Plugging the Sony FS5 ND filter gap

Before I say anything bad about the built-in ND filter on the Sony FS5, let me begin by saying that it doesn’t suck. In fact, the Sony FS5 ND filter is so good, it’s part of the reason I switched from Canon to Sony a couple years ago. I’m still amazed by how easy it is to dial in precisely the level of ND you need every time. Well, almost every time.

When you need just a little bit of ND, there’s a gap.  It’s not a huge gap, a tad more than 2 stops of light when you go from no ND to the lightest 1/4 setting. But it’s one that I’ve encountered again and again when, for example, shooting an interview wide open.

A common situation

I often want to shoot interviews wide open to separate the subject from her background. So with an f/2.8 lens, I’m as wide as I can go. And what I often find is that the room is just a little too hot, about a stop over. When I engage the variable ND, at its lowest setting, it takes the room down 2 1/3rd stops. So now let’s say I’m a good stop under exposed.

A common workaround

The only in-camera solution that won’t degrade the image (apart from increasing the shutter speed, which I don’t want to do for aesthetic reasons) is to stop down to f/4. Note, if you’re shooting glass faster than f/2.8 (and you don’t mind really throwing your background out of focus) all you have to do open to f/2.0, and engage the ND. Boom, done. But a lot of my glass is f/2.8, and that’s where I find this gap.

What the gap looks like on a monitor

F2.8 wide open without any ND. I’m looking at those highlights and saying we’re 1 stop too hot.

But when I engage the ND at lowest 1/4 setting, now we’re 2 1/3 stops under exposed. Too dark.

Turning off ND and closing the aperture to f/4 gives me the exposure I want – but I want to set f/2.8.

Finally, here’s the shot at f/2.8 with a Tiffen .3 Water White ND filter to bring us down one stop. Just right!

Closing the gap

I’ve found the right tool for plugging this gap is a .3 neutral density filter. The .3 gives you just one stop of light reduction, the least powerful ND filter that you can readily buy.

The one I prefer is the Tiffen 77mm Water White Neutral Density 0.3 Filter. The quality of the glass is superb.

I’ve also got a 4×4″ Neutral Density 0.3 Resin Filter made by Lee, which is also excellent. But I like the 77mm screw in best, because, with appropriate step ring, I can screw it on to the front of most of my lenses very quickly without rocking a matte box.

Have you encountered this situation with your Sony FS5? How do you “mind the gap”?

 

2 thoughts on “Plugging the Sony FS5 ND filter gap

  1. Peter H

    Great blog. Can’t you simply adjust the ISO down a bit on an FS5 and call it a day? When I encounter this issue on the C100 I dial the ISO down from [850] to 800 or 640.

    Reply
    1. Dan McComb Post author

      Hi Peter,
      You can’t dial the ISO below the native ISO like you can on the Canons. But when you do that on Canon, you lose dynamic range. Sometimes that’s an acceptable trade off, but with Sony, it’s not an option.

      Reply

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