jaapv Posted August 5, 2012 Share #121 Â Posted August 5, 2012 Advertisement (gone after registration) There is also a consideration of the weight distribution. If it is concentrated up front it makes matters worse. Link to post Share on other sites More sharing options...
Advertisement Posted August 5, 2012 Posted August 5, 2012 Hi jaapv, Take a look here SLR Magic 50mm f0.95 M Lens. I'm sure you'll find what you were looking for!
ashwinrao1 Posted August 5, 2012 Share #122 Â Posted August 5, 2012 The bayonet has a spring mount, and with a heavy lens there is a possibility that the top of the lens will "lean" against the mount, and throw the RF roller out of adjustment. Â Possibly counteracted by supporting some of the weight of the lens with a hand when adjusting focus? In this manner? Â Â Alternatively, I'd be curious as to what long term impacts that carrying around a body with said lens or other heavy M lens (i.e. noct) may have on the mount and RF roller... Link to post Share on other sites More sharing options...
Rick Posted August 5, 2012 Share #123 Â Posted August 5, 2012 975g vs 780g for the 135/f2.8... that is about 200g difference or less than the weight of the little 90 macro elmar. Not much difference in weight. I doubt the problem is with the Leica M mount. Â So, it would seem like, if it isn't a problem with the Leica M mount distorting, I guess we are back to the complexity of designing a shipping box. Link to post Share on other sites More sharing options...
jaapv Posted August 5, 2012 Share #124 Â Posted August 5, 2012 My R cameras used to get the mount bent due to carrying the 280/4.0 to the extent of having them repaired each time after extended use. Link to post Share on other sites More sharing options...
pop Posted August 5, 2012 Share #125 Â Posted August 5, 2012 Is this the reason why the 135mm 1:2.8 has its own tripod mount? Link to post Share on other sites More sharing options...
Rick Posted August 5, 2012 Share #126 Â Posted August 5, 2012 My R cameras used to get the mount bent due to carrying the 280/4.0 to the extent of having them repaired each time after extended use. Â Interesting if, we were talking about the R mount. Â Come on this has been a fun exercise regarding pointing fingers at the M mount but, isn't this just another excuse for a poorly designed lens. This has long since left the area of being just a little disingenuous when SLR claimed they were having problems with the shipping boxes and were halting shipment for a month to redesign the box. Do we have to dissect this mount excuse now? Link to post Share on other sites More sharing options...
jaapv Posted August 5, 2012 Share #127 Â Posted August 5, 2012 Advertisement (gone after registration) Anyway, we are talking here about the lens giving against spring pressure due to its weight, not about the mount distorting, which is a convincing scenario imo. Link to post Share on other sites More sharing options...
bill Posted August 5, 2012 Share #128 Â Posted August 5, 2012 So here we have a lens that is heavier than any that Leica make and it is allegedly causing problems with the mount. That doesn't sound like a Leica problem... Â Game over. Â Regards, Â Bill Link to post Share on other sites More sharing options...
gyoung Posted August 5, 2012 Share #129 Â Posted August 5, 2012 The bayonet has a spring mount, and with a heavy lens there is a possibility that the top of the lens will "lean" against the mount, and throw the RF roller out of adjustment. Â This does happen with the Komura 2x converter I have if a heavy lens is used, I wondered why my pics with 135 Elmar were out of focus! You need to support both camera and lens. Â Gerry Link to post Share on other sites More sharing options...
andyedward Posted August 5, 2012 Share #130  Posted August 5, 2012 975g vs 780g for the 135/f2.8... that is about 200g difference or less than the weight of the little 90 macro elmar. Not much difference in weight. I doubt the problem is with the Leica M mount. So, it would seem like, if it isn't a problem with the Leica M mount distorting, I guess we are back to the complexity of designing a shipping box.  Thomas Crapper (1836-1910) perfected the method by which the SLR Magic should now be shipped. Its called the "flushing toilet" Link to post Share on other sites More sharing options...
M9reno Posted August 5, 2012 Share #131  Posted August 5, 2012 That's a wake-up call, if true. What a terrific oversight. Factoid:  These numbers say it all. I have never been gladder to "settle" for f/1.4 maximum aperture. Link to post Share on other sites More sharing options...
jaapv Posted August 6, 2012 Share #132 Â Posted August 6, 2012 Is this the reason why the 135mm 1:2.8 has its own tripod mount? I would not be surprised if that were the case. Link to post Share on other sites More sharing options...
brianv Posted August 6, 2012 Share #133 Â Posted August 6, 2012 Lenses with their own tripod mounts: more to relieve stress that would be induced on the camera's tripod mount rather than the lens mount of the camera. Link to post Share on other sites More sharing options...
mmradman Posted August 6, 2012 Share #134 Â Posted August 6, 2012 On point of mechanics; once you attach lens, regardless of the weight of the lens, to a camera body & lens flange remain parallel so there should be no stress on the camera if overall combination is held/supported at centre of gravity. I can't see how this would be a problem and would love somebody to provide technically sound explanation. Â Problem starts if you try to fix top heavy camera on a tripod, for that reason well designed heavy lenses, mostly teles, come with own tripod foot and often carrying lugs/strap, warning too not to carry combination by camera strap. Link to post Share on other sites More sharing options...
farnz Posted August 6, 2012 Share #135 Â Posted August 6, 2012 Mladen, Â There is a turning moment comprising the weight of the lens and the distribution of its weight over its length (FxD) because the lens is essentially a cantilever if not supported. Â Pete. Link to post Share on other sites More sharing options...
mmradman Posted August 6, 2012 Share #136  Posted August 6, 2012 Mladen, There is a turning moment comprising the weight of the lens and the distribution of its weight over its length (FxD) because the lens is essentially a cantilever if not supported.  Pete.  Agree, but it only works on top heavy not evenly supported camera+lens combinations.  I still can't see how marginally heavy lens can affect camera flange & focus wheel nestled behind. Both camera and lens flanges are metal flat rings with decent width and diameter and geometry (parallelism) shouldn't change unless there is a very loose fit. Only stress would be on the camera body to which flange is fitted to or tripod bush if handled wrongly.  In case of M & earlier RF cameras there were front heavy accessories intended for handheld shooting e.g. Visoflex & Lens so i can't see how 900 g or 2 lb lens is worse than 700 g pound and a half approx.  Let's face it Lens Magic or what ever name contender is suffering from own internal ailments nothing to do with lens to camera interface. Link to post Share on other sites More sharing options...
farnz Posted August 6, 2012 Share #137 Â Posted August 6, 2012 Agree, but it only works on top heavy not evenly supported camera+lens combinations. Â I still can't see how marginally heavy lens can affect camera flange & focus wheel nestled behind. Both camera and lens flanges are metal flat rings with decent width and diameter and geometry (parallelism) shouldn't change unless there is a very loose fit. Only stress would be on the camera body to which flange is fitted to or tripod bush if handled wrongly. .... I'd expect that the failure mode would be distortion of the mounting rings from excessive loading (downward force) imparted by a lens. The distortion might not be visible to the naked eye and there only needs to be a 0.1 mm delta to cause a focussing problem (according to brianv in post 114). (I presume) the mounts are designed to cope with a certain load based on Leica's heaviest lens and a margin so if another lens exceeded the loading then mount failure (even if not catastrophic) could be expected. Â Pete. Link to post Share on other sites More sharing options...
Phil U Posted August 6, 2012 Share #138 Â Posted August 6, 2012 Let's face it Lens Magic or what ever name contender is suffering from own internal ailments nothing to do with lens to camera interface. Â +1 Link to post Share on other sites More sharing options...
jaques Posted August 6, 2012 Share #139  Posted August 6, 2012 (I presume) the mounts are designed to cope with a certain load based on Leica's heaviest lens and a margin so if another lens exceeded the loading then mount failure (even if not catastrophic) could be expected. Pete.  I would presume the mount would be significantly over-engineered to cope with stress far great than the heaviest lens alone would impart. For instance if the camera is mounted on a tripod; and a hand rested on the lens: the force on the mount will be considerably greater than would be the case from the weight of the lens alone... Link to post Share on other sites More sharing options...
farnz Posted August 6, 2012 Share #140 Â Posted August 6, 2012 I also would hope so, which is where the margin I mentioned comes into play. But, as in all things, a higher spec generally means more cost so the blessed bean-counters may have had their way and the mounts designed for enough rather than having a safety factor of 2 or 3 that would allow for resting hands, stabilising bags et al. I don't know either way so this is pure conjecture based on more years of Engineering experience than I care to recall. Â Pete. Link to post Share on other sites More sharing options...
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