All modern digital cameras have optical low-pass filters (OLPFs). These small optical elements sit between the lens and the sensor, and they serve to suppress high frequency detail that can cause aliasing and moire, as well as overly sharp images. We've talked about changing out OLPFs before with the 5D3. Unfortunately, on most cameras the process of removing or changing the OLPF requires physically taking the camera apart, which can damage sensitive electronics and void your warranty. With Sony's F5 and F55, however, the OLPFs sit beneath the native FZ mount, and they can be changed simply and quickly for ultimate control of the image. Adam Wilt of DVInfo shot some tests with the new OLPF's. Check out the details below:
For most cameras, a single OLPF oftentimes makes perfect sense due to the fact that many cameras don't offer a wide variety of methods for interpreting the sensor readout. Because of this, an OLPF optimized for that singular sensor and a specific type of readout can be highly effective.
However, Sony's F5 and F55 offer a veritable plethora of options in how the sensor is interpreting visual information. There are full 4K and oversampled HD readouts, alongside a native 2K readout with a range of high frame rate options (thanks to the recent release of the v2.0 firmware).
As a result of the wide variety of options offered by the F5 and F55, a singular OLPF wouldn't suffice. The cameras ship with an OLPF that is optimized for the 4K readout of the sensor, but an OLPF optimized for 2K capture and HFR recording should be available right now.
Here's the 2K/HFR OLPF mounted in front of the F55's internal ND filters:
The differences in image sharpness in 2K HFR mode with the various OLPF's are staggering. Shooting at 240fps with the 4K OLPF produces images in which the sharpness is exacerbated to the point of heavy moire, as evidenced in the photo below:
On the other hand, shooting HFR with the 2K OLPF produces an image that is still finely detailed, but without the overly harsh sharpness.
Obviously, the 2K/HFR OLPF is going to be a must-have accessory if you intend to shoot slow motion or native 2k with the F5 or the F55. However, the fact that the accessory is so inherently simple to swap within the camera means that it can become a unique aesthetic tool. Depending on the look that you're going for, the 2K OLPF used in 4K mode might provide the perfect in-camera softening effect. Conversely, you could use the 4K OLPF with HD capture to produce clinically sharp images (just avoid fine patterns because the moire would be off the charts.)
Another added benefit of the simplicity of the Sony OLPF design is that it could potentially make it very simple for companies to produce 3rd party OLPF's for the F5 and F55. In this case, unique OLPFs could exist for every imaginable scenario, and sharpness and softness could be controlled entirely in-camera, as opposed to doing it in post production.
For more test images and a more in-depth explanation of Sony's interchangeable OLPFs, head on over to DVInfo and read their excellent article on the subject.
What do you guys think? Are interchangeable OLPFs going to change the way we control sharpness in-camera? Do you think that other companies will begin to feature interchangeable OLPFs in future camera designs? Let us know in the comments!