Why would I use a ND filter indoors?


Today, being bummed out about not getting to do my sunrise shot, I decided to play around with my ND8 neutral density filter and do some indoor flash portraits. For those who don’t know, a ND filter is like putting sunglasses on your lens in order to lower the amount of light entering the lens and lower the shutter speed and/or f/ stop.

This is commonly used for landscapes, long outdoor exposures, and harsh sunlight conditions. But in this case I wanted to show how the ND filter can help in a small studio environment with an over powered flash head. Let’s set the scene, Your in a small studio or room, your model is looking lovely, your background is just right, you’ve put your softbox on your flash head to wrap the light around the model, and you’ve put a little distance between your model and your background to throw it into underexposure using the inverse square law (more on that in a future post).

All is ready, you’ve decided to use a wide open aperture of f/2.8 to get a shallow depth of field for a nice creamy bokeh to really bring attention to the model; however shooting wide open means turning down the flash power. Ok not a problem you crank down the 500 watt second head and test the exposure.

What happens? The meter shows f/8 would be the correct setting for the shot. But that wont give you a shallow DOF and there’s no more room to back up the flash which would ruin the quality of light you wanted anyway because of the (you guessed it) inverse square law. So, what to do?

Bring out the ND filter. This will allow you to limit the amount of light entering the lens and lower the effective f/ stop without changing the aperture on the camera. So by using a ND8 filter (which lowers the light by 3 stops) we’ll bring that f/8 light down to the appropriate exposure stop of f/2.8. Now we get to keep the quality of light on the model (who is still looking lovely) and throw the background into a shallow DOF and underexpose it somewhat.

The key here is controlling the light. When you have a vision for your photograph and your light source can’t be physically modified anymore, bring out the filter and get the shot. So get out there get some practice in by cranking your speedlight up way to high and control the light with the ND. Find out what happens to the background both indoors and out. What happens to the shadows? What kind of mood gets produced with this technique?

If you have questions on how to use equipment or get a certain shot or even how to get a certain effect in your photographs leave comments below or email me using the address listed on the sidebar. As always happy shooting.


About Mark Birks
Professional photographer specializing in fine art photography and portraiture.

5 Responses to Why would I use a ND filter indoors?

  1. great post, very informative thanks 🙂

  2. Mark Birks says:

    Your welcome Ben. If you have any questions on photography or would like to see more tutorials let me know.

  3. thanks Mark, things relating to flash gels and wireless flash use would be useful, as I have been experimenting recently with them 🙂

  4. Mark Birks says:

    Now we’re talking. I’ll get on it, just give a little bit of time. I’ll most likly have to make it a multi post subject.

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