Hi Moose, Mike and all,
From: Moose <olymoose@xxxxxxxxx>
>To illustrate, here are simulated samples of the far ends small source
highlight bokeh.
><http://www.moosemystic.net/Gallery/tech/Lenses/Misc/Bokeh_Simulation.htm>
>
>ULeft = really bad. If you don't think this is realistic, look at the top
image here.
<http://www.moosemystic.net/Gallery/tech/Lenses/Misc/5018bokeh.htm>
There are worse examples out there... Nikkor 50/1.8, for instance.
>LLeft = not so bad, but still annoys me. If you look at the overhead lights
on the left of "Cowboy Passenger", a couple
>brightish and one below them quite dim, you will see the same sort of
slightly darker center, surrounded by a bright
>halo.
But as mentioined in an earlier post, it could be the sharpening for web
presentation.
>URight = Pretty perfect, a nice airy disk, bright in the middle and gently
feathering off into invisibility. This is a
>good example, but comes at the price of softness in the focal plane.
Not necessarily. AFAIK, the Airy disk is the actual rendering of a point
lightsource by a "perfect" optical system. But I agree that sometimes a
sharp focal plane is achieved via overcorrecting the spherical aberration,
leading to the edgy bokeh of the ULeft sample.
>This is pretty darn good bokeh for a highly
>corrected lens that's very sharp in the focal plane.
><http://www.moosemystic.net/Gallery/tech/Lenses/SIMA/pages/27__0116.htm>
Well, a 105mm at such close distance, even at f/4 blurs the background a
lot, which may hide some edginess...
>Nope, I don't know of a 50 mm with great bokeh.
Not every 50mm is a double-Gauss formula ;-) Did you see any samples with
the CV Skopar 50/2.5?
<http://www.flickr.com/photos/zuiko21/4874932557/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4874935297/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4874876963/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4874889045/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4875543028/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4875498024/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4875503124/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4875499648/sizes/l/>
<http://www.flickr.com/photos/zuiko21/4874915003/sizes/l/>
And about foreground bokeh:
<http://www.flickr.com/photos/zuiko21/4874921027/sizes/l/>
>Guess I need to start a roll of film,
Yes, you should :-)
>file off the back of the CZJ
I've got no 5D, but the Contax RTS, with its large mirror (it has a gorgeous
vierfinder)
>Tessar or just use its center on the 300D as a start.
Tessars show lower performance than most double-Gauss but have a very nice
rendering. I did a photoshoot with a (modern) Zeiss 45/2.8 pancake on my old
300D, and it came out fine -- despite some focusing problems. But that pics
are buried into one of the harddisks "floating" at home...
From: usher99@xxxxxxx
>I think it is probably
>correct that it is easier to design lenses with smoother bokeh in
>larger formats.
Well, you're right in that LF has less DOF than smaller formats, thus making
easier to blur *more*, but not necessarily *better*^.
>Bokeh in some respects can be a zero sum game as if the
>foreground is improved the background may suffer
Yes, I'm afraid it's a typical design consecuence... anyway, I usually
dislike blurred foregrounds, so not an issua to me -- provided the
"background bokeh" is nice. Thanks for the link!
>As Nasse and Moose both state the nature of the bokeh is complicated in
>any given lens and can depend not only on the relative
>foreground/subject/ background distances but focusing distance as well
>as aperture of course.
And aberration correction...
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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