Checking of Zoom Lens
- First you should look for any scratches on
the front and rear glasses against the reflection of a fluorescent lamp.
- Turn the focus and zoom ring to see if they are smooth.
- For tele-zoom, zoom to long range, then point the lens
(lens mount side) to a fluorescent lamp*, look
through the lens from front lens side, it should be clear, then try to
focus your eyes to each lens inside to see if any scratches or dirt inside.
A little fine dust should be okay in most cases.
For wide-zoom, zoom to widest range, then point the lens
(front lens side) to a fluorescent lamp*, look
through the lens from lens mount side, it should be clear, then try to
focus your eyes to each lens inside to see if any scratches or dirt inside.
A little fine dust should be okay in most cases.
*Caution: don't point to high intensity
point source lamp, such as incandescent, halogen or compact
fluorescent lamp as the strong light might hurt you eyes.
- Check the lens-release
to see if it works then carefully mount the lens to a camera (use
your own camera if possible, since you know your camera well), zoom to
long range and look
through the viewfinder to a distance object, focus the lens to see if
the infinity mark aligned. Don't forget to check the image quality at the
edges of your viewfinder. Focus your lens to a close object and check if the
view is clear.
- Zoom to long range, fix the focus at an object, adjust the zoom from
long to wide to see if the focus will change or not. As far as I know
for all OM Zooms, the focus will not be changed during zooming, but for
some vary-focal-length lens (like the old Vivita Series 1 28-105mm zoom),
the focus will vary during zooming.
- Turn to minimum aperture, look from the lens front, release the shutter to see
if the diaphragm works.
