85mm PC-E and D700 auto mode

[ken_i_h]

<p>I have been playing with this lense with the aperture ring set at "L" and found something. Taking two photos of the same object from the same place (inside the apartment almost dusk - no flash), same ISO (non-Auto at 3200), A mode set at f/2.8 - one with tilt up and another tilt down. Tilt up, D700 chose 1/160s and tilt down D700 chose 1/500s (and no tilt at 1/320s). The result is tilt down photo is far darker.<br>

Next, switch the camera to M mode and set the shutter speed at 1/160. So, everything is on manual mode in this camera. Took photos with one tilt up and another tilt down - the brightness is almost the same. Why does camera computer bother to change the shutter speed between tilt up, non-tilt, tilt down while aiming the same object and thus end result brightness are totally different?<br>

Can someone explain why and how this is happening? If this is too obvious, sorry for my ignorance.... Thanks!<br>

Ken</p>

[dcphotography]

<p>This is why they tell you to meter with no tilt or shift movements :).</p>

[ken_i_h]

<p>Oops. Like I said, sorry for my ignorance :-)</p>

[dcphotography]

<p>Yeah, I don't know why it happens though. Maybe I'll look into it...</p>

<p>edit: Ah, one thread here on photo.net says "The TTL sensor is fussy about the angle of the light entering it".</p>

[dan_south]

<p>You have three choices.</p>

<p>(1) Meter the scene before you apply movements. This assumes that the light won't change as you focus and apply movements, i.e. you won't be able to use this approach in changing lighting considitions (such as around sunset or dusk).</p>

<p>(2) Set up your camera, make all of your movements and focus settings, and then meter with an external meter or with a second camera. You might need to make some slight adjustments if, say, the amount of shift applied darkens your image a bit.</p>

<p>(3) Take a wild guess, shoot in Manual exposure mode (M), and adjust the exposure parameters until your histogram looks about right.</p>

<p>My Pentax 67 II has the same issue when I use the 75mm shift lens. The meter won't work correctly when the lens has been shifted.</p>

<p> </p>

[ken_i_h]

<p>Thank you, folks. Sorry for my ignorance.<br>

Dan, I will take the route (1). I learn something every day!</p>