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Focal Flange Distance Fix

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  • Focal Flange Distance Fix

    The Thread On Blackmagic's Official Forum:

    Direct Link to Kristian Lam's post:

    Originally posted by Kristian Lam
    Hi guys,

    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.

    Looks like you'll have to send your camera to the nearest BMD office to get it fixed, but it is a fix.

    If you send your camera back, which I imagine a lot of people will be doing, let us know how fast you had it returned, condition, how you shipped, etc etc.

    These will likely be repeated questions here.

    Eventually I'll unstick this thread, as I imagine the cameras going forward will not have this problem.

    SKYPE (best way to talk to me): Camera_Kholi | twitter
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  • #2
    I wonder how we'll know if the camera coming from a seller is pre or post fix... I mean in this early stage. Since we have no idea when sellers get cams . And I'm talking about before one gets the cam to avoid having to send it back. I imagine later on it won't be an issue as all cams will be sent out with the fix. I also wonder if you can delay your camera shipping to get a "fixed" cam. I guess that option rests with the seller. Or maybe BM will recall the cameras which are now at the resellers and fix them before they ship... which would be a good idea.
    Last edited by jambredz; 02-27-2013, 06:34 AM.
    Darren Scott
    Freelance Director/Director of Photography


    • #3
      This is great news and says much good about the company in my opinion. Thanks go out to Kristian Lam and the others who worked to resolve this issue.


      • #4
        Message i just got from bm, hopefully will have something to report eod.

        Hello Rob,

        I'm waiting to hear back from engineering as to how we are handling the Flange/infinity focus issues... apparently there has been some new developments overnight that I have not received all of the fine details yet. I will get back to you before the day is over.


        • #5
          Just a quick note that I called BMD support in the USA and they said usually the general RMA times are 7-10 days, but in this case it might be a little longer or shorter, depending. He recommended that I send it in when I have some downtime.

          Also, they mentioned that new cameras coming out of the facility will have the new calibration rather than the old one.
          Paul Del Vecchio - Director/Producer


          • #6
            Hi Paul,

            can you post a link or a phone number so we can also contact the office and make arrangements to send off our cameras?


            • #7
              Just sent my camera to California to re calibrate it... 10 business days!!!


              • #8
                Eli, did BM pay for the shipping? I'm awaiting my RMA and I'll be pissed at the principal of paying to ship a defective camera!


                • #9
                  So Canon's "nominal" 44mm flange depth turns out to have some substantial "wiggle room." I.e. it's actually less, to accommodate manufacturing tolerances. So when the BMC 44mm flange depth runs up against lenses that are designed around the "real world" spec (44mm - X), they are unable to focus at infinity.

                  Should BMC be liable for not knowing the secret X-factor, which apparently is common knowledge among the other, more experienced lens and camera manufacturers? Those other mass manufacturers are apparently aware enough that they know how to make their focus-shifting, non-parfocal, AF lenses, economically built to wide manufacturing tolerances, focus at infinity on the EF mount. Personally, I think the EF mount problem is part of BMD's growing pains. Whether they should pay is a matter of corporate ethics - and will be a great test of character.

                  I'm just glad the MFT standards and tolerances are transparent to members of the group (or so I assume), so this should not be a problem when the MFT version is released.


                  • #10
                    Noap... I paid 83$ with insurance to ship to them.


                    • #11
                      So lame Eli, I'm about to ship mine back as well. Maybe it will magically be returned as an MFT for my trouble?


                      • #12
                        BM emailed me a fedex shipping label so unless I get charged for it, it looks like they are arranging for shipping now.


                        • #13
                          Originally posted by Yuns View Post
                          BM emailed me a fedex shipping label so unless I get charged for it, it looks like they are arranging for shipping now.
                          Yep, if you ask for it they will. I shipped mine off too early, and then got a label the next day!


                          • #14
                            so... I spoke to BM this morning about the fact that it is not cool that I spent the money to ship the camera to them. I was promised a phone call from a manager that will "fix" this by the end of today. phone call never came in, so I called them just now only to be put on hold for 30 minutes before hearing "sorry but we can't give you the shipping money you spent back"
                            I asked "can you at least expedite this so I can get my camera faster since you made me spend $85 on shipping and the response was "huh... NO"
                            BM really starting to piss me off.


                            • #15
                              I'm in my 10th business day since the camera was shipped back to adjust the back focus issue and still no word as to when it will return to me.
                              the folks at BMC are very nice and polite and ask me to allow them till this coming monday to find out what is going on with my camera...
                              I will do that and keep the forum updated.