ho_co Posted October 22, 2007 Share #1 Posted October 22, 2007 Advertisement (gone after registration) Anyone else seen this? A number of pictures I've made show the light reflection arc seen at left below. It has happened with the 21/2.8 (pre-ASPH), the 28-35-50 at 28mm, and the 75/1.4. (Picture here is from 21mm.) Two of the lenses are coded, all had UV/IR-cut filters. In all cases, it's the same shape and at the same location, so I'm guessing it's due to an internal reflection. Any suggestion appreciated! --HC 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/36337-arc-in-m8-images/?do=findComment&comment=382770'>More sharing options...
Advertisement Posted October 22, 2007 Posted October 22, 2007 Hi ho_co, Take a look here Arc in M8 images. I'm sure you'll find what you were looking for!
Hookeye Posted October 22, 2007 Share #2 Posted October 22, 2007 Sorry, Howard. I've given it some careful thought and I am completely at loss as to what it could be. I have never experienced anything like it myself. That it happens in the same way with several lenses has me flummoxed. Nor can I claim to be anything like an expert. We'll have to leave it to the "heavyweights" here at the forum. Meanwhile - could you do some more experimenting? Are you able to say whether it related to lens-detection on/off, whether you shoot raw or jpeg, a particular type of lighting condition? Maybe you can find a trend by looking at the images where it occurs and also compare the exif data? Do you have any scratches on the black surfaces in front of, or behind the shutter? Link to post Share on other sites More sharing options...
jonoslack Posted October 22, 2007 Share #3 Posted October 22, 2007 Hi Howard I'm afraid I've seen nothing like this either - does it happen on all photos? Link to post Share on other sites More sharing options...
Jamie Roberts Posted October 22, 2007 Share #4 Posted October 22, 2007 Nope--never seen this in thousands and thousands of shots. Link to post Share on other sites More sharing options...
dpattinson Posted October 22, 2007 Share #5 Posted October 22, 2007 Sorry, never seen anything like that myself. Might be worth checking that there isn't a hair or something similar on the sensor? It could be an internal reflection, but that seems pretty unlikely given how close the back of the 21 is to the sensor? I do quite a lot of shooting into the light, and I do get flare, but not like that. David. Link to post Share on other sites More sharing options...
Ben Marks Posted October 22, 2007 Share #6 Posted October 22, 2007 The image is light and specific as opposed to flare-y. . . I would conclude that something is blocking light getting to the sensor in that specific location. Hair? Check the shutter gate with a bright flashlight. Ben Marks Link to post Share on other sites More sharing options...
M6J Posted October 22, 2007 Share #7 Posted October 22, 2007 Advertisement (gone after registration) Yep, it should be hair. Link to post Share on other sites More sharing options...
gravastar Posted October 22, 2007 Share #8 Posted October 22, 2007 I notice in your example the subject is back lit with the sun in front of the camera. You wouldn't by any chance be using silver rather than black mount filters would you? Does the arc always appear the same size and in the same position regardless of the lens used? Bob. Link to post Share on other sites More sharing options...
wparsonsgisnet Posted October 22, 2007 Share #9 Posted October 22, 2007 If, as suggested, it is a reflection from the filter mount, you should be able to discern this by shooting first with the sun on one side of the lens, and then on the other. I would expect this arc to switch sides in the image. I favor the hair inside the shutter. Link to post Share on other sites More sharing options...
ho_co Posted October 22, 2007 Author Share #10 Posted October 22, 2007 Many good suggestions. Hair sounds good, but it's on very few images, and the dust I've got shows up consistently. Also, when I get dust on the sensor, it turns up dark--why would hair be light? All the UV/IR filters are Leica filters in black mount. The arc is a relatively rare occurrence--on about 17 of 1400 images shot in the last two weeks. I *think* that all the cases are on backlighted images, but that they're not all back-lighted from the same side. Some of the suggestions are very provocative, and I'll check the images and come back with more information. Thanks for the input. I'll keep hunting. --HC Link to post Share on other sites More sharing options...
jonoslack Posted October 22, 2007 Share #11 Posted October 22, 2007 Many good suggestions. Hair sounds good, but it's on very few images, and the dust I've got shows up consistently. Also, when I get dust on the sensor, it turns up dark--why would hair be light? All the UV/IR filters are Leica filters in black mount. The arc is a relatively rare occurrence--on about 17 of 1400 images shot in the last two weeks. I *think* that all the cases are on backlighted images, but that they're not all back-lighted from the same side. Some of the suggestions are very provocative, and I'll check the images and come back with more information. Thanks for the input. I'll keep hunting. --HC Hi Howard I'm for the hair explanation - certainly worth a check, and definitely the easiest . . . especially if they come up with small aperture. Link to post Share on other sites More sharing options...
Julius Bjornsson Posted October 22, 2007 Share #12 Posted October 22, 2007 Many good suggestions. Hair sounds good, but it's on very few images, and the dust I've got shows up consistently. Also, when I get dust on the sensor, it turns up dark--why would hair be light? All the UV/IR filters are Leica filters in black mount. The arc is a relatively rare occurrence--on about 17 of 1400 images shot in the last two weeks. I *think* that all the cases are on backlighted images, but that they're not all back-lighted from the same side. Some of the suggestions are very provocative, and I'll check the images and come back with more information. Thanks for the input. I'll keep hunting. --HC I just recently bought two filters and inadvertently got sliver, when I wanted black. I just paid for them, got out of the shop and later on realized that they were silver and unfortunately too late for going back. I have to check if I get this reflection. What angle of light would you guys guess could produce this? Link to post Share on other sites More sharing options...
gravastar Posted October 22, 2007 Share #13 Posted October 22, 2007 What's puzzling is the center of the arc is not on the optical axis. Most of the camera/lens construction is symmetrical about the axis yet the arc center is situated beyond the left hand side of the frame. Bob. Link to post Share on other sites More sharing options...
jrc Posted October 22, 2007 Share #14 Posted October 22, 2007 What's puzzling is the center of the arc is not on the optical axis. Most of the camera/lens construction is symmetrical about the axis yet the arc center is situated beyond the left hand side of the frame. Not only that, it seems to be a consistent width, which you wouldn't get with a flare. Hair or scratch, or possibly a very subtle smear put on the sensor during cleaning, which might not be visible to the naked eye. I'd try cleaning the sensor with some cleaning solution. JC Link to post Share on other sites More sharing options...
ho_co Posted October 23, 2007 Author Share #15 Posted October 23, 2007 John & Bob, I think you've hit a major point. I've done a bit more study on the issue. First, all the images were made with a dirty sensor; I had no cleaning fluid due to airport restrictions. Second, all the lenses used were close to wide open to minimize the image of dust on the sensor. Third (though you don't see it here), the arc varies its width depending on focal length--very broad but less distinct with the 75mm, generally slightly less broad but more distinct with the 21mm. However, the arc is always in exactly the same place *when* it appears, viz in 16 (I had double-counted above when I said 17) of about 1400 images. Fourth, I may (or may not) have destroyed the evidence, since I cleaned the sensor when I got home from vacation. Most images that show the effect are backlit, but below are two that are less so: In the first, the light is coming from over my right shoulder; in the second, the day is overcast to the point that there are no shadows. In this second image, the arc is much less noticeable. Both of these (like the first) are from the 21. All the images with the arc either are backlit to some degree (see second picture below); have the sun within or just outside the image, usually near center; or are either back- or side-lighted from the right. None are illuminated from the left side. I'm buffaloed, but you've all certainly helped to get me into analytical mode. I'm only guessing, but try this one: What if there were a grain of sand--a piece of rock--lodged somewhere on the sensor or maybe elsewhere in the body cavity? It might have one shiny but curved surface that threw these arcs when directly illuminated. BTW @ Julius--My personal feeling is that silver-finish filters are highly unlikely to give problems. Leica has been making them for years, though of course not with a product as finicky as the M8. I say go ahead and use them. You may get flare from time to time, but it's not likely to come from the filter mounts. Just my guess. --HC 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/36337-arc-in-m8-images/?do=findComment&comment=383151'>More sharing options...
Dan States Posted October 23, 2007 Share #16 Posted October 23, 2007 My friend, you have crap on your shutter. A chunk of crud is likely lodged at the edge of your shutter blades. The shutter does not travel in a straight up and down motion. The faster the shutter speed, the more notable it will become because the shutter slit is narrower at higher speeds, while the size of the crud remains the same. This is identical to a problem I had in my old R4 when a chunk of the light trap from the back door adhered itself to the shutter. I was ready to pull my hair out until I realised it was not my lens or my film, but good old gunk in the works. Set your camera to "sensor clean" and look for a bit of junk on the edge of the shutter blades. This could be pretty hard to do on an M8. With a film camera I had access to both front and back sides of the blades... Best wishes, Dan Link to post Share on other sites More sharing options...
ho_co Posted October 23, 2007 Author Share #17 Posted October 23, 2007 Great thought, Dan! I guess I'm going to have to get that Visible Dust Magnifier after all! And I love your term--to all the 'standard' M8 problems like Green Blob, Sudden Death Syndrome, Venetian Blind Effect, we now have to add the "Chunk of Crud Display"! --HC Link to post Share on other sites More sharing options...
wparsonsgisnet Posted October 23, 2007 Share #18 Posted October 23, 2007 ... "Chunk of Crud Display"! --HC And this *is* a CCD display, of course. Link to post Share on other sites More sharing options...
stunsworth Posted October 23, 2007 Share #19 Posted October 23, 2007 My friend, you have crap on your shutter. A chunk of crud is likely lodged at the edge of your shutter blades. If it was something attached to the shutter blades wouldn't the arc be darker than the background rather than lighter as it would be blocking light from reaching the sensor? Link to post Share on other sites More sharing options...
lxlim Posted October 23, 2007 Share #20 Posted October 23, 2007 I once had a thread of fabric come loose from between the edge of the mirror box and the shutter. It appeared only occasionally and being part of the assembly it kept appearing. While it was a dark colour thread it showed up light gray on film. Found it after patiently shooting about a hundred shots against the light (being a film camera it was easy to shoot without lens and film back opened). Alex Link to post Share on other sites More sharing options...
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