Before they were built into your phone's camera. From a Seattle Filmwork's catalog found among a late relative's personal effects. Winter, 1985: <https://imgur.com/a/YDakITI>
Analog (optical) filters
Started by ●January 20, 2023
Reply by ●January 21, 20232023-01-21
On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote:>Before they were built into your phone's camera. From a Seattle >Filmwork's catalog found among a late relative's personal effects. >Winter, 1985: > > ><https://imgur.com/a/YDakITI>There's a story in https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 about multilayer optical filters. Feynman was surely an alien life form.
Reply by ●January 21, 20232023-01-21
On 2023-01-21 16:49, John Larkin wrote:> On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote: > >> Before they were built into your phone's camera. From a Seattle >> Filmwork's catalog found among a late relative's personal effects. >> Winter, 1985: >> >> >> <https://imgur.com/a/YDakITI> > > There's a story in > > https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 > > about multilayer optical filters. Feynman was surely an alien life > form. > >He looks quite human to me, even though he did his own thinking. What did he have to say about multilayer optical filters? Jeroen Belleman
Reply by ●January 21, 20232023-01-21
On Sat, 21 Jan 2023 19:14:03 +0100, Jeroen Belleman <jeroen@nospam.please> wrote:>On 2023-01-21 16:49, John Larkin wrote: >> On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote: >> >>> Before they were built into your phone's camera. From a Seattle >>> Filmwork's catalog found among a late relative's personal effects. >>> Winter, 1985: >>> >>> >>> <https://imgur.com/a/YDakITI> >> >> There's a story in >> >> https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 >> >> about multilayer optical filters. Feynman was surely an alien life >> form. >> >> >He looks quite human to me, even though he did his own thinking. >What did he have to say about multilayer optical filters? > >Jeroen BellemanAs I recall, someone suggested something to him in a hallway encounter. A few days later he delivered a complete theory of multilayer optical filters. He was far more intelligent than humans can be. His hobby, as a kid, was seeking out difficult differential equation to solve. At 13.5 nm, nothing refracts and nothing reflects... except extreme multilayer coatings. That makes for interesting mask reducing optics.
Reply by ●January 21, 20232023-01-21
On 2023-01-21 20:17, John Larkin wrote:> On Sat, 21 Jan 2023 19:14:03 +0100, Jeroen Belleman > <jeroen@nospam.please> wrote: > >> On 2023-01-21 16:49, John Larkin wrote: >>> On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote: >>> >>>> Before they were built into your phone's camera. From a Seattle >>>> Filmwork's catalog found among a late relative's personal effects. >>>> Winter, 1985: >>>> >>>> >>>> <https://imgur.com/a/YDakITI> >>> >>> There's a story in >>> >>> https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 >>> >>> about multilayer optical filters. Feynman was surely an alien life >>> form. >>> >>> >> He looks quite human to me, even though he did his own thinking. >> What did he have to say about multilayer optical filters? >> >> Jeroen Belleman > > As I recall, someone suggested something to him in a hallway > encounter. A few days later he delivered a complete theory of > multilayer optical filters. > > He was far more intelligent than humans can be. His hobby, as a kid, > was seeking out difficult differential equation to solve. > > At 13.5 nm, nothing refracts and nothing reflects... except extreme > multilayer coatings. That makes for interesting mask reducing optics. >Multi-layer optical filters obey the same laws as consecutive pieces of coax alternating between two impedances, except that the working frequency is much lower, and the coax is just a single pixel. Jeroen Belleman
Reply by ●January 21, 20232023-01-21
Jeroen Belleman wrote:> On 2023-01-21 20:17, John Larkin wrote: >> On Sat, 21 Jan 2023 19:14:03 +0100, Jeroen Belleman >> <jeroen@nospam.please> wrote: >> >>> On 2023-01-21 16:49, John Larkin wrote: >>>> On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote: >>>> >>>>> Before they were built into your phone's camera. From a Seattle >>>>> Filmwork's catalog found among a late relative's personal effects. >>>>> Winter, 1985: >>>>> >>>>> >>>>> <https://imgur.com/a/YDakITI> >>>> >>>> There's a story in >>>> >>>> https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 >>>> >>>> >>>> about multilayer optical filters. Feynman was surely an alien life >>>> form. >>>> >>>> >>> He looks quite human to me, even though he did his own thinking. >>> What did he have to say about multilayer optical filters? >>> >>> Jeroen Belleman >> >> As I recall, someone suggested something to him in a hallway >> encounter. A few days later he delivered a complete theory of >> multilayer optical filters. >> >> He was far more intelligent than humans can be. His hobby, as a kid, >> was seeking out difficult differential equation to solve. >> >> At 13.5 nm, nothing refracts and nothing reflects... except extreme >> multilayer coatings. That makes for interesting mask reducing optics. >> > > Multi-layer optical filters obey the same laws as consecutive > pieces of coax alternating between two impedances, except that > the working frequency is much lower, and the coax is just a > single pixel. > > Jeroen BellemanAnd optical coatings have to work at different angles of incidence and two polarization states. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●January 23, 20232023-01-23
On 21/01/2023 03:00, bitrex wrote:> Before they were built into your phone's camera. From a Seattle > Filmwork's catalog found among a late relative's personal effects. > Winter, 1985: > > > <https://imgur.com/a/YDakITI>Analogue traditional dye and gelatine optical filters are still available to professional photographers today. eg https://www.srb-photographic.co.uk/square-filters-1222-c.asp Edmund Scientific have an even wider range for filters for science and industry including dopes glasses and dichroic filters (for a price). https://www.edmundoptics.co.uk/c/optical-filters/610/ -- Regards, Martin Brown
Reply by ●January 23, 20232023-01-23
On Sat, 21 Jan 2023 07:49:54 -0800, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:>On Fri, 20 Jan 2023 22:00:04 -0500, bitrex <user@example.net> wrote: > >>Before they were built into your phone's camera. From a Seattle >>Filmwork's catalog found among a late relative's personal effects. >>Winter, 1985: >> >> >><https://imgur.com/a/YDakITI> > >There's a story in > >https://www.amazon.com/Genius-Life-Science-Richard-Feynman/dp/0679747044 > >about multilayer optical filters. Feynman was surely an alien life >form. >A simple fader is usefull in getting relative lux/power measurements for emitters, while keeping detector in linear range. RL
Reply by ●January 23, 20232023-01-23
On Mon, 23 Jan 2023 11:26:02 +0000, Martin Brown <'''newspam'''@nonad.co.uk> wrote:>On 21/01/2023 03:00, bitrex wrote: >> Before they were built into your phone's camera. From a Seattle >> Filmwork's catalog found among a late relative's personal effects. >> Winter, 1985: >> >> >> <https://imgur.com/a/YDakITI> > >Analogue traditional dye and gelatine optical filters are still >available to professional photographers today. eg > >https://www.srb-photographic.co.uk/square-filters-1222-c.aspIs there any reason to use a filter in digital photography? Imager chip pixels have extreme dynamic range and one can digitally post-process an image.
Reply by ●January 23, 20232023-01-23
On 23/01/2023 15:23, John Larkin wrote:> On Mon, 23 Jan 2023 11:26:02 +0000, Martin Brown > <'''newspam'''@nonad.co.uk> wrote: > >> On 21/01/2023 03:00, bitrex wrote: >>> Before they were built into your phone's camera. From a Seattle >>> Filmwork's catalog found among a late relative's personal effects. >>> Winter, 1985: >>> >>> >>> <https://imgur.com/a/YDakITI> >> >> Analogue traditional dye and gelatine optical filters are still >> available to professional photographers today. eg >> >> https://www.srb-photographic.co.uk/square-filters-1222-c.asp > > Is there any reason to use a filter in digital photography? Imager > chip pixels have extreme dynamic range and one can digitally > post-process an image.Yes. The most common reason would be to photograph in some narrow wavelength band to isolate particular elements. Scientific imaging tends to be done with monochrome CCDs and very well characterised glass filters in astronomy and fluorescence microscopy for example. https://astrobackyard.com/narrowband-imaging/ Most colour Hubble shots are in SII, Halpha, OIII narrow band as R,G,B. You can get a roughly plausible colour image from Halpha to R and OIII 496nm to a turquoise green using two bandpass filters. Single shot colour imaging is popular with hobby astronomers, but even there many push the technique using narrowband filters (which helps cut out a lot of the light pollution). In discussions about lights near observatories they offered to use yellow LEDs as an alternative to LPS - missing the point that it wasn't the yellow light so much as the very narrow waveband it pollutes (and sodium is so ubiquitous there is always some sky glow at sodium D lines. -- Regards, Martin Brown
