Originally posted by TropicalMonkey I also have a Super Tak 50mm f/1.4. Wondering if the bokeh on 1.2 would be that much better? Even if it is going to have slightly better bokeh, DOF will be harder to handle wide open, correct?
I had one for about a year. I had a Buy/Try/Sell fetish where I wanted to have every legendary Pentax MF lens I could never afford when they were new, at least have them for a while, so I would know I had. I sold it because I didn't want to have that much money tied up in one lens. It was either
only the K50/1.2 or
no K50/1.2 and many other 50's.
IMHO (and I will likely attract contrary opinion here) the f/1.2 merely allows you a slightly thinner DoF (@10ft on 35mm film, 0.86 feet vs. 1.02 ft for f/1.4), so your subject can be slightly closer to OOF foreground and background elements and thus achieve isolation or the 3D effect in more settings (closer to backgrounds, for instance). In my case it was very difficult to achieve necessary critical focus in an APSc viewfinder (because I have old eyes and an eye disease), where you only get a tiny bit more than 6" of DoF with either lens at 10 ft. At 5 ft you get about an inch with both lenses, so it is really neither easier nor harder to use the f/1.2 lens than the f/1.4.
On APSc I thought the CoC was so thin wide open (0.02mm) that it wasn't really useable. I'm sure the lens was better in this regard on 135 film. I tend to do my best with bokeh at f/5.6, which is also where most of my lenses get really good. At 10 feet @ f/5.6 you get about 2.75 ft APSc and 4.25ft 135. The standard I was taught is:
- 100mm lens, 10 feet @ f/5.6 on 135 = 1 foot DoF
[EDIT]:
Someone pointed out below that the 50/1.2's have a sepcial, ethereal quality to them. I don't beleive that is so much the larger minimum aperture as it is the glass and lens design elements. I tried to briefly address that in the following. The actual quality of the OOF highlights is more the result of the specific lens design, the glass and the number of aperture leaves, whatever the largest aperture of the lens.
I still believe the real advantage of the f/1.2 lenses is low light focusing.