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24 mm lens with 0.64 speedboster , the math

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  • #16
    Not necessarily. The paper Aaron linked explains it well beyond the depth necessary to grasp the concept. When you’re building and compositing with 3d spaces, it’s best to use an approximation to get your perspective in the ballpark and then wrangle the rest by eye. There are tons of variables that will make your calculations inaccurate that aren’t available in any modeling or compositing software. Hell even the manufacturer specifications aren’t completely accurate - at least not to a degree for the type of workflow you're attempting.

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    • #17
      when we work on VFX for movies we get lidar, photoscan and take extensive surveys of a set to reconstruct it as close as we can, we don't want to build the same set from the perspective of each camera. And we do get very close by capturing the cameras location angles etc when we have everything dialed in. in my case, it might be within the margin would be interesting to do the same test without a speedbooster to see where I end up. I dont have a native m43 lens
      Peter A

      Meshmen Studio Youtube channel

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      • #18
        Originally posted by Meshman View Post
        when we work on VFX for movies we get lidar, photoscan and take extensive surveys of a set to reconstruct it as close as we can, we don't want to build the same set from the perspective of each camera. And we do get very close by capturing the cameras location angles etc when we have everything dialed in. in my case, it might be within the margin would be interesting to do the same test without a speedbooster to see where I end up. I dont have a native m43 lens
        You should also try it with multiple lenses of the same focal length and even some zooms set to the same focal length. You'll start to notice variations because of this. So when it comes to modeling, if you're not modeling the entire lens design, then the best you can do is an approximation.

        I learned this all when exploring the larger format "look"/"perspective"/"mojo" by cropping a sensor to 2x and comparing lenses that were half the original focal length.

        While trying to find this often talked about perspective change, what I found is that even the same focal lengths across the same format size showed noticeable perspective changes. On subjects very close to the camera, the differences in each lens became more apparent, but objects further away showed less change. This is when I learned that each lens is drawing its own virtual "position" or center of perspective and simply lining the sensor plane for all lenses was not going to allow me to match the perspectives exactly.





        Aaron Lochert

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        • #19
          This is why Cookes are so good! They customized the way the lens is distorted on purpose, instead of trying to clean all of it.

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          • #20
            yeah sure you can even see focal length shift when focusing some lenses so I guess why my lens speed-booster combo is about 10 cm off in world position to get to the correct perspective in the 3d program is not so strange
            Peter A

            Meshmen Studio Youtube channel

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            • #21
              Indeed. I had a sigma 50-150 that at 150mm, the breathing made it closer to a 50-120. Thats a huge difference. Of course, I sold it.

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              • #22
                here is a video for the workflow I use
                Peter A

                Meshmen Studio Youtube channel

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