DSLR versus Mirrorless

 

First of all: The photo has nothing to do with the topic. So, don't expect a connection. The dog was just a lucky coincidence, although the town hall in Memmingen would have made a nice image anyway.

Old guys defend their old ways. I fall in this category too. And I defended the mirror for a long time. The advantage is obvious, isn't it? Through an optical viewfinder you see the world as it is, unobstructed, in clear colors, and with real light. There is no delay and no pixelation. How can an electronic display beat that?  Moreover, those DSLRs had a distinct autofocus systems, working fast and reliably and independent of the sensor.

The first generation of mirrorless cameras did indeed have terrible viewfinders, and their AF was lacking. Someone who had used a DSLR for some time had no idea why to switch to such an inferior system. But times have changed! A modern EVF is getting close to the real scene, and the AF performance has vastly improved with processor power. So, the arguments for the mirror become weaker and weaker. Add to this the youngster style of photography which does not use the viewfinder at all, and the DSRL is slowly dying.

The mirrorless design, on the other hand, has clear benefits. 

• The camera can be made smaller and lighter without the box for the mirror and its weight. Or it can use the free space for more battery power or a larger grip. Moreover, the lens moves closer to the sensor which frees designers of some optical limits.
• The user experience is now built around the live view. That is no longer just an added feature which turns off the good autofocus system system (and the specific sensors for exposure). Enhanced elements like a histogram or a level can be displayed, even in the viewfinder. It is possible to see a magnified image for more precise manual focussing, or focus peaking, or zebras for overexposure, on the display or on the viewfinder.
• The lack of the mirror and the progress of sensor technology makes silent shooting possible. On the recent cameras, this is faster than the shutter, and the Nikon Z9 does not even have one.
• Modern processor power brings AF modes which were previously impossible, such as eye focus for animals or advanced subject tracking. All these modes rely on the live image from the sensor. 
• For the old ones, there is another argument: Because you can now use the display or the view finder equally well, you no longer have to lie on the ground or bend down to get a low shot. And you are invited to abandon the boring eye level photography.

I am sure I forgot a few things, such as not having to calibrate the AF for specific lenses anymore. I could not think of going back to a mirror. The only remaining disadvantage is the higher battery drain. Typically, a DSLR still offers twice as many shots per load.

For the very old ones (or the rich) let me discuss the range finder style of photography. It has the advantage that the view in the viewfinder is larger than the actual image crop which is outlined with a frame. So, it was loved by photo journalists who used it to capture an image cut out of the real scene they saw through the view finder. You are able to see things outside your photo too. 

The optical view finder in a DSLR could have mimicked the range finder style. I believe that there were cameras who actually showed a bit more than the actual image which reaches the sensor. But modern DSLRs didn't do this to my knowledge. It could be done on one of those high resolution mirrorless cameras, leading to a crop, of course.