Rodenstock Sironar 150mm

[rfesk]

The 150mm Symmar convertible that I own is much more symmetrical in design than the later models. That may account for the better bokeh. The Compur shutter has many more blades for a round iris.

[Bob Salomon]

The 150mm Symmar convertible that I own is much more symmetrical in design than the later models. That may account for the better bokeh.

Very bad phrasing. The old Sironar was symmetrical. The later ones are not.

[Bernice Loui]

Plasmats are cross section "symmetrical" as it was a variation of the Dagor by air spacing.

Symmetry alone is one aspect of how any lens can achieve good Bokeh and into out of focus rendition, as does a round iris like these lenses in barrel.


The round iris thing is one of the reasons why lenses in barrel are preferred over lenses in shutter. For lenses used on the TK23s, they are older Compur, Ilex, Compound specifically preferred for their round iris shutters. Second, many of the excellent Tessar formula lenses were made during that era.

Bokeh, into out of focus rendition importance depends on the image maker's needs and goals or another aspect of the tools used to achieve a given image goal.


Bernice






[QUOTE=rfesk;1641713]
The 150mm Symmar convertible that I own is much more symmetrical in design than the later models. That may account for the better bokeh. The Compur shutter has many more blades for a round iris.

UOTE]

[JLNims]

Dan and Sean: Great links! I've already learned a lot! Dan, thanks for posting the Rodenstock literature on those lenses. That brochure appears to be circa 1977 or so? I did, in fact, see my lens in the list.
Thanks again!

[ridax]

The 150mm Symmar convertible that I own is much more symmetrical in design than the later models. That may account for the better bokeh.

Symmetry alone is one aspect of how any lens can achieve good Bokeh and into out of focus rendition <...> Second, many of the excellent Tessar formula lenses were made during that era.

Symmetry has nothing to do with the out of focus rendition. The OOF rendition depends on the residual spherical aberration (SA), and SA is not dependent on symmetry at all. A prime example are those tessar-type lenses that are pretty good in their OOF rendition and are as far from being symmetrical as any lens could ever be.

[ridax]

Modern Plasmats like this Rodenstock Sironar are not optimized for Bokeh or into out of focus rendition. They are designed and optimized to be used about f22 with majority of the image in apparent focus. <...>

Going back one generation of lens designs and lenses produced, Bokeh and into out of focus rendition was a priority. This is why that generation of vintage lenses were non Plasmat designs

While I agree with your general observations on the lens generations,

(1) Plasmats can easily be optimized for the background blur, too. Just no manufacturer ever bothered to design them to be as good as Dagors in that respect.

(2) Plasmats are quite different in their out of focus rendition, too. Of those known to me, the best are the Convertible Symmars and Sironars, with the Apo-Sironar-S and the Apo-Symmar-L not far behind. The Schneider G-Clarons are quite good and equal to the Convertible Symmars at f/32 but ugly at all the rest f-stops. Enlarging plasmats like Componons and Rodagons are pretty bad in their out of focus background rendition at all apertures but wide-open, they make the out of focus foreground really beautiful.

And by the way, the Convertible Symmar was just too costly to manufacture compared to its successor Symmar-S. The Convertible had its cemented glass surfaces prominently curved, and the -S had flat ones. Flat glass is (a) much easier (and cheaper) to polish and (b) a lot more easy (and a lot more cheap) to center. Of course Schneider didn't shout out loud 'we now offer you an ugly cheap lens instead of the real one which we can't afford to produce anymore'. They advertised their new Symmar-S as a better lens.... (That's just one example.)

[ridax]

If you're curious about view camera lens Bokeh and into out of focus rendition, consider getting a previous generation lens like a Kodak Commercial Ektar. <...>the Bokeh and into out of focus rendition might appeal to you, and they offer excellent color balance with moderate contrast.

Yes a lot of tessar-type lenses are better than the best of plasmats in their out of focus rendition but in tessars, almost all the spherical aberration is gone when the lens is stopped down beyond f/16 while plasmats retain their moderately good OOF background rendition up to about f/32. In LF, that's important, and I prefer tessar-type lenses for medium and small formats only.

The f/6.3 and slower tessars have their astigmatism corrected very well (while the f/4.5 and faster ones do not) so the slow tesssars like the Commercial Ektar are much sharper. But bokeh-vise, the slow tessar-type lenses are way inferior to the f/4.5 and f/3.5 ones (though those have to be stopped down to at least f/5.6 to about f/7, dependent on the individual lens properties, for the good background; at wider f-stops, they usually aren't good background makers but wide open, some of them do make the OOF foreground really great). So if the OOF rendition is the goal, why stop half-way with the Commercial Ektar (though it's certainly a very good lens)?

....And anyway, I've never seen any lenses that could ever compare to the f/6.8 (f/7.7 if longer then 300mm) Dagors and the f/9 Serie IIIa Protars in their OOF background rendition - at all apertures from f/10 for Dagors and from f/12 for IIIa Protars up to the smallest f-stops.

[ridax]

I've never seen any lenses that could ever compare to Dagors and Serie IIIa Protars in their OOF background rendition

- except the single Protar VII cells and especially the single Half-Dagor cells which a much better still; but those are way inferior in sharpness.

[Oslolens]

Speaking of out of focus rendition, do any of you have a working link to what Jim Galli has put out on his site?
Further on bokeh, it is still up to the viewers to say what they like, I am no fan of Leica or Petzval. My liking is for the modern plasmats and the achromatic long lenses, like Canon, Nikon or Leica, 300-500mm on 8x10" film.

Sent fra min SM-G975F via Tapatalk

[ridax]

Speaking of out of focus rendition <...> it is still up to the viewers to say what they like. I am no fan of Leica or Petzval. My liking is for the modern plasmats and the achromatic long lenses, like Canon, Nikon or Leica, 300-500mm on 8x10" film.

Yes that's certainly subjective. Myself, I am not fond of Petzval swirly background (made up by severe vignetting in those long-barrel lenses) either. And most of the soft-focus lenses (the long focus achromats you mention may also be in that category) are usually great in their OOF rendition, too. But those aren't my cup of tea as I just don't like any soft-focus images.