abufletcher Posted July 13, 2003 Share Posted July 13, 2003 Does the location of a scratch make any difference. For example, is a scratch on the rear element less of a problem than a scratch on the front element -- or vice versa? What about a scratch on an interior element? Link to comment Share on other sites More sharing options...
ralph_barker Posted July 13, 2003 Share Posted July 13, 2003 It would seem to me that a scratch on the rear element would have a greater potential for adversely affecting the image than one on the front element. The logic being that at the rear element, the final image has been formed. It would follow that a scratch on an interior element (e.g. on a lens where the front assembly is removeable) would be potentially more of a problem than one on the front, but less than one on the rear. Flare-wise, however, the reverse might be true. The position of the scratch, center vs. edge, is probably more of an issue. The preferred location of a scratch, of course, is one someone else's lens. ;-) Link to comment Share on other sites More sharing options...
peter_n1664876959 Posted July 13, 2003 Share Posted July 13, 2003 Depends on the size of the scratch. Don't know about the rear, but I would think that a scratch on the front element might only be a problem in macro work - you should be OK otherwise. Link to comment Share on other sites More sharing options...
jay_. Posted July 13, 2003 Share Posted July 13, 2003 Surely this can't be a relevant topic for the Leica Forum as we've all been assured that Leica coatings are scratch-proof ;>) But if you're in the same parallel universe where I live, where Leica coatings can be scratched, and someone failed to use a good quality UV filter (such as a B+W MRC)and there is a scratch on your front element then its effect on the image increases the longer, deeper and closer to the center of the lens it happens to be. Multiple faint "wipe marks" will not affect sharpness or cause flare hotspots, but they will reduce overall contrast. Scratches on the rear element (which can't be protected with UV filters on most lenses)are 100% avoidable, if you always quickly replace the rear caps, and change lenses very quickly, and shield with your body or change down inside your bag if the wind is blowing. But actual scratches in the glass anywhere on the rear element are much more serious in terms of loss of performance, though by contrast, faint wipe-marks are less contrast-robbing than on the front element. Link to comment Share on other sites More sharing options...
rolpahof leikonblad Posted July 13, 2003 Share Posted July 13, 2003 As far as one lens element is concerned, the scratch at the center is the worst. Link to comment Share on other sites More sharing options...
sammer Posted July 13, 2003 Share Posted July 13, 2003 I have a nikon lens with a scratch on the rear element (pretty long but not at all deep - right in the center) and have never observed any impact on image quality. I would think that the same scratch on the front element would certainly make the lens more flare prone; however, I wouldn't expect it to affect image quality otherwise. Link to comment Share on other sites More sharing options...
albert knapp md Posted July 13, 2003 Share Posted July 13, 2003 Rear element scratches are far more serious than front element ones BUT... there are other important factors including the location, extent and depth, SO... one cannot make a generalization! UV filters and caution changing lenses (and capping them ASAP are good habits that will prevent scratching. Link to comment Share on other sites More sharing options...
matt_m__toronto_ Posted July 13, 2003 Share Posted July 13, 2003 has anyone used a scratched lens for a desired effect? or scratched a lens on purpose to go for a look? i've got an old zoom lens for my nikon that i was thinking of giving away, and am now wondering what would happen if i lightly sandpapered the rear element...any one here experiment with this? m Link to comment Share on other sites More sharing options...
kevin_baker___heidelberg_ Posted July 13, 2003 Share Posted July 13, 2003 Matt, I always sandpaper the rear element on my new lenses. It really softens that irritating sharpness the Leica glass produces... :-) Link to comment Share on other sites More sharing options...
al_kaplan1 Posted July 13, 2003 Share Posted July 13, 2003 I'd be leary of a lens with an interior scratch. Somebody took it apart and wasn't careful. I'd wonder if it had been properly put back together! Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted July 13, 2003 Share Posted July 13, 2003 Most all stratches are due to cleaning; ie caused by humans rubbing; fondling; scrubing of the surfaces in a circular motion.......Actually the worst lenses I have seen abused are on Rolleiflex's; where the f2.8 taking lens are really all abused; like the camera was taken to the beach; and then wiped clean with sand still on the element...........Sometimes dealers will swap out the front element only; from a junker; and the focus will be goofed up; and the collector/user will declare that his Xenotar or Planar is crap.........................Usually a rear scratch is more damaging to a lens; but a front scratch seams to drop the contrast...in telescopes; one blackens the open pits; that dont get removed when grinding a mirror......Blackening the scratch with black matte india ink will up the contrast of your favorite Leica lens; but radically drop the value! <BR><BR>it takes time to get the crud off; that gets cemented to a front element. Forcing the cleaning issue; but a too quick cleaning; causes the crud to scratch the element........This is like brushing ones teeth; while having a mouth full of sandblasting grit; and wondering why ones teeth are getting scratched and worn out....<BR><BR> Link to comment Share on other sites More sharing options...
alex_lofquist Posted July 13, 2003 Share Posted July 13, 2003 The closer that the scratch is to the rear nodal point (surface), the less likely it is to affect the final image. For a symmetrical design, the question is probably moot. More important is the location with respect to the optic axis. If a scratch really bothers you, the effect can be suppressed by filling it with India ink which will eliminate most scatter. I bought a 50mm Summicron with a light scratch on the rear element, but can see no deleterious results. Link to comment Share on other sites More sharing options...
kevin m. Posted July 13, 2003 Share Posted July 13, 2003 Scratches are great because they allow you to pick up a lens you normally couldn't afford for a reasonable price. Link to comment Share on other sites More sharing options...
jay_. Posted July 13, 2003 Share Posted July 13, 2003 And the original owner saved the cost of a UV filter. Everyone wins! Link to comment Share on other sites More sharing options...
wind.dk Posted July 13, 2003 Share Posted July 13, 2003 Generally a scratch on the rear element has as much greater an effect as the rear element is smaller than the front, as that is an indication of how much greater a part of the light is affected. But on the front element there's more light hitting the scratch, which shouldn't be part of the final image, but is scattered into it by the scratch, so it will produce more flare compared with it's relative size. Which of the two effects is the greater will depend both on the specific lens design and the conditions for a particular photograph, but on the whole, I think I'd prefer a scratch on the rear element. (The final image isn't formed at the rear element, it's formed at the film plane or maybe focus plane is more accurate) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now