More on bokeh (Was: Re: PESO: 3D pop?)

Toine toine at repiuk.nl
Mon Oct 5 15:19:25 EDT 2020


Igor,

Thanks for the references. I should be able to access the full text of
the DOI through my university account. Maybe I need to refresh my
physics and optics courses from 40 years ago :)

It's difficult to reproduce the 3d pop. I think foreground and
background should be blurred.

Toine

>
> > On Oct 5, 2020, at 1:10 PM, Igor PDML-StR <pdmlstr at komkon.org> wrote:
> >
> > 
> > Toine,
> >
> > First, let me say that you've got a very nice image!
> >
> > Paul has given a very simple explanation for the visual effect you (we) observe. The further difference is (as Paul and a few others pointed out) comes from the quality of the bokeh for the particular lens.
> >
> > As you probably know, the lead (actually, lead oxide!) in the lens glass raises its refractive index. This allows for thinner lenses for a given focal length. However, glass with a higher refraction index has higher dispersion that needs to be corrected to make the lens achromatic (i.e. to minimize chromatic [and spherical] abberations).
> > So, the combination of these factors *can* affect the bokeh.
> >
> > I've found this informative write-up on B&H website:
> > https://www.bhphotovideo.com/explora/photography/tips-and-solutions/understanding-bokeh
> > It gives a nice overview of what and how plays a role in the bokeh - with some nice illustrations.
> > In particular, I didn't know that there are lenses with adjustable bokeh.
> >
> > Now, I was curious about how much is known scientifically about bokeh.
> > It is clear that at least some lens manufacturers pay attention to it.
> >
> > While I didn't do a deep comprehensive search in the scientific literature, it seems, - not much seems to be published on that topic.
> > I've been able to find a few research articles adressing the theory and theoretical calculation of the bokeh, but there are literally handful of those. (And there was some research on how to fake bokeh, - I assume aimed at creating "creative filters" for the phone-shooters.)
> >
> > Of those, one paper I looked at was  Viktor P. Sivokon, Michael D. Thorpe
> > Optical Engineering, 53(6), 065103 (2014). https://doi.org/10.1117/1.OE.53.6.065103
> > (Sorry, it requires paid access. Feel free to contact me directly for detail.)
> > They were able to model bokeh mathematically (analytically) and compare
> > to the actual bokeh produced by lenses with a reasonable accuracy.
> > Here is one of their results:
> > http://42graphy.org/misc/BokehCalculated-SivokonThorpe.jpg
> >
> > Cheers,
> >
> > Igor
> >
> >
> > Toine Sun, 27 Sep 2020 10:56:03 -0700 wrote:
> >
> > Yes I agree thats the main effect. However this guy even includes lead in
> > glass as a pop factor. The rendering of bokeh also adds to the effect.
> > Zooms have a busy bokeh.
> >
> >
> > https://photographylife.com/the-death-of-beautiful-rendition-and-3d-pop-on-modern-lenses
> >
> > I can hardly see the difference in his before after shot with the slider
> >
> >> On Sun, 27 Sep 2020, 18:46 Paul Stenquist, <pnstenqu... at comcast.net> wrote:
> >>
> >> What is seen as 3D “pop” is just limited depth of field. And because
> >> primes generally have a larger app wide open than zooms, they give you
> > more
> >> control over DOF.
> >>
> >> Paul
> >>
> >> > On Sep 27, 2020, at 10:44 AM, Daniel J. Matyola <danmaty... at gmail.com>
> >> wrote:
> >> >
> >> > That certainly does "pop"!
> >> >
> >> > Dan Matyola
> >> > *https://tinyurl.com/DJM-Pentax-Gallery
> >> > <https://tinyurl.com/DJM-Pentax-Gallery>*
> >> >
> >> >
> >> >
> >> >> On Sat, Sep 26, 2020 at 2:54 PM Toine <to... at repiuk.nl> wrote:
> >> >>
> >> >> I read a lot about primes vs zooms and old designs of primes. That
> >> >> should result in something like 3D pop. Never noticed it until today:
> >> >>
> >> >>
> > https://www.repiuk.nl/albums/new/#&gid=1&pid=005-899-20200926-imgp3095-edit
> >> >>
> >> >> I find myself lugging the DA*300 around on a daily basis. Maybe
> > because
> >> it
> >> >> pops.
> >> >>
> >> >> Do I need new glasses?
> >> >>
> >> >> Toine
> >
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