May 25, 2018, 01:33:05 AM

Author Topic: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens  (Read 9053 times)

neuroanatomist

  • CR GEEK
  • ***************
  • Posts: 22606
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #15 on: December 15, 2017, 11:57:59 AM »
Which part justified a patent? It's not like mirror telescopes are something new. The LCD for ND?

The optical formula.  Canon had a 35/1.4L, yet they patented the MkII design...
EOS 1D X, EOS M6, lots of lenses
______________________________
Flickr | TDP Profile/Gear List

canon rumors FORUM

Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #15 on: December 15, 2017, 11:57:59 AM »

neonlight

  • EOS Rebel 300D
  • ***
  • Posts: 68
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #16 on: December 16, 2017, 10:50:14 AM »
I thought people had given up on donuts. What would be impressive is an off-axis mirror that does not have donut bokehs. Might look a little strange on a camera with the primary axis offset from the sensor. And something bigger than f/5.6.


AvTvM

  • Canon EF 400mm f/2.8L IS II
  • *********
  • Posts: 3165
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #17 on: December 18, 2017, 06:34:58 AM »
I doubt this will come to life. Donut bokeh combined with huge form factor = DOA.

No idea why the patent thing is so long ... 120 to 150mm physical length of lens should be more than sufficient for a crop (APS-C) catadioptric 400/5.6 ... definitely one of the weirder Canon patents I've seen in some time.

Canon would be better off dedicating a bit of R&D effort towards a nice EF-M 85/2.4 IS STM lens instead of wasting time and money on useless exotics. 

GMCPhotographics

  • EOS 5DS R
  • ******
  • Posts: 1353
    • GMCPhotographics
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #18 on: December 19, 2017, 06:29:34 AM »
It's nice to see that Canon are still considering re-inventing old ideas and designs.
What if Canon could build a small, cheap and light 400mm f5.6 lens with descent sharpness and contrast (usually the problem with catadioptric lens design). I think it could be a strong seller for some photographic niches. 

Just because most of these types of lenses are made by dodgy Chinese clones of ancient designs and poor manufacturing tolerances shouldn't prejudice our opinion of Canon entering the Frey and making a well designed and thought out lens. Auto aperture, auto focus...IS are all options on this lens and it could easily be shorter than a  135mm (although a lot fatter) and maybe lighter. It could easily become a small, cheap and light walkabout '400.

AvTvM

  • Canon EF 400mm f/2.8L IS II
  • *********
  • Posts: 3165
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #19 on: December 19, 2017, 10:17:16 AM »
sorry, but catadioptric lenses for (general photography) are stillborn technology, no matter how "hi-quality" optical formula and implementation are. Law of optics are still in effect, even for Canon.  :P

Michael Clark

  • EOS Rebel SL2
  • ***
  • Posts: 76
  • Now we see through a glass, darkly...
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #20 on: December 20, 2017, 07:18:38 AM »
What the patent actually claims is that it can vary the effective aperture by dimming the light as it basses thru the lens elements.  (LCD?).  As many know, it is not possible to put a variable aperture in a mirror lens, so ND elements must be used if f/8 is not sufficient.  They have rear drop in lens holders to do that.

"The imaging system which was caused conventionally, especially used the reflection system as the method of overall-length shortening of a telephoto lens is proposed. However, when a physical diaphragm is placed as problem peculiar to a reflection system, at the time of a small diaphragm, the light volume of an image periphery is reduced substantially, or may be intercepted altogether. In recent years, needs to make animation correspondence also in a digital camera are growing, and it has become an important element to have a mechanism in which light volume is adjusted. On the other hand, it is not a physical diaphragm and there is a means to change voltage and to adjust light volume. 
 [0003]
 The example with above means to change voltage to a catadioptric system and to adjust light volume to it is disclosed (Patent document 1). It has a bending reflection member and the example which carried out the luminous energy regulating means owner is disclosed"

The invention could be applied to a mirror lens for any lens mount.

I was hoping they had solved the bokeh issues with mirror lenses, but thats not the case.

You've never heard of or seen the Ohnar 300/5.6 Mirror (also sold under other names such as Hanimex, Makinon, Panagor, etc.), have you?
It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive. - C. W. Leadbeater

5D3 7D2 5D2 EF70-200/2.8 II EF24-70/2.8 EF 135/2 EF50/1.4 EF100/2 EF24-105/4 EF17-40/4

Michael Clark

  • EOS Rebel SL2
  • ***
  • Posts: 76
  • Now we see through a glass, darkly...
Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #21 on: December 20, 2017, 07:24:11 AM »
But it will have awesome donut bokeh!

mmmmmmmmmm...... donuts.......

This could be an interesting lens, particularly for food photography!


This might gain them a niche in the police surveillance market as well...
It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive. - C. W. Leadbeater

5D3 7D2 5D2 EF70-200/2.8 II EF24-70/2.8 EF 135/2 EF50/1.4 EF100/2 EF24-105/4 EF17-40/4

canon rumors FORUM

Re: Patent: Canon 400mm f/5.6 Mirror (Catadioptric) Lens
« Reply #21 on: December 20, 2017, 07:24:11 AM »