Why not a film camera with an EVF?

[Alan Edward Klein]

That doesn't quite explain the modern f/1.4 - f/1.8 primes we see pop up all the time specifically for mirrorless camera systems.

It;s an ego thing or they're not aware of how small DOF is at such large apertures. Also, you carry around a heavier lens that costs more because of all that extra glass.

If you shoot a "standard" 50mm at f/1.4 on a full frame camera of someone's upper body from 5 feet, (roughly 2 1/2' x 3 1/2' field of view) you only have less than 3" DOF. That's less than 1 1/2" in front and in back of the focal point. So if you focus on the eyes, the subject's ears and tip of the nose will be out of focus. IF his head is at an angle, the second eye will also be out of focus. IF your focus is slightly off, even the eyes will be out of focus. f/4.0 will give you about 8" DOF.

In fairness, at ten feet, the field of view of 5' x 7' approx, you have almost a 12" DOF at f/1.4. SO you may want that. But in most cases, f/1.4 just isn;t needed with modern cameras as much as the old low ISO film SLRs with OVFs.

 

[koraks]

It;s an ego thing or they're not aware of how small DOF is at such large apertures.

I'm not so sure. That sounds like a bit of a harsh judgement on the decision making of people you apparently didn't know that existed.

Most of the arguments I see from them are in the direction of the quality of unshrapness rendering (bokeh), the ability to use relatively low ISO even under adverse lighting conditions but also other attributes of the lens that do not directly relate to the maximum aperture, like build quality, focus speed/precision etc.

As to the argument of "need": most photos aren't really needed anyway. That argument almost never goes anywhere. Most of us do it for enjoyment; it's inherently irrational.