Anamorphic Chop Shop – Panasonic LA7200 fix with +0.25 Diopter – Part 2

August 23, 2015

This video has the explanation of the question raised last week about a +0.25 diopter between the taking lens and the Panasonic LA7200.


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Hey guys, welcome back to our Anamorphic Chop Shop, I’m Tito Ferradans and in this episode we’re going back to what I presented last week, about Mark’s video on fixing the Panasonic’s issues with chromatic aberration around the edges, close focus and lowlight performance thanks to a +0.25 diopter. Once again, thanks to Rob Bannister at Creative Camera Rentals – my associate, look how fancy I’m getting! – and Gearhouse Camera Rentals for providing the gear for this video. Thank you all for the comments, some people did pretty good on the guessing and explanation!

Test Video with all specs revealed!

On the shots with the Contax Zeiss 28mm and the Canon 5D3, it’s pretty easy to spot when we have the diopter on because of the massive vignetting the additional rings create. Also, there’s some more spreading of the light around the source, like a haze, but no real improvement in quality. Maybe just a tiny bit. Without the diopter, the taking lens was focused at 1.3m, and then at 2m with the diopter, which means something changed in the system. On the 35mm the vignetting doesn’t appear so it’s a 50/50 change of guessing it right. I can’t tell the difference. We’re really pushing the Panny here at f/2.8 and full frame.

Now onto the 50D shots. The 17-40mm is a great lens and its entire zoom range is covered by the Panasonic. This adapter has a thing for modern wide angles. It pairs perfectly with the 16-35mm f/2.8L as well, and even at the widest end of the 24-70mm f/2.8L. Anyway, back to the test, for me it’s a guessing game. I can’t tell the difference between having the diopter and not having it on!

So, does the diopter affect low-light performance, edge quality and close focus, or is it just one more element in the system? Let’s try some math and see if the initial idea makes sense. First, we have our taking lens, that focus from let’s say, half a meter, to infinity. Then we have the Panasonic, focus fixed from 4m to infinity. The diopter is a +0.25, which means its infinity sits at 4m. Now if we put the diopter in front of our taking lens, we’re limiting its infinity to 4m. The Panasonic’s focus range STARTS at 4m, so this whole thing should only work well at infinity for the taking lens and a subject sitting 4m away from camera, at least, that’s what the math leads us to.

In a straight answer: does this diopter improve the Panasonic’s image quality if sitting between it and the taking lens? Nope!

Of course there are tolerances which allow rack focusing, f/4 improves sharpness overall, by reducing the circle of confusion, so the blurred areas are not that noticeable. Should you put the diopter in front of the Panny, that could bring you some advantage because the combination of the taking lens and the Panasonic is now subject to the diopter’s effect and your system’s infinity now sits at 4m.

Now, this was a more “scientific” video. Do you guys like this kind of subject? Do you hate math? Please comment below so I can work on more ideas! If you like anamorphics overall, then subscribe because this channel is for you! There are plenty of other videos here on this subject! Last but not least, head on to my blog for the full – FREE! – Anamorphic on a Budget guide. See you next week!