LewisM
04-03-2013, 07:07 PM
When measuring CCD sensor from say a focal reducer, where does the measurement begin in regards to the focal reducer - I know the reference point for the CCD is the face plate of the chip itself.
Some literature has said you measure from the rear of the focal reducer housing back - yet others reference the apparent midpoint of the FR lens itself. The Vixen FL102S focal reducer has quite some distance from the lens rear to the FR encasement rear (Vixen shows a diagram of how to mount it for visual or photographic, but NO dimensions or reference points).
I need to know as I am having a custom rotatable adapter made - step from M43 x 0.75 to M42 x 0.75, but with a rotatable section in between, as the threads naturally will leave the CCD askew. Would like to get the inter-distance of the adapter spot on so I dont need spacers etc, and so, I need to know how/where to start measuring the optimum focal distance.
Some literature has said you measure from the rear of the focal reducer housing back - yet others reference the apparent midpoint of the FR lens itself. The Vixen FL102S focal reducer has quite some distance from the lens rear to the FR encasement rear (Vixen shows a diagram of how to mount it for visual or photographic, but NO dimensions or reference points).
I need to know as I am having a custom rotatable adapter made - step from M43 x 0.75 to M42 x 0.75, but with a rotatable section in between, as the threads naturally will leave the CCD askew. Would like to get the inter-distance of the adapter spot on so I dont need spacers etc, and so, I need to know how/where to start measuring the optimum focal distance.