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G2 Focusing Accuracy

keoj

Active Member
Quick question on G2 autofocus. For soem on this forum, this will be an easy one. If I am trying to measure focusing accuracy, where does one measure from? As an ex&le, if I see in the DX LCD a measurement of 1.72 meters, where is plane in the camera that distance is measured to...the film plane(which is the same as the paralax that the AF sensors are set to) or is it something else? Thanks.

Joe
 
I didn't look at my G2 yet since it's not here at work. My Nikon has a mark indicting the film plane. Does the G2 have the same thing?
 
I was right! I never had a reason to know this about my G2 and I'm sure that I've looked at it a million times. But I'm glad our friend has had his question answered!
 
Joe,

If my memory right. The distance value on the LCD, according to the manual, is the distance between subject to the film plane. It's NOT necessarily the AF sensor plane coincides the film plane, as long as the perpendicular distance between two planes in known. The placement for the AF sensors is compromised with the body design.

The sensors detect the distance from the subject to the sensor plane (relatively easier 'cause only simple double-convex is used where principle points are fixed) based on contrast phase difference, then calculates the subject distance to the film plane.

Rgds, David
 
Colin, Yes G1 does have the mark for the film plane and the distance reading. Rgds, David
 
"I didn't look at my G2 yet since it's not here at work. My Nikon has a mark indicting the film plane. Does the G2 have the same thing?"

K Michael,

If your Nikon takes zoom lens, distance marks on the lens will be the distance from the subject to the lens front element.

Rgds,
DAvid
 
I've measured from the film plane to the subect and then set the lens to the correct distance mark. The pictures have always been in focus.
 
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