File :-(, x, )
thefamilyman
Ever wondered how a D type lens hows the distance of the subject?

pulling apart my broken 50mm f/1.8D i saw how the lens knows the distance via the focus ring.

you can see here how it has little arms that rub against 3 tracks, these intern decode into the position of the focus ring thus telling the camera how far the subject is.
EXIF data available. Clickhereto show/hide.
Camera-Specific Properties:Equipment MakeNIKON CORPORATIONCamera ModelNIKON D70Camera SoftwareAdobe Photoshop CS2 WindowsMaximum Lens Aperturef/4.6Sensing MethodOne-Chip Color AreaColor Filter Array Pattern822Focal Length (35mm Equiv)123 mmImage-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution300 dpiVertical Resolution300 dpiImage Created2007:05:24 00:17:10Exposure Time5 secF-Numberf/11.0Exposure ProgramAperture PriorityExposure Bias0 EVMetering ModePatternLight SourceTungstenFlashNo FlashFocal Length82.00 mmCommentCopyright 2007 Patrick BridgmanColor Space InformationsRGBImage Width1024Image Height681RenderingCustomExposure ModeAutoWhite BalanceManualScene Capture TypeStandardGain ControlNoneContrastNormalSaturationNormalSharpnessHardSubject Distance RangeUnknown
>> thefamilyman
     File :-(, x)
this is the chip that decodes the tracks and sends it to the camera (hence CPU lens)

Camera-Specific Properties:Equipment MakeNIKON CORPORATIONCamera ModelNIKON D70Camera SoftwareAdobe Photoshop CS2 WindowsMaximum Lens Aperturef/4.6Sensing MethodOne-Chip Color AreaColor Filter Array Pattern822Focal Length (35mm Equiv)123 mmImage-Specific Properties:Image OrientationTop, Left-HandHorizontal Resolution300 dpiVertical Resolution300 dpiImage Created2007:05:24 00:17:41Exposure Time1.6 secF-Numberf/8.0Exposure ProgramAperture PriorityExposure Bias0 EVMetering ModePatternLight SourceTungstenFlashNo FlashFocal Length82.00 mmCommentCopyright 2007 Patrick BridgmanColor Space InformationsRGBImage Width1024Image Height681RenderingCustomExposure ModeAutoWhite BalanceManualScene Capture TypeStandardGain ControlNoneContrastNormalSaturationNormalSharpnessHardSubject Distance RangeUnknown
>> Anonymous
>>49831
>>49833
OH THE HUMANITY.
>> Anonymous
Very interesting, thanks! Thankfully, I don't have a broken lens to dismantle!
>> Anonymous
Seeing your broken lens sure makes me feel stupid now for not getting the $75 insurance Ritz offered me on this $120 lens.