Laws of Light: ND Filter VS High Speed Sync

Hi it’s Jay P here out in the woods today and we’re going to have Kelem help us take some pictures.

We’re going to look at high speed sync vs ND filter. Which is better? Do they work the same? Are they as easy to work with? Or does the ND filter work at all? Let’s take a look at those two next here on TSL.

First off, high speed sync is when you’re trying to match a bright back to a subject that you brought into the shade and you’re lighting with a strobe. You want to be at 2.8 – you want to be wide open so that background falls way out of focus. I don’t want harsh sunlight on her face so I brought her into the shade. So I’ve got 2.8, my subject in the shade and now I turn my strobe on to light her face. At 1/200 of a second I can’t make the background dark enough – it’s just too blown out at 2.8, so I set my strobe and trigger to sync and I can now move my shutter past 1/200 but it does create some issues. HSS cuts the power down on your strobe – the strobe is not near as powerful when you go into HSS because it’s having to pulse, it’s just not near as powerful. So I want to see if I go back to a ND filter starting off from HSS if that strobe light power coming up is equivalent now to the sunlight I’ve got in the background and I can balance then just using the ND filter by bringing everything down so I can expose at 2.8.

Let’s take a look at those. We’ll test those two – HSS VS ND filter!

HSS Test

My strobe setting in the background is at 1/2 at 2.8 at 1/4000 sec, but my background is way too dark so I’m going to move my shutter to 1/2000 and what’s going to happen is her face is going to get too bright so now I have to dial my strobe down to a 1/4 from 1/2.

The background is a little brighter than before – not a lot but a little bit so I’m going to go up another stop to 1/1000 of a second and I’m going to dial my strobe down another stop.

Now the background looks really nice – I think I could go up to 1/500 but I’ll have to dial my strobe down to 1/16.

Let’s try 1/200 and 1/30.

This is pretty but it’s a little bright so I’ll bring it down to 1/48.

You can decide which one of these you like – but the principal is here that in HSS you have to dial your strobe up or down depending on which way you go with your shutter. You can make your shutter longer, giving more light to the background if gives more light to her face so you’re going to have to dial the strobe down.

ND Filter Test

We’ve got 3 stops of ND at f/2.8, 1/200 sec which is as fast as I can go to be able to sync with the strobes cause it’s not on HSS now and my strobe power is at 25% and I get a nice image there.

From here, I can only do 1 of 2 things – I could give myself less ND which means I’m going to take 1 stop away which makes everything brighter because it’s effecting both the strobe and the ambient sunlight the same.

I’m going to dial it back to a 1/12 of the power. So the background got a little brighter because I went from 3 to 2 stops of ND which allowed the sunlight to be brighter in the background so I had to dial my strobe power down because her face got brighter. Now it looks excellent.

I could go the other way and do 4 stops of ND and make the background much darker, but now I’m going to have to dial my strobe up to half.

I balanced the foreground and the background and it looks great. If i wanted the background to be lighter I’m going to go down to basically 2 stops of ND – so my background got brighter because I went from 3 stops to 2 stops, I had to cut my power in half to keep her face exposed properly.

Now I’m going to go down to 1 stop of ND and I’m going to have to cut my power in half again. It’s not quite as bright as I like on her face, but that’s not the point. The point is that the ND is going to effect both the power of the strobe, it’s going to make it brighter or darker as well as the background.

So it’s very easy, I’m just changing the ND filter to give myself more or less exposure and when I do that though now, I’ve got to change the power on my strobe to compensate.

ND Filters

So it’s just a lancing act between the light in the background and the power of the strobe in the foreground making sure you get a nice exposure on her face and the background is as dark or as light as you want it.

There’s a look at ND filters VS HSS. I have always said that ND filters just don’t work, but I stand corrected! I love when I do one of these things and I learn something and I really have learned something today. When you go to high speed sync, it kills the amount of power from your strobe because they’re having to pulse so you don’t get as much power out of the strobes. But when you take it off high speed sync, you get that power back and now you use it to match the strobe power to the ambient. It’s a balance act on both of them. I was very surprised at how easily it worked and it looked incredible using the ND filter.

Now I think everyone should carry an ND filter all the time because it helps you unlock the entire capability of the exposure triangle and a tripod – if you don’t have those 2 things, all your images are going to look the same.

If you want better information about HSS, check out our HSS course that will make you a master at high speed syncing.