Thursday, November 22, 2012

Playtime with the Sony NEX FS700

I get more and more filming jobs than real VFX work lately which in a way is a pitty but I also see it as an opportunity to learn new things. For one of my latest clients we needed a high speed camera. Luckily for us Sony released the NEX FS700, an affordable 1080p camera with amazing frame rates.

Not a Review

First of all I like to say this is not really a review but merely my thoughts after using the camera for two days. I didn't have time to do an in depth test or read the complete manual. We only used the camera for shooting at high frame rates as we wanted cool slow motion shots.

The Kit

The camera was a rental and came with the kit zoom lens which isn't the best glass around. It did do ok but having Nikon glass on my DSLR we are used to better. It has an apperture of 3.5 at 18mm and 5.6 at 200mm. There are lens adapters for sale so it is possible to use the glass you already own. We used a 32GB SDHC memory card which records the video in AVCHD. A great feuture is the build in ND filter. It also comes with a XLR boom mic. This is hardly important for a slow motion shoot but a great feature none the less. 

Handling the Camera and Shooting Slow Motion

If you ever used a video camera like a HVX200 then you will quickly get around using the FS700. It took us less than an hour to get used to handling the camera in manual mode.

We had the PAL version of the camera so the available frame rates for me were 200, 400 and 800 fps. The NTSC version does 240, 280  and 960 fps. At 200 fps you get full HD. The resolution goes down a bit at 400 fps but it still looks great. The resolution and quality at 800 fps really drops. So 800 fps is great fun to test but it is no longer usuable if quality is an issue. You can really see the difference, even on the LCD screen of the camera as the image gets cropped to record only a smaller section of the sensor.

Some remarks when shooting slow motion:
  • You need extra light. The shutter speed goes up quite a bit which lowers the light input considerably. You could adjust the ISO to a higher value but that really brings out a lot of noise in the image.
  • Don't use lights which are flickering like fluorecent tubes. We did the test and the flicker is horrible. Tungsten and sunlight are much safer here. We haven't checked HMI lights but as far as I know they flicker as well even with high frequency electronic ballasts. In a pinch you can get rid of bad flicker with the FurnaceCore tools from The Foundry but why fix it in post if you just avoid making the mistake while shooting.
The camera records the footage to a buffer which is only big enough for around ten seconds of footage (It depends on the frame rate you choose). After recording your scene, the camera needs time to write the images to the memory card which can take half a minute or so. It is stored as 25 fps footage so you can immediatly play it back on the camera to see if your shot is ok. We connected the camera with a HDMI cable to a monitor so the client was able to look as well without everybody having to bend over the little built in view screen.

The result of the Test

As a picture is worth a thousand words and a video even more I like to show you the video we made after an evening of test shooting. We used a 1K tungsten lamp to light the scene and shot various items at 400 fps. This is not the footage we shot for our client.