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Canon 8-64mm T2.4 MTF QUESTION

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Shawn Convey

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I was wondering if you could help me understand something about the Canon 8-64mm T2.4 and other S16 lenses. Most info about using these types of lenses is either geared towards the ORIGINAL Blackmagic pocket (1080) or how to use it on Sony or Red, or Arri in a 2k crop mode. However the NEW BlackMagic Pocket 4k camera is still a S16 sensor but at 4k (double the resolution of it's predecessor)... To the best of my understanding the 2 most important factors in determining lens compatibility is the Image Circle (will it physically cover your sensor) which I believe this lens will cover the MBP4k sensor perfectly and the lesser mentioned but possibly more important MTF (Modulation Transfer Function) with regards to optical quality. Again my understanding is that high quality S16 lenses such as this have and MTF of 80 lp/mm or possibly greater... MY QUESTION -- assuming the lens does indeed cover the BMP4k sensor completely (or mostly) will the MTF be high enough to resolve beautifully on a 4k S16 sensor OR will the image quality start to suffer at a certain point... IF it will start breaking apart would anyone happen to know when? (ie 2k, 2.5, 3k etc) -- Any help in answering this question would be greatly appreciated!
 
Shawn, I own both, the Canon 8-64 and the new Pocket. The Pocket has an MFT sized sensor. The Canon lens does not cover the sensor. In regards to resoluton, the 8-64 was an industry workhorse for S-16mm (I used it many years with my Arri SR) It's way better than old Angenieux 16mm zooms and has an edge over the Zeiss 10-100 but it's surely not a 4k lens. But it does give interesting vintage looking, texture-rich footage on a Dragon in 2.5k HD mode and will probably fit the Helium in 3K.

Hans
 
Noticed too that the BPCC4K uses a 4/3rds sensor (was looking it up while Hans wrote).

Super-16 - 14.58 mm diag

4/3rds - 21.60mm diag

Don't know how much you'd have to crop into the sensor to avoid the vignetting from the lens, but I suspect at that point it would be the sensor looking worse than the lens.
 
OK so my bad on the sensor size for sure... Somehow I had it in my head that they kept the same sensor size but I guess I was confusing that with the MFT mount.
@ Hans you would happen to have any footage of the two handy would you?

Also Les & Hans - While I understand this is not a Blackmagic forum would either of you know how BM captures images at say 2k or UHD? the Sensor uses the entire chip and then scales it down internally to export the lesser resolution correct? and with RED in 2k or 2.5k HD mode they actually "crop" into the sensor and only use that image size correct? -- Is there a way to do that with BMD cameras? I know they have Windowed mode for HFR but can you enter a similar mode for not HFR? and is that essentially the same thing that RED is doing?
 
Hans -- I just watched a bad YouTube video of someone using a B4 Lens on a UM4.6k and they were able to shoot in WINDOW MODE in UHD (https://youtu.be/4h51HxrQcwg) j
I am wondering if it is possible to do that on the BMP4k and still shoot BRAW. There would need to be some cropping in post of course but it seems like it may be a similar solution to the tests I have seen with the FS7 which I thought looked stunning https://vimeo.com/197840863

Curious as someone who has this combination what you think.
 
Shawn Convey said:
Hans -- I just watched a bad YouTube video of someone using a B4 Lens on a UM4.6k and they were able to shoot in WINDOW MODE in UHD
Click to expand...
They may have engaged the doubler (x2) which increases the image circle quite a bit.

If it does in fact double the image circle size that would mean - 11mm image circle (standard 2/3"), increases to 22mm image circle (doubler engaged). The Pocket 4k needs image circle of 21.44mm so it just might work. I'll try to test soon.
 
Shawn Convey said:
Hans -- I just watched a bad YouTube video of someone using a B4 Lens on a UM4.6k and they were able to shoot in WINDOW MODE in UHD (https://youtu.be/4h51HxrQcwg) j
I am wondering if it is possible to do that on the BMP4k and still shoot BRAW. There would need to be some cropping in post of course but it seems like it may be a similar solution to the tests I have seen with the FS7 which I thought looked stunning https://vimeo.com/197840863
Click to expand...

You can do that with the Pocket too. But the cropping has to be done in post later. Result wise it will look similar.

Hans
 
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