Re: Filters and contrast
Anti-reflective coatings work by cutting the unwanted reflection/scattering/diffusion of light (where it should not go) at each and any air-to-glass surface. So the coating has to be wehere it can do its work, i.e. on each and any air-to-glass surface. Perhaps even between glasses of different refraction indexes. A filter in front of the whole lens cannot do that. Dario -Messaggio originale- From: CollinB Sent: Thursday, November 14, 2013 1:15 PM To: pdml@pdml.net Subject: Filters and contrast I noticed in the camera store review of the K3 that a comparison of the 2 versions of the DA40/2.8 displayed the difference produced by coatings, between (presumably) SMC and HD. Has anyone come out with a set of HD filters that might contribute a similar image improvement? -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. - Nessun virus nel messaggio. Controllato da AVG - www.avg.com Versione: 2013.0.3426 / Database dei virus: 3629/6834 - Data di rilascio: 13/11/2013 -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
Anti-reflective coatings work by cutting the unwanted reflection/scattering/diffusion of light (where it should not go) at each and any air-to-glass surface. So the coating has to be where it can do its work, i.e. on each and any air-to-glass surface. Perhaps even between glasses of different refraction indexes. A filter in front of the whole lens cannot do that. Dario Of course it can. Just not nearly as well or in the same fashion. Not all that the HD coatings does is anti-reflective. I suspect some of it is color-correcting as were the different SMC variations. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
On 14/11/2013 6:28 AM, CollinB wrote: Anti-reflective coatings work by cutting the unwanted reflection/scattering/diffusion of light (where it should not go) at each and any air-to-glass surface. So the coating has to be where it can do its work, i.e. on each and any air-to-glass surface. Perhaps even between glasses of different refraction indexes. A filter in front of the whole lens cannot do that. Dario Of course it can. Just not nearly as well or in the same fashion. Not all that the HD coatings does is anti-reflective. I suspect some of it is color-correcting as were the different SMC variations. Collin, you can put the best filter in the world on an uncoated lens, and you will get flare because of internal reflections. All a coated element can do is keep reflections off of the element it is applied to at bay. Once the light has moved to another piece of glass, it's a whole new ball game. Lens coatings are primarily for flare protection. Any color correcting they do is secondary, though possibly by design. bill -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
Sendt fra min iPad Den 14. nov. 2013 kl. 13:59 skrev Bill anotherdrunken...@gmail.com: On 14/11/2013 6:28 AM, CollinB wrote: Anti-reflective coatings work by cutting the unwanted reflection/scattering/diffusion of light (where it should not go) at each and any air-to-glass surface. So the coating has to be where it can do its work, i.e. on each and any air-to-glass surface. Perhaps even between glasses of different refraction indexes. A filter in front of the whole lens cannot do that. Dario Of course it can. Just not nearly as well or in the same fashion. Not all that the HD coatings does is anti-reflective. I suspect some of it is color-correcting as were the different SMC variations. Collin, you can put the best filter in the world on an uncoated lens, and you will get flare because of internal reflections. All a coated element can do is keep reflections off of the element it is applied to at bay. Once the light has moved to another piece of glass, it's a whole new ball game. Lens coatings are primarily for flare protection. Any color correcting they do is secondary, though possibly by design. Or you may see it this way: Independent of the lens quality a filter will add two more reflecting surfaces reducing the overall quality. How much each of these surfaces reflect the light and reduce the quality will depend on the coating. Uncoated each surface reflect about 4% og the passing light. A surface with a good coating will reflect a lot less, but I don't have the numbers of the HD-coating. So the best solution is always to go without a filter if you don't want to protect the front lens. DagT -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
Collin, you can put the best filter in the world on an uncoated lens, and you will get flare because of internal reflections. All a coated element can do is keep reflections off of the element it is applied to at bay. Once the light has moved to another piece of glass, it's a whole new ball game. Lens coatings are primarily for flare protection. Any color correcting they do is secondary, though possibly by design. Bill Yes. You've probably shot more LF than me, and we both know what color correction filters can do for bw as well as enhancing color results, both neg and reversal. But. I'm thinking (though I might possible be wrong) that there might be an optical improvement to using the lens coatings on the filters. (Didn't Pentax even market SMC filters at one time?) We improve contrast with polarizers and UV/1A filters. Why not one more contrast improvement? -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
I took it to be filters as in a plugin for photoshop. like Nik Filters. On 11/14/2013 7:24 AM, Dario Bonazza wrote: Anti-reflective coatings work by cutting the unwanted reflection/scattering/diffusion of light (where it should not go) at each and any air-to-glass surface. So the coating has to be wehere it can do its work, i.e. on each and any air-to-glass surface. Perhaps even between glasses of different refraction indexes. A filter in front of the whole lens cannot do that. Dario -Messaggio originale- From: CollinB Sent: Thursday, November 14, 2013 1:15 PM To: pdml@pdml.net Subject: Filters and contrast I noticed in the camera store review of the K3 that a comparison of the 2 versions of the DA40/2.8 displayed the difference produced by coatings, between (presumably) SMC and HD. Has anyone come out with a set of HD filters that might contribute a similar image improvement? -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
On Thu, Nov 14, 2013 at 12:46 PM, John johnsess...@yahoo.com wrote: I took it to be filters as in a plugin for photoshop. like Nik Filters. The lens coatings slide right off those. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Filters and contrast
On 14/11/2013 7:25 AM, CollinB wrote: Collin, you can put the best filter in the world on an uncoated lens, and you will get flare because of internal reflections. All a coated element can do is keep reflections off of the element it is applied to at bay. Once the light has moved to another piece of glass, it's a whole new ball game. Lens coatings are primarily for flare protection. Any color correcting they do is secondary, though possibly by design. Bill Yes. You've probably shot more LF than me, and we both know what color correction filters can do for bw as well as enhancing color results, both neg and reversal. But. I'm thinking (though I might possible be wrong) that there might be an optical improvement to using the lens coatings on the filters. (Didn't Pentax even market SMC filters at one time?) We improve contrast with polarizers and UV/1A filters. Why not one more contrast improvement? We are talking about the same thing, except I'm drunk and you didn't catch on.. The best imaging comes when all surfaces are coated, even the cemented one, if I am not mistaken. bill -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
