Internal ND filters are incredibly helpful on set, especially if you're in a situation where you are trying to move quickly. We've seen that the particular filters inside the Canon C100/C300/C500 are actually very specific to the cameras themselves, and they do a good job of blocking out infrared light, which starts to appear more with standard ND filters as you block out visible light. It seems Canon has had some issues with keeping this area of the camera dust-free, so they've made some modifications. Check out the details below.
Here is the situation from Canon (thanks to Thierry at Digital Cinema Tools for sending this over):
As part of the on-going feedback process with customers Canon has implemented a revised design in the filter and sensor units of the Cinema EOS System’s EOS C100 and EOS C500 digital cameras that further improves dust prevention performance.
The new design further minimises any possible ingress of dust within the sensor and filter array and, after additional development, the same upgrade can now be performed on all existing purchased EOS C300 cameras and it will be implemented in all future EOS C300 and C300 PL models.
The update can only be done at a Canon Regional Competence Centre (RCC) service facility and, as the upgrade involves a significant amount of time, you must contact and book the update directly with the service facility. To find out your nearest official Canon RCC service facility please click here.
I don't personally own any of these cameras, but have heard about some of these issues through some folks at rental houses. It's definitely great having internal NDs, but if you're having issues with dust in a part of the camera that is not user serviceable, it's certainly going to be a problem. The good thing is that if you'd like to have the new hardware improvement, it's now available for all of their C series cameras.
While this is a message from Canon Europe, I have to assume that the hardware is the same for the cameras, and this issue should be able to be resolved anywhere else in the world, but you'll have to ask a repair facility in your area to make sure that they can perform the upgrade. If someone has more information on whether this is available elsewhere, feel free to share that below.
[via Digital Cinema Tools]