 158.29mm
> ...



No, I'm not referring to the size of the entire lens unit, just the optical system. In the text of the patents, the "lens length" is the optical system, not the length of the entire unit. It's not hard to discern the how this contraction would occur. In WE1, the total length of the optical system contracts 20.58 mm while the back-focus expands by 18.64 mm; the front element must move inward by the difference, 1.94 mm. However, this is not a substantial amount.

A moving inner barrel is what I was envisioning in this patent as well.

In going through the numbers, WE1 extends slightly while contracting, WE2 retracts slightly while contracting, WE3 and 4 both extend while contracting. These extensions/retractions are still small enough for a fixed lens unit length.


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## neuroanatomist (Dec 23, 2015)

Wizardly said:


> No, I'm not referring to the size of the entire lens unit, just the optical system. In the text of the patents, the "lens length" is the optical system, not the length of the entire unit.



Of course. Your statements that the _lens_ retracts/contracts is what I was questioning. I guess I didn't see the point in calling it out, since current UWA zooms behave the same way.


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## Wizardly (Dec 23, 2015)

neuroanatomist said:


> Wizardly said:
> 
> 
> > No, I'm not referring to the size of the entire lens unit, just the optical system. In the text of the patents, the "lens length" is the optical system, not the length of the entire unit.
> ...



Overall the 2 mm retraction to 6 mm extension are very minor. A static-length outer barrel could still be feasible.


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## Wizardly (Dec 23, 2015)

One thing that would be nice is to compare the distortion graphs between existing lens designs and the new ones.
I might be mistaken, but I believe Japanese application 2001-085215 is embodied by the original 16-35mm f/2.8 L.


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## neuroanatomist (Dec 23, 2015)

Wizardly said:


> neuroanatomist said:
> 
> 
> > Wizardly said:
> ...



Yes...just like the EF 17-35/2.8L, EF 16-35/2.8L, EF 17-40/4L, EF-S 10-22, EF 16-35/L IS, EF-S 10-18, etc. Nothing surprising.


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## Canon Rumors Guy (Dec 23, 2015)

If you look at past patents as they're presented here, the length is actually the physical length of the lens and tells us if it's internal zoom or not from what I can see from the examples below, if anyone cares. 

http://www.canonrumors.com/patent-canon-ef-200-600mm-f4-5-5-6-is/ (Length doesn't change, internal zoom)

http://www.freepatentsonline.com/20090296231.pdf EF 70-200 f/2.8L IS II (Length doesn't change, internal zoom)

http://www.canonrumors.com/another-ef-100-400-patent/ (Length changes, not internal zoom)

http://www.canonrumors.com/canon-ef-24-70-f2-8l-ii-patent/ (Length changes, not internal zoom)


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## RGF (Dec 23, 2015)

If canon widens the 16-35 to 14-xx what will the xx be? To outdo Nikon, they might stick with 35 or go to 28.

A 14-24 would be too much of copy cat lens and overlap with the 11-24 too much, even if a stop faster.

Now an 11-24 F2.8 would be very interesting if they could hold optical quality.


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## Canon Rumors Guy (Dec 23, 2015)

RGF said:


> If canon widens the 16-35 to 14-xx what will the xx be? To outdo Nikon, they might stick with 35 or go to 28.
> 
> A 14-24 would be too much of copy cat lens and overlap with the 11-24 too much, even if a stop faster.
> 
> Now an 11-24 F2.8 would be very interesting if they could hold optical quality.



An 11-24 f/2.8... i'm not sure who'd want a 5lbs ultra wide.


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## TeT (Dec 24, 2015)

bseitz234 said:


> but then, has anyone _really_ understood the 24-70 f/4L IS?



Best 24 70 out there behind the 2.8 II L... unless you need 2.8, then its the canon mark II or lesser IQ for another..


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## neuroanatomist (Dec 24, 2015)

Canon Rumors said:


> If you look at past patents as they're presented here, the length is actually the physical length of the lens and tells us if it's internal zoom or not from what I can see from the examples below, if anyone cares.



Sort of...the length in a patent is the physical length of the optical formula, which is the distance from the front element to the sensor. The physical length of the lens will be close to the patent 'overall length' minus the flange focal distance of 44 mm (close because the lens itself usually extends a bit beyond the front element). When you posted the patent for the 35/1.4L II, there was some initial surprise and dismay at the length of the lens, until it was clarified that some people were thinking the lens would be 44 mm / 1.75" longer than the patent really meant. 

If the patent overall length of a zoom changes with focal length, it means the front element moves during zooming. In most cases, that means an extending zoom like the 24-70 or 100-400. However, in the case of ultrawide zooms with their retrofocal design, the front element doesn't really move all that far – Canon has designed those lenses so the front element is in an inner barrel which moves with zooming, but that movement is entirely behind the front of the outer barrel (the filter threads are on that outer barrel). So for the UWA zooms, even though the front element moves and therefore the patent shows a changing length for the optical formula, the outer barrel is fixed so the physical length of the production lens doesn't change. 

As I pointed out before, it's only those lenses where there is an inner barrel moving within/behind a fixed-length outer barrel that Canon states require a front filter for sealing – that's the UWA zooms where the inner barrel moves with zooming, and the 50/1.2L where the inner barrel moves with focusing.


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## ahsanford (Dec 24, 2015)

bseitz234 said:


> but then, has anyone _really_ understood the 24-70 f/4L IS?



That lens is a joy to use. Relatively small, light, sealed, IS, sharper than the 24-105 and it packs an unheard of 0.7x max mag. It's a 24-70 and a macro rolled into one and it does both jobs very well. I _cherish_ that lens.

- A


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## JohanCruyff (Dec 24, 2015)

StudentOfLight said:


> With the success of the 16-35/4 IS and 17-40/4 presumably discontinued, Canon might need a new fighting grade ultrawide full frame zoom. My guess is Canon EF 16-40mm f/4 STM. (So this could be non-L, non-IS, non-weather sealed)
> 
> So entry-level, single-lens-kit:
> 6D with 24-105 STM
> ...


 
Replace "6D" with "6D Mark II DPAF" and it sounds better.


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## StudentOfLight (Dec 27, 2015)

JohanCruyff said:


> StudentOfLight said:
> 
> 
> > With the success of the 16-35/4 IS and 17-40/4 presumably discontinued, Canon might need a new fighting grade ultrawide full frame zoom. My guess is Canon EF 16-40mm f/4 STM. (So this could be non-L, non-IS, non-weather sealed)
> ...


... or EOS 6D-M (DPAF)


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