Aliasing and moiré

To answer this question, it is important to understand the job of an optical low pass filter on a camera. You might have heard of the term anti-aliasing if you’ve played games on PC. That’s nowhere close to what an AA filter does on a camera. However, it gives a good starting point. Aliasing refers to distortions that occur when different signals that are sampled together become indistinguishable (or aliases of one another). In photography (or videography) aliasing occurs when the frequency of repeating patterns appears to be the same when seen on the imaging sensor in the camera. The sensor has a hard time separating these frequencies and blends them together instead, creating a phenomenon called moiré.

Moiré usually happens in situations where the object in the frame has ‘high-frequencies’ of repetitive patterns like multiple lines. Common examples include fabrics and animal feathers. The camera creates wavy patterns that are not seen on the actual subject being shot in such scenarios. Consider the photo below. Given there’s a repetitive pattern on the fabric which is beyond the sensor’s ability to resolve, we see resulting moiré in the image.

Solving for moiré using an Anti-aliasing filter

Of course, nobody likes moiré. While there are ways to remove it in post-processing, pitching that to the customers won’t win camera makers a lot of customers. Instead, they deploy anti-aliasing or optical low pass filter on the sensor. As the name suggests, the sensor blocks high-frequency information getting to the sensor that is responsible for moiré. In simple words, it softens the image to some extent so that the sensor doesn’t have to resolve for these conniving high-frequency repetitive patterns.

It is what it sounds like and the result is that you lose some level of detail and sharpness. Not a bad trade-off for photos you can actually appreciate.

why do new cameras skip on the anti-aliasing filter then?

Improvement in sensor technology as well the higher resolution of these sensors allows them to capture and resolve much more details than what was possible until a few years back. This higher resolution has eliminated moiré to a great extent. So much so, that an AA filter is no longer worth the loss in sharpness that it brings.

Of course, you may still find some moiré in some situations, especially when working with video. But those instances are few and far in between. Simply saying, it is worth taking off the AA filter in these high-resolution cameras.

However, not everyone has given up on these filters yet. Canon, for one, continues to use an optical low pass filter in its latest R6 and R5 mirrorless cameras. It is rather interesting that they decided to use one on the R5, given the high-resolution sensor. However, as per Canon, this a new low-pass filter design that features a quad-layer, 16-point subsampling. It combines this with a Gaussian distribution technique to deliver sharpness. In layman’s terms, Canon claims it reduces moiré without reducing the sharpness.

Conclusion

Optical low pass filters aren’t necessarily dead or bad. You will see them on most of the premium sub-25 megapixel shooters from leading manufacturers since it is still a requirement at this resolution. However, due to the sensor’s ability to resolve detail, most high-resolution cameras (40MP+) don’t require an AA filter. That said, having an AA filter in such a camera isn’t necessarily a bad thing. We recommend checking detailed reviews of such cameras to ensure they don’t lose out on the sharpness.

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Alongside the R5, Canon also released a slightly cheaper (emphasis on slightly) model, the Canon R6. This one comes with a smaller 20.1MP sensor and doesn’t match up to its elder sibling’s 8K recording capabilities. The 4K recording is also ‘limited’ to 60FPS. While it doesn’t match up to R5’s video capabilities, it does share a lot with its more expensive sibling. Both cameras share the Dual Pixel CMOS AF II system with 100% coverage of the AF area. Both models also shoot up to 12FPS with the mechanical shutter and up to 20FPS with the electronic shutter. And for the first time, both these models have been fitted with a 5-axis in-body stabilization.

But of course, the point of this post is not to talk about the technical specs of Canon’s new flagships. You will find extensive coverage for that all over the internet already. What we did want to talk about through the means of this post is how both these cameras are more than just their video recording capabilities. Canon had been languishing behind its competitors in the mirrorless race for some time now and the R5 and R6 seem to be its redemption.  When we compare it with its biggest competitors from Sony and Nikon, it seems like Canon has done its homework and has a couple of tricks up its sleeves to try and beat its nearest competitors.  We aren’t going to talk about the video capabilities, because nothing comes close to the R5, as far as shooting videos are concerned.

THE NIKON Z7: THIS ISN’T A BATTLE, IT IS CARNAGE

While Sony has been a serious competitor in the high-end camera market only recently, Nikon and Canon’s hegemony and rivalry goes back decades. While both haven’t been at the best of their respective games in the mirrorless era, it doesn’t mean they haven’t created fantastic products at all in the last 18 months or so. Point in case, Nikon’s Z6 and Z7 cameras which have been praised universally for their performance (maybe not as much as the Sony counterparts, but still).

Again, we don’t want to do an all-out spec war, but there are a few areas where the R5 beats Nikon’s Z7 flagship. The R5 and Z7 are comparable when it comes to pixel count and in-body stabilization.

What sets the Canon on a higher hill starts from the viewfinder, where the R5 beats the Z7 with a 5.76 million dot viewfinder vs. a 3.7 million dot screen on the Z7. The R5 also beats the Z7 when it comes to its burst shooting speed which can top out at 12/20 FPS depending on the shutter type. The Nikon Z7 can only pull an 8FPS burst mode which is significantly slower.

Unlike the Nikon, which, for some unfathomable reasons, decided to just have one pricey XQD slot on the Z7, the Canon R5 allows users to load two cards, one of which is the much more affordable SD UHS II standard. This might tilt the scales in favor of the R5 more than any other reason on the list.

The R5 also offers a bigger buffer capacity (180 RAW vs. 19 RAW on the Z7), more focal points (5,950 across 1,053 zones vs. 493), and a newer Bluetooth standard (5.0 vs. 4.2). Nikon also does not have an answer to Canon’s recently released super-telephoto lenses such as the Canon RF 100-500mm f/4-7.1L IS USM, the RF 600mm f/11 IS STM and the RF 800 f/11 IS STM.

The only major factor that works in Nikon’s favor is the price. While the R5 will set you back by $3,899, the Nikon Z7 can be had for a much lower US$2,800. For purists, who want the best of the best, that might not be a critical factor, but for a lot of other folks that $1,100 difference can be a major consideration.

However, it is rumored that Nikon should be releasing a refreshed and a more up to date refresh to the Z7 this fall named the Z7S. Hopefully, that should address some of the concerns with the rather quickly aging Z7, given that other competitors are killing it.

Canon R5 all the way because:

• Much higher autofocus points
• Higher shooting speed
• Bigger buffer
• Dual memory card slots
• Better native lens catalog
• Better viewfinder

What about the SONY A7R IV?

Who would have thought Nikon would be the first one to be routed in this battle. But here we are comparing Sony’s flagship a7R IV which was released only recently. To start things, the a7R IV comes with a similar-sized sensor, albeit with a much high pixel count at 61 megapixels. How useful those extra pixels are is debatable.

When comparing to the Sony model, the newer Canon R5 hits it out of the park as far as the autofocus points go (5,950 across 1,053 zones vs. 567). It also races ahead in areas such as the burst shooting speed  (12/20FPS vs. 10 FPS on the a7R IV) and a bigger buffer.

The only upper hand Sony has is the larger assortment of lenses (who would have thought?), but that is not something that is unfixable in the future. The a7R IV will set you back by approximately $3,400, so we don’t really see many reasons to not go for the Canon R5 instead. We’ll have to see how good Canon’s eye and subject tracking is, and if it is good enough, we’re all for team R5.

Why the R5 wins again:

• Much higher autofocus points
• Higher shooting speed
• Bigger buffer

WAIT, IS CANON THE CLEAR WINNER THEN?

Unless there’s something grossly wrong with the R5, we think yes. Price no bar, the competitors from Nikon and Sony seem to fall short on a number of parameters compared to the new R5. It beats the competitors on so many parameters, that we might have recommended it even without its video capabilities. Looks like Canon has a winner on its hands. Meanwhile, Nikon, more than Sony, should be getting sleepless nights. Not only does their flagship languish behind, but the company has also failed to support its product with an adequate number of lenses since launch.

While expensive, the Canon R5 seems like the king of mirrorless and we expect it to hold that title for some time. What remains to be seen is how well is Canon able to build a solid ecosystem around the camera with its own and third-party lenses. Meanwhile, you can also check out some more affordable offerings from these manufacturers that are still mighty impressive.

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