valtof Posted July 10, 2007 Share #1 Posted July 10, 2007 Advertisement (gone after registration) As I received my E55 Leica UV/IR filter last week and its JM adapter two days ago, I did some tests with my CV12 coded as a WATE and used at 16. As many of you perhaps in this case, I noticed that the M8 correction isn't enough to get rid of the (moderate) vignetting and the (enormous) cyan drift phenomenons, even if it does a part of the job. I was not surprised too much as soon as a 12 isn't a 16mm and a Voigt isn't a Leica... it's obvious. So I decided to test CornerFix and after a while to understand the process (proper install, profile generation, etc...) I managed to get some very good results, but... here comes the thread : I noticed on several images (let's say all of them in similar situation) a very nasty kind of "red clock" artifact in the dark areas. This has nothing to deal with CornerFix, these artifacts are visible in the original DNG files especially when you manually overexpose them in C1 (see attached images at top and bottom). This doesn't happen without the UV/IR filter... and it seems that with the UV/IR filter but no detection, it does not happen either. Has anybody there already noticed such a strange behaviour and what that is ? PS : congratulations to John Milich for its CV12 adapter (a very smart solution) and Sandy McGuffog for CornerFix. Link to post Share on other sites More sharing options...
Advertisement Posted July 10, 2007 Posted July 10, 2007 Hi valtof, Take a look here CV12 & E55 Leica filter strange artifacts. I'm sure you'll find what you were looking for!
sean_reid Posted July 10, 2007 Share #2 Posted July 10, 2007 I'm not sure about what artifacts you are seeing but I'd recommend not double correcting the file. Leave the lens uncoded and do it all in CornerFix. Cheers, Sean Link to post Share on other sites More sharing options...
kidigital Posted July 10, 2007 Share #3 Posted July 10, 2007 I had the same artifacts (mysterious red blotches or reflections) in a lot of my shots with the filter and adapter ... it was very frustrating. Lately, I've just been shooting with the lens coded as a 16mm with lens detection on without the UV/IR correction selected. Kurt Link to post Share on other sites More sharing options...
ArtZ Posted July 10, 2007 Share #4 Posted July 10, 2007 Christophe, Take a look here: http://www.l-camera-forum.com/leica-forum/forum-zur-leica-m8/23392-m8-und-wate-mit-uv-ir.html (in the German M8 forum under the topic "M8 und WATE mit UV/IR-Filter") You will see the same artifacts (much worse). Sorry but my German is not good enough to translate it. Amicalement, Manuel Link to post Share on other sites More sharing options...
carstenw Posted July 10, 2007 Share #5 Posted July 10, 2007 In the German forum they are saying that it is caused by white letters written on the filter which reflect light onto the front side of the filter. What does your filter look like, Christophe? Link to post Share on other sites More sharing options...
valtof Posted July 10, 2007 Author Share #6 Posted July 10, 2007 Sean, John M, Manuel, As a follow-up to my initial thread, here is the result of my investigation. Please take this into consideration if I'm not too stupid or not too drunk and my poor english... but... When I received JM's adapter yesterday, I understood that the "smart" solution was consisting in screwing the E55 filter in the holder and screwing the hood onto the E55 filter, but all this meant using the filter upside down... and that's what helped me tonight to play my poor Sherlock Holmes, as puting an UV/IR cut filter the wrong sens was a bit disturbing to me... and I think I was not wrong with this intuition. I experimented to take a picture on a tripod with the E55 filter held (in my hands) in front of the lens, in place, then upside down. You'll see in the attached animated GIF what's the big difference... So John, your "smart" indeed solution wouldn't consist in puting the glass in the correct position ? And if that's the point, how do we do that ? Best regards Christophe Link to post Share on other sites More sharing options...
Guest M8-Freak Posted July 10, 2007 Share #7 Posted July 10, 2007 Advertisement (gone after registration) In the German forum they are saying that it is caused by white letters written on the filter which reflect light onto the front side of the filter. What does your filter look like, Christophe? sorry carsten, thats not right. The white letters are from the WATE, not from the filter. It´s not importent if you use the original 67er Filter or the solution from John Link to post Share on other sites More sharing options...
carstenw Posted July 10, 2007 Share #8 Posted July 10, 2007 Sorry, I read the German thread too quickly and posted a slightly wrong summary, but "M8-Freak" has sent me the details. The problem is that the letters on the front of some lenses reflect off the inside of the IR filter, back into the lens! His problem lens is the WATE, whereas here it is the 21mm, but it is most likely the same problem. He had Leica paint the letters on the front of the lens black, but it didn't fix the problem. I suppose the letter wells are somehow still reflective. Apparently Leica is mostly interested in fixing their own solution, not the WATE adapter from John Milich, which is to be expected. Leica is now meant to be implementing a solution which consists of laying a plastic ring inside the filter holder. I am curious how that will look. Presumably, it will block the letters without intruding on the field of view, for both film and M8. I don't know what the easiest solution is here, but perhaps an O-ring again, which this time is laid around the circumference of the front element, and is then squeezed by the filter as it is screwed on, and then blocks the letters. Perhaps some other material might be better, like black felt cut to the right size. Link to post Share on other sites More sharing options...
valtof Posted July 11, 2007 Author Share #9 Posted July 11, 2007 In the German forum they are saying that it is caused by white letters written on the filter which reflect light onto the front side of the filter. What does your filter look like, Christophe? Carsten, Indeed, the problem was the white and red letters in front of the CV12 : I apologize for the wrong way I was yesterday night, presuming that the reason would have been JM's adapter holding the E55 filter upside down... Sorry John ! I managed to carefully take off the retaining ring of the E55 and reverse the glass, but it finally didn't really change anything apart that the strange red artifacts were somewhat different. Then I decided to put some black electric tape all around the letters in front of the lens, as its unglossy aspect shoudn't lead to any reflection... and Bingo ! it worked perfectly, no more artifacts at all. (attached image) Everything is OK now but what remains strange to me is that this problem of reflection of the letters' lens doesn't occur with the Elmarit 21 with the same Leica UV/IR filter (E60). It's the same configuration : same white letters in front of the lens, same kind of filter... but no artifacts at all. The only big difference is that the 21mm is properly coded and receive the accurate corrections from the M8, of course... Hope all this helped. Cheers Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.