BMPCC4k dark spots in footage

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chimitata

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BMPCC4k dark spots in footage

PostMon Apr 12, 2021 9:47 am

Hi, I recently discovered numerous dark spots on my footage that appear especially clear when I stop down to f22. I am fairly certain these are not from my lens; and I've tried to dust/clean the glass that sits in front of the sensor but the spots are still there. Does anyone have any guess what the problem could be?

Link to the footage: https://imgur.com/IRRAbAy
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Sean van Berlo

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Re: BMPCC4k dark spots in footage

PostMon Apr 12, 2021 3:30 pm

That's an insane amount of dust that is either on the back of your lens or on your sensor glass. Have it cleaned professionally (should not be that expensive) or do it yourself with PROPER gear, like a lens swab. Don't touch it with a cloth or anything like that.
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Bromine 18

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Re: BMPCC4k dark spots in footage

PostMon Apr 12, 2021 3:33 pm

Have you stored away your camera for long in a dark place with no desiccants between uses? Is the relative humidity at your place constantly above 60%?

From what I’ve read, relative humidity and storage play a crucial role in fungal colonies developing on the sensor glass, which might be what the dark spots are.

Try the elimination approach by cleaning each sensor and lens glass surface one-at-a-time to recheck on which surface the particles are located. If they’re not fungal colonies, then they might just be dust particles of some kind stuck inside one of the lens elements.

Did you dry wipe the sensor glass or try using a cleaning solution with a flat cotton swab?
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John Griffin

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Re: BMPCC4k dark spots in footage

PostMon Apr 12, 2021 3:43 pm

It's impossible to shoot at such small apertures and not get dust spots. Anything over F8 is asking for trouble. It's not mentioned much in debates around sensor size but one of the disadvantages of larger sensors is that to get deep focus you have to stop down to apertures where dust spots become a visible problem that can ruin footage but with smaller sensors like M43 even F5.6 is giving you pretty deep focus. Unlike stills where healing brush actions are a fairly easily fix it 's much harder to do on moving footage.
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