Leica invented 35mm(135) format compact camera, and soon after added a rangefinder framing/focusing system. Nikon cloned it, then replaced the viewfinder with Single Lens Reflex system, a system that uses a mirror behind the lens and a prism in shape of pentagram, forward of viewfinder, to directly view through the lens to frame/focus.

Those were introduced in 1930s and 1950s respectively. Since the launch of Nikon F in 1959 until some time in 2010s the viewfinder technology didn't change. Means shutter became metal and electronic, autofocus invented, man went to the Moon and back, digital CCD/CMOS photography came around, Sun goes down but mirror and prism SLR technology of 1950s just kept on.

One of the reasons why mirrorless didn't appear sooner is because LCDs or OLEDs viewfinder suck(ed). They used to be in SVGA or XGA resolutions, refresh at 30-60Hz or less, few hundreds ms late, dim, power hungry and whatnot. Wasn't so advantageous in terms of weight or cost as well. Optical quality of SLR viewfinder never disappointed its users on the other hand. It is and always had been a joy to be able to just look into it and see through the lens, especially when films take hours to develop.

Sony, however, knew that no one uses viewfinder in a point and shoot digital cameras, or no one has any problems without SLR viewfinder in video cameras, dad on holidays and professional broadcasters alike. So after they merged camera division from Konica Minolta in 2006, they just walked out and spoke out the obvious. Camera nerds were shocked, I was shocked, so were Nikon and Canon. Leica may have been laughing, Zeiss was happy collecting licensing fees. I was skeptical, and I could verify it feels very disappointing looking into EVF. But Sony knew it ain't a problem and it wasn't.

Nikon and Canon probably thought the quality of EVF never satisfies professional photographers, from their narrow expertise.

> I was skeptical, and I could verify it feels very disappointing looking into EVF.

My reaction is the opposite. I always felt disappointed by how primitive the optical view finder on modern cameras is versus electronic ones. It doesn't get the light levels right and it can barely show you any relevant information; there needs to be a separate 7-segment display on the body showing pertinent information. How primitive!

EVFs, on the contrast, show you everything you need to know right in the viewfinder (including advanced features like histograms, zebra stripes, etc., that an optical viewfinder could never possibly do).

I think good EVFs were available since about 2013. I compared the optical viewfinder of the Canon 5D with the electronic of the Olympus E-M1, and the EVF of the Olympus offered an equally large image, that also was brighter if the outside light wasn't very strong. The only complaint might be the limited resolution, but since then much higher resolution viewfinders have become available. And basically any optical viewfinder for smaller than 35mm formats is inferior, because the amount of light in the smaller format makes building of a large and bright optical viewfinder basically impossible

The big advantage of EVFs is that it can do so much more than an optical viewfinder. You can enlarge it, display focus peaking, but most of all, you get a preview of the image you would take - especially previewing the exposure is very helpful. And of course, if you want to do video, the viewfinder of a SLR wouldn't be usable at all.

>Nikon cloned it, then replaced the viewfinder with Single Lens Reflex system

As far as I know Nikon started off making Contax clones, not Leica clones. Canon did Leica clones, though. Keep in mind that Leicas up until the M3 didn't have a combined viewfinder/rangefinder. That was an innovation from Zeiss first used in the Contax II.

And there's been quite a few SLRs before the Nikon F, it was just Nikon that made it so solid and efficient that made professional photographers switch from using a rangefinder to SLR.

Mirrorless is electrically and mechanially a MUCH MUCH MUCH simpler design (SLR is essentially two cameras in one, with the pentaprism allowing light to go to a second sensor used for autofocus, and also to your eye) and it has a lot of compromises in complexity, reliability, and performance.

Mirrorless allows the camera to use the image sensor itself to do all the work. That means autofocus can be much better, using every pixel on the sensor for autofocus. It means you can run computer vision software in real time to do fancy things, like finding out if there are eyes in the image - most likely, you want the eyes to be in focus. You can focus in near darkness, when it's too dark for you to see. And other stuff.

The biggest downsides are 1) the electronic viewfinder, these are not as nice for most people, but with the big caveat that they do allow you to frame an image in near total darkness where an SLR wouldn't allow you to do that and 2) the big one is battery life, it is 5-10X worse with mirrorless than with SLR.

A major upside of the electronic viewfinder is the live depth of field and exposure preview.

As somebody who wears glasses, the biggest advantage of mirrorless is that you're not forced to hold the camera up to your eye.

As someone who wears glasses, I can use the optical viewfinder on my Nikon D850 without specs but need my glasses to use liveview, e.g. when shooting video. The D850 lets you set the viewfinder close to the prescription of your glasses.

DSLRs have live previews on the screens on their back, so that at least you don't need mirrorless for.

I like using the viewfinder though, and I like digital ones over optical ones.

Yeah but until much more recently, using the live preview on a DSLR meant you lost your fast AF.

Nikon and Canon's flagship products are DSLRs, which are cameras that have an analog viewfinder and a moving mirror inside to redirect the image to either the viewfinder or sensor. Mirrorless cameras use an LCD viewfinder instead.

The biggest things holding back mirrorless technology previously was battery life and autofocus technology. I am not sure why Nikon and Canon didn't invest more into mirrorless technology sooner, and I'm no photography expert, but I think they were just too entrenched in the DSLR technologies they pioneered.

They are in the same trap as traditional car manufacturers are with combustion engine cars. The profits are in the established technology, yet the writing is on the wall for the new technology. You know where the market is going eventually, but for sure you don't want to disrupt your current revenue stream until the new technology is really ready to replace the old one.

For many years, basically Nikon and Canon split up the "professional" market between each other. They already had this position with analog SLRs, and continued after the transition to digital. The reason is a mix of having very good cameras, a large lens setup, especially considering the more exotic/expensive lenses mostly used by professionals and most importantly, with the service organizations. At each olympics, they would have large service centers on-site, for repair and exchange. And also outside of these events, they have services networks which enable a professional to get the equipment serviced/exchanged with loaners in minimal time, which is a very obvious benefit. Which basically prevented other brands to make a huge inroads in the professional markets.

So their profits were driven by the established systems. They were milking this cash cow and consequently were late to the mirrorless game. Their recent offerings are nice, especially Canon has some very interesting lenses for their new mirrorless system, but even for those companies it takes a whole lot of time to have a remotely complete lens offering.

It might also be worth while to look beyond the 35mm format. In 2013 Olympus brought the OMD E-M1 to the market, which was possibly the first mirrorless camera, not only matching but in a few aspecs exceeding the performance of comparable DSLRs. This shows, how much Canon and Nikon are lagging behind.

”They are in the same trap as traditional car manufacturers are with combustion engine cars. The profits are in the established technology, yet the writing is on the wall for the new technology. You know where the market is going eventually, but for sure you don't want to disrupt your current revenue stream until the new technology is really ready to replace the old one.”

I think that’s it. But it seems they are catching up very quickly now. The upcoming EOS R5 looks like a very good camera.

Yes, they have good cameras on offer, but you could see, that Sony, Olympus and Panasonic have a few years more experience to polish their features. The big challange will be to switch their customer base over, that will be a long process.

> I am not sure why Nikon and Canon didn't invest more into mirrorless technology sooner, and I'm no photography expert, but I think they were just too entrenched in the DSLR technologies they pioneered.

You nailed it on the head for the most part.

Nikon had a mirrorless camera in the J1 series, which had some very nifty features but was just an absurdly expensive system for what you got (especially since it is basically a dead end, proprietary platform.)

Canon did a bit better with their first MILCs, but they weren't amazing. At the time they were introduced Canon suffered from a lack of on-sensor Phase Detection AF, and Contrast detection systems weren't as fast as they are now.

I mean, a big issue is glass; While there are exceptions to this, you can't just re-use an existing lens design on a mirrorless without making the thing longer than it needs to be (Which looks off on a Mirrorless.) Which means that Nikon/Canon can't just release the 18-55 EFAF Mark 10 lens.

Designing proper lenses takes time and money. I mean, the first few years I had an E-mount, the pickings were slim for lenses, while the a6000 was a good start it wasn't till the A7II and A7RII with their ability to do usable PDAF with adapted lenses that the platform felt safe to pick up.

But is that really the plan, to build an entirely new assortment of lenses, to avoid making the bidy wider than needed? It seems like the benefit with mirrorless would mostly be other things than size...?

There’s an added benefit - shorter flange distance/ larger mount diameter. Nikon especially went with a large mount. A larger mount = potential for faster glass.

But also think about it from a marketing perspective - even now most people buying cameras aren’t professionals. A big bulky camera right next to a svelte one in a store will look dated. That said Sony went too far with it, in my opinion. A nice grip is important for professionals.

I've been trying to keep up with all the new photography concepts in this thread, but "Faster Glass" is throwing me off?

How can glass lenses be "faster?" Allow you to shoot with a faster shutterspeed?

Faster is taken to mean that a lens has a larger maximum aperture, meaning more light gets in, so you can use a faster shutter speed, and hence get less motion blurring. Non-intuitively, because depth of field gets smaller as the aperture increases, faster lenses can also offer better separation of the subject from foreground / background features

I think that's correct (because it lets more light reach the sensor due to the bigger aperture, so less exposure is necessary)