Dust on BMPCC4K sensor

Hi everyone,

in the last months it happened to me for 3 times to find dust on the sensor of my BMPCC4K. I mean directly on the sensor, not on the sensor glass. For 2 times I had to take the camera to an assistance service to clean the sensor before to use ti for a job.
A few days ago I found the dust for the third time. I tried to clean the glass surface with a cleaning kit but, as always, the problem is not on the glass, but below it. I always leave the camera in a closed bag, and I generally use it only once or twice a month.

How is it possible? Where does this dust come from? Is it a common problem?
Is there a safe way to clean the sensor by myself?

Uhm it’s very strange if you not work in a place filled of dust. I did work on many place with every kind of dust and only rarely I found dust on sensor glass (never behind).
Lenses cam breath and suck dust from environment but you should be very unlucky to suck so often dust on sensor, especially behind glass. It’s so strange. Give us more infos about your work, what kind of environment and if you change often lenses.


Inviato dal mio iPhone utilizzando Tapatalk

Is it definitely dust or could it be mold? Where do you live?

The space between the sensor cover and the sensor should be airtight but maybe something got in there during manufacturing. It's possible to remove the cover glass with basic tools and there are instructions to do this on Youtube for the Rawlite OLPF which I have done. I'd use a puff of air or a gel stick to remove any dust spots and not a fluid or wiping type cleaner.

BMPCC4K specks 3.jpg (917.32 KiB) Viewed 3428 times

I think I've got the same problem with my BMPCC4K - it's definitely under the sensor glass. I'd be surprised if it's mould because I do monitor the humidity where I store my gear, and I don't really shoot in any extreme environments. The camera also basically lives with a SpeedBooster on it, which should reduce the chances of any external debris getting in.

The specks start to appear on the image somewhere around f7.0

This is the second time it's happened for me. The first time I sent it back for service and BlackMagic just replaced the entire camera. It looks like I'm going to have to send this one in again and rent a camera again while I wait for it to get fixed - not a cheap problem to have!

I work in various kind of environment, in the last months places where I worked were definitely not full of dust (gardens, schools,...). I am persuaded that the problem appeared in the break period, between the last two jobs, because the shots I made after the first job where clean. After that, I left the camera in a camera backpack for weeks, maybe not in the cleanest room of the house, but the backpack was definitely closed.

The space between the sensor cover and the sensor should be airtight but maybe something got in there during manufacturing. It's possible to remove the cover glass with basic tools and there are instructions to do this on Youtube for the Rawlite OLPF which I have done. I'd use a puff of air or a gel stick to remove any dust spots and not a fluid or wiping type cleaner.

Info about OLPF are very useful, I found this tutorial on YouTube and I think I'll try!

If the dust is under the cover glass the cause is not due to usage or the storage storage environment as it's sealed from the environment.

Sorry if I insist, but if there was high humidity when the camera was packed up in a closed bag, it might still be mold.
Fungus likes it dark and humid.

Sorry if I insist, but if there was high humidity when the camera was packed up in a closed bag, it might still be mold.
Fungus likes it dark and humid.

The area between the sensor and cover glass 'should' be airtight.

If it has been serviced twice before, maybe it's not airtight any more.

This is the situation before and after cleaning the sensor glass surface:

What F stop are you seeing these spots at? On most sensors they will start to show at F8 and higher.

What F stop are you seeing these spots at? On most sensors they will start to show at F8 and higher.

I don't remember exactly, but it was certainly between f17 and f22

I’d avoid such small f-stops. They’ll reduce sharpness due to diffraction.

Ok, I tried to clean the internal surface of the glass and it's definitely worst then before. it's damn hard to clean it without leaving any traces. I'll take it to the assistance service

I’d avoid such small f-stops. They’ll reduce sharpness due to diffraction.

I can't avoid to use them when I'm shooting a wedding under the Sun of July

Get ND filters. They’ll also give you controlled focus instead of a smartphone look, where everything is in focus (depending on focal length).

Look for screw-on IRND filters that attenuate infrared as well as the visible light spectrum.

Any camera will show spots on the cover glass at those apertures- you are seeing microscopic particles. As others have said get some ND’s and don’t shoot above f5.6.

When folks come with years of still camera experience, it takes an adjustment to shoot motion with a cinema camera. The stills shooter likely is used to shooting f/8 through f/32 even though they’re not using a 8x10” view camera.

With the cinema camera and typically smaller sensors they need to adjust to shooting T2 through T5.6 ideally and the lenses are often designed to perform their best within a stop of T4 so you get a quality image without diffraction (and usually without discovering dust in your image.

Given the typically slow shutter used in cinema, quality IRND are recommended for most outdoor shoots, either screw-on circular form or rectangular form for a matte box that also helps control flares or veils of light in your image.