masjah Posted June 13, 2007 Share #1 Posted June 13, 2007 Advertisement (gone after registration) In his review of the 280/4 Apo Telyt R, Erwin Puts says: "Atmospheric turbulence and heat waves can destroy the image quality at these large magnifications and one needs a skylight filter with colour film and a medium orange filter with black-and-white film". In my simple minded way, I thought that the way in which atmospheric turbulence and heat waves could degrade an image would be because of resultant changes in the refractive index of the air (hence for example the "shimmering" above a hot surface). Please could someone explain how a skylight filter could reduce this? Or is he making two completely separate statements that have got conflated into the same sentence? The 280/4R has got a slot-in UV filter which has to stay in as part of the optical design, and also a hard protective plane front glass, so should I really put another E77 filter on the front? (Actually I do normally put a protective UV filter in front of my lenses, but I am in two minds in this case.) Any thoughts anyone? Link to post Share on other sites More sharing options...
Advertisement Posted June 13, 2007 Posted June 13, 2007 Hi masjah, Take a look here Puzzled by E Puts remark on 280/4 R. I'm sure you'll find what you were looking for!
stunsworth Posted June 13, 2007 Share #2 Posted June 13, 2007 Can't understand it either John. Perhaps he means that the filter will provide more contrast by filtering out the blue that's more apparent at longer distances? Link to post Share on other sites More sharing options...
telyt Posted June 13, 2007 Share #3 Posted June 13, 2007 Seems like two streams of thought in one sentence. I'm not putting another filter on my 280. Link to post Share on other sites More sharing options...
jaapv Posted June 13, 2007 Share #4 Posted June 13, 2007 Heat waves?? If he means IR that could- in theory - impair sharpness by overlaying and unsharp IR image. In that case an IR filter would help - not the ones he mentions. And the distortion caused by turbulent air? That is hard to see how it could be filtered - lets put this one in the gallery of Putsisms. Link to post Share on other sites More sharing options...
wizard Posted June 13, 2007 Share #5 Posted June 13, 2007 Seems like two streams of thought in one sentence. That's how I understand it, too. He combined two unrelated issues in one sentence, and suggests the Skylight/Orange filter for the reasons Andy (Stunsworth) mentioned already, I assume. Andy Link to post Share on other sites More sharing options...
zapp Posted June 13, 2007 Share #6 Posted June 13, 2007 In his review of the 280/4 Apo Telyt R, Erwin Puts says: "Atmospheric turbulence and heat waves can destroy the image quality at these large magnifications and one needs a skylight filter with colour film and a medium orange filter with black-and-white film". In my simple minded way, I thought that the way in which atmospheric turbulence and heat waves could degrade an image would be because of resultant changes in the refractive index of the air (hence for example the "shimmering" above a hot surface). Please could someone explain how a skylight filter could reduce this? Or is he making two completely separate statements that have got conflated into the same sentence? The 280/4R has got a slot-in UV filter which has to stay in as part of the optical design, and also a hard protective plane front glass, so should I really put another E77 filter on the front? (Actually I do normally put a protective UV filter in front of my lenses, but I am in two minds in this case.) Any thoughts anyone? Heat waves and turbulences in the air change refraction and cannt be corrected with a filter. UV light may be filtered with UV or Skylight filter.The Skylight filter is nothing but a UV filter with a waming color pinkish or brownish (1A, 1B) Link to post Share on other sites More sharing options...
jaapv Posted June 13, 2007 Share #7 Posted June 13, 2007 Advertisement (gone after registration) Pretty hard to filter UV on that lens. It has 100% built-in UV blocking -as do all Leica lenses (except the 90/2.8) Link to post Share on other sites More sharing options...
garyp Posted June 13, 2007 Share #8 Posted June 13, 2007 I'm no longer puzzled by anything that Puts writes Link to post Share on other sites More sharing options...
masjah Posted June 14, 2007 Author Share #9 Posted June 14, 2007 Thanks to all for responding! It's reassuring to know that my initial impressions were perfectly correct. Link to post Share on other sites More sharing options...
rob_x2004 Posted June 14, 2007 Share #10 Posted June 14, 2007 That's how I understand it, too. He combined two unrelated issues in one sentence, and suggests the Skylight/Orange filter for the reasons Andy (Stunsworth) mentioned already, I assume. Andy Well ... three. And a healthy dose of yawn. "Atmospheric turbulence and heat waves can destroy the image quality at these large magnifications comma and one needs a skylight filter with colour film comma and a medium orange filter with black-and-white film". coma wake up. Link to post Share on other sites More sharing options...
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