Irakly Shanidze Posted May 23, 2007 Share #1 Posted May 23, 2007 Advertisement (gone after registration) I played with M8 and IR-pass filters for quite some time now. Now results seem to be fairly predictable and reproducible. What really blows me away is that there is no need in focus correction for IR wavelength. First I thought it was due to large DOF of my 2.8/28 Zeiss Biogon ZM, which was the first lens that I purchased an IR-pass filter for. Later, however, I tried it with Konica 1.2/60 UC wide open, and the focus what right where the ringefinder told me. The secret of colour is in setting WB manually though the IR-pass filter. 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/24904-m8-infrared-technique/?do=findComment&comment=262944'>More sharing options...
Advertisement Posted May 23, 2007 Posted May 23, 2007 Hi Irakly Shanidze, Take a look here M8 infrared technique. I'm sure you'll find what you were looking for!
misha Posted May 23, 2007 Share #2 Posted May 23, 2007 batono, very cool ) Link to post Share on other sites More sharing options...
Irakly Shanidze Posted May 23, 2007 Author Share #3 Posted May 23, 2007 a real advantage of rangefinder in IR photography is that one can actually see what is going on in a viewfinder Link to post Share on other sites More sharing options...
stunsworth Posted May 23, 2007 Share #4 Posted May 23, 2007 The M8 is a superb IR camera - no surprise there :-). The focussing is dependant on the filter used. I have a B+W 093 which is opaque to visible light. With this filter the focussing is way off if I use the normal focussing scale. One other effect is that as the filter is opaque to visible light there is no colour present - apart from a very strong magenta cast :-) Link to post Share on other sites More sharing options...
Irakly Shanidze Posted May 23, 2007 Author Share #5 Posted May 23, 2007 I use heliopan. If the white balance set to Auto, there is strong magenta cast. Did you try setting it manually by shooting something white or natural grey? Link to post Share on other sites More sharing options...
stunsworth Posted May 23, 2007 Share #6 Posted May 23, 2007 No I haven't tried that, I just desaturate in Photoshop. There probably isn't any point in doing anything else as the filter is totally opaque to visible light - but I'll give it a try at the weekend. Link to post Share on other sites More sharing options...
Irakly Shanidze Posted May 23, 2007 Author Share #7 Posted May 23, 2007 Advertisement (gone after registration) the point is, IR is not just one wavelength, its a fairly large band. different frequencies will render with different color by a sensor. Link to post Share on other sites More sharing options...
john_nyc Posted May 23, 2007 Share #8 Posted May 23, 2007 Irakly, Which filter did you use to make this? Thanks, John Link to post Share on other sites More sharing options...
scho Posted May 24, 2007 Share #9 Posted May 24, 2007 I use heliopan. If the white balance set to Auto, there is strong magenta cast. Did you try setting it manually by shooting something white or natural grey? Irakly, I don't which Heliopan you have, but if it cuts just inside the visible (red) like the B+W 092 (Wratten 89B equiv.) then there may be enough visible red light to provide accurate focusing. Look at each channel in Photoshop and see if there is a focus difference in the red channel vs green and blue. Carl Link to post Share on other sites More sharing options...
Irakly Shanidze Posted May 24, 2007 Author Share #10 Posted May 24, 2007 I use Heliopan RG715. According to their nomenclature, 715 stands for the wavelength that it is passing. I checked all three channels, and focus seems to be the same on all three. What do you now... Link to post Share on other sites More sharing options...
scho Posted May 24, 2007 Share #11 Posted May 24, 2007 I use Heliopan RG715. According to their nomenclature, 715 stands for the wavelength that it is passing.I checked all three channels, and focus seems to be the same on all three. What do you now... 715 nm is probably the 50% transmission point for the filter so it is cutting right near the visible/near IR boundary and should be letting through a significant amount of red visible light - perhaps enough for accurate focusing? Link to post Share on other sites More sharing options...
Irakly Shanidze Posted May 24, 2007 Author Share #12 Posted May 24, 2007 In this case only the red channel would be in focus, right? Link to post Share on other sites More sharing options...
scho Posted May 24, 2007 Share #13 Posted May 24, 2007 In this case only the red channel would be in focus, right? I'm not so sure. Look at the red, green, and blue channel images of the tree on this page. Taken with a 715 nm filter (over the sensor instead of lens) in a converted canon rebel. Red channel is also apparently affected most by the near IR so it looks a little fuzzy compared to the green and blue channels. Hard to tell what the sensors, bayer filter, and processors are really doing with the IR in these cameras. http://www.pbase.com/scho/ir_rebel Link to post Share on other sites More sharing options...
gravastar Posted May 24, 2007 Share #14 Posted May 24, 2007 715 nm is probably the 50% transmission point for the filter so it is cutting right near the visible/near IR boundary and should be letting through a significant amount of red visible light - perhaps enough for accurate focusing? At 700nm it only has about 10% transmission, 50% @ 715nm so it has quite a steep cut off in the very deep red. Irakly's results have made me want to try the 715 filter, luckily I have several including the 690 from a few years ago. Bob. Link to post Share on other sites More sharing options...
Woody Campbell Posted May 24, 2007 Share #15 Posted May 24, 2007 Irakly - Is that a Norwich terrrier? I use a Russian Orion F6 28mm that I heard about on this board and found on e-bay. The Orion focuses infrared perfectly. I use a Hoya R72 filter which passes almost no visible light. If you do an expodisc custom white balance through the filter the result in warm grayscale (ie the custom white balance eliminates the magenta). I usually do gray conversions anyway. The Orion is compact so it's part of my carry-around kit. Here's an example: 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/24904-m8-infrared-technique/?do=findComment&comment=263257'>More sharing options...
arthury Posted May 24, 2007 Share #16 Posted May 24, 2007 Here's something I tried this evening and it was processed in LR ... 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/24904-m8-infrared-technique/?do=findComment&comment=263258'>More sharing options...
Woody Campbell Posted May 24, 2007 Share #17 Posted May 24, 2007 The same image in color: 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! Kind of looks like split toning. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! Kind of looks like split toning. ' data-webShareUrl='https://www.l-camera-forum.com/topic/24904-m8-infrared-technique/?do=findComment&comment=263262'>More sharing options...
Irakly Shanidze Posted May 24, 2007 Author Share #18 Posted May 24, 2007 nice wheels yes, your colour image looks pretty much like what i get. try shooting a brunette and see if hair comes out light blue. Link to post Share on other sites More sharing options...
arthury Posted May 24, 2007 Share #19 Posted May 24, 2007 I thot the colorizing of IR photos can be adjusted in PS any time to whatever levels you want ... why is that related to the camera? 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/24904-m8-infrared-technique/?do=findComment&comment=263268'>More sharing options...
Irakly Shanidze Posted May 24, 2007 Author Share #20 Posted May 24, 2007 I thot the colorizing of IR photos can be adjusted in PS any time to whatever levels you want ... why is that related to the camera? [ATTACH]38841[/ATTACH] why whould i want to adjust something in photoshop if it can be done in-camera? Link to post Share on other sites More sharing options...
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