[Prof_Pixel]

I would argue that the instant return mirror is not especially useful unless used in conjunction with an automatic diaphragm.

I guess you really had to be there to appreciate what the instant mirror return meant - even without an automatic aperture.

I was shooting a lot of college sports photography and the instant mirror return was game changing. Typically I was shooting at close to full aperture to maximize my shutter speed and did't miss not having an automatic aperture.