Patent Application: Canon RF-S prosumer lenses

[EricN]

I brought R10 as my wife use my camera for her product photography (she need a simple menu camera as I had M50 before R10). For her work 18-45 works well as the IS of this lens allow her to go up to 1/30 shutter speed hand held. But for my YouTube work I need an fast zoom and a fast prime which I do not have and also Canon not offering. If Canon go for 15-70 f/2.8-4, it will be a relief for me. And for studio video now am using EFS 24mm f/2.8.

I wish Canon will allow Sigma or Tamron for their 17-50 f/2.8. Or they can release like those one.

A few ideas for you:

If you're using it inside, you could add another light or three.
If you're outside, why not take advantage of the sun?
Have you thought about adapting SLR lenses?

 

[ghalib737]

A few ideas for you:

If you're using it inside, you could add another light or three.
If you're outside, why not take advantage of the sun?
Have you thought about adapting SLR lenses?

Thank you for the ideas, but
Sometimes product photo in natural light is demanded by the customers.
I found no lens offering 35 equivalent focal lengths except EFS- 24mm F/2.8 for my studio talking work. However, RF 24mm F1.8 is expensive for me.

 

[EricN]

Many people don't realize this, but you can use flashes outside.
You'll want to choose your backgrounds carefully because blur quality is not fantastic with the EFS- 24mm F/2.8, but it has good sharpness.

 

[SwissFrank]

A stretched star is a bad look even in the corners.

Curious why you say this? Can you either explain why this would be bad or just show a photo? What things would you look for to detect that the photo had a distortion correction?

 

[SwissFrank]

Image stretching needed at the widest angle focal lengths. Makes it not useful for astrophotography. Questionable for architecture, but the jury is still out on that.

Curious why you say this? Can you either explain why this would be bad or just show a photo? What things would you look for to detect that the photo had a distortion correction?

I mean, if your initial subject has a straight line... the camera produces a highly distorted image on the sensor... and the software corrects it back to a straight line... how would you detect this distortion and perfectly offsetting correction happened? How would you know that it wasn't simply shot with a lens with absolutely no distortion?

 

[SwissFrank]

All these lenses have some form of image stretching at the wide end but it's relatively minimal. I've been totally against Canon doing this as it does incur a slight resolution loss in the wide end

You often make such remarks but I've never been able to figure out what you're referring to. Why would this be?

 

[Quackator]

they use computer aided design to develop the optical formulas. no need to go old school.

One can do it this way, sure. But there will always be problems you run into
that simulations alone will not show. That's why prototypes are still state of the art
after simulation.

 

[neuroanatomist]

One can do it this way, sure. But there will always be problems you run into
that simulations alone will not show. That's why prototypes are still state of the art
after simulation.

How do you know that Canon makes a physical prototype of every example in every patent, which is essentially what you stated? As I said, there’s no requirement in the patent process for that.

Are you aware that many patents are filed not with an intent to make a product, but to prevent competitors from making products. Why waste resources building a prototype for a blocking patent?

 

[Quackator]

How do you know that Canon makes a physical prototype of every example in every patent, (...)

And how do you know they don't? Moot discussion.

 

[neuroanatomist]

And how do you know they don't? Moot discussion.

1. I understand IP law sufficiently to know that prototypes are not a requirement.
2. I have worked for several large companies with strong patent portfolios, and I know that most patents are filed without examples actually being produced.
3. Canon files many patents (they had >3000 awarded last year, the fifth most of any company), and each patent typically has many claims and examples. Simple logic indicates that making tens of thousands of unnecessary prototypes each year would be a significant drain on resources.

Your suggestion that it’s moot most likely derives from the fact that you made the initial claim, but can’t substantiate it.

 

[EricN]

1. I understand IP law sufficiently to know that prototypes are not a requirement.
2. I have worked for several large companies with strong patent portfolios, and I know that most patents are filed without examples actually being produced.
3. Canon files many patents (they had >3000 awarded last year, the fifth most of any company), and each patent typically has many claims and examples. Simple logic indicates that making tens of thousands of unnecessary prototypes each year would be a significant drain on resources.

Your suggestion that it’s moot most likely derives from the fact that you made the initial claim, but can’t substantiate it.

I didn't know they filed that many patients!

There is no other logical reason I can think of to ask a question and then say it's moot.

 

[neonlight]

Just the other day I posted a wish to see a 17-55 f/2.8 RF version which could be extended to 15-65 to seem like a 24-105. But I really like the f/2.8 and 2.8-4 may be OK but would have liked an f/2.8.
But is there a new rule that says the shorter back focussing distance gives better resolution? Canon seem to be aiming for lower costs on APSC (and other lenses like 800f/5.6L despite the skyhigh price - it's a 400f/2.8 with a turboextender, and from what I have seen the MTF;s are worse than the 500 II or 600 II.)

 

[SwissFrank]

is there a new rule that says the shorter back focussing distance gives better resolution

For wide-angle lenses, the "natural" way to design the lens will put some glass closer and closer to the film/sensor. If you have an SLR, then you need to modify the design a lot to leave more room. Those modifications make the lens bigger and not quite as sharp. That is why Leica M wide-angles are small and sharp.

 

[neuroanatomist]

For wide-angle lenses, yes, a bit better. That's why SLR lenses <35mm are pretty big while rangefinder (Leica M, etc.) lenses <35mm are very small.

The question was about resolution. Your answer is about lens size. Do you believe that lens size and resolution are correlated? Lol.

 

[neuroanatomist]

But is there a new rule that says the shorter back focussing distance gives better resolution?

As with longer flange focal distances, it’s still down to the lens design and like everything in optics there are trade-offs. With short back-focusing distance, the light from the periphery hits the sensor at a very oblique angle, that was fine with film but is problematic for sensors.

 

[Del Paso]

As with longer flange focal distances, it’s still down to the lens design and like everything in optics there are trade-offs. With short back-focusing distance, the light from the periphery hits the sensor at a very oblique angle, that was fine with film but is problematic for sensors.

And this is why all - or almost all *- Leica lenses wider than 35mm produce an ugly magenta or green cast on the sides of the picture when used on a non-Leica M mirrorless (EOS R, A7, Z9 etc...) Leica M cameras need specially oriented microlenses on the sides of the sensor plus an electronic in-body correction, as well as "6 bit coded" lenses. No issues whatsoever above 35mm focal length.
PS: the small size is partly due to the lack of AF...and to the small diameter of the bayonet.
* one exception being the Voigtländer 15mm Super Heliar III

 

[EOS 4 Life]

For wide-angle lenses, the "natural" way to design the lens will put some glass closer and closer to the film/sensor. If you have an SLR, then you need to modify the design a lot to leave more room. Those modifications make the lens bigger and not quite as sharp. That is why Leica M wide-angles are small and sharp.

Interesting.
This could be why Canon never seemed to put in the same amount of effort into wide-angle prime lenses.
On the other hand, the Sigma 14 mm is one of their best lenses.

 

[Del Paso]

Interesting.
This could be why Canon never seemed to put in the same amount of effort into wide-angle prime lenses.
On the other hand, the Sigma 14 mm is one of their best lenses.

No so sure about this.
The Leica M 28 and 35 mm are absolutely great lenses. Yet, the Leica L equivalents are even better. I could also name the Zeiss 28mm f1,4, the EF 35mm f1,4, the Sigma 35mm f1,2 and a few more lenses whose design is based on Angenieux's retrofocus patent... With former conventional designs, DSLR mirrors had to be raised to mount the VWA lens (Leica, Nikon, Minolta etc...)
Of course, retrofocus design leads to longer and bigger lenses.