Play the video from 8:50 to 10:35. Starts with: "A huge thing that that nobody talks about that much is sensor dust .....
My inclination is to take seriously a reviewer who sees an actual phenomenon and describes it in depth.
Yeah dust can be a problem if you don't know what you are doing or don't take proper precautions. This is an image from my 5D in 2006 (the original) my 2nd DSLR, first day of a 2 week trip got a ton of dust from changing lenses in windy conditions by the water. The 5D wasn't a mirrorless camera, I didn't bring a rocket blower so I had to do a ton of spotting. Dust can get in any camera. I've used all sorts of Canon DSLRs and now 3 different Sonys and dust isn't any more or any less of an issue for me. I like that I can see the sensor now.
The Canon Integrated Cleaning System was introduced in 2006 - http://cpn.canon-europe.com/content/education/technical/eos_integrated_cleaning_system.do
Your original 5D, introduced in 2005, predated ICS. Further, the fluorine coating to repel dust wasn't introduced until the 5DII, and there have been subsequent modifications to prevent dust sticking. You original 5D is not a good example to cite for dust on a sensor since there have been tons of improvements in the last 13 years.
Perhaps, but it is certainly appropriate when discussing how much influence the presence of a mirror has on protecting a sensor, or the inset of a sensor within the body for that matter.
Those later improvements, which made a significant difference, are not unique to SLR.
Of course they are not unique to SLR. It is pretty pointless, however, comparing the dust resistance of a state-of-the-art modern sensor with an ancient one to evaluate the modern mirrorless vs the modern mirror box, as is being done in the review. The mirror is protective against dust for the 5DIV
vs A9, and that is the main point of Tyler.
I’m willing to stipulate that it might be, since the mirror provides additional surfaces where dust can settle. However I’m also well aware that the mirror doesn’t prevent dust ingress into the compartment (it’s hardly a “tortuous path,” which is the terminology often used in the design of electronics where sand and dust are of concern), and that any dust in the compartment has a propensity to move, no matter the material lining the compartment, when the mirror actuates.
If a mirror offers protection, it’s unquantifiable without lab testing, but I’m betting marginal relative to other methods. Anecdotally, I found my mirrorless camera (sold my A7Rii when I bought a 1Dx) no more prone to dust than any SLR I’ve ever owned.