01af Posted July 25, 2013 Share #181 Posted July 25, 2013 Advertisement (gone after registration) If this is not what Andy is talking about, please explain your interpretation of what he said. His point is, the rear element's shape causes the central veiling flare. And even though thinking of a concave rear element surface as a reflector concentrating a reflection on the sensor's center may appear compelling, I disagree because I have seen enough lenses having the same issue with their rear elements being convex. So I think the rear element's rear surface's shape is not the primary cause. Instead, the whole lens geometry is. And some peculiarities of the lens barrels may be a factor, too. Link to post Share on other sites More sharing options...
Advertisement Posted July 25, 2013 Posted July 25, 2013 Hi 01af, Take a look here APO Summicron 50/2 ASPH: Central veiling flare / fogging. I'm sure you'll find what you were looking for!
Rick Posted July 26, 2013 Share #182 Posted July 26, 2013 First of all, I believe the 35mm lens Andy showed isn't a reflection effect from the rear element. It is flare from the sun. I think we agree on that. Secondly, I stated before you that it is more complex than the rear element being concave (post 171). I pointed out that my 28 Summicron has a convex rear element and it it displays this effect. The effect I'm referring to is not the effect of Andy's 35mm family shot (sun flare), more like his chicken shot. But, my 28 Summilux has a second from the rear lens that does have a concave element that sits behind what looks like a weak Aspherical lens. I have no idea if this second surface causes the effect we are talking about, but I think that it makes sense that it is a reflection off of the rear surface of one of the rear elements (or both) that is responsible for "chicken-type-flare" and some of the central veiling flare in some of the other posted images on this thread. Some or most of the other images posted on this thread are just flare. I'm home and I'll try and get to a few images in my catalog. I also think we are not far off on what we believe. I assume that you aren't comfortable agreeing with me. Link to post Share on other sites More sharing options...
Rick Posted July 26, 2013 Share #183 Posted July 26, 2013 Ok, first off, here is the first time I saw this central veiling flare. It was in 2011 with my 28mm Summicron at f5.6 on the M9. Common knowledge was that this lens is one of the most flare resistant lenses. This is the image I discussed in post 171. Is this what we are talking about? Pretty bad, huh? 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/208297-apo-summicron-502-asph-central-veiling-flare-fogging/?do=findComment&comment=2382407'>More sharing options...
Hookeye Posted July 26, 2013 Share #184 Posted July 26, 2013 Thank you Rick. Wow, that is odd indeed. Look at the shadows: Here the sun was clearly behind you! Surely, it cannot be a sun flare. Is it a sensor reflection you think? Link to post Share on other sites More sharing options...
Rick Posted July 26, 2013 Share #185 Posted July 26, 2013 Thank you Rick. Wow, that is odd indeed. Look at the shadows: Here the sun was clearly behind you! Surely, it cannot be a sun flare. Is it a sensor reflection you think? I really don't know for sure. I am suspecting Andy has the right idea. I remember switching to the 28 Summicron that day because, I wanted to take in the narrow street scene. I thought maybe in the hot humid day there was some moisture on the rear element or that I forgot to turn the camera off and back on in order to reset the lens recognition. But, I checked it all and none of it was the fact. I have seen this several times with this lens and other lenses. I shoot tens of thousands of images a year. I'm not sure, but I think it is an internal sensor reflection. I'll post more like this from other lenses this weekend when I have a chance to shoot with them at the window I described. It is a real phenomenon and I can duplicate it for you. Because of this, I wouldn't worry about the 50 APO. Link to post Share on other sites More sharing options...
250swb Posted July 26, 2013 Share #186 Posted July 26, 2013 It looks like condensation, if the atmosphere was humid did you make it worse by perhaps having your hand over the lens while walking around or taking the camera quickly from hot sun to cool shade? Steve Link to post Share on other sites More sharing options...
Rick Posted July 26, 2013 Share #187 Posted July 26, 2013 Advertisement (gone after registration) It looks like condensation, if the atmosphere was humid did you make it worse by perhaps having your hand over the lens while walking around or taking the camera quickly from hot sun to cool shade? Steve No. I saw the effect on the LCD and like I said I checked the lens by taking it off and inspecting it and I turned the camera off and on. I continued to shoot at that location and produced a few more random pictures with the same effect. If, you want I can post pictures with the same effect taken after I turned the camera off, replaced the lens and then tried again. These pictures are all of varying degrees the same effect when shot in the same direction. Link to post Share on other sites More sharing options...
lct Posted July 26, 2013 Share #188 Posted July 26, 2013 If the overexposed buildings had been on the right, flare around it would have been on the right as well. Another consequence of the Expose To The Right dogma i guess. But CVF i don't think so. Link to post Share on other sites More sharing options...
jankap Posted July 26, 2013 Share #189 Posted July 26, 2013 If it would be a reflection of the sensor, could there be structures detectable? Like the first cameras with Foveon sensors. Should not the computer program of the lens designers trace the reflections of the sensor too? The backside of the iris of my Lux 35 preFLE is not so very black. I´ll test the situation with different f/stops (crop camera). Jan Link to post Share on other sites More sharing options...
01af Posted July 26, 2013 Share #190 Posted July 26, 2013 Ok, first off, here is the first time I saw this central veiling flare. To me, this doesn't look like central veiling flare. Instead, it looks like fog from a dirty lens ... such as a big fat juicy fingerprint on the front or rear element. You say you double-checked the lens for condensation ... but I still think there is, or was, something wrong with the lens. Did you also get a few clean pictures from that lens that day? If so, under which lighting conditions? Link to post Share on other sites More sharing options...
lct Posted July 26, 2013 Share #191 Posted July 26, 2013 ...a big fat juicy fingerprint on the front or rear element... Ha ha! I really did not imagine you with fingers like that Rick. Too much Mozarella perhaps? Link to post Share on other sites More sharing options...
01af Posted July 26, 2013 Share #192 Posted July 26, 2013 I just played around with my Summicron-M 28 mm Asph at f/5.6, in moderately dark rooms with bright windows, one room with a small and another with a big window, window at the frame's center, off-center, at the frame's edge, outside the frame. No undue flares or fogging whatsoever. Yesterday night I already tried the same but with various room lights rather than windows, as it was dark outside—again, no flares. Link to post Share on other sites More sharing options...
lct Posted July 26, 2013 Share #193 Posted July 26, 2013 No flare if you did not overexpose the bright parts of your images i guess. Otherwise you will find some flare around the overexposed parts but it won't be centered if the bright parts are not in the middle. So far no CVF if i'm not mistaken. Link to post Share on other sites More sharing options...
jankap Posted July 26, 2013 Share #194 Posted July 26, 2013 If the overexposed buildings had been on the right, flare around it would have been on the right as well. Another consequence of the Expose To The Right dogma i guess. But CVF i don't think so. The presence of CVF is independent of the amount of light. It is always there: more or less. Jan Link to post Share on other sites More sharing options...
lct Posted July 26, 2013 Share #195 Posted July 26, 2013 Reason why i've seen none out of my lenses i guess. But i don't have the 50/2 asph. Link to post Share on other sites More sharing options...
01af Posted July 26, 2013 Share #196 Posted July 26, 2013 Wait ... now I did get some central veiling flare with the Summicron-M 28 mm Asph! It will happen with medium or small aperture at short distance (less than 1 m/3 ft) when the subject at the frame's center is dark and some bright light source (such as the sky, even when cloudy ... or a big window when indoors) is outside the frame. It basically is the same central flare pattern as with the Apo-Summicron-M 75 mm Asph. I wouldn't be surprised if the Apo-Summicron-M 50 mm Asph had a similar issue. Test at f/5.6 - f/16 and at short distance! It is always there, more or less. I'm afraid you're right ... Link to post Share on other sites More sharing options...
lct Posted July 26, 2013 Share #197 Posted July 26, 2013 ...Sit on your couch, look through your own EVF and shoot towards a window across the room in a somewhat darkened room yourself... Tried this with a couple of lenses but no CVF so far. Just usual flare around highlights (sky). No significant difference between concave and convex rear elements either. (15 MB files) Summicron 28/2 asph (11604), f/5.6 (http://tinyurl.com/pppdpbk) Summicron 35/2 asph (11879), f/5.6 (http://tinyurl.com/nqb7m3k) Summilux 35/1.4 asph (11663), f/5.6 (http://tinyurl.com/ow5drqh) Summilux 50/1.4 asph (11891), f/5.6 (http://tinyurl.com/qxveyog) Summilux 50/1.4 (11114), f/5.6 (http://tinyurl.com/o957o74) Summicron 50/2 (11826), f/5.6 (http://tinyurl.com/pwro57o) Link to post Share on other sites More sharing options...
01af Posted July 26, 2013 Share #198 Posted July 26, 2013 Tried this with a couple of lenses ... Try the same at shorter distance (between 0.7 and 1 m), give more exposure so the dark parts will be exposed properly, and leave the bright sky outside the frame. Link to post Share on other sites More sharing options...
Hookeye Posted July 26, 2013 Share #199 Posted July 26, 2013 Referring back to Rick's post # 183 Could it be that this kind of flare could have something to do with the large central section of the image that is overexposed? I was thinking that this would generate a bright central spot on the sensor that again could be reflected back to the lens etc.. Well, at least it's a theory of sorts Link to post Share on other sites More sharing options...
Bill W Posted July 26, 2013 Share #200 Posted July 26, 2013 We have a term for this now "chicken-type-flare" Thanks Rick. We can always refer to it as CTF.. Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.