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BlackWhite Photography

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Home / Articles/News / Daytime long exposures
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Daytime long exposures

You´re wondering how to take those long exposure pictures without having to wait until the sun goes down, finding your way in the dark with flashlight, falling on the rocky beach and breaking your camera gear?  Believe me, I´ve been there!

heidiDon´t worry, there is a way - ND filters.

Nd filter is a piece of gray colored glass you put in front of your lens to reduce the amount of light hitting the camera sensor allowing you to use either a wider aperture or slower shutter speed. The deeper the color the stronger the effect.  You can think of them as sunglasses for your camera.

 


Uses

There are many other uses for ND filters but we´ll be talking about long exposures for smoothing out water and clouds. Examples of what ND filters can be used for:

- Reduce visibility of moving objects.
- Adding motion blur.
- For using wider aperture to stay below diffraction limit.
- Reduce depth of field on a bright day.
- Get below the flash sink speed and still use large aperture.

 

Types

filterYou can have either a filter that you screw on to your lens or you can have one that you slide in a mount attached to your lens.  The sliding one is more convenient since it´s easier to remove but the screw on is the cheeper choice.  I personally use screw on filters. One could even argue that you´d put more thought into the composition when using the screw on filters since you don´t want to spend much time unscrewing the filter, recompose or focus and then screw the filter back on. 

Then you´ll have to choose what strenght you´d like to have, that is how much light the filter will let through. If you´re looking for long daytime exposures like we are talking about here I would recommend a 10 stop filter like the B+W Nd 3.0.

TIP: You can “stack” up filters. But that usually causes vignetting at wide angle shots along with other unwanted effects.

Filter Density:

Density 0.1   0.2   0.3   0.4 0.5 0.6   0.7 0.8 0.9   1.0 2.0 3.0  
Reduction (f-stops) 1/3 2/3 1 1 1/3 1 2/3 2 2 1/3 2 2/3 3 3 1/3 6 2/3 10

 

NOTE

You can find cheaper filters than the B+W but I recommend it cause it has minumum color cast and a good quality glass.

When buying the screw on filters you´ll have to choose what size to buy. The sizes will equal your lens size. 52mm, 55mm, 58mm and so on.. I recommend that you buy the 77mm and a step up ring so if you later buy a 77mm diameter lens you can still use the filter.

I would recommend that you buy the 77mm even if you don´t have a lens that it fits. The reason is that a good quality filter is expensive and you can buy a step up ring (also known as adaptor ring) for the fraction of the filter price. Then if you later buy a 77mm diameter lens you can still use the filter.

Step up ring screws onto your lens threading providing a larger thread that you can then attach the filter on. Look for the thinnest adaptor ring that you can find as these will keep the filter close to the lens.

 

Gear

In addition to the obvious gear, the camera, lens and filter you´ll need something more to be able to shoot daytime long exposures.

An essential would be a tripod to minimise camera shake and keeping a sharp image. And then a shutter release since you´ll probably be shooting exposures exceeding 30 seconds. I will not go into what to get in that department since that varies depending on what camera you have.

 

Camera settings

So now you´re out in the field and you want to use your filter. How to set up the camera!?

First decide what is the desired exposure time or f‐stop. Use the camera AV mode to find the correct exposure for your settings. Then switch to manual mode.
Set the same aperture as you used in AV mode and set the exposure time corresponding your filter strength.

At the end of the article  you can download a chart you can use it to calculate easily the correct exposure time:

FINDING THE CORRECT EXPOSURE TIME

Let´s say you are using a ten stop filter and want to have the exposure time one minute. Look at the chart - There you´ll see that for 1 minute exposure with 10 stop filter corresponds 1/15sec without the filter. Set the camera to AV mode(aperture priority) and use the aperture(f-number) to control the exposure time. When you have found the aperture that produces 1/15 correct exposure time switch to Manual mode and set the same aperture there.

Ok, now you have found the aperture that will give you the correct exposure after one minute with a 10 stop filter.

10 stop filter is so dark that you won´t be able to focus with it on and you won´t see anything through the viewfinder so you´ll have to compose the shot before you put the filter on.

TIP: If you are using a digital camera with LIVE VIEW you can use that to recompose since you will be able to see "what the camera sees" through that.

Now when you have composed the shot and focused switch the lens to Manual focus. You have to do that so the lens will not try to focus after you put the filter on. Set the camera exposure time to BULB since your exposure time will be longer than the 30sec that your camera will allow, press the shutter release and expose for the desired time..

Thank you for reading. If you have any questions or comments feel free to comment below.

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Attachments:
Download this file (ND_Filter_chart_.pdf)ND Filter Chart[Chart for calculating exposure times with Nd filters]75 Kb4443 Downloads

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