Mirrorless in practice really just means the camera works more like your phone camera. You view the image on a screen instead of through an optical viewfinder. That brings some nice benefits, none of them are necessarily a game changer on their own but together it makes for a major step forward in the experience. Now the viewfinder shows you the picture more like it will actually look, the processor can see the image as you’re composing it before you take the shot and provide hints and show you that information overlayed on the image, the processor is involved in auto focusing and can do things like use ai models to focus on eyes, plus the physical benefits like there’s a big complex moving piece the camera no longer needs.

Camera makers then used this change to make a bigger platform shift at the same time. Just like a major version bump in software, if you have breaking changes you’ve been waiting to make you might want to make them all at once. They widened the mount diameter of lenses, which combined with the shorter distance to sensor because of the lack of a mirror gives more flexibility in letting in more light to the sensor. And they built a new set of lenses around it, whereas a lot of the lenses in their old lineups were sometimes decades old and not designed for the crazy high megapixel sensors we have now and in the near future. Most of these new lenses released in the past few years have been very high quality, so to answer your question that’s really where the improved image quality comes from, this new generation of lenses.

Sort of. The diameter of the front element is predetermined, a function of the sensor size, focal length, and aperture. Mirrorless cannot escape this.

But, the shorter distance from sensor to lens does simplify the design of a good wide angle. Sadly, wide angles were never the big heavy lenses in the first place.

The whole smaller & lighter thing is not a lie but pretty oversold. Some of the RF glass is actually bigger and heavier than the equivalent EF glass.

It's a trade-off, though. Seeing the actual image through the lens, and not a digital representation, which is what you get with a mirrorless system, has its benefits.

I never found those benefits. What would you say they are?

Early on, the problem was mirrorless were slow in autofocus, and they had relatively terrible EV quality. Now they have better autofocus than mirrorless, and more importantly, with the very high resolution EV displays they have now [1], what you see is exactly what you end up getting. You don't have to guess about anything anymore, like what's going to blow out, which is fantastic. What you see in an optical viewfinder with your eye is not what your sensor sees is going to portray. I don't see any benefit to optical viewfinders at this point.

[1] 5.7MP OLED EV!: https://www.bhphotovideo.com/c/product/1494679-REG/sony_ilce...

Which is fine for what it is! If you aren't shooting in a studio, the reduced mass of equivalent lenses with mirrorless systems is a big quality of life upgrade all on its own, for example. But the color representation just isn't there, and it isn't going to be until we get better color in our display systems. It's being worked on, of course, but there's a long way to go.

I don't understand this. The EV displays are calibrated. It's what you're going to get on your high end monitor when you get home. Eyes do not work like camera sensors, so I don't see how this is a plus. White balance being a great example.

> the true dynamic range,

How can your eye tell you this though? Unless your'e doing HDR/exposure stacking, dynamic range from the perspective of the sensor is all you're going to get. With the EV, you get clipping/black indicators, and even a histogram. I'm never wondering if I'm going to blow out the sky or crush some details in shadows anymore. I can see if I am, without having to snap then preview.

> the ability to see to edges of the focal plane with greater clarity.

I don't understand this at all. The new EVs give you 100% crop (with some slightly reduced zoom so it fits), with complete clarity edge to edge.

I would suggest giving a new high end EV another try.

1. The color space of the EV's display (and even the wide-gamut monitors available for desktop use) do no fully encompass the colors we can see. https://i2.wp.com/digital-photography-school.com/wp-content/... for a diagrammatic example of common colorspaces vs. what our eyes are capable of perceiving. In particular, the greens and purples are abbreviated, and I prefer composing with the true colors in my eyepiece.

2. Knowing the condition of the light before it hits the sensor lets me compose more accurately. If I'm looking at the true light, I can tell at a glance if there is detail worth working to preserve in the highlights or shadows (by using a split neutral density filter, for example, to bring the sky brightness down some) or not.

3. I'm not talking about edge-to-edge clarity. I'm referring to the depth of the focal plane, and the rate of falloff. If you're shooting with a very wide aperture before infinity-focus distance, the plane is going to be very narrow, and seeing the rate of the falloff is easier when it isn't pixelated.

Hope that helps.

In either case, when the photo is taken, the mirror whips out of the road (which generates mirror slap, another problem), and the light travels to the film or sensor. Since this path is a different distance to the one used for focusing, it requires only a small calibration error between the body and lens to end up with out-of-focus images. It is very normal to have to tweak the focus (higher end bodies will let you do this), or to have to have a body or lens physically corrected. No matter how exquisite your optics - in fact paradoxically, this effect is worst with high-end optics - the way the light path works here can be a real pain for getting good focus.

Because mirrorless systems focus and capture from the same medium, this literally can't happen with your mirrorless camera.

Modern zoom lenses have anywhere from 11 to 30 elements, in 3-11 groups, that move at different speeds relative to each other. Doing that with a tiny electric motor, precisely, for a decade is a tough task, especially when the mass of the glass starts to exceed 1kg.

With a mirrorless camera, you can reduce the mass of the lens by ~10% for a full frame camera. With an APS-C sensor, mirrorless, you can reduce the mass by 33%. With a "micro four-thirds" sensor, the mass of the lens is less than 50% of a full frame. Rough numbers. As with everything, there are pros and cons to going with smaller sensors than full frame.

For example, for many years fast normal lenses on SLRs were 58mm “Biotar” not 50mm because a a new kind of focusing (retro focus) had to be adapted to work with a mirror in the way.