Canon Patent Applicaton: DO Supertelephoto with Built-In Extender

#41
padam said:
The EF lens is limited to the EF TC, which is not as good as an RF TC - unless one uses a hacked aftermarket EF adapter, seems to work quite well, albeit IS will be a little less effective, since it won't register the change in focal length.
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Well, unfortunately your opinion of the EF tc’s vs the RF tc’s isn’t true and certainly aren’t shown that way in Canon’s own MFT charts. The EF mk III versions are slightly sharper than the RF versions.
There are two lenses that are identical on the EF and RF mount, the EF 400mm f2.8 LIS III and the EF 600mm f4 LIS III.
Compare the MFT charts for either lens with EF tc’s and compare them to the RF versions (which are the same lens). You will find the EF TC’s are superior in every case (both lenses with both TC’s).
Sure you can use the RF TC’s behind a hollowed out adapter but don’t be tricked into thinking that it’s better than the EF mk III in front of the adapter. In fact I don’t understand why anyone would go to the bother when it’s based on an assumption and not observable fact.
 
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#42
padam said:
Not just "any" TC. Made specifically for that optical formula. That's a big performance advantage, flipping it in and out is a huge practical benefit.
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Hmm, I agree with you with the practical benefit. However you are over exaggerating the optical performance.
The custom designed / bespoke flip in 1.4x tc in the EF 200-400mm f4 Lis was a bit sharper, but wasn’t much sharper than the ef 1.4x TC mk III placed behind the lens.
The problem mirrorless has with TC’s is that they don’t perform as well as they did on DSLR designs.
 
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#43
GMCPhotographics said:
Well, unfortunately your opinion of the EF tc’s vs the RF tc’s isn’t true and certainly aren’t shown that way in Canon’s own MFT charts. The EF mk III versions are slightly sharper than the RF versions.
There are two lenses that are identical on the EF and RF mount, the EF 400mm f2.8 LIS III and the EF 600mm f4 LIS III.
Compare the MFT charts for either lens with EF tc’s and compare them to the RF versions (which are the same lens). You will find the EF TC’s are superior in every case (both lenses with both TC’s).
Sure you can use the RF TC’s behind a hollowed out adapter but don’t be tricked into thinking that it’s better than the EF mk III in front of the adapter. In fact I don’t understand why anyone would go to the bother when it’s based on an assumption and not observable fact.
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Be careful comparing recent and older MTF charts. There was a change to Canon's standards in 2018. So, looking at a EF lens versus an RF lens will not directly correlate.

IMO, it is tough to judge. The EF Version III TCs will be attached to EF Version II super teles, which will have an advantage over the RF and EF Version III super teles. My guess is, the RF TCs are better (marginally), but the EF Version II super teles make the EF III TCs look like rockstars compared to the RF/RF combos.
 
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#44
GMCPhotographics said:
The problem mirrorless has with TC’s is that they don’t perform as well as they did on DSLR designs.
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Hmm... that's not what I've found. Honestly, I would say the exact opposite. RF bodies VASTLY outperform DSLR TC performance. The RF bodies have just come so far in AF performance, they literally run circles around all past DSLRs, especially with TCs on.

However, if you are specifically referring to how the EF Version II super-teles produce a better and sharper image with the corresponding EF TC, that is different. That is true, IMO, but not because mirrorless in inferior to DSLRs. This is purely a lens design feature. The need to lighten the RF lenses required the larger elements of glass to be moved back deeper in to the lens. This saved weight because the large elements were now smaller elements, but this introduced issues correcting the aberrations. Canon did an excellent job in correcting things, but I have to assume, these elements were big in the first place for a good reason. I'm sure over the 20-30 years of producing these lenses, this idea had to have been known, but technology wasn't converging with the problem until recently. And honestly, I'd bet technology isn't fully caught up yet, but the small IQ degradation is outweighed by the immense improvement to portability.
 
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#45
MiJax said:
Be careful comparing recent and older MTF charts. There was a change to Canon's standards in 2018. So, looking at a EF lens versus an RF lens will not directly correlate.

IMO, it is tough to judge. The EF Version III TCs will be attached to EF Version II super teles, which will have an advantage over the RF and EF Version III super teles. My guess is, the RF TCs are better (marginally), but the EF Version II super teles make the EF III TCs look like rockstars compared to the RF/RF combos.
Click to expand...
The MFT chart measuring and reporting methodology was updated and aligned before the MK II tele's were introduced. So they are directly comparable. Canon have updated some of the older EF lenses using the new MFT charts (such as the EF 135mm f2.0 L). The RF teleconverters are showing an uneven sharpness across the frame, sharpness wise in the centre, there's not a lot between them.

1729727972400.png
Here's the 1.4x TC taken from the Canon website:
1729728034061.png Here's the 2x: 1729728126580.png
Both sets of charts are using the same optical formula, the EF 400mm f2.8 LI S III and the RF 400mm f2.8 LIS. The only difference here is the teleconverters.
The RF teleconverter MFT charts are quite hard to find now, I suspect Canon are aware of this comparison and are now hiding the RF teleconverter charts from their website.
 
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#46
MiJax said:
Be careful comparing recent and older MTF charts. There was a change to Canon's standards in 2018. So, looking at a EF lens versus an RF lens will not directly correlate.
Click to expand...
Canon Japan has the new format MTFs for all lenses. The EF 800/5.6 does have better resolution on the MTFs than the RF 800/5.6 (and as you point out, the EF MkII lenses beat their MkIII successors, which is one reason I continue using the EF 600/4 II).

MiJax said:
My guess is, the RF TCs are better (marginally), but the EF Version II super teles make the EF III TCs look like rockstars compared to the RF/RF combos.
Click to expand...
I found the EF III and RF 1.4x TCs to be equivalent, and the EF 2x III to be better than the RF 2x (enough so that stacking the EF 1.4xIII and RF 1.4x was similar to the RF 2x). That’s based on testing them with the above-mentioned 600/4 II. Certainly there could be copy variation.
 
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#47
MiJax said:
Hmm... that's not what I've found. Honestly, I would say the exact opposite. RF bodies VASTLY outperform DSLR TC performance. The RF bodies have just come so far in AF performance, they literally run circles around all past DSLRs, especially with TCs on.

However, if you are specifically referring to how the EF Version II super-teles produce a better and sharper image with the corresponding EF TC, that is different. That is true, IMO, but not because mirrorless in inferior to DSLRs. This is purely a lens design feature. The need to lighten the RF lenses required the larger elements of glass to be moved back deeper in to the lens. This saved weight because the large elements were now smaller elements, but this introduced issues correcting the aberrations. Canon did an excellent job in correcting things, but I have to assume, these elements were big in the first place for a good reason. I'm sure over the 20-30 years of producing these lenses, this idea had to have been known, but technology wasn't converging with the problem until recently. And honestly, I'd bet technology isn't fully caught up yet, but the small IQ degradation is outweighed by the immense improvement to portability.
Click to expand...
Sorry, my failure to explain has led to this mis-understanding of my point.
The DSLR mirror box means that a TC would be mounted closer to the rear group of the native lens than on a mirrorless design. If you take an EF super white, you would put a TC on it and then convert it for the RF mount using an adapter.
On the RF version of the same lens, the TC has to be mounted closer to the sensor because the lens has a built in adapter (assuming a RF 400/2.8 / 600/f4). That extra inch is the complications. I think the reason why there's a drive to put an internal TC into some of the new lenses is so they can put the TC earlier into the optical path and optimise it better than it would be if it was on the end of an RF lens.

The bigger question to all of this is if the zoom versions will eclipse the need for a prime with a inbuilt TC. The roumoured RF 400-600 f2.8-F4 zoom is a pretty tasty preposition. Will anyone need a suit of teleconverters?
 
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#48
neuroanatomist said:
Canon Japan has the new format MTFs for all lenses. The EF 800/5.6 does have better resolution on the MTFs than the RF 800/5.6 (and as you point out, the EF MkII lenses beat their MkIII successors, which is one reason I continue using the EF 600/4 II).


I found the EF III and RF 1.4x TCs to be equivalent, and the EF 2x III to be better than the RF 2x (enough so that stacking the EF 1.4xIII and RF 1.4x was similar to the RF 2x). That’s based on testing them with the above-mentioned 600/4 II. Certainly there could be copy variation.
Click to expand...
I think that's the best way of consisely putting it...they are roughly equivalent and possibly copy variation is a bigger factor.
 
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#49
Just waking up and needing popcorn to read these pages.

One thing to mention, but I think this was more on canonnews and i didn't do nearly as much on CR.

From the 400mm DO II until now, there have been a lot of diffractive optics patents. We're talking all the way back to 2014, 10 years ago for that lens.

thinking that the performance of a new DO lens would be similar to that of the original 400mm DO or even the Mark II is most likely extremely pessimistic.

oh and @AlanF .. in regards to buying another 400mm F4L DO II

images (10).jpg
 
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#50
Nikon putting TCs into their 400/2.8 and 600/4 Z mount lenses all but guarantees that Canon and Sony will follow suit. Very logical thing for these high end lenses.

Regarding DO and PF, Sigma managed to create & release an incredibly compact 500/5.6 (with patents for equally tiny 400/5 and 700/8 versions) lens that does not use DO or PF elements. Would think Canon could do something similar. Tiny telephoto primes that do not cost an arm and a leg would be very welcome additions to RF.
 
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#57
Regarding the comment on the DO/PF fresnel tech... The 600mm and 800mm consumer lenses that Canon came out with just a couple years ago were pretty wild, and I don't think this community has quite yet digested how cool they are. Yes, they're very wonky with their trombone mechanism, but holy smokes, they're sharp. And cheap. Couldn't be a better proof-of-concept that you can get high image quality with DO, and that it can be cheap.

Someone pointed out that maybe there's a big decline in yield when you get larger elements. This could be true. The recent consumer supertelephoto lenses are so small in aperture that the elements aren't large. But, still, the lack of more and wider-aperture offerings does make me think that Canon isn't prioritizing, say, a DO 600 f/5.6, probably more for protecting their expensive lens lines than lack of capability.

This plays into the built-in TC issue in a fashion. If there is pressure to keep a DO element small, you're probably making a thinner-aperture lens. The TC will lose another stop of light. A product manager may want to choose one or the other when finding the right balance. I used to think that this would encourage built-in TCs, but now that you can buy a 600mm f/11 lens used on eBay in the 400s, I'm thinking the fresnel lens elements are probably the cheaper way to go for efficient oomph for focal length versus size/cost.
 
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#58
john1970 said:
Canon once made a prototype 600 mm f4 DO lens in the EF mount and showed it at the Canon EXPO in 2015 so they definitely can make it.
Click to expand...
I know, but it was scraped quite a while ago. My first feeling was it could be back in RF, but now it seems that for bigger primes, built-in TC like Nikon seems to be the way to go in the future and they keep the 400/4 1.4x as the "practical" DO lens.
 
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#59
Canon Rumors Guy said:
Neither... DO (Diffractive Optics). The green ring.

View attachment 220559

EF 400mm f/4 DO IS USM II // Image from The-Digital-Picture
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Except for the 600 f/4 DO lens they showed off in 2015. That one had the L on the nameplate and the red ring.
I've always hoped that one day they would go back to that prototype and create an RF 600 f/4 DO with built in TC. Unfortunately this patent doesn't show that :(
 
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#60
GMCPhotographics said:
So, looking back a the core of this thread....if this new patented optical formula actually translates into a real lens that is available to buy...what will be it's tangible benefits over the current EF 400mm DO mk II? Especially considering it's going to be an expensive new lens. Is it going to be even lighter? Is the flip in/out 1.4x TC it's only advantage? Is it going to be even sharper than the current mk II, which would reverse a recent RF white prime trend?
What would I get over a trade in of an existing superlative EF mkII lens apart from loosing a mssive pile of hard earned cash?
Click to expand...
There is no question if one was to trade in (or even better, sell) their EF 400 DOII and buy this RF 400DO/TC lens that they would be putting out a lot of extra cash.
You bring up the three potential benefits that could materialize:
1) Convenience and flexibility of a built-in TC
2) Sharper/better optics than a lens from 2014
3) Lighter weight than a lens from 2014

If those are important enough then it could be worth it. I'd seriously consider one if I was shooting Canon. The EF 400DOII was probably my all time favourite Canon lens and the last one I sold after I was adapting it to my Sony gear for awhile.
 
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