# Patent: Canon EF 300 f/4L IS II



## Canon Rumors Guy (Aug 24, 2012)

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<strong>New Patent


</strong>Canon has filed a patent for the optical formula of a new EF 300 f/4L IS II.</p>
<p><strong>Patent Publication No. 2012-159726</strong></p>
<ul>
<li>2012.8.23 Release Date</li>
<li>2011.2.1 filing date</li>
</ul>
<p><strong>Example 3</strong></p>
<ul>
<li>F = 300mm focal length</li>
<li>Fno. 4.0</li>
<li>Tele ratio 0.68</li>
<li>Inner Focus</li>
<li>φr = 68.8mm</li>
<li>φg1 = 67.8mm</li>
<li>φg2 = 70.2mm</li>
</ul>
<div><strong><a href="http://www.bhphotovideo.com/c/product/129188-USA/Canon_2530A004_Telephoto_EF_300mm_f_4_0L.html/bi/2466/kbid/3296" target="_blank">Canon EF 300 f/4L IS at B&H Photo</a></strong></div>

<div><!--more--><strong>Technical background</strong></div>
<ul>
<li>When the miniaturization of the optical system, longitudinal chromatic aberration, chromatic aberration of magnification is remarkable</li>
<li>As the focal length becomes longer, the telephoto lens system, chromatic aberration is noticeable</li>
<li>There is a method of correcting the aberrations of a material having an anomalous dispersion resin, the resin is difficult to produce high-precision thick</li>
<li>There is a method of sandwiching a thin glass resin material, the bonding peeling distortion problem bonding at high temperature</li>
</ul>
<p><strong>Canon patent</strong></p>
<ul>
<li>Joining three or more optical elements</li>
<li>The outer diameter of the resin is increased to reduce the distortion at the time of bonding</li>
<li>Not adhere to each other resin outer glass element</li>
<li>Between the optical element of the outside is gone, adhesive, the thickness of the adhesive distribution occurs</li>
<li>Using a sealing agent to prevent change in shape of the resin and the refractive index change due to moisture absorption</li>
<li>Do the black outer peripheral portion of the glass element</li>
<li>Prevent flare and ghosting resin at the outer periphery</li>
<li>Surface resin glue is not good</li>
</ul>
<p><strong>Source: [<a href="http://egami.blog.so-net.ne.jp/2012-08-24" target="_blank">EG</a>]</strong></p>
<p><strong><span style="color: #ff0000;">c</span>r</strong></p>
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## Rienzphotoz (Aug 24, 2012)

Just out of curiosity ... how long does Canon generally take from Patent to Production?


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## hammar (Aug 24, 2012)

If this lens becomes reality and is decently priced and optically awesome, I would definitely swap it for my 70-200 f/4 IS.


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## Daniel Flather (Aug 24, 2012)

$2499


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## Daniel Flather (Aug 24, 2012)

Rienzphotoz said:


> Just out of curiosity ... how long does Canon generally take from Patent to Production?



One to ∞ year(s).


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## hmmm (Aug 24, 2012)

I'm interested in this lens... I just hope they do not use too much surface resin glue. That is not good.


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## hammar (Aug 24, 2012)

Daniel Flather said:


> $2499



You think? How about Canon being a little friendly for once and consider the poor L-lens users


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## candyman (Aug 24, 2012)

Interesting.


What do you think? Will it be followed by a patent for a new Canon 400mm f/5.6 ? And, maybe coming with IS?


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## AdamJ (Aug 24, 2012)

hmmm said:


> I'm interested in this lens... I just hope they do not use too much surface resin glue. That is not good.



;D


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## Bosman (Aug 24, 2012)

yawn


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## mortadella (Aug 24, 2012)

Here is a patent filing that made CR over a year ago....

http://www.canonrumors.com/2011/05/patent-ef-300-f4l-is-ii/

The current version was released in March of 1997, so an update would be nice sometime within the decade.

Price-wise, look on the bright side, however much the II costs ($2000+ ??) went does get released it will be a fraction of what you would have to pay to get your hands on a 200-400 1.4x. We should all be happy that there are a few big whites we can get our hands on under $3000, and count our lucky stars there are a few under $2000 (at least for now)... right Canon? right?


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## Gcon (Aug 25, 2012)

I'd much rather use the 7-200 f/2.8 IS II USM plus the 1.4x extender than this lens - so much more flexible.


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## Viggo (Aug 25, 2012)

I'm sure a used mkI 2,8 IS will be my alternative.


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## tron (Aug 25, 2012)

It will be hard for Canon to beat the quality of the 300mm f/4L non-IS. We'll see...


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## wickidwombat (Aug 26, 2012)

i just hope they keep the integrated lens hood, I love the 300 F4L IS
More modern IS and full weather sealing would make great improvements as well as the more modern coatings supressing flare and CA, depending on cost I would look at an upgrade. although the sigma 120-300 f2.8 is really tempting even if i got it the 300f4L would stay just for its super well balanced and convenient sized when used with a 5D body


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## pwp (Aug 26, 2012)

I traded my 300 f/4is on a 300 f/2.8is. The 2.8 is absolutely brilliant, but I often wish I'd hung onto the f/4 as well. It was pin sharp wide open, was completely hand holdable & weighed next to nothing compared to the 300 f/2.8 which meant I took it with me far more often. And it focuses much closer than the f/2.8. I shot a lot of food with the 300 f/4is. It looked brilliant.

IMO it's one of the true performance bargains in the Canon L lens lineup and would be difficult to improve on, especially for the price. The current lens has a lot of fans. 

I doubt we'll see this lens updated for quite some time.

-PW


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