First shots with my GoPro using a 16 stop filter.

I recently brought a new GoPro (a Hero 8 black) to upgrade my trusty old GoPro Hero 3 Black. One of the features I had been interested in with the newer GoPros is the Night Mode, this allows it to capture a long exposure of up to 30 seconds.

But could you use the 30 second exposure during a bright sunny day?, of course with a ND filter, but how much do you need to stop it down by?


The GoPro's main draw back for long exposures during the day is its fixed f/2.8 aperture. It has a fixed f/2.8 aperture because it is an action camera and needs to draw in as much light as possible for the fast action shots. Most cameras have an adjustable aperture range between f/2.8 and f/22, by adjusting the aperture you can reduce the amount of light hitting the sensor and make a longer exposure.


On a nice sunny day with the right setting on a DSLR a 10 stop filter can easily make a 30 second exposure and a 16 stop 5-8 minutes.

Using a GoPro setting the ISO to 100 max (adjusting the ISO changes the camera’s sensitivity to light, ISO 100 is the lowest GoPro goes) with its f/2.8 aperture on a sunny day you will get an exposure of around 1/500 sec, using the same filter stops will get different results.

10 stop = 2 seconds
16 stop = 2 minutes 11 seconds

The 10 stop filter will be good for faster moving subjects which you just want to add a bit of motion, waves crashing, waterfalls etc. 
The 16 stop gives an exposure too long for the GoPro, but by adjusting the ISO you can bring down the shutter speed.
  • ISO 100 = 131 seconds
  • ISO 200 = 66 seconds
  • ISO 400 = 33 seconds
  • ISO 800 = 16 seconds 
So by adjusting your ISO to 400 you can max out the GoPro's shutter speed on a sunny day.

You can either guess the settings as you go by trail and error, I use a Light meter app to get the exposure (as GoPro don't show these on screen) then add the setting into an Exposure Calculator app where I can add the filter stops and adjust ISO the find the right settings needed.

Attaching the holder to a GoPro I used a 52mm Filter Adapter Ring Mounting Bracket then a 52mm - 77mm step up ring.

The filter holder did show up in the frame, but by adjusting the lens correction in Lightroom to remove the fish eye effect, it did remove the filter holder out of the frame. 
A 77mm screw in filter did now show up in the frame.



Water swirling 
ISO 400 - 30 Seconds 

Using a headband behind the mounting bracket helps prevent light leaks which can reflect off the inside of the filter and show on the photos.

Eastbourne Pier
ISO 100 - 30 seconds 

Black and white version.


Using a 10 stop filter, I had accidentally left the ISO on 800 from a previous shot, so it only slowed the shutter down to 1/7 of a second, but enough to add a bit of movement to the incoming wave. 
If I had dropped the ISO down to 100, it would off been a 2 second exposure.


Images were all shot in RAW and edited in Lightroom.

Overall I am really pleased with the results, a GoPro won't come close to quality of a DSLR but it will give amazing results with the right gear and settings, if you don't want to carry a bigger camera around and still want some wide-angle long exposures shots, the GoPro does the job.

I will use this set up a bit more and try a few different shots, but I think a 13 stop filter will works much better.
Being able to keep the ISO low is an advantage on quality, higher ISOs will start to make the images more noisy/grainy, and so you don't want to go too high if you don't need to.
With a 13 stop filter and keeping the ISO at 100, these different shutter speeds will get these results.
  • 1/1000sec = 8 seconds
  • 1/500 = 16 seconds
  • 1/250 = 33 seconds

TIPS FOR LONG EXPOSURES
  1. Use a tripod 
  2. Use self timer, remote or GoPro App
  3. Set GoPro to RAW (output settings)
  4. Shoot at the lowest ISO possible
CHOOSING THE RIGHT CONDITIONS.

Conditions for long exposure photography are important, If there are no clouds or moving clouds, no water movement, no people, no motion what's so ever, you will just get a normal shot, with a longer exposure. Windy days, dappled clouds, waves on the beach, fast flowing rivers and busy areas work well with long exposures.
Shooting around sunrise/sunset will also give some amazing results with the right conditions.




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