# Crazy Patent: Canon EF 40-800mm f/4.5-5.6



## Canon Rumors Guy (Jul 20, 2016)

```
Here’s a crazy optical formula patent from Canon, an EF 40-800mm f/4.5-5.6 superzoom lens. The folks at Egami say it’s for a full frame DSLR and is an internal zoom lens.</p>
<p>Patent Publication No. 2016-128846 (Google Translated)</p>
<ul>
<li>Published 2016.7.14</li>
<li>Filing date 2015.1.9</li>
<li>Zoom ratio 19.42</li>
<li>Focal length 41.09 92.80 152.20 225.00 797.99</li>
<li>F-number 4.67 4.66 4.65 4.67 5.71</li>
<li>Angle of view 27.79 13.13 8.10 5.50 1.55</li>
<li>Image height 21.65</li>
<li>Overall length of the lens 489.32</li>
<li>BF 39.28</li>
<li>Inner zoom</li>
</ul>
<p>As <a href="http://www.canonrumors.com/forum/index.php?topic=30329.msg608857#msg608857">pointed out on our forum</a>, the patent contains 4 lens designs, two of them are for full frame, and two are for a PowerShot application. The likelihood of such a lens coming to fruition in full frame form? I’d say zero chance, but stranger things have happened.</p>
<span id="pty_trigger"></span>
```


----------



## Maximilian (Jul 20, 2016)

*lol*
That would be a great "allround" tele lens. 
Maybe a little bit too long and too heavy but at a reasonable price... :


----------



## candyman (Jul 20, 2016)

What?!  
O, what will be the weight of such lens? - if they really make it....


----------



## Maximilian (Jul 20, 2016)

dilbert said:


> ... and 2 for 6-120 (3.88 mm image).
> 
> The final image in the patent is for a compact camera.


I don't know if 3.88 mm is fitting to a 1" sensor but referring to that size this would mean a FF eq of about 16-330 mm. 
Quite interesting reach but but the starting aperture seems too small for a compact camera, IMO.
Comparing this to other PowerShots this would be (the?) one of the weakest starting apertures.
==> this would lead to EF lens again.

Edit: and it would be the first compact camera with a fixed lens and inner zoom for a long time.


----------



## Mistral75 (Jul 20, 2016)

dilbert said:


> The patent has 4 lens designs, 2 for 40-780 (FF image height) and 2 for 6-120 (3.88 mm image).
> 
> The final image in the patent is for a compact camera.



Could you please post a link to the patent itself? Thank you in advance.


----------



## seamonster (Jul 20, 2016)

I would settle for a 200-600 5.6


----------



## TAF (Jul 20, 2016)

New kit lens for the EOS-M42

(42 being the answer to the question of what a mirrorless should be)


----------



## Wizardly (Jul 20, 2016)

Maximilian said:


> dilbert said:
> 
> 
> > ... and 2 for 6-120 (3.88 mm image).
> ...



The image height for a 1" sensor is 7.93mm. 3.88 mm is the imaging height that fits a 1/2.3" sensor, e.g. PowerShot SX620 HS or SH540 HS. The crop factor of 5.58 for this class puts the 135-format equivalent focal length at a nominal 35-650 mm. With so much space between lens groups 2 and 3 it is easy to envision this design collapsing for storage on a compact camera. 

This might be the lens for a PowerShot SX 630 HS.


----------



## Maximilian (Jul 20, 2016)

Wizardly said:


> Maximilian said:
> 
> 
> > dilbert said:
> ...


Thank you, Wizardly, for providing this. 

Still I think a starting apertures of f4.5 is far from being competitive. 
SX 620 HS starts at f3.3 for example.


----------



## Wizardly (Jul 20, 2016)

Maximilian said:


> Wizardly said:
> 
> 
> > Maximilian said:
> ...



Starting aperture is f/2.8-4.


----------



## RGF (Jul 20, 2016)

When can I pre-order one?


----------



## Mistral75 (Jul 20, 2016)

dilbert said:


> Mistral75 said:
> 
> 
> > dilbert said:
> ...



Thank you, much appreciated.


----------



## Marauder (Jul 20, 2016)

Does it come with an anti-grav module for hand-holding? Swapped out with the tripod mount perhaps?  :


----------



## Maximilian (Jul 20, 2016)

Wizardly said:


> ...
> Starting aperture is f/2.8-4.


Man, you really make me look like a fool 
But thank you for helping a blind one. 
There's to much text in the full patent, so I missed that important point. 
Maybe it's todays heat (seems like summer has finally started at 33°C/91°F) or I need some glasses.


----------



## tr573 (Jul 20, 2016)

candyman said:


> What?!
> O, what will be the weight of such lens? - if they really make it....



Sigma 300-800 5.6 is almost 13lbs, so that's a good starting point


----------



## j-nord (Jul 20, 2016)

Id prefer if it was a 16-1200 and it came with a donkey to carry it for me


----------



## rfdesigner (Jul 20, 2016)

if they produced that it would make a seriously cool video lens, if it was par-focal of course.. I'm sure it is


----------



## neuroanatomist (Jul 20, 2016)

j-nord said:


> Id prefer if it was a 16-1200 and it came with a donkey to carry it for me



How far would it need to be carried? You realize this will ignite furious debates about Donkey Range, don't you?


----------



## Mt Spokane Photography (Jul 21, 2016)

Canon claims that the use of two or more lens groups with anomalous dispersion glass and a negative refracting power reduce the size and weight compared to such a lens without the elements.

Analomous dispersion glass delays light passing thru it, but delays long wavelengths more than short wavelengths, so it works to correct chromatic abberations when the lenses are formulated properly.


Selections from the patent translation:

"The present invention relates to optical length's miniaturization and the zoom lens which can reduce especially a magnification color blot, and is suitable to especially a digital camera and a video camera. 


The example which uses two anomalous dispersion glass for a negative lens with a short focal distance relatively in the second lens group of negative refracting power as an example which corrects optical performance, especially a chromatic aberration satisfactorily is disclosed.

Then, the present invention finds out the conditions for reducing a chromatic aberration, though it is related with a suitable zoom lens, the path of the second lens group of negative refracting power is made small and size and weight reduction of the second lens group of negative refracting power is attained, when mounting on a digital camera etc. "


Example 1.

Various data 
Zoom ratio 19.42 

Focal distance 41.09 92.80 152.20 225.00 797.99 323.00 575.00 781.02 
F number 4.67 4.66 4.65 4.67 5.71 4.93 5.22 5.59 Field angle 27.79 13.13 8.10 5.50 1.55 3.83 2.16 1.59 
Image height 21.65 21.65 21.65 21.65 21.65 21.65 21.65 21.65 
Whole length of the lens 489.32 489.32 489.32 489.32 489.32 489.32 489.32 489.32 
BF 39.28 39.28 39.28 39.28 39.28 39.28 39.28 39.28 


Example 2.

Various data 
Zoom ratio 19.70 

Focal distance 40.50 92.80 152.20 225.00 798.00 323.00 575.00 783.52 
F number 4.67 4.61 4.57 4.67 5.32 4.87 5.06 5.22 
Field angle 28.13 13.13 8.10 5.50 1.55 3.83 2.16 1.58 
Image height 21.65 21.65 21.65 21.65 21.65 21.65 21.65 21.65 
Whole length of the lens 490.00 492.69 493.84 494.58 497.89 495.22 496.32 497.32 
BF 40.00 40.00 40.00 40.00 40.00 40.00 40.00 40.00 

Example 3

Various data 
Zoom ratio 18.18 
Wide angle Middle Looking far 
Focal distance 6.60 45.00 120.00 
F number 2.80 4.01 4.00 
Field angle 30.42 4.92 1.85 
Image height 3.88 3.88 3.88 
Whole length of the lens 135.94 153.33 155.71 
BF 12.70 10.22 13.73 

Example 4

Various data 
Zoom ratio 16.67 
Wide angle Middle Looking far 
Focal distance 6.60 56.14 110.00 
F number 2.80 4.10 4.00 
Field angle 30.42 3.95 2.02 
Image height 3.88 3.88 3.88 
Whole length of the lens 137.20 156.46 153.20 
BF 16.00 13.46 16.26


----------



## dcm (Jul 21, 2016)

For a quick comparison, the Tamron 150-600 is f/5-6.3, extends from 257mm to 340mm, weighs 1960 grams and has an MFD of 2.7 meters while the EF 800 f/5.6 L is 460mm long and weighs 4500 grams, and has a MFD of 6 meters. This design would always be around 500mm long (or is it around 460 when allowing for flange distance?), even when shooting at 40mm. Probably wouldn't handhold it, not for long anyway. The MFD could be quite interesting - I'm not sure the patent addresses this.


----------



## Marauder (Jul 21, 2016)

Thank you for all of that. Wouldn't it be even more advantageous for this to be a DO lens, or does the massive zoom range create technical obstacles for DO optics?





Mt Spokane Photography said:


> Canon claims that the use of two or more lens groups with anomalous dispersion glass and a negative refracting power reduce the size and weight compared to such a lens without the elements.
> 
> Analomous dispersion glass delays light passing thru it, but delays long wavelengths more than short wavelengths, so it works to correct chromatic abberations when the lenses are formulated properly.
> 
> ...


----------



## Antono Refa (Jul 23, 2016)

I wouldn't be surprised if this lens was made in small numbers, just like the two monster lenses made for the Koshien Stadium, but gave the company a lot of PR which leads to secondary sales.


----------

