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

Paul Stenquist pnstenquist at mac.com
Mon Oct 5 13:34:33 EDT 2020


Great information. Thanks!

Paul

> 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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