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Photo Forum / Digital Photography / DSLR Cameras / April 2006Nikkor 50mm F1.8 ghosting issue with D70
Hi everyone. I spent some time this evening in downtown Toronto and made some pictures, using a D70 with 50mm f1.8, non-D lens. I just took a look at the lens and it says AF Nikkor, 50mm, 1:1.8 on the front. Nikon AF Nikkor, 50mm 1:1.8, Made in Japan, on the barrel. I have a B+W F-Pro 52 010 1x filter on it. Workflow is raw file into RawShooterPro and then into PSP X. I was quite surprised when some of the pictures had blue-green circles in them. Looks to me like ghosting ... but I thought this lens would be almost impervious to that. Example pictures are at: http://rolfsphotography.smugmug.com/gallery/1303852 with white paint around the affected areas. I'm a new Smugmug user, so if there are problems accessing the site, plese let me know. What's up here? Is this normal for this lens? Do I have a bad sample of it? Should I have bought a newer lens? Anything else I should keep in mind? Many thanks for any and all feedback ... Rolf. > Hi everyone. I spent some time this evening in downtown Toronto and made > some pictures, using a D70 with 50mm f1.8, non-D lens. I just took a [quoted text clipped - 6 lines] > them. Looks to me like ghosting ... but I thought this lens would be almost > impervious to that. Definitely looks like reflections to me. Try taking off the filter. For that kind of night shot, with lots of bright light sources, the filter is always going to cause a problem. It appears that the light sources being reflected are in the pictures, so a hood wouldn't have stopped those reflections in particular, but is still a good idea for that kind of shooting, and can serve as "protection" in the absence of a filter for that purpose as well.  SignatureJeremy | jeremy@exit109.com Never use a filter when shooting at bright point sources (lights). All it takes is the 0.5% reflection at each surface to generate what you see. > Nikkor, 50mm 1:1.8, Made in Japan, on the barrel. I have a B+W F-Pro 52 010 > 1x filter on it. > I was quite surprised when some of the pictures had blue-green circles in > them. Looks to me like ghosting ... yes, it's ghosting. I'd suggest that you take off the filter unless you *really* need it. See also http://www.luminous-landscape.com/columns/sm-feb-05.shtml B. > Hi everyone. I spent some time this evening in downtown Toronto and made > some pictures, using a D70 with 50mm f1.8, non-D lens. I just took a [quoted text clipped - 10 lines] > > http://rolfsphotography.smugmug.com/gallery/1303852 In addition to what the others wrote, it is indeed a reflection. The two bright lights are originated from the headlights of the car just above the reflection. There are also two smaller lights they are also reflections, these lights appear in the windshield of the same car. If you look at the pattern of the ghost lights they are a repetition of exactly the same pattern off lights but then rotated 180 degrees over the centre of the picture. This type of reflections are normally caused by a plane glass element in the lens or in front of the lens. In your case most probable cause is the filter in front of the lens. Removing the filter normally will resolve the problem. ben > In addition to what the others wrote, it is indeed a reflection. > The two bright lights are originated from the headlights of the [quoted text clipped - 11 lines] > of the lens. > Removing the filter normally will resolve the problem. Thank you Ben and everyone else who responded. I'm now convinced it's the filter and weather permitting will be out tonight to find out for sure. I'll let you know. Rolf. >If you look at the pattern of the ghost lights they are a >repetition of exactly the same pattern off lights but >then rotated 180 degrees over the centre of the picture. If the light sources weren't clipped, it may have been possible to flip a copy horizontally and vertically, reduced its color to the blue of the ghosts, increase the gamma and subtract, but so many things are clipped that don't have ghosts, and they would be subtracted as well. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >If the light sources weren't clipped, it may have been possible to flip >a copy horizontally and vertically, reduced its color to the blue of the >ghosts, increase the gamma and subtract, Sorry, that should be "decrease" the gamma. I was thinking of the direction I had to move the slider in PS' "Levels", which is to the right. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > > http://rolfsphotography.smugmug.com/gallery/1303852 > > [quoted text clipped - 13 lines] > of the lens. > Removing the filter normally will resolve the problem. This type of ghosting occurs because some light reflects off the sensor (or film), is recollimated by the lens on the way out, then reflects off the filter back into the lens (still collimated), and is refocused by the lens into ghost images. The reflections are what cause the ghost image to be rotated 180 degrees about the optical axis, as Ben noted. If the lens is focused moderately close to infinity the ghost reflections are in focus, which makes them bright enough to be noticeable on a high contrast subject. The reflection off the sensor or film occurs all the time, but it doesn't get reimaged as an in-focus ghost unless there's a flat filter surface in front of the lens. Otherwise it's just scattered around as a low level of non image forming light. > This type of ghosting occurs because some light > reflects off the sensor (or film), is recollimated by the [quoted text clipped - 12 lines] > it's just scattered around as a low level of non image > forming light. Yes, you are correct. I finally got the chance to get out at night with the camera again and without a filter there is no problem at all. Another lesson learned. Thanks again to all that responded! Rolf. |
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