DSLR camera body - distance to sensor

[Jammy]

Hi there

Does anybody know what the distance in mm is from the front of a Canon EOS 600D camera body to the sensor inside?

I've been trying to find it on the internet for the last two hours and I've seen conflicting information.  Does anybody know the definitive answer?

I don't really want to be poking a tape measure inside my camera 

I thought I'd best come onto SGL and ask the experts 

I'm trying to work out what I need to buy to get 105mm back focus from Celestron f6.3 focal reducer to camera - and to fit an off axis guider in there somewhere (not bought one yet).

It's all very frustrating!! 

[JohnC64]

44mm springs to mind.  take a look here, it has most of the backfocus of different cameras

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

cheers john 

[Jammy]

Thanks John. I didn't think to look on Wikipedia.

Now I just need to work out what else I need

[lensman57]

Hi there

Does anybody know what the distance in mm is from the front of a Canon EOS 600D camera body to the sensor inside?

I've been trying to find it on the internet for the last two hours and I've seen conflicting information.  Does anybody know the definitive answer?

I don't really want to be poking a tape measure inside my camera 

I thought I'd best come onto SGL and ask the experts 

I'm trying to work out what I need to buy to get 105mm back focus from Celestron f6.3 focal reducer to camera - and to fit an off axis guider in there somewhere (not bought one yet).

It's all very frustrating!! 

Hi,

44 mm is the correct  distance , which by the way is the back focus of the canon EF and EFS lenses.

A.G

[pixelsaurus]

 

http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html

[Russe]

Thanks John. I didn't think to look on Wikipedia.

Now I just need to work out what else I need

M48 adapter, coma corrector

Or/and

M42 adapter, 1.25" or 2" T-mount adapter

And clear skies...

[Jammy]

Hi,

44 mm is the correct  distance , which by the way is the back focus of the canon EF and EFS lenses.

A.G

Does this mean that the 44mm is from the back of the lens to the face of the sensor, and not from the outside of the lens mount?  I know it's not that critical really, just curious.

[lensman57]

Does this mean that the 44mm is from the back of the lens to the face of the sensor, and not from the outside of the lens mount?  I know it's not that critical really, just curious.

The distance is from the flange to the sensor, if you buy one of the better constructed T adapters distance sould be about 55mm which is the correct backfocus distance for for the standard SW or Televue Ff/FRs.

A.G

[laser_jock99]

A comprehensive list of CCD FLANGE DISTANCES

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

[IanL]

Most of the Canons will have a marker on the body which looks like it shows the plane of the sensor (though I guess it might be for measuring flash distances instead).  It is a small circle with a line through it (e.g. on the 500D is is on the 'shoulder' to the left side of the pop-up flash). If it is the sensor not much use if you're trying to measure to the face of a reducer or similar since the mark is too far above it to be much help; probably more helpful for measuring distance to a still-life or macro subject for daylight use so probably the flash.

[Jammy]

Thanks for the info guys.

Am I correct in thinking that to get the correct spacing to camera sensor from focal reducer I need to subtract 44mm from the optimum 105mm (for Celestron f6.3 reducer/flattener), leaving 61mm?

I've just measured the length of my Celestron SCT adapter (#93633-A) and it measures 60mm.  Fantastic!

Only problem is that this doesn't leave any room for a OAG.

I assume that if I use an OAG which is, say, 13mm thick, I'd then need adapters and extension tubes to make up the remaining 48mm length?  Sorry if this is basic, but I want to make sure I buy the correct equipment.

Thanks again for your help, it's much appreciated