Asahi Optical Co. Super-Multi-Coated 50mm f/1.4-16.0

Lens categoryNormal
Vendor nameAsahi Optical Co.
Type nameSuper-Multi-Coated
Product year1971
Focal min (mm)50
Focal max (mm)50
Focus min (cm)45
Aperture max1.4
Aperture min16
Diaphragm blades8
Filter size (mm)49
Asahi Optical Co. Super-Multi-Coated 50mm f/1.4-16.0

There several versions, but without optical difference, which is good because
the 7-element 50/1.4 Takumar design is a legitimate claimant to the title of sharpest
normal lens ever made; and bad for another reason, noted below.

There was a cosmetic change from scalloped knurled focus grip, to the
rubberized one which was cheaper to make. This was simultaneous with
the name change. Some users have also noted that the “feel” of the
focusing on the earlier, Super-Multi-Coated version is silkier and
smoother, both when new and as the lenses age. I can’t remember a
reason why this should be so, but I haven’t taken one of the SMC version
apart recently, either.

The bad news: unfortunately, both versions, and the SMC Pentax 50/1.4
with 52mm filter ring, have an internal element made of material known as “hot glass”
which turns yellowish to brownish with age. The affected lens element contains
thorium, a radioactive rare earth element. Several lens makers including
Pentax, Kodak, Leica, and Canon used this manufacturing technique in the
1940s to early 1960s to lower the index of refraction of specific lens elements.
The yellowing is curable by exposure to ultraviolet or sunlight, as has been
discussed on the Spotmatic Yahoo! Group.The earlier 8-element 50/1.4
Super-Takumar and the various 55/1.8, 55/2.0 and 55/1.9 Takumars do
not turn yellow, nor do the newer 50/1.4 SMC Pentax-M/A/F/FA.

7 Comment(s). Add a comment or Trackback

  • Ina Jookerv, Belgium  18:15 Mar 09, 2005 

    I have this lens, it has a amazing resolution. A must have!

  • Georg Weber, Berlin  01:22 Dec 28, 2006 

    About the ‘hot glass’, Markus Wottrich has done radioactivity measurements of some lenses, ;which confirms that there are some ‘real hotties’ around.
    As always, handle with care 🙂

  • Jiri Soucek, Czech Republic  09:43 May 02, 2008 

    The source of brownish tint isn’t the thoriated glass itself, but Canada balsam (optical glue), which turns yellow or brown owing to radioactivity of the glass. It can be replaced by an specialist, or bleached by UV light (one week under 11W UV tube removes about 70% of the coloration, one month roughly 95%).

  • A. Seka  10:05 Mar 10, 2011 

    “The” Pentax’s reference, even over the only m42 mount lenses…
    Optical and mechanical jewel, warm render, razor sharp and wonderfull bokeh, this well done lens is truely powerfull, no doubt !

    “La” r?f?rence Pentax,
    dont la r?putation d?passe largement le cadre des m42…
    Perle optique et m?canique au rendu chaud et velout?, piqu? et bokeh superlatifs, d’une qualit? quasi-irr?prochable et tr?s agr?able ? manier.
    A consommer sans mod?ration…


  • Emmanuel Corr?ia  10:06 Mar 10, 2011 

    Taken the 28 Avril 2005 with a 10D at Balaruc les Bains ( France )…summer is comming.

    People on the beach

  • Emmanuel Corr?ia  10:07 Mar 10, 2011 

    Useless to present that lens it is very famous 😉
    I’ve made a subjectif comparison with the canon Ef 50mm and the results seam to be very close , but the bokeh is nicer with the Takumar.

    J’aime beaucoup cet objectif ! Il semble tr?s bon ? pleine ouverture et son bokeh est super beau !
    Il est tr?s bien construit mais ? tendance ? jaunir avec le temps . Une cure d’UV et hop c’est reparti !

    Thomas et croute de pain

  • Gunja  02:38 Jun 07, 2012 

    If he’s looking for relatsiic dept of field lens blur then he would really honestly need to use the quickmask in Photoshop. notice the van in the picture behind the lady, half is blurred and half isn’t, that’s not relatsiic. in all likelihood the most relatsiic faux lens blur effects will always have to be done using the quickmask or some variant way. nice program though, especially for miniature/tilt shift stuff.

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