focus point affecting matrix meter?

My F5's focus point changes the meter reading by a 1/3 stop. Is this

an error or is it a feature meant to fine tune exposure. When hand

holding indoors, metering for ambient light, changing the focus point

alters my reading in matrix mode. Thankyou for your answers.

Are you using a D lens and what type of lens? It may be that the focusing point may tell the matrix metering to emphasisze the segment that the focus point is in. this could change your exposure depending whether the tonality in the focus point is different than the rest of the image.

Jonathon I was using a 50mm 1.4 auto focus and I assume D compatible. I placed the focus point on a lit painting and the to an area that was unlit. I was practicing my exposure compensation when I noticed the matrix was not constant regarding the focus point.

The 3d Color Matrix meter in the F5 isn't an averaging type meter and yes

changingthe focusd on area will bias the meter to some degree to take into

account your implied choice of most important area. it may also be affected by

the different color of light in that area and also possibly by the movement ofthe

lens' nodal point when focusing aon a different area (assuming that you are

photographing a wall that is parallel to the film plane.