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Author Topic: Patent - EF 50 f/1.4  (Read 9815 times)

neuroanatomist

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Re: Patent - EF 50 f/1.4
« Reply #15 on: May 26, 2011, 02:18:33 PM »
What is the thing marked as "Ggi 1"?... So, anyway - what ever they'll do I hope it'll be better mechanically.

An optical element Ggi1 includes a medium that has a refractive index distribution. This optical element satisfies conditions of:

|θF(pmax)−θgF(pmin)|≧0.02, |ΔθgFgi(p1)|≧0.0272, Δθgdgi(p1)|≧0.0250, and |θgFgi(pmaxgi)−θgFgi(pmingi)|≦0.1.

Even if it's not mechanically better, it'll be mathematically better.   :P

(Translation: Ggi1 is what the marketing department calls subwavelength structure coating.)
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Re: Patent - EF 50 f/1.4
« Reply #15 on: May 26, 2011, 02:18:33 PM »

7enderbender

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Re: Patent - EF 50 f/1.4
« Reply #16 on: May 26, 2011, 02:55:28 PM »
What is the thing marked as "Ggi 1"?... So, anyway - what ever they'll do I hope it'll be better mechanically.

An optical element Ggi1 includes a medium that has a refractive index distribution. This optical element satisfies conditions of:

|θF(pmax)−θgF(pmin)|≧0.02, |ΔθgFgi(p1)|≧0.0272, Δθgdgi(p1)|≧0.0250, and |θgFgi(pmaxgi)−θgFgi(pmingi)|≦0.1.

Even if it's not mechanically better, it'll be mathematically better.   :P

(Translation: Ggi1 is what the marketing department calls subwavelength structure coating.)

Ah! Makes sense. So in other words: we may be looking at the same 50 1.4 we enjoyed since the 70s with different coating - and hopefully better mechanical qualities.

I would love that and be willing to trade in mine for a premium.

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IronMike

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Re: Patent - EF 50 f/1.4
« Reply #17 on: May 26, 2011, 03:35:23 PM »
It looks like a different optical design, this patent has 8 elements in 6 groups, and the original has only 7 in six groups. It is the elements behind the stop that have changed.

http://www.canon.com/camera-museum/camera/lens/ef/data/standard/ef_50_14_usm.html?p=2

The performance wide open of the current lens is not that great, it suffers from spherical aberation causing halation. The good news is that this patented lens has 2 aspherical elements which might (speculatively) improve the image at 1.4.

While the focusing on my 50mm f1.4 has never bothered me that much (and is still working fine, fingers-crossed)
it is not super accurate and an upgrade to true ring-USM would be welcome. Hopefully if it does come out it won't be too expensive...

Mike

dgsphto

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Re: Patent - EF 50 f/1.4
« Reply #18 on: May 26, 2011, 06:48:59 PM »
Yes, the optical design seems to have been changed from the current 50/1.4.

Hopefully they will introduce it soon.

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Re: Patent - EF 50 f/1.4
« Reply #19 on: May 26, 2011, 11:31:18 PM »
It appears to feature a coating with a radial gradient refractive index (The gg1 and gg2). Canon seems to be releasing a whole host of patents for lenses using the process, so they may have perfected a process to manufacture lenses to the required and repeatable tolerances, or might be just protecting their invention until it becomes practical to manufacture.

This is basically what the gg coatings do:

An optical system includes a positive lens unit, wherein the positive lens unit includes an optical element containing a base material and minute particles that are mixed with the base material and have Abbe number that is lower than that of the base material, and the minute particles are higher in density at a peripheral portion of the optical element than on an optical axis of the optical element.


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Re: Patent - EF 50 f/1.4
« Reply #19 on: May 26, 2011, 11:31:18 PM »