Distance from back of lens to sensor?

[Kingsly]

On a Canon EF mount camera, how far is it from the back of the lens to the image sensor (or that flappy stuff they call "film" :rolleyes:)?

I'm making a homebrew digital cine rig and need to get my measurements for the gorund glass distance right!

[astrostu]

On the top of your camera there should be an indicator of where the sensor plane is. On mine (350D), it looks like the Greek letter phi and is to the left of the built-in flash.

[Kingsly]

Wow, my eyeballed measurments were nearly correct! 1 3/4".

thanks! :)

[Big-TDI-Guy]

Are we talking about F-lengths here?

Not an SLR person (yet) but that data should be readily available on the Lens and/or the camera too.

[ChrisBrightwell]

Although Canon does not endorse (and in fact warns against) the use of third-party lenses and adapters, the EF lens mount is ideal for the use of adapters, due to its large diameter and the relatively short flange focal distance of 44.0 mm.

http://en.wikipedia.org/wiki/Canon_EF_lens_mount

[astrostu]

Wow, my eyeballed measurments were nearly correct! 1 3/4".

Although Canon does not endorse (and in fact warns against) the use of third-party lenses and adapters, the EF lens mount is ideal for the use of adapters, due to its large diameter and the relatively short flange focal distance of 44.0 mm.

1.75" = 44.45 mm. I'm guessing Kingsly will not be able to measure to the sub-mm scale so this difference won't affect it too much.

[Kingsly]

Thankfully there seems to be a bit of range in the back-focus. I was off by 1mm in my final product, but I can just compensate with the lens (DOF charts won't be accurate though... :()