As luck would have it, a casual visit to Easycam ended up with me bringing home a mint condition 50mm 1.2 lens. Why do I need such a wide aperture? Wouldn't the images be blur/unsharp? Well of course the images would not be as sharp as you shooting at f8 or f11 but and the big BUT, I have ultra duper super creamy BOKEH~!
At this point in time you must be saying to yourself..ok he's a bokeh addict..forgive him, but yes I am and one of the main reasons for this is the image separation you get and the WOW factor :) Take a look at the first image of the cherry. All I did was to ask my kind wife to please hold up the cherry in front of her..and f1.2 later...bam! In your face cherry bokeh image.
Some of you who are creative will say, wait a minute, I might be able to do the same with an 85mm f1.8. Well technically you might be able to pull off the same image but the minimum focusing distance of the 85mm is close to 1metre. Well talk about standing on your next door diner's table for the shoot. The 50mm has a minimum focusing distance of 0.5m so roughly 1.5 feet..wonderful working distance for me anyway.
Ok I'm not even going to go to the ISO I was shooting at but basically the 50mm f1.2 allows me to shoot at ISO 100 in a reasonably lit restaurant..AT NIGHT. Now lets compare the light bokeh size produced by this lens versus the 85mm f1.8.
Photo above is a full frame shot of light bokeh on the Canon EOS 7D using the 50mm f1.2 versus the light bokeh shot of the 85mm f1.8 below.
Oh yes, size does matter guys and gals and for those who tells you otherwise, ask them to go eat bokeh lights..lol.
So to summarize, in layman's terms the benefits of 1.2 and bigger aperture lens - crazy bokeh, super fast shooting speeds, incredible night shooting ability with low ISO, great skin tone and off camera usable pics, crazy image separation..etc etc.
All in all, you need to own one of these lenses, in your photographic life.