Patent: New Diffractive Optic Patents

[Canon Rumors]

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More DO Lenses?
A few patents in regards to diffractive optics have come about. 70-300 f/4.5-5.6 DO IS, 14 f/2.8 DO and a 600 f/4 DO IS.

Diffractive optic patents keep coming up, though no new products are being announced. It does appear Canon is invested in the technology and thinks there is a market for it. I am a big fan of the 400 DO and hope to see longer DO lenses in the future.

Read more about the patents after the break.

Patent Publication No. 2012-78397

• 2012.4.19 Release Date
• 2010.9.30 filing date

Example 1

• Zoom ratio 4.01
• 135.50 – - 290.90mm 72.50 focal length
• Fno 4.66 -. 4.97 – 5.87
• 9.07 – - 4.25deg 16.62 a half angle of view.
• Image height 21.64mm
• 171.47 – - 204.08mm 144.08 full-length lens
• BF 40.08mm
• 18 sheets 12 group lens configuration
• 3 UD glass sheet
• A plane diffraction
• Seven-group zoom positive and negative positive positive and negative polarity
• Inner Focus (Group 6)
• Shake correction (group 2)

Example 2

• Zoom ratio 2.84
• 200.00 – - 292.50mm 103.00 focal length
• Fno 4.67 -. 5.44 – 5.77
• 6.17 – - 4.23deg 11.86 a half angle of view.
• Image height 21.64mm
• 189.12 – - 210.66mm 162.16 full-length lens
• BF 45.16 – 58.25 – 70.16mm
• 13 pieces in 11 groups Lens Construction
• 2 UD glass sheet
• A plane diffraction
• Five-group zoom of positive and negative positive positive and negative
• Rear focus

Example 3

• 14.36mm focal length
• Fno. 2.89
• 56.38deg half angle of view.
• Image height 21.60mm
• Length 133.66mm lens
• BF 38.47mm
• 16 pieces in 10 groups Lens Construction
• 2 UD glass sheet
• Two surface diffraction
• Two positive lens group a negative
• (Part of the front group) Inner Focus

Example 4

• 584.94mm focal length
• Fno. 4.12
• 2.12deg half angle of view.
• Image height 21.64mm
• Length 404.06mm lens
• BF 123.32mm
• 18 sheets 12 group lens configuration
• 3 UD glass sheet
• One fluorite
• Two groups of positive-positive lens
• (Part of the front group) Inner Focus

Conventional diffractive optical element

• Because there is a thick diffraction grating, and obliquely incident light, the diffraction efficiency is reduced
• When the diffraction efficiency is reduced, flare, ghost, imaging performance deterioration, such as contrast degradation occurs

Canon’s patent

• Can be in close contact with another medium to a diffraction grating, to reduce the thickness
• Capable of suppressing a decrease in diffraction efficiency
• With another medium, and fine particle dispersion ultraviolet curing resin material

cr

[TrumpetPower!]

Unless the IQ on that 14 beats the 14 they already have, I really don't see the point -- and I really don't see the IQ of a DO anything beating a non-DO version.

On the other hand, if the IQ of a 600 f/4 DO doesn't suck and if the lens is as light as the new 300 f/2.8, it'll sell like hotcakes.

Otherwise, meh. Another 70-300 slower than molasses in January.

Cheers,

b&

[jrista]

Oooh! That 600 f/4 DO sounds really intriguing! It seems diffractive optics lenses do take a bit of a hit to resolution, however even the 400 DO gets better resolution than most of the lenses in my current kit anyway. If a 600 f/4 DO lens had 4-stop IS, was compatible with teleconverters, and light enough to be hand-holdable, I'd SERIOUSLY consider one of them. I've been saving money for a 5D III, which for the time being I'm putting of, and I've considered putting the money saved for one towards a 600 f/4 L. If a 600 f/4 DO actually materializes and weighs in at around 5 pounds, and was cheaper than the 600 f/4 L, I'd buy one in a heartbeat!

• Because there is a thick diffraction grating, and obliquely incident light, the diffraction efficiency is reduced
• When the diffraction efficiency is reduced, flare, ghost, imaging performance deterioration, such as contrast degradation occurs

I'm guessing that isn't a problem with telephoto DO lenses, so long as you have the lens hood on? I don't see how you could get flare-causing oblique light otherwise. Perhaps the 14mm DO lens might have this problem, as it would need a lens hood akin to the 16-35mm (which barely blocks any light and doesn't do a whole lot to mitigate flare and ghosting.

[Daniel Flather]

Why would Canon want a DO 14/2.8?  I was under the impression that DO was to make big telephoto lenses smaller and lighter.  What will DO do for the already small, in relation to the big white teles, 14/2.8?

Or is this so we can have a new lens at a new price?  New = higher. 

[dr croubie]

Why would Canon want a DO 14/2.8?  I was under the impression that DO was to make big telephoto lenses smaller and lighter.  What will DO do for the already small, in relation to the big white teles, 14/2.8?

Or is this so we can have a new lens at a new price?  New = higher.

What he said.

Although maybe there's another aspect to a DO that we don't know about, like maybe it can make faster lenses with better borders or better wide-open performance (which is where most fast lenses fall apart, 24/1.4 L II, 35/1.4L, 50/1.2L and 85/1.2L)? Or maybe there are some people complaining about the size of those lenses, and DO would make it smaller? I'd consider a 35/1.4 DO as a nice small street-lens if it were the size of a 50/1.8.

There's absolutely nothing wrong with the 14/2.8 L II though, except for the price (and no filter threads). The only way a 14/2.8 DO would even sell one unit is if the IQ was amazingly better (TS-E 24 L II kind of better), or it was cheaper than the current 14/2.8 L II. Although, DO would probably make for a flat front-lens that you could mount filters onto without vignetting, maybe that's it?

[lol]

It might be worth a refresh on the DO technology by reading EF Lens Work Book section 9. Download from Canon site somewhere. The benefit claimed of DO elements are they can offer superior colour correction than UD or even Flourite elements. That in turn allows you to make shorter telephoto lenses.

In a wide angle, maybe they don't need to reduce the size, but from what I've seen the 14 II does suffer from some lateral CA so perhaps that can be improved on using DO. Having said that, it is one of the easier things to fix in post processing so wouldn't be high up on my list of things to do.

As for a possible 70-300 DO II, I would love to revisit that. I used to have the 70-300DO although I sacrificed mine towards the L. I do miss the DO in size terms. What it lacked was quality wide open, thus needing to stop down which was somewhat limiting. If they can produce a revised version with better wide open performance at a similar physical size, I'd reconsider it for sure.

[Marsu42]

Unless the IQ on that 14 beats the 14 they already have, I really don't see the point -- and I really don't see the IQ of a DO anything beating a non-DO version.

They would sell tons of the do lenses if e.g. the 70-300 wasn't that expensive - it's the ideal travel lens. Maybe the price is due to the complicated design, maybe it's due to the little quantities produced, or maybe Canon marketing screwed up and thought they could put a premium on new tech when the iq didn't go along with the price tag.

[Mt Spokane Photography]

The new diffractive optics seems to be different, and might be coming soon  The resin with small particles in it can be bonded to a glass lens element to correct its optical properties for CA in a way that no other method can do.  This means shorter and lighter lenses that are better.  Its a big difference from DO lenses of the 1990's.
 
I think we will be seeing announcements later this year, perhaps a new 100-400mm L.

[moreorless]

What he said.

Although maybe there's another aspect to a DO that we don't know about, like maybe it can make faster lenses with better borders or better wide-open performance (which is where most fast lenses fall apart, 24/1.4 L II, 35/1.4L, 50/1.2L and 85/1.2L)? Or maybe there are some people complaining about the size of those lenses, and DO would make it smaller? I'd consider a 35/1.4 DO as a nice small street-lens if it were the size of a 50/1.8.

There's absolutely nothing wrong with the 14/2.8 L II though, except for the price (and no filter threads). The only way a 14/2.8 DO would even sell one unit is if the IQ was amazingly better (TS-E 24 L II kind of better), or it was cheaper than the current 14/2.8 L II. Although, DO would probably make for a flat front-lens that you could mount filters onto without vignetting, maybe that's it?

Isnt a large part of the issue with boarder performance on wide lenses the angle at which the lights hitting the sensor? you look at the UWA lenses released post digital and theres been a steady increase in lenth, perhaps increasing the degree of retrofocus to improve boarder performance? introducing DO would allow Canon to take the 14mm in the same direction without increasing the lenght of the lens significantly.

[jrista]

What he said.

Although maybe there's another aspect to a DO that we don't know about, like maybe it can make faster lenses with better borders or better wide-open performance (which is where most fast lenses fall apart, 24/1.4 L II, 35/1.4L, 50/1.2L and 85/1.2L)? Or maybe there are some people complaining about the size of those lenses, and DO would make it smaller? I'd consider a 35/1.4 DO as a nice small street-lens if it were the size of a 50/1.8.

There's absolutely nothing wrong with the 14/2.8 L II though, except for the price (and no filter threads). The only way a 14/2.8 DO would even sell one unit is if the IQ was amazingly better (TS-E 24 L II kind of better), or it was cheaper than the current 14/2.8 L II. Although, DO would probably make for a flat front-lens that you could mount filters onto without vignetting, maybe that's it?

Isnt a large part of the issue with boarder performance on wide lenses the angle at which the lights hitting the sensor? you look at the UWA lenses released post digital and theres been a steady increase in lenth, perhaps increasing the degree of retrofocus to improve boarder performance? introducing DO would allow Canon to take the 14mm in the same direction without increasing the lenght of the lens significantly.

Pancake W/A DO primes, anyone?

[dilbert]

Pancake W/A DO primes, anyone?

The 14mm lens in the patent above is 133mm long, or just over 5 inches.

For the zoom lens, is there a copy paste error because there's something weird, e.g."

135.50 – - 290.90mm 72.50 focal length
Fno 4.66 -. 4.97 – 5.87
9.07 – - 4.25deg 16.62 a half angle of view.
171.47 – - 204.08mm 144.08 full-length lens

Why are there three groups of numbers?

[tron]

Can I have a cheap 600mm f/4 DO please? 

OK now I asked for the impossible (cheap)

[CR Backup Admin]

Can I have a cheap 600mm f/4 DO please? 

OK now I asked for the impossible (cheap)

I think Canon would consider $11,000 cheap, so it depensa on who you are asking

[dilbert]

What is the original URL for these patents?

[Woody]

A 12-24 f/4 DO lens with excellent border performance and front threading will be most welcome.