mhoutman Posted December 4, 2006 Share #21 Posted December 4, 2006 Advertisement (gone after registration) leica does not make filters that i know of ..... Guy, which company makes the current Leica UV filters ? B + W too ? Michiel Link to post Share on other sites More sharing options...
Advertisement Posted December 4, 2006 Posted December 4, 2006 Hi mhoutman, Take a look here Definitive answer on the IR filter. . I'm sure you'll find what you were looking for!
Guest guy_mancuso Posted December 4, 2006 Share #22 Posted December 4, 2006 Honestly I am not sure since i rarely buy filters, I just know B+W is there prefered vendor Link to post Share on other sites More sharing options...
stevme Posted December 4, 2006 Share #23 Posted December 4, 2006 We don't need an edict from Solms, and sensors will also vary individually. What they need to do (and I hope for JPEG shooters they make this a switch in firmware) is update their JPEG profile to take whatever affect the filters have on visible light into account and 2) get Phase to do the same thing for RAW profiles. Jamie If you don't know what color frequency the sensor (using light filtered through the lens and IR cut filter) is trying to output color data for, how do you correct that output in your profiles? Don't you need to know that the sensor (within a manufacturing tolerance range) will output the following color information (as indicated by Solms and the folks at Kodak) with an over and underemphasis on this and that color frequency in order to construct your profile? Presumably, the sensor reacts in certain ways to lesser and greater amounts of IR light, at various IR frequencies, and Solms can tell you, given the filter chosen by Leica, that the color output will be thus and so based on use of the Leica designated filter. If you don't know the camera's native color profile when using a filter, how can you correct for it? Or do you need to do a profile for each filter type, size and each Leica lens, like color management profiles on monitors and printer/paper combinations? As is obvious, I don't know how profiles are created or how they differ from garden variety color adjustment through curves and the like. For example, Lightroom, Adobe's new premier photo application, still in development, uses no camera profiles, unlike, e.g., Capture One. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted December 4, 2006 Share #24 Posted December 4, 2006 Basically a pretty accurate color chart is shot with the filter on and than they use a profiling software to adjust to the numeric value of each color in the chart , so essential no matter the strength it should work mathmatically to a certain color numeric value. Hope i said that right Link to post Share on other sites More sharing options...
Jamie Roberts Posted December 5, 2006 Share #25 Posted December 5, 2006 Basically a pretty accurate color chart is shot with the filter on and than they use a profiling software to adjust to the numeric value of each color in the chart , so essential no matter the strength it should work mathmatically to a certain color numeric value. Hope i said that right Guy--that's pretty much it. Add a contrast curve, some judgement on saturation and a bias towards some colours and not others, and you can build a pretty "accurate" input profile--at least under the lighting conditions you shot the chart Which, BTW, is why a lot of medium format cameras have specific response profiles for different lighting... Fortunately, for most purposes, "accurate" colour by-the-numbers in a per-lighting situation is not a critical as "pleasing colour" in different lights. Sometimes, accurate doesn't look so good for general purposes. If that wasn't true, no-one would have shot Kodachrome or Velvia Link to post Share on other sites More sharing options...
ho_co Posted December 5, 2006 Share #26 Posted December 5, 2006 I don't know how much assistance this offers, but since the UV/IR cut filters offered by Edmund (at least the 49mm which I bought) are B+W's, and since they list and diagram spectral response at least loosely, you might want to draw more information from the data at http://edmundoptics.com/onlinecatalog/DisplayProduct.cfm?productid=1524. --HC Link to post Share on other sites More sharing options...
rvaubel Posted December 5, 2006 Share #27 Posted December 5, 2006 Advertisement (gone after registration) I just made an interesting discovery with my huge 77mm Heliopan UV/ IR filter. This thing is so big its easy to hold it at an angle and look thru it at very acute angles....like 20 degrees. Guess what color I see? Would you guess cyan? I would expect this is the phenomanom that creates the cyan vignetting. Rex Link to post Share on other sites More sharing options...
waterlenz Posted December 5, 2006 Share #28 Posted December 5, 2006 snip I would wonder if Leica could coat the very thin sensor glass with the same coatings that B+W does to make their IR filters. That way, the IR is blocked at the chip, and there is no "wide angle cyan" effect as acute angle light rays in wide angle lenses cause red to be reflected as well. I would think the image sensor IR coating thickness surely cannot affect the vignetting problems of the chip (as coating are nanometers in thickness). 'I would wonder if Leica could coat the very thin sensor glass with the same coatings that B+W does to make their IR filters.' Nope this won't work, due to angle of incidence at the sensor. The angle of light hitting the corner of the sensor is very acute and hence interference filters, similar to the B+W 486, will not work with short BF RF lenses (probably all the M8 lenses less than 90mm FL). The angle - cyan - shift effect for front mounted filters OTOH is only a concern for the wide-angles. Tom Link to post Share on other sites More sharing options...
rvaubel Posted December 5, 2006 Share #29 Posted December 5, 2006 Holy Sh*t, those Edmund/B+W filters are expensive! The Heliopans are about 1/3 of that from German sources. And they are very well made, Schot glass, multicoated, brass (!) threaded cells, etc. I thought I would try to download a chart of the spectral sensitivity for the Edmund filter. I'm looking for the same chart for the Heliopan. Wish me luck Rex Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/10640-definitive-answer-on-the-ir-filter/?do=findComment&comment=111018'>More sharing options...
jaapv Posted December 5, 2006 Share #30 Posted December 5, 2006 From Heliopan Lichtfilter-Technik Summer GmbH & Co KG They list the spectral response of all their filters. "Digital" = the 8025/8125 filter Link to post Share on other sites More sharing options...
rvaubel Posted December 5, 2006 Share #31 Posted December 5, 2006 jaap You beat me to it. I posted the same two charts over on the Rangefinder Forum. Anyway, the frequency response looks pretty much the same to me. I would quess that they would perform almost identically. Rex Link to post Share on other sites More sharing options...
rvaubel Posted December 5, 2006 Share #32 Posted December 5, 2006 jaap You beat me to it. I posted the same two charts over on the Rangefinder Forum. Anyway, the frequency response looks pretty much the same to me. I would quess that they would perform almost identically. Rex Does anyone have both filters and had an opportunity to compare? Rex Link to post Share on other sites More sharing options...
sean_reid Posted December 5, 2006 Share #33 Posted December 5, 2006 What do you mean by objective? Yes, photo evaluations are fairly subjective. The Reid Review comparison pix have numerical values, is this what you want?Tom In Part Four of the M8 review series I have comparison pictures with and without the 486 filters (same workflow for each otherwise) and numerical RGB readings for each. Sean Link to post Share on other sites More sharing options...
sean_reid Posted December 5, 2006 Share #34 Posted December 5, 2006 Does anyone have both filters and had an opportunity to compare? Rex Hi Rex, I'll have 55 mm 486 and Heliopan filters here soon and, when time allows, will compare. It won't be very soon, I'm afraid. Cheers, Sean Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted December 5, 2006 Share #35 Posted December 5, 2006 I am waiting on a 55mm B+W for Sean to ship out to him so he has a filter big enough to run a test Link to post Share on other sites More sharing options...
pat308 Posted December 5, 2006 Author Share #36 Posted December 5, 2006 In Part Four of the M8 review series I have comparison pictures with and without the 486 filters (same workflow for each otherwise) and numerical RGB readings for each. Sean Sean in your view did the any of the filters conclusively and completely solve the problem with the magenta cast on M8. I am not asking which filter, people that want that information should pay and read your reviews. But I am asking if the problem was solved. Yes or No. Link to post Share on other sites More sharing options...
jaapv Posted December 5, 2006 Share #37 Posted December 5, 2006 Maybe Sean does not want to answer that himself. Yes, in my evaluation of the very informative photo's posted.- but look at the other threads in this forum. Link to post Share on other sites More sharing options...
ho_co Posted December 5, 2006 Share #38 Posted December 5, 2006 Holy Sh*t, those Edmund/B+W filters are expensive! The Heliopans are about 1/3 of that from German sources. And they are very well made, Schot glass, multicoated, brass (!) threaded cells, etc. Rex: Expensive indeed. White box. Brass mount. Quality control certificate by Schneider Kreuznach. Engraved "486." But available, even if not in many desired sizes. And I'm sure they have to pay extra for B+W to produce a batch without their own logo. Didn't someone on the forum (perhaps Canadian?) compare the Heliopan and the B+W and find that the latter did a slightly better job of reducing the magenta cast? (Maybe just wishful thinking, since I've got the Edmund 486. ) I remember that someone did say that his Tiffen hot mirror didn't work as well as whichever of the German versions he tried. By the way--in the interest of Political Correctness, in addition to "Holy Sh*t" you should probably also say "Holy Sun*i." Link to post Share on other sites More sharing options...
ho_co Posted December 5, 2006 Share #39 Posted December 5, 2006 Sean in your view did the any of the filters conclusively and completely solve the problem with the magenta cast on M8. Pat-- Jaap is right. The other threads on the forum answer the question completely. But your phraseology is the problem--what does "conclusively and completely solve the problem" mean? The nature of the IR-Cut filter is that it generates cyan problems when image-forming light strikes it from an acute angle less than ca 30 degrees. Does that meet your definition of solving "the problem with the magenta cast"? In other words, yes, in this case the magenta cast is gone, but in its place appears a cyan cast that increases radially from the center of the image. The question may not be as straightforward as you wish, but clearly if Leica is giving away filters, then that is the solution. To get more info, read other threads on the topic. Link to post Share on other sites More sharing options...
pat308 Posted December 5, 2006 Author Share #40 Posted December 5, 2006 Pat--Jaap is right. The other threads on the forum answer the question completely. But your phraseology is the problem--what does "conclusively and completely solve the problem" mean? The nature of the IR-Cut filter is that it generates cyan problems when image-forming light strikes it from an acute angle less than ca 30 degrees. Does that meet your definition of solving "the problem with the magenta cast"? In other words, yes, in this case the magenta cast is gone, but in its place appears a cyan cast that increases radially from the center of the image. The question may not be as straightforward as you wish, but clearly if Leica is giving away filters, then that is the solution. To get more info, read other threads on the topic. I am not sure why people are so afraid of questions. I have my view and though nobody has asked for it I don't think the IR filters out there today do solve the problem. And frankly I don't see how they possibly could, certainly not in an optimal way, unless they were designed for the M8 with Leica's input. As this is not my field I asked those people that make it their business to know these things, people who have been happy to render all sorts of positive praise on the M8, if they had a view. I used precise words because I wanted an answer to the question and not an opinion. I was interested in the IR filter usage and not correction using profiles. I read all available posts here and many other places and formed an opinion before popping up. I saw nothing that answered the question completely, if had I would not be wasting readers bandwidth. I thought and still think it is a fair question. In the view of those that test these things on a regular basis do the IR filters available cut the IR seen by M8 sensor completely and are the tests conclusive. Link to post Share on other sites More sharing options...
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