Pentax 50mm F1.2

[todd_k.]

Does anyone have any experience with this lens? I could really use a

super low light lens, and since this is the fastest thing available

for Pentax its at the top of my list. How sharp is it wide open?

Feel free to post examples.

Thanks,

Todd K

[mendel_leisk]

Wouldn't the light gathering advantage over an f1.4 be negligible, and at what expense?

[stemked]

Todd,

 

While I have never had this lens I've read a lot of reviews on it. It is a super-fantastic lens at f8 but generally all I ever hear is 'soft' at those wide aperatues. If you really need the speed, you are right, it can't be beat. But as the other poster noted the 50mm f1.4s are great lenses (I personally like the A to the M version myself) only 1/2 fstop slower and they are excellent optics at f1.4.

[alkos_en]

The main advantage over 1.4 version is _amount and quality of bokeh_ it produces. And at virtually no light, even 0,5 EV makes a big difference sometimes... Also, the image in viewfinder is brighter and easier to focus (extra-shallow DOF!)

 

Oh, and its indeed a little soft wide open, but much sharper than M1.4@1.4... It has less contrast from 1.2 to 2 and - in my opinion - a bit more flare.

 

My resolution test, center only (FP4@Xtol):

 

 

1.2 - 56

1.4 - 67

2 - 68

2.8 - 81

4 - 89

5,6 - 96

8 - 95

11 - 89

16 - 75

22 - 67

[jim kerr]

Alkos, That is one super f1.2 you tested there, even for center only. Did you get distinct separation of lines and spaces in both directions? I know it is possible that your lens gets l/mm readings that high, but in over 35 years, I haven't ever tested any lens(except super high quality macros in close focus mode) that ever got over 88 at any f-stop at a normal test distance(1:50). Please don't feel like I'm talking down to you,forgive me for sounding like I know it all. I'm just surprised at your high l/mm....Curious.....Jim

[alkos_en]

No, only vertical lines. I've used test of my own construction, but measured quite precisely - it was 100x70cm chart with five groups of lines - from 30 to 110 per mm on film. I.e. for 30 l/mm it was group of 10 black lines measuring 9mm altogether in original, what gives 0,324mm on negative. For 110 l/mm it was 2,5mm / 0,09mm. Close enough.

 

I've put the camera just to fill the viewfinder (95% coverage - K2) with chart and shoot on ilford fp4@100, developed in stock xtol for 5 min. Exposure times - from 1/60 to 4 seconds afair.

 

I've enlarged the negative with 50x good microscope and counted the blocks of lines previous to ones that appeared as flat squares.

[alkos_en]

Oh, the black lines were separated by white spaces of the same width :)

 

But - it was only 30 times the focal lenght from film to chart. Maybe that's why.

 

Anyway, good result, isn't it? :->

[jim kerr]

Alkos, at any way of checking resolution, I think you have a very satisfactory lens. I have for many years wanted an f1.2 for astro-photography even though the outer 1/3 of the frame would be suffering severely from light fall-off....Jim

[andy_s5]

<p>I know I'm raising the dead by posting in this thread, but I'd like to know if anyone knows where someone could buy an f1.2 lens, old or new. I love my Asahi 50mm f1.4, it's got the best IQ of all the lenses I own (And I own a few), but I would go crazy over a 1.2</p>

<p>Just to answer the OP's question two years too late, check out this guy's work with it:<br>

http://www.flickr.com/photos/fuctupfactory/502685426/in/set-72157594261988532/<br>

It's quite mesmerizing.</p>

[andrewg_ny]

<p>KEH has the Pentax-A 50/1.2 for about $500. I see one on e-bay with a $389 BIN. I think some other forum participants have Cosina (?) 50/1.2 that they found for considerably less. Be careful as some sellers list garden-variety 1:2 as 1.2.</p>