starless Posted March 24, 2014 Share #1  Posted March 24, 2014 Advertisement (gone after registration) Hi,  I've been using this Summicron (ver 3) on the M6 for 6 years now and have always got excellent results.  Twice however a strange thing has happened. Both times the picture was taken at f4 or wider, and there is an area on the right, strangely out of focus. This has happened only twice in the last 6 years and I am curious why. Can it be that this occurs only at a certain aperture and certain focusing distance?  99% of my photographs are taken at f4 or above, because I like a lot of DOF. But I have also shot a few at wider f-stops without the issue in question.  The problem is not due to scanning and it has only appeared on these photographs. Camera and lens are CLAed every 3-4 years.  Picture 1 is from 2014, 3 years after CLA Picture 2 is from 2010, 2 years after CLA  Thank you  http://www.vitaobscura.com/sum3.jpg http://www.vitaobscura.com/sum4.jpg Link to post Share on other sites More sharing options...
Advertisement Posted March 24, 2014 Posted March 24, 2014 Hi starless, Take a look here 35mm summicron: spherical aberration or lens defect. I'm sure you'll find what you were looking for!
250swb Posted March 24, 2014 Share #2 Â Posted March 24, 2014 I doubt it can be the lens introducing occasional blurring or out of focus areas, so if it isn't film curl during scanning (are you sure ?) it may be film curl in the camera, maybe if it has been hot or been in the camera for an extended period and the film has become 'set'. Â Steve Link to post Share on other sites More sharing options...
starless Posted March 24, 2014 Author Share #3  Posted March 24, 2014 I doubt it can be the lens introducing occasional blurring or out of focus areas, so if it isn't film curl during scanning (are you sure ?) it may be film curl in the camera, maybe if it has been hot or been in the camera for an extended period and the film has become 'set'. Steve  Thank you for the input.  Definitely not curved film. The first image was scanned on an Imacon and their holders are very efficient in that regard (and also printed in a darkroom to check). Also it was not the first or last image on the strip.  Also in both cases the pictures were taken at no more than minutes apart from the previous frames, but different focusing distance and/or aperture.  I am afraid it is the lens, but I have no idea how to test it to replicate the effect/defect. Link to post Share on other sites More sharing options...
pgk Posted March 25, 2014 Share #4 Â Posted March 25, 2014 I am afraid it is the lens..... I doubt it if it only occurs so rarely - I can't see any way that the lens could physically change and produce this effect and if it could I think that you would notice the rattle;). My guess would be film movement - it would only take a marginal movement of the film during exposure, due to tension in the film perhaps, or springiness in the camera drive or something to do with the shutter mechanism or whatever, which on an M6 with its horizontal shutter may well only affect a part of the frame. If it starts happening more often ten a CLA might be worth considering but probably not yet if its only happened twice in 6 years. Link to post Share on other sites More sharing options...
starless Posted March 25, 2014 Author Share #5 Â Posted March 25, 2014 Thank you, Paul. Â The lens looks fine on inspection. No rattling or anything suspicious. Those early Summicrons were built like tanks. Perhaps you are right that it might be something due to film tension. I will have to speak to a Leica technician about this before sending the camera for CLA. Link to post Share on other sites More sharing options...
fotomas Posted March 25, 2014 Share #6 Â Posted March 25, 2014 Hello, Â you easily can have out of focus areas in scans even with a Flextight scanner. Especially with the long film-holders for 6 frames 24 x 36 or 120 film type. After the pre-scan sometimes the magnetic foil comes up and the film is no longer fixed there. This not necessarily leads to an unsharp scan, but could be. You have to watch this carefully. Normally this affects only the first pictures of the strip. I can't really tell by the pictures you posted. The resolution is to low for that. If you have a higher resolution available you shout easily tell yourself. If the film grain gets partly blurred than it should be a scanning issue. If the film grain stays sharp everywhere it could be film distortion during the exposure or the lens. In case of film distortion the film should only be possible to move in direction towards the lens, so the focus in the picture shifts to wider distance in this area. If focus comes closer or is totally gone it's probably the lens. But unfortunately it cloud also be the lens if focus goes to a wider distance. Â Hope this helps. Â Frank Link to post Share on other sites More sharing options...
UliWer Posted March 25, 2014 Share #7 Â Posted March 25, 2014 Advertisement (gone after registration) Well - on both photos you showed I cannot see anything which I'd call problematic. You have to take into account that the early design of the 35mm Summicron was weak in the corners, so add the out of focus region and you get bad sharpness. Â To get a realistic impression you might try a test photo of a flat surface - but take some pains to ensure that your camera is exactly parallel to the surface. If then one side is conserably less sharp than the other, there is a problem, if not, you have a good lens. Link to post Share on other sites More sharing options...
starless Posted March 25, 2014 Author Share #8 Â Posted March 25, 2014 I appreciate your comments. Â Frank: looking at the scan, the grain is consistent everywhere, including the blurred part, so it is definitely not the scan. I have 4 images in a succession from this scene, all at the same shutter and aperture, but different focusing distance. This is the only problematic one. Â Uli: I ran some tests today to see if I can replicate this, but haven't developed the film yet. It could really be a normal thing for the lens, which I never noticed before, because of never shooting wide open or near wide open. Â Thank you! Link to post Share on other sites More sharing options...
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