Is F 1.2 really that difficult ??

Started Oct 19, 2013 | Discussions thread
miles green
miles green Veteran Member • Posts: 6,664
It's a very specialized lens...

Yes, f/1.2 is difficult to make, and to use. I have a 50/1.2 which i use with an aps-c camera. Regarding fast wide lens (35mm equivalent about) aps-c is in about the same boat as MFT. Actually you guys might be better off. And yes, i would love a 20mm f/1.4 for aps-c, but....

These are specialty lens, designed for a specific use: portraiture in proper lighting. At such speeds, it's hard to make a lens with few chromatic aberrations, so there are tradeoffs. They are designed for good center sharpness, and a bokeh with smooth transition, hopefully with well-controlled longitudinal chromatic aberrations (but that's expensive). You're likely to have some haloing / blooming, which can be used to your advantage. For non-portraiture, such a lens is at a disadvantage compared to a much cheaper f/1.4 lens, as it will be more prone to flare, have less contrast, more distortion and vignetting, purple fringing in high contrast areas, etc... It's a moody lens, and it's easy to be disappointed by it if you're not using it within its design limitations. What you do get is a different look, a different rendering, and slightly blurrier backgrounds.

For better subject isolation, you're better off using a longer focal length and step back, which also allows you to select your background more carefully. If you stop down you also get more of your subject in focus. IMHO, to isolate your subject, you want both a blurred background and a sharp subject. At f/1.2 the only sharp thing in a portait will be your subject's eyes, IF (big if) you manage to get them in focus. If your subject it not facing you directly, only one eye will be in focus. Check out MF (medium format) lens - I don't think anyone makes anything faster than f/2.4. If you want less DOF than that, you have to use a longer lens, not a faster one. One of my favourite "subject isolators" on aps-c is a 135mm lens which i usually shoot at f/4.

Or a tilt-shift lens.... but not for environmental portraits.

Short of a FF camera, how about a speed booster?

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Miles Green
Pentaxian with chronic LBA
Corfu, Greece

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