Tokina 10-17 overexposed at 10mm

Hi,

I've noticed several times now, that my images are very easily overexposed when I'm using the Tokina 10-17 at 10mm. Even with low iso (100), a fast shutter speed (1/320) and small aperture (f22), images are often over exposed, especially with sunburst close to the surface. But when zooming in just a little bit, like 10.5 or 11.0 mm the exposure (with the same settings) is completely different: almost completely dark! Is this expected? I understand that due to the wider angle of view, more light is captured, but I didn't anticpated such a drastic change. Do I miss something?

Jef

I'd suggest getting the lens serviced. My guess is that there is something mechanically wrong with the lens, or there is oil on the aperture blades, that is preventing them from closing during exposure.

You can test this further with DOF preview.

How do I test this? Can you explain in more detail?

DOF preview button is generally on the front, to the right of the lens on Nikon. Set your camera, check your settings and then push the button to see what your picture will really look like.

http://imaging.nikon.com/lineup/dslr/d7000/compatibility03.htm

Button 6 : Depth-of-field preview button

I know where the DOF button is. My question was more like: how do I use it to confirm whether there is indeed a mechanical problem or not?

Sorry for stating the obvious.

I guess you should set your aperture to f/22 (at 10mm), check the actual aperture

of the diaphragm by looking through the front of the lens. Then do the same at

a different focal length and see if the diaphragm is smaller (or different).

Looks like you were right. At 10mm the aperture doesn't seem to close properly. If I use the aperture lever to open the aperture, it remains stuck in that position. When zooming in just a little bit, the aperture blades do close just fine.

Is this something that can easily be fixed (for a reasonable price) at a service center? I have zero experience with that.

Mine has done this for years. If zoomed to just past 10mm, the aperture sticks open, causing over exposure.

Solution is to not quite zoom to 10mm. Or get it repaired!

Alex

The lens has been repaired by Tokina and is working fine again. Thanks everyone for the good advice!