Will a single semi-circular coating scratch on the rear element produce any image

[awilder]

I inadvertantly put a single semi-circular hairline scratch on the rear element of a 50/1.5 C Sonnar located mid-peripherally on the glass. Fortunately, the center portion of the glass is spared so not all light rays are affected. By f/5.6 the aperture blocks any rays from reaching the affected area. Other than causing a significant loss of potential resale value, will it have any decernable effect on image quality and flare given the use of T* coating?

[ClaremontPhoto]

A rear element scratch is more detrimental than a front element scratch.

Try using it and see in varied conditions, and using your knowledge of image quality, to judge if you've messed up or if you're a lucky guy this time round.

[ZorkiKat]

Rear element scratches sometimes show in my Epson R-D1s shots. Lens in question is a Jupiter-12, whose rear element comes very close to the focal plane. The scratches which show in the picture are likely reflections caught on the sensor's shiny surface bouncing off the rear element.

[Roberto]

Originally Posted by awilder

I inadvertantly put a single semicircular hairline coating scratch on the rear element of a 50/1.5 C Sonnar located mid-peripherally and about 3/4 of a circle in length. Other than causing a significant loss of potential resale value, will it have any decernable effect on image quality and flare given the use of T* coating? I seriously doubt it goes down to the glass, just the coating itself.

A friend of mines told me to hold the lens under examination with the front element close to your eye, then use it like a loupe to read some paper or something with lot of details, do it in bright light.

He said every issue you see this way, it'll be in the picture..

Not sure this is true.. but it's easy to do.
R.