Here is another in a long line of diffractive optics patents we've seen from Canon over the last couple of years. Since the Canon EXPO in 2015, we've all been wondering where the EF 600mm f/4 DO IS lens is, a lens we don't think is ever coming at this point. A lot has changed over the last 3 years, and we expect any new DO super telephoto lens to be for Canon's new RF mount.
This latest USPTO patent showcases both a 500mm and 600mm optical formula. As Canon News points out, this patent shows Canon moving the lens elements closer to the camera body to improve balance. This is the same sort of design we saw in the brand new EF 400mm f/2.8L IS III and EF 600mm f/4L IS III lenses.
Example 1:
- Focal Length: 487.49mm
- F-Number: 4.12
- Half angle of view: 2.54º
- Image height: 21.64mm
- Total lens length: 409.74mm
- Backfocus: 98.42mm
Example 2:
- Focal Length: 584.99mm
- F-Number: 4.12
- Half angle of view: 2.12º
- Image height: 21.64mm
- Total lens length: 474.74mm
- Backfocus: 109.42mm
Ya, pretty much. Why would they, with the new VerIII lens weight reduction. If a DO 600mm ever comes, it'll be RF mount.
higher frame rates, better servo focus, less expensive lenses. Lighter equipment.Is there a third party lens for the R mount yet?
I thought that canon was way ahead of Nikon in the DO space, but right now it looks like a leap frogging situation.
Why should it? RF mount is perfect for lenses with a short backfocus, like lenses with a focal length of up to ~100 mm. I don't see a benefit of the RF mount for longer lenses: (super) telephoto lenses have a huge backfocus anyway (as is also shown in this patent), that makes them perfectly suited for the EF mount. I think it makes just more sense to make those lenses physically shorter EF lenses an use an adapter for RF mounts than make them physically longer (with an empty tube at the back) and make them RF-natively. At most, Canon could release EF- and RF- supertelephotolenses of the very same design just a different end-barrel (plus offer a mount conversion service).
The only advantage I can imagine could come from the (slightly) larger mount diameter of the RF mount, but I have no idea whether that makes designing RF-supertelephoto lenses easier than EF-supertelephoto lenses. But it could be... But for the back focus: no!
So apart from avoiding the use of an adapter there should be no mechanical/optical advantage to making an RF supertele lens over an EF one.
The note from DanCarr about the sizes is interesting. According to the Canon Website the current 600mm III is 448mm long and the post above suggests the DO version would be 474mm long. Am I missing something about the way these are measured?
The increase could be explained in part by the addition of 24mm empty tube to an RF lens. But if a DO Version actually becomes bigger than its regular counterpart, I imagine the weight the reduction would have to be really significant to still sell well.
https://www.canonrumors.com/the-benefits-of-the-large-diameter-of-the-eos-rs-rf-mount-explained/
explains, that the RF mount is larger than the EF-M mount.
UPS. I confused EF-M with EF/EF-S. Yes, indeed, RF and EF mounts have the same inner diameter of 54mm.
So, really no reason I see to make large backfocus lenses with a native RF mount...
No technical/mechanical reason you mean. Plenty of business and marketing reasons to make it an RF lens.
I checked, and saw that. Unless the length would include the hood, I don't see the advantage. The 500 f/4 II IS is an awesome lens. Lightening and/or reducing the size is what it needs. But if they do to it what they did to the 400 and 600, then I'm not sure that there's a place for DO.
They could easily make any of the super-telephoto lenses in either EF or R mount as the situation demands. The backfocus distance is much larger than the spacing between the lens and sensor on either mount.
The big differences would be no adapter needed for the R mount, and the additional communications that R offers between the lens and the camera. Optically, they could essentially be identical.
EF and RF mount diameter are identical 54mm.
EF and RF are 54mm in diameter.
Those who claim the R focuses poorly should perhaps use one for a bit of time in real photo world conditions. For me the camera focused the 500 very, very well, at least on par with my 7D ii and 5DS, and likely better. Yes, there is a bit of a stutter in the viewfinder at 5 fps. I found it minor and did not hinder me. If it had I would have switched out camera bodies. Instead, I used it for nearly 900 exposures.
Also, I photographed my border collies chasing frizbees. I did it from in front of the dogs near where they were making their catches, using the RF 24-105/4. When I performed keeping the camera on target well, the camera focus system performed well. Same as with the flying eagles. I found interesting the camera did not seem to have the viewfinder stutter at 5 fps with the RF lens. Perhaps the capability of much higher rate communication between lens and camera with the RF mount explains this. This would certainly make purchase of fancy DO RF lenses tempting. Likely increase the divorce rate, too.
What could be interesting to many, I think, is adding some good cheaper options. E.g. 500mm f/5.6 DO (like the Nikon's one) or 200-600mm f/4.5-5.6 (a rumored "larger" 100-400mm). Here I can see a source of possible hesitation (aside from development difficulties and times) - fear to draw some customers from their more expensive lenses. On other hand, many will buy such lenses for sure. I would. And this wouldn't draw me from expensive super-tele, since I don't think I will ever justify five-figure price for a single lens.