# Patent: APS-C Compact Lens Optical Formulas



## Canon Rumors Guy (Jul 5, 2018)

```
A patent showing three different optical formulas for APS-C sensor cameras has appeared.</p>
<p><a href="https://www.canonnews.com/canon-patent-application-aps-c-compact-camera-lenses">According to Canon News</a>, this patent is missing some good information that would help narrow down what these embodiments are for.</p>
<p><strong>The 3 embodiments:</strong></p>
<ul>
<li>15-45mm f/2.8-5.6</li>
<li>15-45mm f/2.0-5.0</li>
<li>15-60mm f/2.0-5.0</li>
</ul>
<p><!--more--></p>
<p><strong>From Canon News:</strong></p>
<blockquote><p>Our assumption with this patent application is that these lenses are for APS-C given the focal lengths of the lenses, however in this patent application, unlike most, the half image width is curiously missing from the patent application.  This could be for a mirrorless EF-M camera, or even a APS-C compact camera.  It’s hard to tell without the image half width.  The patent description seems to be talking more about a compact camera.</p></blockquote>
<p>It looks like the 15-60mm f/2.0-5.0 has an extremely short back focus suggesting it may be for a PowerShot application and not for mirrorless or APS-C DSLRs.</p>
<p>We wouldn’t be shocked to see a new EF-M 15-45mm lens announced alongside the EOS M5 Mark II, as we’ve been told that a new kit lens of some kind is on the way.</p>
<span id="pty_trigger"></span>
```


----------



## Antono Refa (Jul 6, 2018)

What is the purpose of the perfectly flat element right next to the sensor? Why does the lens have two apertures?


----------



## Kit. (Jul 6, 2018)

Looks like a PowerShot.



Antono Refa said:


> What is the purpose of the perfectly flat element right next to the sensor?


To demonstrate reflections from the sensor's optical filter that are dissipated (instead of concentrating into ghosts) when reflected back by a meniscus-shaped GPR.



Antono Refa said:


> Why does the lens have two apertures?


SP1 is the actual variable aperture. SP2 is just a flare cutoff screen.


----------



## Etienne (Jul 6, 2018)

I don't generally like kit lenses, but f/2 at 15mm on an EF-M camera does sound interesting .... if they can do it well.


----------

