Blackmagic Forum

Hello, BM Forum.

I'm working on a spreasheet for BCC6K calculations.
I let it here for you to use and analyse, if so.

In the L3 cell you can input your own focal distance.



If there is any mistake, please let me know.

https://docs.google.com/spreadsheets/d/ ... =828836795

João Marco wrote:Hello, BM Forum.

I'm working on a spreasheet for BCC6K calculations.
I let it here for you to use and analyse, if so.

In the L3 cell you can input your own focal distance.



If there is any mistake, please let me know.

https://docs.google.com/spreadsheets/d/ ... =828836795

Hi there, I’m curious how the field of view compares between these two:
BMPCC 4K with Metabones .71 booster and EF lens
BMCC 6K FF with a normal L-mount full frame lens

Hello.

Using math, not my experience, I came up to this.

1,9 (bmp4k crop factor) x 0,71 (speedbooster) = 1,349 (relative to full frame)

Which means that a 50mm focal lens shows as 67,45mm.

In that way, you must use a 37mm focal distance lens to achieve that same 50mm on a full frame.

In a pratical usage, less bokeh, but bigger deep focus.

Using a speedbooster on your 4k you'll have a bigger angle view than a BM6k pro: 1.56x crop factor.

Your crop factoring seems correct to me and I'm glad you posted about this! I don't think many people fully understand how good the 4k with .71 speed booster is. I've been shooting with one for seven years. It is better than the 6k at everything but resolution. Also cheaper/ lighter! The new full frame cameras are the first real upgrade in my view. That said if anyone out there still loves their Pocket 6k, that's cool and I'm very happy that you are happy! But I'm always glad to see people talking about the 4k w/ speed booster because it still rules.

focusandshadow wrote:Your crop factoring seems correct to me and I'm glad you posted about this! I don't think many people fully understand how good the 4k with .71 speed booster is. I've been shooting with one for seven years. It is better than the 6k at everything but resolution. Also cheaper/ lighter! The new full frame cameras are the first real upgrade in my view. That said if anyone out there still loves their Pocket 6k, that's cool and I'm very happy that you are happy! But I'm always glad to see people talking about the 4k w/ speed booster because it still rules.

Thanks, I agree. I was really trying to see if going to the BMCC 6K Full Frame would be a good idea based on the current amazing deal. There are a few upgrades on it that I would love, however there are a few things my 4K Pocket has over it in my opinion, one being internal ProRes. Also I have the Tilta flip screen mod which is very handy when self-shooting!

I’m still a bit confused on comparing the field of view though:
P4K & .71 booster gets you 1.349 as Joao mentioned.
But what would be the FOV on the 6k FF cam if shooting 4K windowed?

As you can see in my spreadsheet, linked in OP, the crop for a 4K DCI in a 6K BCC FF is 1,57x. Somewhere the same as a 6K pro super35.

If not yet, take a look a this:

I tried a Duclos rehoused PL mount Tokina 11-16mm F/2.8 on my BMCC6K FF. At 6K 3:2, I could zoom out to 14.5mm. At 6K DCI 17:9, I could zoom out to 13.5mm.

The reason that I was able to get an additional 1mm at the widest angle was because a 17:9 (24x(3200/4032)= 24x0.79= 19.05 mm, SQRT(36x36+19.05*19.05)= SQRT(1296+362.9)= SQRT(1658.9)) 40.73 mm image circle, is smaller than the 43.27mm open gate 6K 3:2 image circle.

The BMCC6Ks 4K DCI 17:9 window has a 27.56mm image circle. When I use 6K DCI 17:9 as the full frame reference, I get a (40.73/27.56) 1.48x crop.

Since the average movie theater uses a 2.35:1 screen, if its 50 foot wide, at 17:9, I would be able to show (855.1 sq. ft./603.6 sq. ft.) 41.7% more image than if I shot in FF 3.2.

At 6K Anamorphic 6:5, the Tokina 11-16mm could zoom out to 13.1mm.

Interesting. I'm not sure if I completly understand your path.

Can you show us examples? That would be great!

I order mine. In about three weeks I'll start my tests. But for now, seams to me that you math and your results are not in the same direction.

Not doubting, just trying to understand it a bit more.