FoCal and Canon 6D support – update

FoCal and Canon 6D support – update

We’ve been getting reports that some (not all) Canon EOS 6D cameras can give erratic results using FoCal. The symptoms manifest as FoCal reporting that it needs to take more shots because of inconsistent results and the resultant graph has shots that are as sharp across all AFMA values. We’ve tracked this down to an issue with changing the AFMA value automatically. For some reason the camera doesn’t always respond to changes of AFMA made via the SDK. We’ve seen this once after some heavy testing after the the first reports came in. It doesn’t seem linked ot any particular feature (we’ve combinations of custom functions such as disabling shutting release before connecting to FoCal) and it doesn’t seem reproducible. In fact the one time we saw this behavior it was after changing lenses with the power left on and connected to FoCal.

What we have found in all cases so far that setting the AFMA to ‘per lens’ and making a change by hand to the AFMA value seems to make the camera behave as expected. So if you see this problem please go into the AFMA settings and set it to per lens and then change the value on the lens you’re testing to say -1. Don’t worry FoCal will make all the actual changes automatically. We’re trying to isolate the problem but as you can appreciate the fact that it appears to be un-reproducible at this point makes it hard to determine if its genuinely a problem in the Canon SDK or elsewhere.

Many thanks for your understanding and we’ll update you as we learn more. In the meantime please continue to use the above workaround until this issue is resolved.

Thanks and all the best from the FoCal Team.

3 comments on “FoCal and Canon 6D support – update

  • I purchased Focal Plus yesterday, and ran into this kind of problem. I calibrated Sigma 35mm 1.4 many times without problems. I ran into this problem each time with Sigma 85mm 1.4 though and never managed to calibrate it. And sometimes the software said that there is problem obtaining image info “retry or stop” and that lead to the program crashing. That was problematic because then the settings Focal made to the camera were not reset, and the camera had MUP on etc.

    • Hi Miika

      I’m sorry you’ve had some troubles. We don’t have a Sigma 85/1.4 in the lab all the time but have done a fair amount of testing with it without any significant issues. We have noticed that Sigma lenses in particular can be a little susceptible to “Failed to Focus” errors at certain specific distances (especially the Sigma 50/1.4). You may find that if you rerun the test with the camera moved a little (20cm or so) either nearer or farther from the target you will get a successful test result.

      Note that this issue is not a problem with FoCal – there seem to be certain times where the camera will fail to report AF lock with some lenses even when manually controlled (i.e. disconnect FoCal and try to take a shot by pressing the shutter button and the camera will fail to focus).

      With regards to restoring the camera settings – before any test starts, FoCal saves the camera settings to disk. If you have any issue and FoCal crashes, if you immediately restart FoCal and connect to the camera you will be given the option to restore the camera settings at this point.

      I hope this helps


  • Some feedback. I purchased FoCal recently to use with my 6D, and calibrated the 24-105 with it just fine; my 50mm 1.8 just fine, but it barfed on the short end of my Tamron 70-300 VC. It got the 300mm end at +6, but would not for the life of it do the short end. I just set it at +6 as well. I’m usually using at or very near 300mm anyway.

    No complaints other than this small issue. Just thought you might like to have another data point for your troubleshooting.

    I think my 24-105 & 50 are definitely producing better images after adjusting with FoCal.


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