Suppose we better start somewhere. There was an interesting thread recently on f/1.2 so might as well start there.
3 contenders, K50 f/1.2, A50 f/1.2 and Cosina 55 f/1.2
All metered with the Green button on a K-5
Camera and Tripod remained constant throughout.
K images needed Exposure compensation in Lightroom, I will detail this.

So a few crops:
K50 - ISO80, f/1.2, 1/15s + 0.36EV Comp in Lightrooom 4.4



A50 - ISO80, f/1.2, 1/30s



Cosina 55 - ISO80, f/1.2, 1/25s



All focused on the 2 little stubs in the main flower using liveview.

Yep... hard to find in KA mount it seems at the moment though + I don't have a spare €1000 or so

Why? or For?

So imagine you visited a friend, who happens to have a fondness for nice lenses and between you could place the following out on the table:

SMC Pentax-FA 1:1.8 31mm AL Limited
SMC Pentax-FA 1:1.9 43mm Limited
SMC Pentax-FA 1:1.8 77mm Limited

SMC Pentax K 50mm F1.2
SMC Pentax A 50mm F1.2

Vivitar 24mm 1:2.0 MC Close Focus Wide Angle
Vivitar 28mm 1:2.0 MC Close Focus Wide Angle
Vivitar Series 1 28mm 1:1.9 Auto Wide Angle
Cosina 55mm 1:1.2 MC

Carl Zeiss Makro-Planar 50mm F2 T*
Leica Macro-Elmarit-R 60mm
Vivitar 90mm f/2.5 Macro
Vivitar Series 1 105mm Macro f/2.5
Cosina 100mm f/3.5 Macro
Vivitar 135mm f/2.8 Auto Telephoto Close Focusing

Olympus F. Zuiko Auto-S 38mm F1.8
Olympus G. Zuiko Auto-S 40mm F1.4

Panasonic Leica G 14mm F2.5 ASPH
Panasonic Lumix G Vario 20mm F1.7 ASPH
Olympus M. Zuiko 45mm 1:1.8 MSC

There is an Olympus pen on a tripod in front of a flower scene. There is also a Pentax K-5 waiting to be mounted on said tripod...

There are a lot of 40 to 50 somethings in there, some even happen to be quite highly rated

Anyone want to see some comparisons?

I'm looking at a set of shots from yesterday. There was a K and an FA43 involved amongst some other lenses , the FA stomps all over them detail wise, better micro contrast. It is such a monster of a lens in such a tiny package.

Hmm, first the Limited and second the K? Only say that because of contrast and richer hues that I find when I compare the Limited's to the K's. Easily fixed with a bit of PP
Dig in though (which I haven't done) and you'll see extra detail.

Yeah, was wondering where Mike got the posher clothes pegs. So unfair

My set were as follows:
Fern = Chinon 50 f/1.9 @ f/1.9
Cerbera (blue tipped flower) = K55 f/1.8 @ f/1.8
Leaves lit by sunlight = CZ T* 50 Planar-Makro @ f/2
Bluebells = FA77 @ f/1.8
Fern = CZ T* 50 Planar-Makro @ f/2
Dreamy = K135 f/2.5 @ f/2.5
Last 2 I named, Helios 44M4 @ f/2 & FA77 @ f/1.8

A50 F/1.2 @ quess what

hmm.. bokeh
Watercolour (my description) type bokeh




Slightly softer effect




This is nice, lovely transition into OOF




This? sometimes I like..




Busy background beautifully handled by the lens




Dreamy (love this)



Helios type (kicks and giggles only)



FA77 pushed to misbehave

Straightened and bumped the exposure




Straightened with no other tweaks. Looking at it now, its almost better for it. I cropped it last night following rule of thirds law