Patent: Canon continues to work on focal length reducers

Jul 20, 2010
7,183
93
Canada
www.canonrumors.com
#1
Canon continues to work on focal length reducers.
What’s a focal length reducer you ask?
It’s an adapter that reduces the focal length of a lens and at the same time increases the maximum aperture, basically the opposite of teleconverters.
Canon has yet to release such a product, but we suspect this type of converter could benefit the EOS M system as well as an upcoming APS-C EOS R body.

Below are a bunch of focal length reduced optical formulas from Japan patent JP-A-2019-003074
Specification and lens arrangement of master lens 1 (18-55mm, F2.8)

Zoom ratio: 3.05
Focal length: 17.50 – 53.3 mm
F number: 2.80 – 2.80
Half angle of view: 36.65 – 13.71
Image height: 13.02 – 13.02mm
Lens length: 148.81 – 172.70mm
Back focus: 35.51 – 40.31mm

Specification and lens arrangement of master lens 1 with reducer 1

Focal length: 11.36mm
F number: 1.82
Half angle of view: 36.67...
Continue reading...


 
Sep 26, 2017
99
55
Madison, WI
#2
I'm not sure how this would affect an APS-C R camera - both of these seem to change it to a back focus 2 mm behind the reducer, which would work with a EF-M. I wonder if both of these are R adapters or if one of them are a new EF to EF-M adapter and the other is an R to EF-M?

Not that they couldn't do this with an APS-C R with a R to R focal length adapter, but I don't think these specific patents apply.
 

Don Haines

posting cat pictures on the internet since 1986
Jun 4, 2012
7,529
642
Canada
#3
I'm not sure how this would affect an APS-C R camera - both of these seem to change it to a back focus 2 mm behind the reducer, which would work with a EF-M. I wonder if both of these are R adapters or if one of them are a new EF to EF-M adapter and the other is an R to EF-M?

Not that they couldn't do this with an APS-C R with a R to R focal length adapter, but I don't think these specific patents apply.
R to M seems to make the most sense to me.....
 

Kit.

EOS T7i
Apr 25, 2011
532
154
#4
With 2mm back focus, it needs to be a fixed lens, otherwise the user risks damaging the sensor while mounting.
 
Jun 7, 2014
225
73
#5
Is this the "concept lens", which was mentioned by Mr. Mizoguchi in the interview with Dave Etchells at Imaging Resource?
 
Jul 16, 2017
96
25
Hamburg, Germany
#6
Exciting stuff. If my calculations are correct, reducer 1 turns an APS-C sensor Camera into an actual FF equaivalent with an effectivw crop of 1 (11.36/17.5*1.6) and reducer 5 yields an effective crop factoe of 1.2 (23.92/34.2*1.6) which is still really nice.

Probably won't be cheap adapters, if they come to market. And they really blur the lines between APS-C and FullFrame.
 
Mar 25, 2012
391
10
#9
Exciting stuff. If my calculations are correct, reducer 1 turns an APS-C sensor Camera into an actual FF equaivalent with an effectivw crop of 1 (11.36/17.5*1.6) and reducer 5 yields an effective crop factoe of 1.2 (23.92/34.2*1.6) which is still really nice.

Probably won't be cheap adapters, if they come to market. And they really blur the lines between APS-C and FullFrame.
Your ratios are correct, but the larger sensor being assumed for reducer 1 is actually APS-C, not FF, and the smaller sensor being assumed is even smaller than APS-C. A linear reduction of 1.58 would change the aperture by 4/3 stop and is awfully close to the 1.60 (or more typically 1.62) crop factor for Canon APS-C sensors. As much as I would like to see such a reducer for FF lenses and Canon APS-C sensors, I have to think that a good one would be extremely difficult to design and very expensive.
 
Jul 16, 2017
96
25
Hamburg, Germany
#10
Your ratios are correct, but the larger sensor being assumed for reducer 1 is actually APS-C, not FF, and the smaller sensor being assumed is even smaller than APS-C. A linear reduction of 1.58 would change the aperture by 4/3 stop and is awfully close to the 1.60 (or more typically 1.62) crop factor for Canon APS-C sensors. As much as I would like to see such a reducer for FF lenses and Canon APS-C sensors, I have to think that a good one would be extremely difficult to design and very expensive.
You are right, the first adapter is shown to be used with an APS-C lens. I didn't pay attention to that. It does not necessarily mean that it could not be used with full frame lenses on an APS-C sensor. Maybe the example actually references a use case flip314 mentioned?

Anyway, these adapters look really strange. Why does the lens length decrease when used with the reducer? And does the reducer sit inside the camera mount to enable this 2mm back focus distance or am I missing something there.

I would have thought that producing such adapters wouldn't be too hard for Canon, seeing that the Metabones ones seem to be quite good and Canon has great Teleconverters, which are similar in principle in my mind. Honestly I'm surprised this generates so little interest on this forum.
 
Sep 29, 2012
295
1
#11
I have always wanted to be a little taller..
...and slimmer...can I have both?

Also ..Can I combine this with the Fountain of Youth?
 
Last edited:
Apr 24, 2013
75
0
#12
Nice of Canon to think about us. Reducers have been around for the telescope people for nearly 50 YEARS now.

For my 8" f/10 Maksutov Cassegrain, I have a choice of a 0.63X, 0.50X , 0.40X, 0.33x and a 0.25X.

For my refractor, a 0.8X reducer/field flattener has been available 30 years.

I guess Cannon could see the writing in the magazines and figured "We should do something to make it look like we know what we are doing."