Sony A7S 120fps slow-mo at ISO 12,800


I shot ‘Nomad’ with my friend Susanna and the Sony A7S a few days ago, in 120fps slow-mo mode.

Light sources were only a candle, iPhone torch and an old industrial German desk lamp with red filter on the front. I am amazed at the clean results. ISO levels were pushing on for 12,800 in most of the shots.

The video actually started out as a little pitch for Philip Selway of Radiohead and his new solo track “Coming Up For Air”. Here it is in modified form.

The Sony A7S continues to amaze me with the creative opportunities it is allowing for during a shoot. Clean at ISO 3200 in S-LOG most of the shots here were so softly lit for effect that I frequently needed to shoot at ISO 12,800 just to get an exposure.

Exposing S-LOG is still tricky, I am leaning more and more towards over exposure with it and applying the correct exposure with my grade. In that sense it is a bit like raw.

Getting clean usable footage at ISO 12,800 – now that is a new thing. There’s not many cameras that can claim great slow-mo with the low light sensitivity of a 12MP full frame sensor. Certainly not accessibly priced ones! If you want a good scare, check out the price of a Phantom Flex!

In the video, my idea was to have ghostly images, as if the woman came alive from under a lace fabric. The lace fabric in slow-mo and at ISO 12,800 looks so soft and glowing, almost like water. The capabilities of the camera was essential in creating the look I wanted here…I also used a prism filter but rather than attaching it to the lens, I whacked it, moving it across the path of the lens between the glass and Susanna. This gave some interesting cross fades, transitions and image splits.

120fps slow-mo on the A7S is 720p not full 1080p like on the GH4 but it is excellent for portraiture shots and soft glowing looks. Actually detail is pretty good for 720p though there is some moire and aliasing in this mode of course, like the GH4 slow-mo, I’d say it is pretty close to the GH4’s 1080/96fps for detail but with the benefit of a higher maximum frame rate (120fps vs 96fps) and cleaner in low light.

The camera does not record from the full frame sensor area in this mode, instead cropping to Super 35mm / APS-C but you can use Speed Booster. Here I didn’t do so, just used the standard Metabones Smart EF adapter, Canon 50mm F1.2L and 85mm F1.2L.

The files come off the card at 120fps and you do the slow-mo conform in your NLE. The GH4 can conform to slow-mo in-camera but not the Sony. Maybe that’s a feature they could add in firmware? I could not find a way to playback the clips in slow-mo in-camera, they just played back at normal speed by default.

Slow-mo clips seem to record continuously without any special limit applied but I have yet to test the maximum recording time for this mode. In the normal video modes it is 30 minutes regardless of whether the camera is a PAL or NTSC model.

There are some ungraded S-LOG shots in the footage. See if you can spot them.