After some issues in the week with a 2x Extender that hadn’t been calibrated with the 400mm I fired up the Reikan FoCal software. Which has been updated since I last used it, so downloaded the latest release and printed a fresh target. Some 3 hours later with the laptop battery nearly dead, after 6 reboots, numerous software re-starts I was no closer to actually calibrating anything. If anything I was in a worse position than when I started as I was unable to calibrate the 400mm with the 2x or the 1.4x I decided to attempt to do just the lens on its own. BIG MISTAKE. It had then threw out my original calibration & unfortunately I hadn’t noted the original calibration details.

So fast forward to Sunday and another attempt, this time just the 400mm on its own. Now the lens & three different camera bodies are properly calibrated, hopefully I will get time tomorrow to do the 1.4x & the 2x extenders as well.

The software is quite intuitive when it works certainly a damned sight easier than doing it manually. I looked at the Canon instructions for calibration and it isn’t for the faint hearted.

Now it is properly pin, not bad for an old EF 400mm F2.8 L IS mkI.