As someone who has shot SLRs (digital and even some analog) for almost thirty years: It's a dying format and it should die. I have about twenty years of investm

As someone who has shot SLRs (digital and even some analog) for almost thirty years: It's a dying format and it should die. I have about twenty years of investment in Canon EF SLR lenses and even so, I bought a mirrorless body last year. I still have my EF lenses (and an EF-RF adapter) but I'll probably sell them gradually and never buy another EF lens again. It's important to understand the history of SLRs. When they were invented, they were competing against rangefinders. With a rangefinder, you have a lens that exposes directly onto the film. Then you have a separate little viewing window that you look through to aim and compose your shot. That little eyepiece is off center from the actual lens and film, so what you see looking through it isn't exactly what the lens will see when you take the shot. Also, you can't preview things like the aperture, depth of field, and focus. SLRs were a radical improvement over that. With an SLR, there's a little mirror/pentaprism thing between the lens and film. When the shutter is closed, it routes light up from the lens to the eyepiece. Then when you press the shutter button, the mirror flips out of the way (this is part of the iconic "take a photo" sound) and the light going through the lens goes straight onto the film. In this way, what you see in the eyepiece is exactly what the lens sees. The whole point of an SLR is to make previewing a photo before taking a shot match the actual taken shot. Digital SLRs have the exact same structure, but with a digital sensor instead of film. When you look through the eyepiece, you are looking through the pentaprism and mirror and then out the lens. So you see exactly what the lens sees, and what the sensor will see when the shutter opens. But the framing tends to not be exactly the same since the sensor may crop in various ways that the eyepiece doesn't. Also, the eyepiece doesn't show you anything that the sensor is doing to the photo, like exposure control, ISO, noise, motion blur, etc. If your goal—which was the original goal of SLRs!—is to make your eyepiece match the final photo, the best way to do it is to have the eyepiece be a digital display that shows what the sensor itself sees. That is as close to the ground truth as you can possibly get. This is what mirrorless cameras do. Not only are they superior when it comes to previewing accuracy, they are lighter, smaller, simpler, and more durable because they don't need the large moving parts for the pentaprism and mirror. I loved my SLRs over the years, but its time has passed.