Case You want to replace the shutter in a newer Canon camera, you will have to take out at first the sensor. And the sensor is positioned regarding the flange NOT with the help of some adjustment washers, but with springs and adjustment screw.
Please trust me: you will NOT be able to put it back only by marking the original position, or counting the rotations of the screw. We are talking about the precision of 0,01 mm at least.
Somebody told me, that the description of the dial gauge holder was not clear enough – so here You have a more detailed description. Sorry for the photo quality – has been made with a phone)
At first, here is the distance, You should measure. Better to say, only one of them, the other 2 they are not accessible at all. But does it have any sense to be measured with a caliper?
Of course: NOT.
Even the precise calipers are not made for this type of measuring. So, You will need a stand for a dial gauge, and a fixture for the camera, to make possible, to hold it with high repeatability under the gauge.
The distance is about 43.0-45.0 mm – o You would need a digital gauge in the 0 – 50 mm range. Not cheap.
I decided to make a cheaper solution, so I used a 0 – 12,5 mm gauge, 0,001 mm resolution (don’t confuse resolution with precision – in this case, the real precision is probably 0,01 mm.
At first, we will set the “0” display using a 40,0 mm steel block – just to make possible a later measurement. I use a steel block made of HSS steel, used as a lathe cutting tool. Important is, that it should be hard and with perfect parallel faces. (I let this made on a grinding machine). You can use for example a 200x20x20 mm bar, cut with an angle grinder to pieces.
2 pieces together give approx 40 mm. The exact size does not count – important is only, to be able to use always the same “etalon”
Now put the steel block on the base surface, and set zero on the dial gauge (the base surface is made of a hard steel plate, in my case on the internal part of a Delphi diesel pump)). This is the most important part – it has to be a perfect plane.
This is the original displayed value, before zeroing:
And this is after pressing the ZERO button.
Now You can take off the steel block. (Next time You can set the same zero point using the same steel block again.
On the CMOS you have to mark the 3 measuring points with a cross, and letters: A, B, C.
Now you position the measuring tip on the cross and measure the height.
Don’t forget to add the 40,0 mm to this, and write it on a card:
Remember, the adjustment screws have TORX head, to help You to rotate them without axial force.
Don’t push or move the CMOS plate during measuring. The case you press it will change its position, and You cannot put it back to the right position. Excepting the case You measured it before…)