October 15, 2013

Sony Increases Versatility of F5/F55 Cameras with Interchangeable Optical Low-Pass Filters

Sony OLPF WideAll 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:

2k olpf

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:

HFR with 4k olpf

On the other hand, shooting HFR with the 2K OLPF produces an image that is still finely detailed, but without the overly harsh sharpness.

HFR with 2k olpf

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!

Link: Sony F5 / F55 Optical Low-Pass Filters -- DVInfo.net

Your Comment

8 Comments

I suspect I'm in a massive minority here commenting on this but I've shot extensively in 2k on the F55 and the 4k is not just noticeably but ridiculously sharper. Even transcoded back to 2k it actually looks like it was shot on a different camera. The standard rhetoric is to claim that you can't tell the difference when it's being viewed at 2k but with this camera it's plain wrong. I wish I'd shot the whole film 4k now but budget didn't allow for the additional processing and hard drive.

Also, don't buy the argument that the F55 is just a cheaper Alexa. It's very much its own beast and I prefer the Alexa by a considerable margin but it's still a very capable camera. Or at least it will be once the promised list of features actually materialise!

October 15, 2013 at 2:25PM, Edited September 4, 11:21AM

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It's worth mentioning that these cameras actually tell you in the viewfinder if you have an OLPF attached and which one is attached. I think that is awesome and the kind of detail Sony have riddled throughout these cameras. I have been thinking about an F5 because of the recent addition of 120fps with firmware 2.0 and I've been reading the downloaded manual and am continually surprised by what these can do that's buried in the manual and not advertised on the web site. Example 4 different types of colour bars, half the cameras out there don't even think to add colour bars. Particularly impressed by raw 4k recording while recording a HD copy at the same time to the sxs with the LUT baked in for proxy editing.

October 15, 2013 at 5:58PM, Edited September 4, 11:21AM

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I want this camera. It's definitely my favorite camera on the market.

October 15, 2013 at 8:48PM, Edited September 4, 11:21AM

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Caleb

I demoed the 55 earlier in the summer and it was an extremely frustrating experience. We came across the insane amount of moire in our controlled test, (which looks to be remedied by this OLFP swap). At the rate production moves I can't imagine making an OLFP swap every time I switch resolution or frame rate, or really anytime on set.

These cameras are capable of so much, but the variety of internal settings is a bit concerning for the rental market. I wish they had spent a little more time finessing the product before launching.

Don't get me wrong, this is a brilliant modification, but some of the stuff seems to be made up as they go along. Why wasn't this addressed at launch, the moire was certainly apparent in the past firmwares. If it shows up on a chart, then they certainly knew about this short coming right away.

October 16, 2013 at 6:11AM, Edited September 4, 11:21AM

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jmg

I was watching a Jets-Steelers game over the weekend when CBS cut to a blimp shot of the Giants/Jets stadium. The top half of the outside walls have long parallel stripes running across it and the moire in that shot was just unbearable. The blimp was probably shooting with the sun above it but the images were just flickering all over the place. I have no ideas what cameras they were using though.
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As to changing OLPF's on the go - major productions will probably have more than one camera on hand, so they could just alternate them when necessary. I won't comment on other imperfections - perceived or real - from the unit but I assume Sony will respond to the users feedback.

October 16, 2013 at 12:09PM, Edited September 4, 11:21AM

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DLD

Nice one.

October 16, 2013 at 11:04AM, Edited September 4, 11:21AM

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Natt

Reading the various sites on the new Sony camera releases (three new cams announced today) and it seems that Sony has solved the moire problem by using a simultaneous full frame readout instead the usual - and now seemingly obsolete - pixel pinning/line skipping method. All Sony needed for that was a more robust CPU. So, while Pentax is using an electronic version of the AA filter, Sony placed a new chip inside its cameras that made the pixel binning/line skipping unnecessary. And, voila, moire is gone.

October 16, 2013 at 1:24PM, Edited September 4, 11:21AM

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DLD

I havent read anywhere that the Sony 4K images had any moire. Just the opposite. The sensor is pixel for pixel 4K, no line skipping etc. In HD I also havent read of any moire but in HD 120fps there have been a few reports of moire and that was what the filter was for.

Looking at vimeo I havent seen any HD clips with moire.

October 16, 2013 at 8:28PM, Edited September 4, 11:21AM

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