Does your camera "lift"?

Hi D,
It sounds like the camera refocuses when you actually take a shot.

If you have enough depth of field and the subject is not going to move
outside that range you could switch off the focus. As well as not
getting the lens movement you may also reduce the dead time between
pushing the button and the shot being taken
I hope this helps.

Cheers,
Allan


On Sun, 24 Dec 2006 18:25:05 GMT, Dingo
wrote:

Imagine you are at a red light. When the light turns green, you stomp
on the gas. For a very brief second, the car's front end feels as
though it lifts up.

Similarly, I have a Nikon D100 mounted on a Manfrotto 3039 head, aimed
outside at a bird feeder. FWIW, it's a 24-120mm lens, currently set
around 80mm or so. When I press the shutter release halfway to
focus, I see the image shift ever so slightly in the view finder, as
if the lens has lifted minutely.

From this position, the image never moves, until I either take a shot,
or remove my finger, at which point the camera returns to its "I'm not
about to take a shot" mode...in other words, back to its original
position.

I hooked up my remote release using the IR trigger, and I can see the
same effect. I hear the lens focus and see the image shift in the
view finder

Hand holding doesn't seem to show this effect.

Is this common on tripods? Is this just me? Perhaps I've never paid
attention because I've always been actively shooting--in this
instance, I've just been waiting for the birds to show.

My current theory is that when the lens receives power to focus and
shoot, the internal mechanism is causing some very slight movement.
One final note, I've examined the tripod and head, and they are both
solid.

Thoughts anyone?

Merry Christmas.

--D