Imaging resource had a chance to sit down with Canon engineers to discuss the development of the brand new Canon EOS system.
We cherry-picked a couple of our favourite questions and answers from the interview.
Does AF coverage change with EF-mount lenses?
Since EF-mount lenses used via the adapter are so much further from the sensor surface, it seems likely that they wouldn't be able to support as large an AF area as native RF-mount ones. I asked, and it turns out this is true. It will vary some based on the specific lens design, but some EF-mount lenses won't have quite as wide AF coverage as the native ones. Native RF-mount coverage is 100% vertically and 88% horizontally, but some EF-mount lenses will only have 80% horizontal coverage (again, depending on the specific lens design).
Why so many electrical contacts? (In regards to the RF mount)
The engineers didn't go into a lot of depth about what sorts of functions needed the increased bandwidth, but one example they gave was that every R-series lens carries a complete set of distortion-, aberration- and diffraction-correction information in an internal memory. All that data gets dumped to the body every time you attach an R-series lens to a body, so it's important to have it happen quickly.
Another use is for the real-time focus-distance information display in the viewfinder. I didn't play with this very much, but it seemed to be extremely responsive to changes in subject distance.
Finally, it turns out that the aperture setting in EOS R lenses can be updated more rapidly (and in steps of just 1/8 EV, vs. the 1/3 EV of EF-series optics). More steps and faster updates benefit from a higher-bandwidth camera/lens connection.
4K video specs, why not better?
When I asked the engineers why the limitations in 4K, their reply was a bit cryptic, mentioning the “CMOS sensor system”. A little might have been lost in translation, but I think what it boils down to is that Canon may not yet have the technology to enable full-frame/no-crop 4K readout from their chips.
As noted earlier, this is, in fact, the same sensor as in the 5D Mark IV, so it's two-year-old technology at this point. Looking at Canon's other products, the slightly older 1D X Mark II only has a 1.3x crop factor, but it's also only a 20 megapixel sensor. Even the top-of-the-line Cinema EOS C700 camera's sensor isn't a full-frame 35mm, but rather a little larger than the “Super 35” format. So, looking across their line, it looks like 4K readout across a full 35mm frame is an issue for them.
As noted, though, the good news is that the EOS R isn't merely as capable as the 5D IV in doing 4K video, but it has a much-improved codec to trim file sizes at the same relative quality as well. Read the full interview
You can preorder the new Canon EOS R camera and lenses through Adorama, our exclusive affiliate partner.
Canon is just reserving FF 4k readout for higher priced models. Why is that so hard for them to admit and consumers to understand?
I do very much believe this. I have a hard time believing they lack any technical know-how regarding full-frame 4K readout.
It's possible that Canon must maneuver around Sony patents, fabrication process issues, etc. Still, Canon has patents in hand that point to a new sensor platform.
I think it is more than just segmentation. I firmly believe it's technical.
In the a7riii Sony is able to apply interpolation to the entire sensor readout of 7952 x 5304 to produce a video frame of 3,840 x 2,160, and do it fast enough to keep high data stream rates. Canon simply can't do that yet. They crop out of the middle of the high-resolution photocentric sensor to get the precise resolution needed for 4K rather than attempting to downsample in real time. Why? Because it's a CPU intensive process and they can't maintain the data stream rate required for video.
I'm fairly certain that Sony's big breakthrough was parallelizing this process on the sensor itself. It's the most logical place to do it, as so much of the sensor handling is inherently parallelized to the pixel. Think of how nVidia does similar processing with vertex shaders and pixel shaders on the GPU. One or two clock cycles and you have an interpolated frame output, vs iterating over each "effective" pixel on an external processor that has to iterate over every pixel and perform "nearest neighbors" interpolation. Canon's sensors don't do that. Yet.
There are other ways to approach the problem, but the most obvious place to solve this is on the sensor itself.
This is just an educated guess, but I bet a more programmable sensor is in the future for Canon.
Yes, I have read other articles that also point this out.
As usual, all the internet nobodies that cry and whine when crop video is mentioned are just Canon bashers and can be ignored.
While no doubt some of the reasons that certain features are withheld or downgraded are product segmentation, only ignorant reviewers and forum dwellers automatically believe it is all because Canon is BAD and wants to screw the consumer. It has been brought up numerous times that perhaps Canon's dual pixel architecture is one of the problems in processing speed. So their can indeed be technical issues that they have not yet overcome. Patents play a big part. Just cause Sony does it, doesn't mean that Canon can do it. Not sure why people can't get that. Overheating issues also get scorned by the internet crowd. Perhaps that is one of the issues why their is no Canon IBIS yet. Maybe Sony can do it because they also have the worst weather sealing in the business. Maybe better weather sealing doesn't allow for heat dissipation? Maybe there is a trade-off there (just guessing). If so, what would you rather have, top notch weather sealing with no IBIS, or IBIS with awful weather sealing?
Doesn't a dedicated piece of silicon process raw information it gets from the sensors? And if so, maybe Sony is better able to design that chip (dedicated registers, etc) to process video, and get patents on what they design. Canon doesn't have the silicon flexibilty that Sony apparently has (being such experts in the whole silicon process).
Some folks here did not (want to) believe it. So, here's one prof. Other EF limitations will surface in due course.
The fundamental issue is that a camera needs to read a 6k-8k image and process it for proper downsampling. This is still teritory of cams with dedicated sensor or 6k-8k video cams costing $30k+ (with active cooling)
I think neither Sony nor Nikon want their customers to read this: https://www.imaging-resource.com/news/2018/09/15/canon-eos-r-qa-with-the-canon-engineers, especially Sony. The consequenc of this can last 30 years long.
- This may impact DSLR/EF lenses sales if customers read this. DSLR/EF look obsolete to me.
- It implies that RF lenses will be much better than EF lenses. It is really bad news for the EF lenses providers, which are still developing EF lenses and more to come.
- This seems to imply that Canon EF-to-RF/ND filter adpater + Zeiss Milvus 1.4/25 may not be a smart purchase. Better wait for RF wide angle lenses?
- If Canon can develop RF 100-200 F2 or RF 135-200 F2 with similar image quality to Canon EF 70-200mm f/2.8L IS III USM, and if Zeiss will develop RF native wide angle lenses with manual focus only, like 1.4/20 or 1.4/25, it will be perfect.
- Another issue, left untouched, is about adapting Leica M-lenses to Canon RF. Will that present similar issue that Sony E Mount has due to the sensor glass thickness?
I don't think that's entirely accurate nor is the interviewer entirely incorrect. I beleive the C700FF reads 6K from the entire sensor. 4K is a crop to a size similar to Super 35 as stated in the interview. In each case Canon is reading the sensor at 1:1 and it's a much lower resolution sensor than the one in the Canon R.
If Canon has demonstrated that they can read an entire high resolution sensor and downsample to 4K in camera I haven't seen it. I think we can assume that it is a technical challenge they are working on vigorously.
With its help autobracking could be done and the step was selectable starting from 1/4 of a stop! YES 1/4 of a stop (Referred in the manual as 0.25) from the late 80s! So all EF lenses already supported that.
Actually C700 FF reads full sensor for 4k. This is from their marketing material:
"Capable of ProRes and XF-AVC internal recording up to 4K to CFast™ cards, the camera can also record 5.9K RAW up to 60 frames per second with the optional Codex CDX-36150 Recorder. The camera uses the full 5.9K of the sensor to create oversampled 4K, resulting in improved video quality. "