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#11
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The Lomography Petzval 58 Bokeh Control Art Lens
In article , android wrote:
Sandman: I'm a backer, love the "normal" Petzval lens and this sounds really interesting! android: Bokeh control = fussy focus? Sandman: More like more control over the things not in focus. It's probably a lot like the "Defocus Control" lenses from Nikon android: Soo... You move an element or two around to create extra spherical aberration, or something... That would translate as fussy focus control to me. Sandman: I read "fussy focus" to mean that it can't focus sharply in the focus plane. The "Bokeh control" affects only the out of focus parts. I also found this on nikonusa.com re that 135mm of yours: "Control the degree of spherical aberration in background or foreground elements for more creative control." http://tinyurl.com/q2jh7up Yup -- Sandman |
#12
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The Lomography Petzval 58 Bokeh Control Art Lens
In article ,
Sandman wrote: In article , android wrote: --- Since your into bokeh at the deep end: What's your opinion on soft focus filters? It certainly has its place. Not that it has anything to do with bokeh though. Sure it does... Some like the Zeiss Softars have a coating of micro lenses giving the image a softer appearance without losing focus... http://tinyurl.com/nqj4sl5 https://en.wikipedia.org/wiki/File:V...uerkirsche.jpg -- teleportation kills |
#13
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The Lomography Petzval 58 Bokeh Control Art Lens
In article ,
Sandman wrote: In article , android wrote: Sandman: I'm a backer, love the "normal" Petzval lens and this sounds really interesting! android: Bokeh control = fussy focus? Sandman: More like more control over the things not in focus. It's probably a lot like the "Defocus Control" lenses from Nikon android: Soo... You move an element or two around to create extra spherical aberration, or something... That would translate as fussy focus control to me. Sandman: I read "fussy focus" to mean that it can't focus sharply in the focus plane. The "Bokeh control" affects only the out of focus parts. That's not entirely correct. Read the link you snippet and you'll see that SA surely affects the focus plane. Here you go: https://en.wikipedia.org/wiki/Spherical_aberration I also found this on nikonusa.com re that 135mm of yours: "Control the degree of spherical aberration in background or foreground elements for more creative control." http://tinyurl.com/q2jh7up Yup It confirms that that I wrote... -- teleportation kills |
#14
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The Lomography Petzval 58 Bokeh Control Art Lens
In article ,
RichA wrote: On Tuesday, 2 June 2015 02:00:35 UTC-4, Sandman wrote: In article , android wrote: I'm a backer, love the "normal" Petzval lens and this sounds really interesting! android: Bokeh control = fussy focus? Sandman: More like more control over the things not in focus. It's probably a lot like the "Defocus Control" lenses from Nikon Soo... You move an element or two around to create extra spherical aberration, or something... That would translate as fussy focus control to me. I read "fussy focus" to mean that it can't focus sharply in the focus plane. The "Bokeh control" affects only the out of focus parts. The Petzval lens employs an optical aberration that is called the "Petzval field curvature", which is slightly different. The Petzval lens is corrected for spherical aberrations, but introduces a field curvature instead, as well as vignetting. -- Sandman You know, the astronomical community has devices that will fix that. 2-element refractive telescopes, Schmidt-Cassegrain telescopes not specially corrected also have curve fields. And there is Photoshop! -- teleportation kills |
#15
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The Lomography Petzval 58 Bokeh Control Art Lens
In article , RichA wrote:
Sandman: I'm a backer, love the "normal" Petzval lens and this sounds really interesting! android: Bokeh control = fussy focus? Sandman: More like more control over the things not in focus. It's probably a lot like the "Defocus Control" lenses from Nikon android: Soo... You move an element or two around to create extra spherical aberration, or something... That would translate as fussy focus control to me. Sandman: I read "fussy focus" to mean that it can't focus sharply in the focus plane. The "Bokeh control" affects only the out of focus parts. The Petzval lens employs an optical aberration that is called the "Petzval field curvature", which is slightly different. The Petzval lens is corrected for spherical aberrations, but introduces a field curvature instead, as well as vignetting. You know, the astronomical community has devices that will fix that. 2-element refractive telescopes, Schmidt-Cassegrain telescopes not specially corrected also have curve fields. So, yeah, the aberrations in the Petzval lens is there by choice. -- Sandman |
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