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2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 5:34 am
by Cedric Akins
Is it possible to make an update to the BMPCC 4K to include the 2.8K 17:9 aspect ratio as well? Theoretically it would allow the Pocket 4K 120fps as well. I REALLY like the P6K, but that would require me to change lens systems and I am about 3 grand invested in micro 4/3 lenses and can't afford to change as of yet.

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 7:22 am
by Nick Heydon
The P4k already has 120p in 1080, but 2.8k would be really nice. When Grant ran through the upcoming update, he didn't mention resolutions, but only crop modes. He said the P4k on the desk already had the new firmware, but was careful not to show us the Record menu, so here's hoping there's a few surprises in there he didn't mention.

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 1:49 pm
by rick.lang
Good idea, Cedric! If one is going to offer a system with a 4K DCI 17:9 sensor, it makes sense to offer 2K DCI and 2.8K windows. Perhaps it’s fairly easy to squeeze that in too as firmware 6.6 isn’t expected until another month or two.


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Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 2:40 pm
by MishaEngel
That would be a really nice update.

2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 4:10 pm
by rick.lang
A 2.8K 17:9 window on the BMPCC4K is a useful fit between UHD and HD. The 2868x1512 resolution would be 13.38x7mm and has more than twice the number of pixels. It would have a ‘crop’ of 2.712x compared to 135 film gate set to 17:9.

The crop is significantly less than using a 2.8K window on the BMPCC6K due to the larger photosites on the BMPCC4K. The BMPCC4K area of a photosite is more than 50% greater than the BMPCC6K.

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Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 4:19 pm
by Kays Alatrakchi
Why then not allow users to set arbitrary capture dimensions? Just let the user type in whichever strange x and y pixel dimensions and have the camera capture that at whichever crop it will.

Seems like it'd be doable.

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 4:24 pm
by Kim Janson
Probably it is not as easy as it sounds in camera, but it is pretty easy to crop higher resolution to what ever smaller resolution on editing.

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 4:29 pm
by MishaEngel
2.8k gives a perfect debayer to 2k/Full-HD.

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 5:05 pm
by rick.lang
2.8K represents oversampling 2K by 1.4x.


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Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 5:49 pm
by MishaEngel
rick.lang wrote:2.8K represents oversampling 2K by 1.4x.


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Exactly what you need for a perfect debayer to RGB (demosaicing).

Re: 2.8K on the BMPCC 4K

PostPosted: Sun Aug 11, 2019 8:25 pm
by rick.lang
If BMD can do it, this would be an excellent choice when I have to record for several hours for 2K/HD deliverables. BMD certainly listens to requests like this but the community needs to show support for Cedric’s suggestion. We are all-in, but hopefully we shall have others voice their support.


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Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 2:18 am
by Denny Smith
I’m in, it’s a great idea. Rick what is the diagonal of the 2.8 window on the PC4K going to be?
Cheers

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 3:22 am
by rick.lang
The 2.8K diagonal is 15mm on the BMPCC4K with a 2.71x crop and 12.2mm on the BMPCC6K with a 3.34x crop.


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Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 5:19 am
by Cedric Akins
rick.lang wrote:If BMD can do it, this would be an excellent choice when I have to record for several hours for 2K/HD deliverables. BMD certainly listens to requests like this but the community needs to show support for Cedric’s suggestion. We are all-in, but hopefully we shall have others voice their support.


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Thank you Rick. I know that I plan on delivering in 2K and saving space on my recording media will be advantageous when on location. I have been recording in 4K at 12:1 and would love to record potentially 120fps at 2.8K.

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 5:24 am
by Denny Smith
Well 15mm is about what the Studio Micro 4K and Ursa Broadcast Cameras are, so,it would work for S16 window. The Original Pocket (BMPCC was 14.32mm). :geek:
Cheers

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 5:52 am
by javier forza
2,8k or 2,7k its a nice idea!
Even better if is not crop factory on the sensor, just an internal downsampling!

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 7:44 am
by Oyvind Fiksdal
This would make the 120fps workable again for 4K delivery. Hopefully it’s possible. Crossing fingers :)

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 11:43 am
by rick.lang
Denny Smith wrote:Well 15mm is about what the Studio Micro 4K and Ursa Broadcast Cameras are, so,it would work for S16 window. The Original Pocket (BMPCC was 14.32mm). :geek:
Cheers


Interesting observation. We know Super 16 is coming so that might be how they offer it: use 2.8K for your Super 16 window.


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Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 2:28 pm
by Jean Capdouzey
rick.lang wrote:A 2.8K 17:9 window on the BMPCC4K is a useful fit between UHD and HD. The 2868x1512 resolution would be 13.38x7mm and has more than twice the number of pixels. It would have a ‘crop’ of 2.712x compared to 135 film gate set to 17:9.


Sounds like a Super 16 type crop or thereabouts.

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 2:48 pm
by John Paines
Jean Capdouzey wrote:
rick.lang wrote:A 2.8K 17:9 window on the BMPCC4K is a useful fit between UHD and HD. The 2868x1512 resolution would be 13.38x7mm and has more than twice the number of pixels. It would have a ‘crop’ of 2.712x compared to 135 film gate set to 17:9.


Sounds like a Super 16 type crop or thereabouts.


The aspect ratio would be 1.9. S16mm is more like 1.66 though, to be fair, 1.66 was typically cropped to 1.85 for 35mm blowups. But, these days, it's hard know what people actually intend to do with S16mm.

Re: 2.8K on the BMPCC 4K

PostPosted: Mon Aug 12, 2019 5:02 pm
by Denny Smith
Their were several aspect ratio gates used when projecting S16, camera gate was fixed, and a little larger than the projector gates. The Picket Camera was 16:9, so a S16 window on the new Picket 4K will not doubt be 16:9, or perhaps 17:9 (since the sensor is a native 17:9), which would work nicely.
Cheers

2.8K on the BMPCC 4K

PostPosted: Tue Aug 13, 2019 1:27 pm
by rick.lang
Based on that 1.85:1 projection of Super 16, it represents a diagonal of about 13.375mm and roughly a 3x ‘crop’ of 135 (haven’t put that in my crop factor spreadsheet) so the BMPCC4K with a 2.8K window is just about 10% larger with a 2.7x crop. We shall soon see which window BMD includes in firmware 6.6. The original Pocket camera was a little smaller than that and quite close to Super 16 as I recall (2.88x crop). Being a little larger has some advantages in post for stabilization and minor reframing.

As Denny mentioned the 17:9 aspect ratio of the 2.8K window is a good choice as it is so close to the 1.85:1 aspect ratio that was very commonly used.

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Re: 2.8K on the BMPCC 4K

PostPosted: Tue Aug 13, 2019 1:35 pm
by MishaEngel
javier forza wrote:2,8k or 2,7k its a nice idea!
Even better if is not crop factory on the sensor, just an internal downsampling!


Then it wouldn't be (B)RAW anymore but a RGB codec.

Re: 2.8K on the BMPCC 4K

PostPosted: Tue Aug 13, 2019 6:27 pm
by Denny Smith
Javier, the idea is to have a S16 window crop of the sensor for BRaw (which is pixel size based recording of raw data, no down sampling processing) and to allow the use of S16 lenses. ;)

Re: 2.8K on the BMPCC 4K

PostPosted: Wed Aug 14, 2019 1:33 am
by javier forza
Denny Smith wrote:Javier, the idea is to have a S16 window crop of the sensor for BRaw (which is pixel size based recording of raw data, no down sampling processing) and to allow the use of S16 lenses. ;)


Yes. I catch the idea and I am totally in.
Recently I learn by you in other post the difference between read out and downsampling. Thank you so much for clarify my thoughts.

My new thinking about this 2,8k if the pockets 4k/6k has the same hardware except sensor, there is no problem in buses and recordings in order to have the same fps. I mean, 120 fps at 2,8x :lol:

That is possible?

Re: 2.8K on the BMPCC 4K

PostPosted: Wed Aug 14, 2019 2:12 am
by Denny Smith
Depends on the sensor read out rate at 2.8K, we will have to wait s d see what happens with the next FW update 6.6.
Cheers