Having a problem with a lens

[zulu42]

One of the lenses I got with Grandpa's Olympus omG. The lens is a 35-75mm 1:3.5-4.8. I had hopes this would be a really handy walk around lens.

I can't focus it. The focusing ring in the center always has one or both halves blacked out. If I play with the direction and angle of light I can occasionally get the whole center to be bright, and focus. But only momentarily when I get the light angle just right.

The 50mm prime doesn't have a problem on this camera.

This was outdoors. Overcast, but good daylight.

What is going on?

Thank you,

Zac

 

[Dave Colangelo]

This can be an indicator that you are in some kind of F Stop preview mode (depth of field preview) that is causing your iris to close to the set F/Stop. The decrease in light passing through can make it so the circle does not completely illuminate. This may also occur in low light situations. Its also possible that even at the lenses maximum aperture of 3.5 there is not enough light to use the split prism.

The angle playing around you describe is simply a limitation of the split prism design, there is most likely nothing wrong with the camera.

 

[zulu42]

Hi Dave, thanks for the reply. The lens aperture is totally manual, so I will try working with it some more wide open in better light.

 

[dxqcanada]

As Dave stated ... this is normal.
This happens with lenses that do not allow a lot of light in.
Just by shifting your eye position you can view half moon darkening ... just concentrate on the split part to get the image focus.