Bob Latham
New member
I have a question for the mathematicians/theorists amongst you good gentlemen........
I have just changed to using my 1DMkIII as my macro body now that I'm happy with the 1DMkIV for larger wildlife species. Previously I've used 40/50D (occasionally 5DMkII) for macro and installed split prism focussing screens to them for accurate manual focus.
I have obtained several split prism screens (OEM versions) for the 1D/1Ds bodies and find that they are giving about 1mm back focus (clearly identifiable when comparing to Liveview and the final image). Canon supported the 40D/50D and 5DMkII with shims (washers in Canon parlance) for calibration but they don't have the same offerings for the 1Dsrs bodies.
Don't worry, we're there now.......
Is it possible to calculate the required shim (or shaving!) required based on the amount of back/front focus being experienced?
I know that I could find the result by simple (albeit fiddly) experimentation but I'd be much happier if I could achieve it by understanding the calculation.
Many thanks in advance folks.
Bob
I have just changed to using my 1DMkIII as my macro body now that I'm happy with the 1DMkIV for larger wildlife species. Previously I've used 40/50D (occasionally 5DMkII) for macro and installed split prism focussing screens to them for accurate manual focus.
I have obtained several split prism screens (OEM versions) for the 1D/1Ds bodies and find that they are giving about 1mm back focus (clearly identifiable when comparing to Liveview and the final image). Canon supported the 40D/50D and 5DMkII with shims (washers in Canon parlance) for calibration but they don't have the same offerings for the 1Dsrs bodies.
Don't worry, we're there now.......
Is it possible to calculate the required shim (or shaving!) required based on the amount of back/front focus being experienced?
I know that I could find the result by simple (albeit fiddly) experimentation but I'd be much happier if I could achieve it by understanding the calculation.
Many thanks in advance folks.
Bob