IR Cut Filter corrosion - because it's not made of glass!!!
Posted: Wed Jan 10, 2024 3:35 pmI noticed some spots on the footage of my BMPCC 4K, and thought it would be some dried-out rain droplets from my previous video shoot, as it started drizzling in the last few minutes - I imagined these could have gotten in through the cooling vents on the side of the lens mount.
After finding the spots on the IR Cut Filter I tried several times to clean these spots, using appropriate MFT swabs and sensor cleaning fluid. No luck. White vinegar, isopropyl alcohol, nothing worked. These spots remained in place, almost as if... they were on the inside? That would make sense, I thought, thinking of how the cooling vents would push air into the sensor, behind the IR Cut Filter.
So I did what any industrious DIY-inclined person would do and, similarly to a filter replacement procedure, removed this IR Cut Filter out of the camera to try to clean these damn spots, this time cleaning both sides of it.
No chance. You may already guess what these spots are: corrosion, right? Let's talk about the why, though.
As I kept trying to clean this IR filter I couldn't help but feel this wasn't even made of glass. Or like there was some kind of plastic film on top, as when you get something new and need to peel these off from the shiny surface it covers. Lightly tapping the filter (on the edges) with my fingernail I could tell that this wasn't a piece of glass, but some kind of polymer/plastic. Which to my knowledge would certainly explain why it can get so easily corroded!!!
?????
I get that the BMPCC 4K is a budget-oriented cinema camera, but using a piece of plastic in front of a digital camera sensor??? And how come we have to forage the internet for a suitable IR filter replacement when this happens?! There is no official replacement, none that Blackmagic Design sells or recommends. It's a guessing game.
Sure, I know about the RAWLITE Optical Low Pass Filter, which also reduces moiré artefacts in addition to reducing IR pollution, but this costs nearly half as much as a BMPCC 4K (and to my eyes, it makes the image a tad softer).
So, as a customer, I am dumbfounded by the lack of options from Blackmagic Design in the all too often event of someone's IR Cut Filter getting corroded (corroded, people, from tiny specs of rain). It's either foraging on eBay for a hit-and-miss replacement or paying around £350 for a good quality (and almost certainly made of glass) proper alternative.
Either that or send it to Blackmagic Design to have the filter replaced for another piece of plastic that will almost certainly get corroded in due time.
After finding the spots on the IR Cut Filter I tried several times to clean these spots, using appropriate MFT swabs and sensor cleaning fluid. No luck. White vinegar, isopropyl alcohol, nothing worked. These spots remained in place, almost as if... they were on the inside? That would make sense, I thought, thinking of how the cooling vents would push air into the sensor, behind the IR Cut Filter.
So I did what any industrious DIY-inclined person would do and, similarly to a filter replacement procedure, removed this IR Cut Filter out of the camera to try to clean these damn spots, this time cleaning both sides of it.
No chance. You may already guess what these spots are: corrosion, right? Let's talk about the why, though.
As I kept trying to clean this IR filter I couldn't help but feel this wasn't even made of glass. Or like there was some kind of plastic film on top, as when you get something new and need to peel these off from the shiny surface it covers. Lightly tapping the filter (on the edges) with my fingernail I could tell that this wasn't a piece of glass, but some kind of polymer/plastic. Which to my knowledge would certainly explain why it can get so easily corroded!!!
?????
I get that the BMPCC 4K is a budget-oriented cinema camera, but using a piece of plastic in front of a digital camera sensor??? And how come we have to forage the internet for a suitable IR filter replacement when this happens?! There is no official replacement, none that Blackmagic Design sells or recommends. It's a guessing game.
Sure, I know about the RAWLITE Optical Low Pass Filter, which also reduces moiré artefacts in addition to reducing IR pollution, but this costs nearly half as much as a BMPCC 4K (and to my eyes, it makes the image a tad softer).
So, as a customer, I am dumbfounded by the lack of options from Blackmagic Design in the all too often event of someone's IR Cut Filter getting corroded (corroded, people, from tiny specs of rain). It's either foraging on eBay for a hit-and-miss replacement or paying around £350 for a good quality (and almost certainly made of glass) proper alternative.
Either that or send it to Blackmagic Design to have the filter replaced for another piece of plastic that will almost certainly get corroded in due time.
