Well the 50mm f1.2 and 90mm f2 are two lens that have very nice
bokeh. The 135mm f2.8 is not bad either.
I think it may have something to do with the number of diaphragm
blades. If you consider that out of focus highlights sometimes have
an angular aspect to them, mirroring the shape of the diaphragm
aperture, the non highlight areas must also be getting this angular
treatment though it is not as obvious. This imparts a flavour to the
out of focus areas, a texture if you like. So the more blades in the
diaphragm the closer the aperture is to a perfect circle and the
smoother, less granular, the out of focus areas. This seems to have
quite an impact, to me anyway, on a smooth transition from an in
focus subject to an out of focus background or foreground. I suspect
that the smoother this transition the more emphasis is imparted to
the in-focus subject seeming to isolate it in space. I think this is
what some people refer to as a three dimensional 'look' or
snap.
I have noticed - alright I admit it, I did not 'notice' I went and
counted them - that the two lenses that for me have the nicest bokeh
also have 9 diaphragm blades. The 90mm f2 and the 180mm f2 zuikos.
I would almost bet the 100mm f2 has 9 also. (?)
All my other lenses have 8 blades except for the 35mm f2 which has 6.
This surprised me greatly as I had theorised that Olympus and other
top lens manufacturers know all about bokeh and its variables. There
seems to be a correlation between lens quality and the number of
aperture blades so the 35mm f2 being the top lens in that focal
length - leaving aside the shift - I would have expected it to have
8 blades also.
Bokeh seems to have more of an effect or be more noticeable with
lenses of longer focal lengths, say 50mm and up, so perhaps Olympus
thought it less important, but then my 24mm has 8 blades so there
goes that theory.
The other thing I believe contributes to a nice bokeh is contrast -
in that the more contrast the lens has the higher the probability of
a nice bokeh. I believe this might be because the greater the
contrast performance the greater the ability to resolve subtle
gradations and transitions in colour tones - which you get more of in
out of focus areas because the colours sort of smear together.
So for great bokeh I suspect one needs both a many bladed diaphragm
and good contrast.
These are just my mad musings on the subject so please do not take
them for fact as they are as likely horse manure as anything else.
Giles
> Giles;
>
> I'm sorry to say I don't feel like I've done enuf shooting with it to answer
> these
> questions. Also, I'm still trying to get my arms around the feel of a good
> bokeh.
>
> george
>
> Giles wrote:
>
> > George
> >
> > How about the contrast and Bokeh? Aside from sharpness, these
> > are the qualities that most impress me about the 180mm f2. Do these
> > qualities hold true for the 250mm f2, I have always wanted to know?
> >
> > Giles
> >
> > > Gary;
> > >
> > > I bought it for 2 main reasons: wildlife and astrophotography. I haven't
> > > actually
> > > been able to use it as mucn as I'd like for either. Oh well, tomorrow's
> > > another
> > > day.
> > >
> > > Not trying to be flip, but based on small experience actually using the
> > > thing in
> > > the past year:
> > >
> > > Cons: HEAVY
> > > Pros: Fast, silky-smooth focussing, fast, sharp, fast, beautiful, bright
> > > viewfinder image, sharp, works great with 1.4 and 2x AND with both of 'em
> > > stacked
> > > (700 F/5.6) slides of moon were STILL sharp. Fits in my new backpack with
> > > 4T
> > > mounted. Did I mention it's sharp as a tack? And fast?
> > >
> > > george
> > >
> > > Oh yeah, forgot another con: It costs what $3700 to 4500 new depending on
> > > who you
> > > believe. Mine was 600f the lower number used, probably condition EX-
> > > Price
> > > included a brand new front element and a clean/adjust at Olympus service.
> > > Do I
> > > think that's what it's worth? I dunno. I'll decide if I ever want to sell
> > > it. Now
> > > please don't embarass me and tell the group that you saw one in a pawn
> > > shop for
> > > $375 last week <g>
> > >
> > > Oh, and I know someone else on the list has or had the 350. I think it
> > > was one of
> > > the Johns out there.
> > >
> > >
> > > george
> >
> > < This message was delivered via the Olympus Mailing List >
> > < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> > < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
>
>
>
> < This message was delivered via the Olympus Mailing List >
> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
>
>
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|