Juicy technical tidbits on the Canon EOS RP - IR Interview/Q&A
posted Wednesday, February 13, 2019 at 11:02 PM EST
We had a chance to sit down with some high-level Canon engineering execs at the recent launch event for the EOS RP, to answer our usual round of technical questions about the product. I was particularly interested to see this model, after having learned that an entry-level EOS-R would be the next model to be introduced, during my exclusive interview with Canon's top camera planning executive, Mizoguchi-san, published earlier this year.
I personally found the RP very enjoyable to shoot with, but check our Canon EOS RP review for senior editor William Brawley's take on it. As usual, though, I had a lot of questions about the product, so was glad for the opportunity to sit down with high-level engineering management to get some of them answered. Hopefully you'll find what's below as interesting as I did! :-)
The EOS RP's internals are shared with the EOS 6D II and EOS R
Dave Etchells/Imaging Resource: OK, so I'll just start in. We've been told that the EOS RP sensor is very similar to the one in the 6D Mark II. In what ways is it the same, and in what ways is it different?
Canon: Basically, it's the same sensor, except the microlenses are fine-tuned to be more optimized for the mirrorless system.
DE: Ah, that makes sense, you need to account for the different light angles with the shorter flange distance. But other parts, all of the sensor electronics, the circuitry, that's the same?
DE: And the RP has a DIGIC 8 image processor. Is that exactly the same DIGIC 8 as is in the R, or is it slightly different?
Canon: It's exactly the same.
[Ed. Note: This is all very interesting. It's for all intents and purposes an EOS 6D II with the EOS R's processor. It hadn't occurred to me previously, but it makes sense that they'd need to have differently-shaped microlenses to handle light coming in from shallower angles, because the back of the lenses will be so much closer to the sensor's surface.]
Somewhat fewer addressable focus points than the EOS R, but performance should be equal
DE: And we're interested in the comparison between autofocus on the EOS RP and the EOS R. The RP has only 143 areas; the R has more than 5,000. But is there any difference in frame coverage?
Canon: Coverage area is exactly the same. Because the EOS RP uses a different sensor from the EOS R, the number of points they can select is slightly different. Also, [both cameras have 143-point coverage when points are selected automatically. The number of] manually selectable AF points [on the EOS RP is] less than the EOS R, but it's more than 4,000.
DE: Ah, so it's essentially the same!
Canon: Yes, the number is not exactly the same and is less than EOS R. But yeah, it's definitely more than 4,000. Sorry for the confusion, but yes, we have two definitions [for the number of focus points].
DE: Ah yes, interesting. And regardless of how many points there are, can the EOS R focus more quickly than the RP?
Canon: If you put those cameras in the exact same conditions, the same shooting situations, they should perform pretty much the same.
DE: Ah, interesting...
Canon: The fact that we market them with the combination of the 24-105 lens, it focuses as fast as up to 0.05 seconds maximum, those numbers are the same.
DE: Ah - I'd been thinking that maybe because it used a different sensor, it couldn't transfer data as fast, that maybe focus would be slower for that reason.
Canon: That's not really the case.
A magnesium inner chassis makes the EOS RP amazingly lightweight
DE: We're very interested in how you made the RP so light. Even though it's so light, it still has excellent feel, it just feels very rigid, very stiff. How did you accomplish that? What can you tell our readers?
Canon: So handling is obviously key in this type of camera. It was really important that we choose to use magnesium in the right places and plastic in the right places, so that we [could] make the camera body substantially smaller, but at the same time maintain the same kind of feel or build quality [as our past cameras]. We didn't want to sacrifice build quality; that was something we paid particularly extreme attention to.
DE: Ah, ok. So there's a magnesium frame inside?
Canon: Yes. Actually, we included a visual inside in your press kit.
DE: You have a picture of the casting? Oh, nice.
Canon: Yeah. Basically, around the mount itself and this area (indicating the central part of the body) is using magnesium.
DE: Yeah. Yeah, the whole camera feels very, very nice, very solid.
Canon: Thank you. We have actually worked on making lightweight parts using magnesium. That is something that we did for the super-telephoto lenses; the 400mm, 500mm and 600mm.
DE: Oh! So you used magnesium there instead of aluminum?
Canon: Yes. Magnesium is a material that brings rigidity and lightweight at the same time, if you use [it] in the correct places.
[Ed. Note: The EOS RP really does have a great feel to it. It's hard to convey in words, but "rigidity" is the best I can come up with. The body felt very stiff, with not the tiniest sense of "give" to it. Along with most other manufacturers, Canon has of course been using magnesium alloy for body castings in their higher-end cameras, so it was interesting to me that they pointed to the deveopment of their super-tele lenses as being a source for the underlying expertise.]
Magnesium brings its own set of challenges to be solved
Wiliam Brawley/Imaging Resource: Are there other factors or qualities to magnesium where you wouldn't want to use it for the entire thing, or...
Canon: Magnesium in general is really hard to cast, and it's really difficult to handle.
DE: Machining is more difficult.
Canon: It's very difficult to machine. In that sense, plastic is pretty easy to mold into any kind of shape, but that's not really the case with magnesium. So that is the downside of magnesium.
DE: And can you mold aluminum, or is it just machined really?
DE: Die-cast, also. Hmm. And die-casting, you make a very accurate mold and then just inject metal. But then to put threads in magnesium, that's hard because it's tough material.
Canon: What was your question again?
DE: I guess it wasn't so much a question.
DE: I was more just kind of thinking out loud that there's not so much machining for magnesium, because you can injection-mold it. But you still have to put threads in holes to be able to turn the screws into it, and so that is machining. <they showed us a photo of the magnesium casting> Oh, yeah!
Lots of trial and error (and 3D printing) went into the EOS RP's physical design
Canon: So it's a small body, but there's a lot of trial and error.
DE: Oh, and these are some of the different variations you went through. We'll have to make sure we get pictures of those.
DE: And then this is a 3D-printed mockup
DE: Hmm! Interesting material. It has a different feeling to it.
[Ed. Note: The 3D-printed mockup was made of an interesting material; it felt very slightly resilient, vs a very hard plastic like PLA or ABS, or the grainy-feeling bonded-powder type of 3D print. The detail was exceptional and layers almost invisible. I'm pretty sure it was from an SLA (stereolithography) printer.]
WB: Huh. Wow, yeah.
DE: Very, very fine layers.
Canon: During the designing process, we make tons of these. Actually we we show just two in the photo, but there were a lot of them.
WB: There were a bunch of iterations before that.
DE: Yeah, I've often heard that there are dozens of iterations on grip designs.
Canon: And the mechanical engineers and the exterior designers work together to make sure that the grip is firm, yet the shape is [comfortable].
DE: Yes, grip is so subtle. Just a tiny change, a little bit more or less, and it's comfortable or uncomfortable for people.
Canon: I believe that the fact that we were able to deliver this camera with a firm grip was thanks to the collaboration of different teams that were involved in the process of this design. They were teams such as [those] that were in charge of exterior design, as well as mechanical designers, and there were evaluation teams, quality-assurance teams that were involved in the process as well. So all of these teams worked together to make sure we get the grip right.
DE: Hmm. Yeah, so someone has to design the exterior, and then mechanical has to make the framework.
The EOS RP doesn't use gaskets for weather-sealing
DE: I asked Canon staff earlier about the RP's weather-sealing, and they said it's sealed to the same level as the 6D Mark II.
DE: When I looked at the body carefully, though, I see that there are no seals inside the battery compartment, no foam, the door is kind of inset into the body, so water would have to follow a zig-zag path. Are there other areas in the camera where there are seals, or is everything just a matter of close-fitting plastic and metal?
Canon: It's more about connection of parts rather than increasing the number of gaskets.
[Ed. Note: This is consistent with the practice of many companies. Lower-end camera models don't have actual foam gaskets in them, but rather just very closely-fitting plastic parts. A common approach is to have overlapping edges on parts, so water would have to follow a circuitous route into the interior of the camera]
The lens roadmap: Can you tell us relative priorities of the new models?
DE: Jumping around a little bit, I'm going to talk about lenses next. (Hah, Kato-san perked up, thinking "Ah! It's my turn!")
Canon: He's excited!
DE: Yeah, so you made six development announcements here, and all of them just say second half 2019.
DE: I know you can't be more specific about individual release dates, but can you tell us relative priority? Which lenses will we see first, which later?
Canon: This isn't something to talk about as of now, sorry. It was a good try, though!
DE: Ah, I had to try, anyway...
Canon: That was a great way to phrase it. <grinning>.
[Ed. Note: Gotta give me points for trying... ;-)]
Canon's 85mm f/1.2 DS lens uses apodization coatings(!) internally for better bokeh
DE: We're very interested in the two different versions of the 85mm f/1.2. You said the DS version will have very smooth defocusing with smooth bokeh.
DE: Is this something like an apodization lens? Can you share any more detail about what the lens is like internally?
Canon: Yes. It uses basically the same technology as apodization. There are several manufacturers that have apodization lenses, but our approach to apodization is slightly different. What we do is we use coating technology to make the apodization.
[Ed. Note: This was quite surprising to me. Apodization is a lens design technique that generally uses a radial graduated neutral density filter in the optical path. This makes for very smooth bokeh (as long as you're not dealing with very strong highlights that swamp the filter's ND range), because the "aperture" forming the bokeh pattern doesn't have hard edges to it. As noted, though, every other apodization lens I've seen uses a radially-graduated ND filter to achieve this. Canon's approach is entirely different; they use optical coating technology to deposit the same sort of graduated ND pattern directly on the elements of the lens themselves. This strikes me as something that would be *very* difficult to control precisely in a production environment; it seems like quite an achievement.]
Canon: Theoretically, it's relatively easy to apply this type of technology to any sort of lens. That's all I can say at this point.
WB: As far as I'm aware, this is the first time Canon's done a special, apodization-style lens. Is there something inherent about the RF-mount lenses that allows you to do that? Why are we seeing a special 85mm now, and what was preventing you from doing it on the EF-mount version of the 85mm?
Canon: With current technologies, it's technically really challenging. So it took time for us to develop this technology to the point where we can apply it to actual products.
WB: Ah, cool. Okay. Thank you.
DE: That's very interesting that it is a coating technology. Other manufacturers make like a graduated neutral density filter, so this is done with coating? Mmm!
Canon's apodization coating can be applied to elements of existing lens designs
Canon: With the case of the apodization film [Ed. Note: By "film", he means a separate filter element], we have to add a lens element to the entire optical system. All we have to do to apply this technology to a lens is apply this coating to one or more of the elements...
WB: ...and then probably apply it in a gradation style, or thicker on the edges and it becomes less and less intense towards the center?
DE: When I think of coatings, I tend to think of dichroic and refractive coatings, but this is not refractive. This is a coating, but it's an optically-dense coating I guess, yes?
Canon: Yes, precisely.
DE: Very, very interesting. We're going to be very interested to see that. One thing that's challenging with apodization is how dense the apodization filter can get, because if you have very strong highlight, it'll be gradual but then still have a hard cutoff.
Canon: In terms of production engineering, it's really challenging.
DE: Very difficult, yeah.
WB: Are there any challenges in terms of autofocus with the DS lens versus the standard version?
Canon: We cannot comment on that at this moment.
WB: Ah, okay.
DE: We know how good our questions are by how many times you can't answer!
Canon: Very true! I hope by next time we can answer that question.
The larger R-mount allows image stabilization for wide-angle too, not just teles
DE: So all of the new zoom lenses that you have announced are equipped with image stabilization. Has the larger R-mount led to any advances with IS? I think the larger barrel could mean maybe more powerful actuators, that sort of thing?
Canon: The general idea is we were able to deliver these lenses with IS thanks to the large mount that they offer. So there are three elements, three factors that we can implement that we'll be able to deliver with the large mount diameter. Optical quality, flatness [Ed. Note: Meaning corner to corner sharpness] and operational specifications. So this introduction of IS in these lenses would be categorized as operational specification improvement.
DE: Yeah, because the 16-35mm IS EF is only f/4, but this time the 15-35 IS is f/2.8.
Canon: I would say this lens is really aggressive. The basic idea is that we always wanted to introduce IS in all of the f/2.8 lenses.
Canon: But with the conventional EF-system, only the telephotos had IS, so we were pretty fortunate that we were able to introduce this technology on the wide-angle side, as well as the standard side.
This makes sense, but wasn't something I'd immediately thought of when I first heard about larger-diameter lens mounts. The resulting larger-diameter lens barrel means there's more room for IS actuators, so Canon can now make wide-angle and standard-range (eg, 24-70mm) zoom lenses with IS. REVISION: Oops, the diameter of the mount is exactly the same as the EF mount, it's just that the back-focus distance is less. This apparently gives them more flexibility in arranging the internal lens elements, and enough room to include IS actuators in the wide and standard f/2.8 zoom lenses. So the bottom line is there's more room internally, but not because the mount itself is larger diameter. Thanks to readers radeon and DrJon for catching this mistake!]
The EOS RP detects eyes when tracking, too (and so will the EOS R, soon)
DE: Oh, that's right, yeah. The 24-70mm f/2.8 was also not IS. The EOS RP has tracking AF with face-detect. Is it also doing eye-detect in servo mode, or is it not?
DE: It is doing eye-detect? Ah!
Canon: The idea is that now we are able to implement the eye AF tracking in the RP. And so actually, back in December [when you asked] is there any update planned, at that time I didn't say anything.
[Ed. Note: He's referring to my interview with Mizoguchi-san, mentioned earlier, which I conducted in December, but published in early January.]
Canon: We knew, of course. Now we introduced it [for the RP] and why not for the EOS R? That's the question.
DE: Got it, right. So RP has that and then this coming firmware update will add it to the EOS R too, yes. So when a face is small, it just detects the face. But if it gets big enough, you see the eye.
WB: You can choose either one. It's the closest eye first. [Ed. Note: William noticed this on the samples we were shooting with.]
DE: ...and you can pick the other. And so when it is focusing on eye, then just the arrow key moves it back and forth. Yeah, yeah.
Eye AF should make really bright portrait lenses easier to use
Canon: Last year we introduced the 50mm f/1.2 lens, and this time, we introduced as a development announcement the 85mm as well. And those lenses feature really shallow depth of field for shooting portraits. The combination of the eye AF technology with the portrait lenses that feature shallow depth of field is really a key combination.
DE: Yes, clearly.
Canon: Thanks to the RF-mount, now with the 50mm f/1.2 and 85mm f/1.2 even at wide-open it's crystal sharp, and so we now recommend that customers trust the autofocus capability and use wide-open aperture with shallow depth of field for their creations, that is the idea. The resolution of this one is very stunning.
DE: Yes, the 50mm f/1.2 especially, was extemely sharp. We haven't posted tests of those lenses yet -- I need to create some calibration curves -- but the 50mm is perfectly sharp all across the frame. I was really amazed at that.
Canon: Thanks! That is something great to hear, from an optical designer's point of view. That's the best compliment. <laughs>
Canon stays mum on its R-mount pro plans :-/
DE: There's one more question to which I think I probably already know the answer. Do we know anything at all about when the pro EOS R body will arrive? Will it be in 2019 or 2020, or you can't even say which?
DE: Like I said, I think I already knew the answer.
Canon: Good try.
DE: Yeah, yeah, right. <laughs> Yeah, as William said, you know you're in trouble if you ask the question and everybody laughs.
Performance will be key for Canon's pro mirrorless body, once it arrives
Canon: We know there's a lot of customers and there's strong demand for a pro body. We're aware of that. But at the same time, the expectations in terms of performance are really high as well, so we need time to make sure that we get everything right in the body.
WB: Mmm. That's very smart.
DE: Well I think the pro body will demand advances at the sensor level for very fast AF maybe. Sensors take a long time to design and bring to market.
Canon: Yes. You know well.
WB: I might have missed a detail in the presentation but has price been announced for this body yet?
WB: US$1,299, OK. And so the, the 6D Mark II entry price or body-only price was $1,999 if I remember correctly.
WB: Is there something inherent about mirrorless technology that allows you to make a full-frame camera starting at such a low price-point, compared to a DSLR?
Canon: It's really difficult to pinpoint what technology made this camera so affordable. There's some components that can be made more inexpensive with the introduction of the mirrorless system, but at the same time, there are other components that need to be implemented for mirrorless. The EVF is one thing that generally makes the mirrorless camera more expensive than a DSLR to produce.
WB: So it's a combination of not just technical but also marketing considerations involved, as well?
Canon: Yes, both. From a technical standpoint, what's important was that we had the experience of producing 6D Mark II, so that experience really helped us to design this camera. That is one factor that was really important in making this price possible.
Several bundle choices and some great launch deals
DE: Yeah. And this is more for in the US specifically, but the price at launch was a little confusing. There were bundles and discounts, and I'm not sure I quite understand exactly where it comes out. The body is US$1,299, and then you're selling a kit with the EF 24-105 and a mount adapter for US$1,999 I think, yes?
Canon: The body only is US$1,299, and the body plus RF 24-105 is US$2,399. The body plus EF 24-105 STM plus mount adapter is $1,999, and only this kit includes the mount adapter, because you need it anyway [to attach the EF 24-105mm STM lens to the RF-mount on the EOS RP]. So that's why we include this, [and there are] those three kits.
Canon: We will start a promotion to encourage people to buy not just the body but the RF 24-105 as well, so on buying this kit you can get US$200 back [as an] instant rebate, so it's going to be around US$2,199 [after the rebate]. And if you purchase kits other than the EF 24-105mm, because it doesn't include mount adapters, we will offer with a free adapter...
DE: ...as a special.
Canon: Yeah, kind of a free gift, right?
WB: Just up to March 30th.
DE: Oh, okay. So the body by itself, special through March 30th, is free adapter and free grip. And then this one, if you buy the RF lens, besides the discount which means US$2,199, you also get a free adapter and grip. OK.
Canon: And for the EF 24-105 STM kit, you will get US$100 IR [instant rebate] for the mount adapter, because it's already included, and you will get the grip.
DE: Oh, great!
4K video is limited to 24p and full auto or manual only
WB: I had one final question about video. I noticed it says 4K 24p only, right? What was the decision behind choosing that frame rate versus perhaps 30p, which is maybe a little more consumer-friendly?
Canon: This is the result of a lot of consideration in terms of the size and the pricing and everything. After all, at the end of the day it's all about the balance of the product. That was, with this particular camera, the best we could do.
WB: Oh, okay. I like 24p, so that's good for me, at least. A consumer, my guess is they probably would just pick 30p, but 24p is more cinematic.
DE: 30p would mean more heat, so it might have required a bigger body...
WB: I also noticed that I can access 4K only in video mode, but if I'm in any other mode, I can't access 4K. It shows up in when the mode dial is set to video mode, but in other modes it only gives me the 1080p HD.
Canon: The reason is because you can't shoot 4K in Tv and Av. You don't get to choose your exposure settings when recording 4K with this particular camera.
DE: Yeah, we did notice that was a difference between this and the EOS R, is that in video in general, you either just have auto or manual or auto+, but in the EOS R you can choose Av, Tv, etc. Was that because of a technical tradeoff, as with the 4K frame rates?
Canon: That was partly the result of the business decision considering the target audience of this camera. You can either go full manual or full auto, so it was more similar to the previous-generation EOS cameras.
DE: Right. Right. And for more of an entry-level audience, Av and Tv might just be confusing [for movie capture]. We already saw today that Fv was challenging for me. <laughs> But now i know, now that you've explained. [Ed. Note: The Fv exposure mode was very non-intuitive to me until I had a Canon staff member walk me through how to rapidly switch between Av, Tv, Full Auto, Full Manual, etc. Now it's my favorite mode!]
Canon: Glad to help. Some of my colleagues only started using Fv recently, and since they started using it they stopped using other modes.
DE: Yeah, I think I would. I think we're all done. Thanks for your time!
As always, I appreciated the opportunity to get a variety of questions answered. I was particularly happy to get sorted out just what the similarities and differences were between the RP and the earlier 6D Mark II's internals, and also to get clarification on the whole question of how many AF points it has. (The difference between the 143 AF points the system will select automatically and the thousands of manually-selectable ones is confusing, especially since the overview briefing for the EOS RP didn't mention the thousands of selectable points at all.)
I was particularly intrigued by Canon's new technology for making apodization lenses, discussed in the context of the RF 85mm f/1.2 DS. It sounds like it's very difficult to do in production, so it's possible that it could be too expensive to be broadly deployed. But the fact that it doesn't require an entirely separate optical element (the apodization filter) means that it could be relatively easy for Canon to make apodization versions of many lens designs. Apodization lenses can be a little confusing, because their T-stop (absolute light transmission) at wide apertures deviates quite a bit from the f-stop value, and also in that their depth of field is a bit different than a conventional lens with a hard aperture. But the bokeh they produce is really beautiful; nothing else can get you the kind of soft, beautiful bokeh that apodization can. We're really looking forward to being able to get our hands on the 85/1.2 DS whenever it comes out.
As I mentioned at the outset, I was very interested to see this new, lower-end EOS-R model, particularly after my interview with Mizoguchi-san, where he laid out Canon's near-term EOS-R strategy. After shooting with it in a variety of situations, I can say pretty confidently that they're going to sell a lot of them, especially given its low price. For anyone who's a Canon crop-frame shooter looking to step up to full-frame, the EOS-R is not only your most affordable option, but it's also delightfully compact and lightweight, and a lot of fun to shoot with besides.
There are certainly a lot of people clamoring for the "high-end" EOS-R model, and at this point Canon's given no idea of when that might be coming. But meanwhile, I think there's a big market for the existing EOS-R models, and the new RP is sure to find a lot of happy homes among the Canon faithful.
What do you think, though? Keep the conversation going in the comments below!