Differences between the ASPH and older 35mm Summicron?

You're tossing up between getting the current 35mm M Summicron ASPH, or perhaps a good condition earlier 4th generation 35mm M Summicron (pre ASPH). What are the trade-offs?

  1. The older Summicron is much more compact — almost half the size of the ASPH
  2. The ASPH lens is sharper out to the edges at wider apertures (ƒ2 — ƒ4)
  3. Ditto less vignetting
  4. On the 2nd hand market, the pre-ASPH 'Cron seems to attract higher prices — see <Photo.net: #00G7RZ>
  5. There are claims the ASPH lens delivers more pleasing bokeh at wider apertures — see <LCU: 314178-post30.html> and <jimarnold.org/galleries/leica_35_test>
  6. Alternatively, the older Summicron and ASPH deliver near identical results at ƒ5.6 and above
  7. Both lenses use the E39 filter size and work with ∅ 42mm clip-on lens-hoods

So the main consideration appears to be, do you mainly shoot at ƒ5.6 and above?

This topic was discussed a fair bit on the old Greenspun.com Leica Forum in 2001. Eg. see <Greenspun.com: #0072ob>.

BTW, trying to locate the serial number of an older, Canadian 35/2? Don't panic! Turn the lens focus ring to the minimum focus distance and look under the aperture ring.