RudiLorenz Posted October 3, 2008 Share #21 Â Posted October 3, 2008 Advertisement (gone after registration) am I correct in assuming that there is some on-board image processing firmware that does "something" to the corners of images, depending on the focal length of the lens, if and only if the firmware knows the focal length of the lens (via the 6-bit coding)? Link to post Share on other sites More sharing options...
Advertisement Posted October 3, 2008 Posted October 3, 2008 Hi RudiLorenz, Take a look here M8 with IR Filters & lenses with NO coding. I'm sure you'll find what you were looking for!
stunsworth Posted October 3, 2008 Share #22 Â Posted October 3, 2008 am I correct in assuming that there is some on-board image processing firmware that does "something" to the corners of images, depending on the focal length of the lens, if and only if the firmware knows the focal length of the lens (via the 6-bit coding)? Â Yes, though in practice it affects mainly the wide angle lenses - say wider than 35mm. I've been using a Pre-ASPH 35mm Summilux without coding and haven't noticed a negative effect. Wider than that and I'd certainly recommend having a lens coded. Link to post Share on other sites More sharing options...
tashley Posted October 3, 2008 Share #23  Posted October 3, 2008 I've never tested this scientifically but I have used a variety of lenses coded and uncoded, of varying focal lengths and both with and without filters and firmware correction and after thousands and thousands of shots I am quite certain Sean is right. With lenses of 35mm and shorter, if you use the filters, use the firmware correction or you will get cyan corners.  They key reason many people don't notice this is that it is so often masked by subject matter. In fact, before I got my CV15 'Miliched', I used to use an inverse mask layer in photoshop to subtract the colour caste. Now that really WAS a hassle!    If one does careful comparisons, the difference is obvious. Some subject matter will disguise the cyan drift but it most certainly exists and that is why Leica has spent a good deal of time and money correcting for it via lens detection and firmware. Cyan vignetting is something I've only seen with files that are over corrected and drift towards red in the outer zones. Puts is mistaken in some of his assumptions and conclusions about this topic, as has been the case several times when he's written about things digital. Anecdotal information is useful but without careful comparisons it would be hard for one to draw conclusions about cyan drift. It exists, but is nearly unnoticeable, even with 50 mm lenses. With 35 mm and wider lenses, it will indeed be evident in pictures where the subject matter does not mask it.  Its the nature of the beast, as I discussed after my interview with one of the optical engineers who designed the 486 filter.  Cheers,  Sean Link to post Share on other sites More sharing options...
Mauribix Posted October 4, 2008 Share #24 Â Posted October 4, 2008 I've never tested this scientifically but I have used a variety of lenses coded and uncoded, of varying focal lengths and both with and without filters and firmware correction and after thousands and thousands of shots I am quite certain Sean is right. With lenses of 35mm and shorter, if you use the filters, use the firmware correction or you will get cyan corners. Â They key reason many people don't notice this is that it is so often masked by subject matter. In fact, before I got my CV15 'Miliched', I used to use an inverse mask layer in photoshop to subtract the colour caste. Now that really WAS a hassle! Â In my experience I'd say both Tim and Sean are right. I still can't explain myself how come the poster doesn't see the cyan corners with the 24elmarit. It's not polemic, of course, but as Tim pointed out, it could be masked by a subject matter, or even a bad calibrated (if not calibrated at all) display? Â I still have shots made with the summicron 28 (coded with Lens recognition disabled) affected by the cyan corners hard to deal with! fortunately there's cornerfix (even if id didn't get comfortable with it...) Â My vote then goes to Sean's test, he measured the value of the cyan shift, and that was precious to me to understand M8's behaviour with UV/IR filter and the importance of a proper coding. Link to post Share on other sites More sharing options...
mm_v8 Posted October 4, 2008 Share #25 Â Posted October 4, 2008 Before I make CV Nokton coding, I still use M8 with "ON + UV/IR" setting. It was an advise from Leica Japan. According to him, if no code is recognized, M8 will just neglect the coding information, but still make a certain UV/IR correction. Link to post Share on other sites More sharing options...
dpattinson Posted October 4, 2008 Share #26  Posted October 4, 2008 You definitely get cyan corners with the 24 elmarit. whether you can see it or not is another matter  case in point: beijing 718 on Flickr - Photo Sharing!  My sharpie coding has worn off. Link to post Share on other sites More sharing options...
steamboat Posted October 4, 2008 Share #27 Â Posted October 4, 2008 Advertisement (gone after registration) Working in CS3 is there an "easy" fix for black stuff shot under artificial light (no ir filter) that turns "purple"? My only experience with the M8 is a two-week loan so the loaner I got had no ir filters. I (now) have an M8.2 on order and am planning on the ir filters going forward. Howabout those old photographs with the purple?? Great forum - many thanks! Link to post Share on other sites More sharing options...
andybarton Posted October 4, 2008 Share #28  Posted October 4, 2008 Welcome to the forum  IR filters are essential for most colour work on an M8 Link to post Share on other sites More sharing options...
SJP Posted October 4, 2008 Share #29 Â Posted October 4, 2008 I was unhappy with my old & decrepit tele-elmarit 90/2.8 that I bought second hand and wasn't really using it until I got the IR/UV filter. Now it is still old & decrepit but the pictures are a LOT better (or at least some of them, still flares like a pig). Link to post Share on other sites More sharing options...
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