Blackmagic Forum

Hi all,

Had a funny thing happen today with my new BMPCC 6kPro. This might be obvious to someone but I can't think of what to google or check!

I was shooting an interview today and ran out of battery power. I swapped out the battery (I use the internals).

After it powered up again, the image was much much brighter. In the moment I briefly checked the previous recorded clip and saw that the ISO, WB, shutter speed, framerate, and aperture were the same in the clip I shot just before swapping batteries, as they were after, but the image was so much brighter now, it was un-useable.

I didn't have much time to troubleshoot so I just reduced my ISO from 2000 to 1250 and stopped down the lens a LOT (like from 8.6 to 14). And then after shooting I had to pack up quickly from subject's house, so no time to troubleshoot again. It was fine even though my depth of field changed a little, client shouldn't notice lol.

Back at my studio I haven't been able to reproduce the issue, so I'm a little stumped - what's happened to me here? Any ideas?

I haven't seen this happen yet...
Did you have ND engaged?

Did it switch from Film to Video?

A guess but perhaps a bit of static charge when changing the batteries affected the O/S ?

Flick H wrote:I was shooting an interview today and ran out of battery power. I swapped out the battery (I use the internals).

After it powered up again, the image was much much brighter. In the moment I briefly checked the previous recorded clip and saw that the ISO, WB, shutter speed, framerate, and aperture were the same in the clip I shot just before swapping batteries, as they were after, but the image was so much brighter now, it was un-useable.

My guess is that your screen went into power saving mode and dimmed down (that is set per default). After you powered up again your screen naturally went into the user set brightness level.
If the screen goes into power saving, just touch it and it will light up again - or you can switch this off altogether.

Probably your image had been too bright anyway before because if you were able later on to get a useful image from ISO 1250 and f14 it must have been very bright at your location.

Never judge your image from your screen alone - use the assisting tools the camera is offering:
* set the zebra to ON and 100% to see areas of sensor clipping
* watch the RGB levels in the lower left of the HUD
* use false color display to show you where your skin tones fall

Your camera has 2 gain stage ranges:
Stage 1: ISO 100 to ISO 1000
Stage 2: ISO 1250 to ISO 6400

Switching ISO inbetween a stage is just applying a different curve. As long as you shoot BRAW you will be able to change the ISO of a stage in post.

In direct sunlight I like to use ISO200, with the sun in the back I use ISO800, in well lit rooms ISO400 should do it most of the time. And in dimly lit rooms I switch to stage 2 with ISO1600 or 3200.

Don't use stage 2 if there is enough light - it will decrease your dynamic range by a stop.
To control your light levels use the built-in ND filters.

Flick H wrote:Hi all,
I didn't have much time to troubleshoot so I just reduced my ISO from 2000 to 1250 and stopped down the lens a LOT (like from 8.6 to 14). And then after shooting I had to pack up quickly from subject's house, so no time to troubleshoot again. It was fine even though my depth of field changed a little, client shouldn't notice lol.

Back at my studio I haven't been able to reproduce the issue, so I'm a little stumped - what's happened to me here? Any ideas?

In general I would recommend to you to take some time to study your camera, its manual and all the menu settings in depth. This will help you later when stress at a location kicks in to know what's going on when something starts to look strange and enables you to troubleshoot quickly.

Hey Robert,

Thanks for all the info.

I don't think the screen would have gone into power saving mode while I was actively recording? But moreover when I looked at the previously recorded clip, via the new battery, it looked fine, then switch back to live and it was very bright with all the same settings. Stopped down / ISO'd down and then it looked fine, switched back to playback and there was the other image, looking almost the same but with totally different ISO and Fstop (but same shutter and frame rate). So unless the screen was swapping power saver off / on in that process, that can't be it!

Back at the lab the two images look almost the same. And as I say, I played for five relaxed minutes at my lab with all settings possible, swapping out batteries, and couldn't reproduce the issue.

I wonder if there was an ND filter I didn't realize was active, and strangely, when i switched batteries the ND filter was the only thing that changed by itself?

It's still a mystery. And particular to this camera, at least in my experience.

I should have added that I have been shooting for 30 years and I spent two months farting around with this camera before taking it into the field. I actually shot three different events this week and on the 4th one this weird thing happened.

* (many years on camcorders, new to Cinema cams. Thus so much to learn that I didn't know I didn't know)

Ok, then two other things crossed my mind:

1) maybe you accidentally switched off the previewing LUT by pressing one of the three function buttons. But the flat image would have been a giveaway.
2) you had your ND engaged first and accidentally switched it off

Can’t think of anything else causing what you experienced.

Ok, vielen dank for that.

I wonder if the ND switched off by itself when I switched batteries. Might be the only thing I can check / test. Or maybe like you said I just hit it by accident. Going from 3ND to "off" might explain the huge discrepancy.

I was baking the LUT into the footage and they both look the same now. In post the first and second shot look the same, so my radical settings switch would not be explained by that.