And yes, they are mostly better than previous generations across the board. Which is pretty cool, that something based on such a simple idea that’s been around hundreds of years still has room for major improvements.

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.

The switch is quite obvious from the Canon release schedule - I don't think they have a single non-RF (mirrorless mount) lens being released this year.

Aside, I enjoy that Ken also loves this lens, despite it being mostly plastic, which he usually shits all over. It actually seems like a feature here, for weight purposes.

Where the 400DO perhaps really shines is paired with a 1.4x TC - it's much more handleable than a 600/4 and paired with a decent body gets results as good as bodies 10 years ago would have got with the 600/4.

I have three different TCs which I got from a friend who switched to Sony. I haven't really used them much because they seem to drastically change the optic behavior in ways I don't like. Maybe I should give them another chance as they never come out of their cases.

But that tradeoff seems hardly new to me. Consumer 70-300 for ~300 $ vs. Pro 70-200 for 2000+ $. The "only" difference is build quality and the pro lens being 2-3 stops brighter. Price difference: ~10x.

Another example is if I focus on something and then zoom in and out some lenses have to refocus and others maintain focus. This is an important feature for video and any kind of fast shooting. Many lenses have much more "focus breathing" than others. That is, the change of the effective focal lens as the lens focuses closer and closer. I had a lens that was 200mm but it was really only at infinity. At close focus is was closer to 135mm since the focus breathing was so pronounced.

Bokeh, chromatic/comatic abberations, geometric distortion are other things I can go on and on about.

It's been a long time since I paid any attention to pro photographic equipment so I don't know if fast lenses are important with modern sensors performing so well in low light. But back in the analog/early digital days 2-3 stops was a huge advantage.

Also something to consider, the pro lenses also focus faster and more accurately. I was never sure if this was down to the software in the lens, which is proprietary and why 3rd party lenses are never as good as manufacturer. I could easily see Canon or Nikon tweaking the firmware on prosumer lenses to focus a fraction slower.

IIRC, the pro lenses (white Canons) focused faster as a result of them letting more light in, as well as having faster motors (USM), though mid-range lenses had these as well.

Around that time, the body also made a big difference since the 1D-series had ~45 AF points, and the lower and mid-range bodes had 9-20 AF points. Not sure if this is still relevant but I think even low end bodies have a ton of AF points these days.

Especially when it doesn't have a nice manual focus ring à la the Olympus m43 lenses.

More importantly, those things combine to make a certain je nais sai quoi that makes photos taken with it seem to have much higher quality. I took a quick test shot of my dog when I got it and my sister remarked that she could practically feel the dog with her eyes, just looking at the photo. Nobody has ever said that about pictures of the dog that I took with the old lens, even if I spent considerable time trying to get lighting right and the dog to hold still.

My old lens ruined a bunch of shots I took in a forest that required running at the extreme edge of its settings. This new lens doesn't look like it will do that.

Actual light transfer (e.g. t-stops in cine, but less quantitatively in SLRs, say - some lenses are brighter than others), sharpness, chromatic aberration, spatial aberration, focal speed and accuracy (assuming autofocus), consistency across the telephoto range (not for primes, obviously) - some lenses will have not just differet f-stops at different lengths, but really different characteristics. This doesn't even get into the subjective aspects (e.g. "bokeh") that some people care a lot about.

Is it brighter for the same camera body, aperture and depth of field?

If so, what would one look for in a lens's specifications to describe this difference?

Which makes it bigger and heavier, harder to manufacture, and smaller market - all of this pushes prices up (an order of magnitude is common)

As for relative aperture adjusted for actual, measured light transmission, that's a T-stop, but these are typically only marked and specified for cine lenses, e.g.,

https://www.zeiss.com/consumer-products/int/cinematography/m...

(IIRC, the Master Primes are geometrically f/1.2 at T1.3)

the maximum f-stop of the lens describes the ratio of sensor length (1D, diagonally is best comparison probably), to the diameter of lens aperture. because the opening and sensor are two dimensional, every sqrt(2) increase in f-stop describes halving the light. for example, a f 1.4 lens can allow ~twice as much light as an f 2.0 lens. Every doubling of light is considered a "stop", like {1.4, 2.0, 2.8, 4.0, 5.6, 8.0}. An important consideration is that this number describes a ratio, not the absolute opening in the lens without respect to sensor size.

One possible conversion method is to consider the sensor size of the system against some popular standard. For example, "aps-c" sized sensors are about 1 stop "slower" than full frame sensors, due to being 1/(2.25) the size of full frame sensors in area, or 1/(1.5) linearly. This means that many lenses can be converted not only on focal length, but also for f-stop, to estimate the total light gathering power of the system, and the output "look" of the image. Full frame sensors (~36mm x 24mm) are most frequently used in the photography world as a standard comparison point. For example, a 50mm 1.4 lens gives 50mm 1.4 on full frame, but that same lens on an aps-c sensor (like a fuji X, sony 6xxx, canon 7d, etc.) would not only give a cropped 75mm [full frame] focal length equivalence, it would also give the depth of field of a 75mm _2.0_ lens [on full frame], not 75mm 1.4. At the same time, the exposure would still benefit from the light gathered at f1.4. This is why many say that smaller sensors give a larger depth of field (more in focus, less out of focus background). In reality, this is due to the lens aperture being measured only as a ratio to the sensor size. Finally, the smaller aps-c sensor will give a larger depth of field at the same f stop, but may also give higher noise at the same ISO (to a similarly advanced full frame sensor). This means that an aps-c camera takes the exact same image when it has ~1 more f stop, ~33% less focal length, ~1 stop lower ISO to the full frame system. A big confusion around any of this "equivalence" discussion is that sometimes people mean equivalence for lens "look", and other times, they mean equivalence for exposure, while others may be talking about absolute image quality and noise. They're actually all related, though much of this discussion isn't important to real world photography.

They also have a 500mm 5.6 that's similarly tiny (compared to a non-PF version) and hard to get.

I'm planning on picking up one of the Nikon mirrorless FFs soon.

On the other hand, it doesn't behave like a good canon ultrasonic lens with immediate focus. not at all.

Sensor size comparison: https://commons.wikimedia.org/wiki/File:Sensor_sizes_overlai...