Cell phones and slow shutter speeds

 

Modern cell phones have the ability to capture images on par with their much larger DSLR and mirrorless cousins, sometimes.  Their convenience and proven portability have made them by far the main way people take pictures today.  The quality of the images also is very good.  The caveat is that there has to be a reasonable amount of light and you don't want to zoom in too much or shoot at a slow shutter speed in bright conditions.

There is a way around these limitations.  It involves using clip-on filters and lenses.  These peripheral devices are relatively inexpensive, especially when compared to their previously referred to counterparts, and expand the abilities of mobile cameras.  Clip-on lenses make ultra wide-angle and telephoto relative focal lengths possible.  If you want to get slower shutter speeds though, you have to consider a special type of filter.

A neutral density (ND) filter is akin to sunglasses for your smartphone camera.  The neutral-gray colour of the filter reduces the amount of light coming into the camera.  You can buy them in various densities, usually starting at 2 stops (1/4 the amount of light) and increasing from there.  A variable neutral density filter features a rotatable ring that changes the filter's density.

Since cell phones have a fixed aperture (it's true!), the only way to alter shutter speed is by changing the ISO or shooting under different lighting conditions.  You can also alter the exposure compensation value, but then you will under or overexpose the image.  The ND filter lowers the amount of light entering the camera and enables slower shutter speeds.  I prefer to shoot in manual (pro) exposure mode because I can pick my ISO and adjust my shutter speed accordingly.  

The first image (left) was taken on automatic without an ND filter; consequently, the shutter speed was very high (1/1200th of a second) even though the camera picked an ISO of 32.  The aperture was fixed at f/2.  Putting a neutral density filter on reduced the shutter speed to 1/160th of a second; a heavier filter (created by rotating the ring) produced a very slow 1/6th of a second.  If I had used a tripod, I could have gotten a much lower shutter speed.

Apple iPhones has a "live photo" feature that takes a short video of your desired still.  You can then view the image and convert it into a simulated long exposure photo.  It does this by taking the individual frames from the short movie, superimposing them, and then averaging out the exposure.  It's actually pretty good, although I found it takes some finagling to export the resulting image.  If you want to get a longer exposure then you have to use an ND filter as you do with an Android device.

My preference is to use my large and bulky DSLR and mirrorless cameras to get the effect I am looking for.  I have variable ND filters for them too.  Of course, I can't fit the entire camera in a pocket the way I can with my cellphone.  And they don't make phone calls either.

Thanks for reading.

Eric Svendsen     www.ericspix.com