There have been a number of reports regarding the Blackmagic Cinema Camera and getting proper infinity focus with quite a few lenses. Earlier in the month we showed you a few videos documenting the issue, and Blackmagic so far has been very responsive, telling us at that point that they were looking into the issue. We now have a solution straight from the company, and it looks like it's going to be a hardware fix if your camera has already been delivered.
Here was the issue, along with one of the worst offenders so far, the Tokina 11-16mm lens:
I want to give you an update about this issue.
The cameras are all shimmed and calibrated to 44mm as per the reported focal flange depth of EF mount. I use the term "reported" as Canon does not publish the specifications officially so the exact expected tolerances are not known.
When checked against a collimated cine lens, we expect the Blackmagic Cinema Camera to get accurate focus according to the witness marks on the lens. For example, at focus chart placed 6 ft from the camera sensor plane will be in focus when the witness mark on the lens is at 6 ft.
When I tried the same collimated lens on some 5Ds, 7Ds and even a C300, the witness marks fall short of the expected distance which indicates to me that there's some fair amount of tolerances built into the Canon cameras to cater for still lenses where the tolerances are not as critical as cine lenses.
To address this, we need to put in the same allowances. We have tested this with some of the cameras from customers reporting this and it works.
If you think you're encountering this issue, please contact your local Blackmagic Design support office and we'll sort you out.
More from Kristian, on whether cameras will need to be sent back, and if this will fix the issue with the Tokina lenses:
1) Unfortunately, yes. The camera will have to be sent back to be recalibrated.
2) Yes, it will. However, this is on the assumption that the copy of the Tokina 11-16 is good as I've read that there are some out there with issues focusing to infinity on other cameras as well.
So the issue stems from the fact that Canon is building in some leeway for their lenses to account for those that might not have the strictest of tolerances. While Blackmagic built the camera to the stated EF mount specifications, there seems to be a slight difference between the stated spec and the actual spec. The good news is that the issue will be fixed, and all lenses should work the way they do on every Canon camera (meaning if there are problems with the lens on a Canon camera, there will also likely still be problems on the BMCC). Unfortunately it does mean that if you are currently experiencing the issue, you will have to send your camera in to have the issue fixed.
All new cameras that are shipping at this point will already have this fix in place, so if you haven't received your camera yet, you shouldn't have a problem when you do receive it.
If you have already taken delivery of your BMCC and you are experiencing issues, you should file a support ticket. Click here, or you can find the link to their support page below. Once there, fill out the information as if you were preparing to download a firmware update or the camera's manual, and you'll find the telephone number or send request button at the bottom of that page (pictured above). The problem will be covered by the camera's warranty, but there may be shipping charges involved to send the camera to Blackmagic.