100-400mm Problem
/forum/topic/790936/0

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mogan
Registered: Dec 18, 2005
Total Posts: 177
Country: United States

Here's a mystery I have yet to solve...

My 1dsMkII takes perfect photos with my basic 24-70L lens. However, when I use the 100-400L, images are underexposed by about 2 stops.

I already sent the lens and camera to the factory for repair and it's still a problem.

Thoughts?

KaaX
Registered: Apr 09, 2009
Total Posts: 290
Country: N/A

Diaphragm problem in the lens...

Kaa

EB-1
Registered: Jan 09, 2003
Total Posts: 18217
Country: United States

Can you determine if it is an aperture problem or not? Does the diaphragm open completely when you look into it on the camera, and close when set to a smaller aperture? What are the camera readings for the 100-400 vs. a known, good lens?

EBH

mogan
Registered: Dec 18, 2005
Total Posts: 177
Country: United States

I did some added playing with the camera/lens.

In manual mode once the light meter has been activated, I get different meter readings if the shutter putton is pushed halfway or not. It doesn't behave this way when using my 24-70. A meter reading is a meter reading regardless of what you do with the shutter button. Does this suggest anything about my problem?

mogan
Registered: Dec 18, 2005
Total Posts: 177
Country: United States

Oy!

Just tried the body with a 600mm lens. Same problem as with the 100-400mm. Ideas?

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