Blackmagic Forum

The Pocket 4K draws almost the same power in idle as when recording - about 10% difference.
I've found that screen dimming also has very little effect - less than 10%.

Running 15.3v PSU input, i measured:
Idle - 0.99A
No screen - 0.93A
Recording - 1.1A

The best way to manage battery life is to constantly turn off the camera when not recording.
However, this is somewhat annoying, and can also cause a ready to shoot delay due to the time it takes to read the SSD content before shooting.

It would be nice to have a mode in between off and on.
A sleep state that turns off the power hungry parts, but is ready to wake up fast.

The sleep state could be engaged with one of the function buttons and deactivated by pressing shutter.

There is also room for using the accelerometer for this.
If the camera is not moving for X time, then it goes into sleep state. And deactivation of sleep state by picking the camera back up again. Obv. this is not for all users.

I tested the screen against black/bright light source, and it seems to draw pretty much the same power.

BrydeSorensen wrote:The Pocket 4K draws almost the same power in idle as when recording - about 10% difference.
I've found that screen dimming also has very little effect - less than 10%.

Interesting finding.

Part of the issue is the mirrorless design. It needs to run the sensor and video processing fully to show the image on the monitor.
Here are some additional findings:

Idle mode, lense attached, no card/ssd attached, 15.3v input:
24FPS, UHD res - 0.87-95A
30FPS, UHD res - 0.94-0.96A
60FPS, UHD res - 1.08A
24fps, 1080P res - 0.83A - 0.92A
30FPS, 1080P res - 0.88A
60FPS, 1080P res - 0.95A

This is both for BRAW and prores.
Changing quality setting did not affect it (though it may when actually recording).

Personally i would be fine with a low fps monitoring mode if that meant cutting the powerdraw significantly outside recording. Maybe 5FPS while monitoring. That's fine for me to adjust settings with until i hit record.

Or if it was possible to get non-cropped 1080P signal from the sensor, that could lower monitoring draw as well.

BrydeSorensen wrote:Or if it was possible to get non-cropped 1080P signal from the sensor, that could lower monitoring draw as well.

There are only really three ways to get a reduced resolution from the full sensor without cropping: line skipping, pixel binning and scaling. Scaling places additional demands on the camera's processor (thus consuming power), and line skipping can look horrible and make it harder to judge what you are looking at.

Pixel binning is a reasonable in-between scenario if it is only for monitoring (particularly on the internal 5" display), but it is not clear why that would be implemented in a camera of this nature, particularly given that some users may be recoding externally and obviously would want the output to look its best even though the camera itself may not be aware of the fact that it is being recorded.

Given that the internal display on the P4K and the HDMI output both run at 1920x1080 chances are fairly high that it is scaling the output already in order to feed those displays, which may be part of the reason for the power consumption that you are observing.

It's a bit silly that the camera draws so much power in idle. There should a least be a toggle option to enter a low power mode.

I'm somebody who really wants Blackmagic cameras (BMPCC4K, 6K, and 6K Pro as well as the BMCC6K) to support binned shooting modes, because it can potential [url=https://www.adimec.com/reducing-noise-and-increasing-camera-frame-rate-through-binning-on-sensor-binning-versus-digital-binning/]offer lower resolution, higher frame rate modes with less noise and larger field of view than cropped modes.[/url]. I hadn't considered using binned readout as a way to decrease power consumption when idle but I think there's some potential.

There's probably a bunch of behaviours that Blackmagic can have for special cases that would lower power consumption little by little but they probably prioritize usage of their FPGA which I assume is what accounts for most of the power usage of their cameras. For example, you could read out a 4K image from the sensor, debayer it, then scale it down to 1080p for preview. I'm assuming this is what Blackmagic does. Instead they could skip debayering by averaging the two green pixels in a Bayer quad and using the red and blue as-is. That would definitely use much less of the FPGA and less power while colorizing and downscaling the sensor data in one step. However since the screen is 1920 x 1080 it would still need to do some scaling to fit a 2048 x 1080 image on-screen without cropping and it would still need to debayer and scale when shooting with an actual 1080p crop. So it needs to use scaling for a bunch of things, including zooming for focus, and it needs to debayer for ProRes or BRAW but there would only be few scenarios where it could use the green averaging mode.

That being said, I don't think debayering or scaling consumes all that much power and I don't think they're major contributors to the difference in power usage you recorded. For example, since 1080p is 1/4th the resolution of UHD, I would expect 1080p60 should still use less power than UHD30 despite being twice the frame rate. Instead they use the same amount makes me think sensor readout is a big contributor. In that case, a binned readout should provide similar power savings.

The only downside I could really see to binning in idle is that the zooming and focus peaking which wouldn't work as well. I'd imagine everything else like frame guides, false color, zebras, sharpening, and LUTs are only happening after the image is downsampled to 1080p anyway so they should be fine. As long as the user knows this is the case though and the mode can be toggled though, it should be a fine trade-off.

This obviously all assumes that the sensor's Blackmagic is using in these cameras supposed binning on the sensor side otherwise the advantages would be negligible. I've heard people say the P4K uses the Sony Starvis IMX294CJK but that was made for security cameras so I'm sceptical. The IMX299CJK came out the same year and has the same specs so I'm under the impression that might be it. The former specifically mentions a binned readout mode that can do 120 fps 2K using the whole sensor but the latter just says to check the datasheet for readout modes and I can't find any mention of binning mode for it. Same is true of the IMX410 which is apparently used in the BMCC6K.

For the P4K just buy the (admittedly rather expensive) Canon LP-E6NH. The offical battery from a reputable source. These batteries last an hour of recording time, if you're recording to cards (not ssd). The P4K is pretty efficient for a FPGA camera.

Mike Potton wrote:For the P4K just buy the (admittedly rather expensive) Canon LP-E6NH. The offical battery from a reputable source. These batteries last an hour of recording time, if you're recording to cards (not ssd). The P4K is pretty efficient for a FPGA camera.

That doesn't really address the problem though. If you can get the camera to more efficiently use it's battery power then any battery is going to last longer including the LP-E6NH.

Mike Potton wrote:For the P4K just buy the (admittedly rather expensive) Canon LP-E6NH. The offical battery from a reputable source. These batteries last an hour of recording time, if you're recording to cards (not ssd). The P4K is pretty efficient for a FPGA camera.

I agree that CFAST should have lower power draw than usb + usb to nvme converter + ssd. But imo not a big difference. Based on my quick testing, 90% of the power usage goes to the camera just being turned on.