S-M-C Takumar 50mm f/1.4

[wtlwdwgn]

<p>I have this a mint copy lens now but I'm having a hard time getting the focus correct. Even with the K20D's focus confirmation it isn't always as sharp as I thought it would be. But once I get it focused it's sharp. The weather's changed just a little from the other day. This is how it looked this morning.<br>

<img src="http://wtlwdwgn.smugmug.com/Lenses/Takumars/S-M-C-Takumar-50mm-f1-4-3/771424292_GtDx2-O.jpg" alt="" width="800" height="532" /></p>

<p>100% focused on center cap.<br>

<img src="http://wtlwdwgn.smugmug.com/Lenses/Takumars/S-M-C-Takumar-50mm-f1-4-7/771431945_CGwTW-O.jpg" alt="" width="800" height="532" /></p>

<p>Inside where it's nice and warm! Available light.<br>

<img src="http://wtlwdwgn.smugmug.com/Lenses/Takumars/S-M-C-Takumar-50mm-f1-4-6/771424239_ykfif-O.jpg" alt="" width="800" height="532" /></p>

<p>With flash.<br>

<img src="http://wtlwdwgn.smugmug.com/Lenses/Takumars/S-M-C-Takumar-50mm-f1-4-5/771424261_rmF7y-O.jpg" alt="" width="800" height="532" /></p>

[laur1]

<p>I usually ignore focus confirmation when focusing manually - it's not that precise if you're shooting wide open. I've also found that the Pentax O-ME53 magnifier loupe makes it much easier to see the fine detail in the area you're focusing on.</p>

[celasun]

<p>You may need a focusing screen (with prism) to be able to use that lens in a more consistent fashion. Otherwise, getting sharp photos at close range with a wide aperture (a DOF of a few centimeters) is a hit or miss affair. At narrower apertures and for distant subjects you may not notice a problem, though...<br>

As Laurentiu mentioned, focus confirmation is unlikely to be very helpful for close range shots with relatively wide apertures.</p>

[joseph_wisniewski]

<p>Neither a focusing screen with prism, AF confirmation, or the focus magnifier will help. All of them have prism angles, sensor angles or scatter angles (respectively) of about 10 degrees, which corresponds to an f5.6 "window" through the lens's exit pupil. The 50mm f1.4 Tak has tons of spherical aberration, which means the f1.4 part of the exit pupil focuse at an entirely different plane than the f5.6 part.</p>

<p>There are only three ways to focus a fast lens with poor SA accurately</p>

<ol>

<li>Liveview, which I don't recall the K20D having (and I used to have one, shame on me).</li>

<li>Fitting the camera with a really coarse focusing screen (at least 20 degrees scatter) or a special "fast lens" split image screen with 20 or 40 degree prisms. This sort of sucks, because a coarse screen is very dark with slower lenses and a 20 degree prism blacks out with lenses f2.8 or slower.</li>

<li>Making a focus offset chart. Get AF confirmation, then shoot a bunch of f1.4 images, manually shift focus nearer and farther than that point, logging which is the best. Either tape thee chart to the lens, or add a new "focus comp" park near the main focus mark, just like the IR comp dot. Then, when you shoot, get confirmation then manually shift focus to the comp mark. (this is a manual version of what the cameras with "AF fine tuning" functions do. AF fine tuning is just compensation for SA). </li>

</ol>

<p>It could be worth the trouble. Who doesn't love a 50mm f1.4 SMC Tak? Mine was my very first "good lens", about 30 years ago.</p>

[snik75]

<p>Joseph, thanks for that explanation. I have noticed that with most of my fast MF lenses, I get better results focusing just a little nearer to me than I would have thought going by confirmation dot and the visual screen in my K100d.<br>

For Steve, keep in mind that the 1.4s aren't that sharp wide open - less so than the 1.7s by general acclaim and my limited testing. But by f/4-5.6 you should be getting extremely sharp images.</p>