Guest guy_mancuso Posted November 15, 2006 Share #41 Posted November 15, 2006 Advertisement (gone after registration) Just tried another little sharpness test but I am noticing i get about a half stop MORE exposure with the filter on than without it in daylight. So I am picking up light Check out the C/V 15mm top with IR filter and bottom without. I held a 52 over it . Go by the left side and not the right. I had something in on the right bottom corner. Well looks I did in both shots . use your imagination. LOL 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/9270-what-is-the-problem-with-ir-filters/?do=findComment&comment=94525'>More sharing options...
Advertisement Posted November 15, 2006 Posted November 15, 2006 Hi Guest guy_mancuso, Take a look here What is the problem with IR filters?. I'm sure you'll find what you were looking for!
plasticman Posted November 15, 2006 Share #42 Posted November 15, 2006 Wow - thanks Guy, that pretty much settles THAT question, anyway. What do you think of the lens, generally? Certainly looks good without the IR filter. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted November 15, 2006 Share #43 Posted November 15, 2006 The damn thing is really nice for 350 dollars . One of those sleeper lenses. I need to rebuild a profile now with the Ir cut filters reason color looks off. C1 did not profile for the filters so we have to come up with something or wait to see what happens here . otherwise this M8 is a killer of a camera Link to post Share on other sites More sharing options...
alexr Posted November 15, 2006 Share #44 Posted November 15, 2006 cyan cast (vignette) very strong in the ir filtered images. Do people really think that lens filters will be 'the' solution in the end? Everyon talks about it in a way that it seems... inevitable. Link to post Share on other sites More sharing options...
Vivek Iyer Posted November 15, 2006 Share #45 Posted November 15, 2006 Guy, It looks like the filter was held in front of the 15mm lens in a tilted position. Could you clarify? Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted November 15, 2006 Share #46 Posted November 15, 2006 It may have been , It was all handheld and I have a hard time holding the camera without the grip , which should be here any minute Link to post Share on other sites More sharing options...
sean_reid Posted November 15, 2006 Share #47 Posted November 15, 2006 Advertisement (gone after registration) That be great Sean as I am stuck in the mud without a bigger filter for my 24mm. I ordered so many filters I think I could start a store, I lost count. LOL Love to see if the 21mm is better or worse than the Zeiss. If you want i could send you a raw Zeiss 21mm for you to compare. Just let me know i have that street one and also the group if this helps at all Thanks Guy, I've actually got the Zeiss 21 here though. Cheers, Sean Link to post Share on other sites More sharing options...
sean_reid Posted November 15, 2006 Share #48 Posted November 15, 2006 That be great Sean as I am stuck in the mud without a bigger filter for my 24mm. I ordered so many filters I think I could start a store, I lost count. LOL Love to see if the 21mm is better or worse than the Zeiss. If you want i could send you a raw Zeiss 21mm for you to compare. Just let me know i have that street one and also the group if this helps at all BTW, if you end up with an extra size 55 486, I'd love to either buy or borrow it for some tests of the Leica 21 and 24. Cheers, Sean Link to post Share on other sites More sharing options...
gravastar Posted November 15, 2006 Share #49 Posted November 15, 2006 Just tried another little sharpness test but I am noticing i get about a half stop MORE exposure with the filter on than without it in daylight. So I am picking up light[snip] I wondered if you would encounter this. I'd previously asked about it here in post #74. I'd expect the difference to be even greater with tungsten light. Bob. Link to post Share on other sites More sharing options...
sean_reid Posted November 15, 2006 Share #50 Posted November 15, 2006 Actual. The new 28/2.8 released at about the same time as the M8 got a real workout in Sean Reid's wedding pictures, scott Hi Scott, Actually it was a coded 28/2.0 Summicron Asph. Cheers, Sean Link to post Share on other sites More sharing options...
sean_reid Posted November 15, 2006 Share #51 Posted November 15, 2006 However, the correction for the fact that a dichroic filter cuts into the visible frequencies well off axis can be done by strengthening the observed RGB data to compensate. It's just like the vignetting correction that the M8 does so well already for coded lenses. The correction for an unknown amount of IR coming into all three channels cannot be done accurately based on the observed RGB data. You simply don't know what is out there to correct. scott Exactly! I wrote much the same thing in the Part 4 review that just went up. Cheers, Sean Link to post Share on other sites More sharing options...
blakley Posted November 15, 2006 Share #52 Posted November 15, 2006 Guy, I don't think you're getting more exposure with the filter - I think what's actually happening is that the camera's meter without the filters is seeing IR and adding that to the total metered value. Since IR doesn't add much "visual brightness" to the pictures you're effectively underexposing unfiltered pictures. When you put the filter on, all the light coming into the sensor is visible and adds brightness to the picture. Therefore the same metered exposure is effectively "more light" because it's all visible light. Does that make sense? Link to post Share on other sites More sharing options...
sean_reid Posted November 15, 2006 Share #53 Posted November 15, 2006 The dichroic filters are recommended only up to an angle of incidence of 30° according to the Edmund Optical site. That would mean that on the M8, the 28mm is the widest lens to be usable without some cyan in the corners. --HC Hi Howard, Remember though, that the spec you quote is for *those* filters, not necessarily all IR-cut filters. I'll hopefully know more about the 25 tonight. Cheers, Sean Link to post Share on other sites More sharing options...
scott kirkpatrick Posted November 15, 2006 Share #54 Posted November 15, 2006 Hi Scott, Actually it was a coded 28/2.0 Summicron Asph. {not the new, small 28/2.8} Cheers, Sean Oops again. You have both, don't you? Which do you prefer, when you're not stressed for low light capability? scott Link to post Share on other sites More sharing options...
ho_co Posted November 15, 2006 Share #55 Posted November 15, 2006 Remember though, that the spec you quote is for *those* filters, not necessarily all IR-cut filters. I'll hopefully know more about the 25 tonight. Sean-- Agreed, but from everything I've seen on the topic, I think the IR-cut dichroic filters must all work identically. Parts of the B+W description of their version read almost identically with the Edmund description. (Imagine the surprise when this previously dead part of the market suddenly picks up with each brand claiming "ours is best because xxx....") But you are certainly correct that a test is conclusive. I'll be interested to see the result! --HC Link to post Share on other sites More sharing options...
Joseph S. Wisniewski Posted November 15, 2006 Share #56 Posted November 15, 2006 Thanks Scott yes in my testing of the filters the Zeiss 21 i did get cyan corners on all sides. I am hoping the 24mm that effect will be a lot less , just waiting on the filter to arrive to try that one. If you want to check the severity of the effect, take a 21mm image and crop it down to 24mm. That's a 90.3% crop, in case you're interested. But the 21mm focal length and i will assume the leica 21mm also will have this effect. I did a quick fix of it with color dodge with a magenta color and painted over the area and with care it can be done successful but a more automated way would be better. If you read the Cut filter theread you will see some of the discoveries of some informal testing with and without the IR filters. The best way to correct the color is with a radial color correction algorithm. The Panorama Tools plugins have one, and it's a free download at epaperpress.com. The effect will be the same regardless of who's 21mm you use. The effect for filters in front of th lens is based on angle, which is determines solely by focal length. The effect on filters in front of the sensor is based on exit pupil location (just like vignetting correction), so two 21mm lenses could need radically different correction. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted November 15, 2006 Share #57 Posted November 15, 2006 Thanks Joseph a man that has been down this path. LOL Link to post Share on other sites More sharing options...
markedavison Posted November 15, 2006 Share #58 Posted November 15, 2006 I can confirm that there is visible cyan "vignetting" with a Tiffen standard hot mirror filter on the 24 2.8 ASPH. Mark Davison Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted November 15, 2006 Share #59 Posted November 15, 2006 Thanks Mark had a feeling there would be some, can you post a shot to see Link to post Share on other sites More sharing options...
Joseph S. Wisniewski Posted November 15, 2006 Share #60 Posted November 15, 2006 One problem I've experienced (with the Epson R-D1) is that the filters when viewed off axis look like a highly reflective magenta colored mirror. Several times people I've photographed have commented on this. It detracts from the unobtrusiveness of a rangefinder. It's not what people expect to see. Bob. Bob, Wait till security checks you out (rather aggressively) because the only other thing they've ever seen that looks like the IR blocking filter is a spotting scope. It happened to me. Link to post Share on other sites More sharing options...
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