« on: December 23, 2014, 01:30:45 AM »
The F1.2 lens has a small increase in brightness compared to F1.4 lens. When using film, this increase in brightness is noticeable, but with digital sensor the difference becomes negligible.
The you add light rays (compared F1.2 to F1.4) reach the sensor at a very tilted angle, causing a loss of advantage mainly in the full frame image corners.
To compensate this loss of light in lens more luminous than F1.4, the Canon pushes the ISO secretly, and the result is that the image quality in full frame corners will suffer much more in digital, compared with film.
Hi AJ, you obviously mean well, but you might be misinformed.
Firstly, f/1.0 to f/1.4 is a full stop of light. Even for digital photography, that *can be* significant.
Secondly, in a lens engineered to have a large aperture as the 50/1.0, there are certain optical aberrations to be expected- but that is intentionally designed into the lens. There is no loss of advantage, because the advantage here is a dreamy background, not a sharp FF corner.
Thirdly, if there are *bendy* rays in the corners, that still wouldn't result in any loss of light (relative to f/1.4 lenses) without violating laws of physics and wouldn't need any ISO push, secret or otherwise. Besides, it would have to be some amazing technology that pushes the ISO only in the FF corners.
Having said that, I wouldn't buy a 50/1.0 that produced results (almost?) the same as an f/1.2, comes with a ton of ergonomic (focus by wire, slow focus, double the weight) and financial baggage, and with no warranty unless I purchased for the sole purpose of collecting antique lenses.