For most trips when I travel, I at carry at least 3 filters which I find essential in photography and are near impossible to create the effect in post editing or any other method. They are a 6 stop and 10 stop ND (Neutral density) and a Polarizing filter. Each for a different purpose and situation ranging from photographing people, landscapes and cityscapes where motion or reflections can be utilised in the scenario. In most instances when using a filter, a tripod is required to ensure that the camera is still while shooting.
There might be times when the light changes quickly and I will change between filters. The key to capturing what you need is to have a look at the result as you shoot and be dynamic enough in making changes when out in the field.
6 Stop ND FIlter - 6 sec exposure at f22. Shot on Sony A7RIII with 16-35mm f.40 at 27mm
An ND filter is essentially a dark piece of glass that allows for a longer shutter speed exposure. This is useful whenever theres motion involved and we can capture motion blur of people, water or clouds for example. Essentially the higher the number of the ND filter (3, 6, 10 stops etc) the more light the filter blocks out.
The motion can leave a ghostly blur, water can be smoothed out to look tranquil and dreamlike, clouds can lose their edges and become a blanket. The “Neutral” refers to the colour not changing with the amount of light being captured.
6 Stop ND Filter - 4 sec exposure at f11. Shot on Sony A7RIII with 16-35mm f4.0 at 31mm
The 6 stop ND filter, as you may have guessed, reduces the exposure by about 6 stops and the related shutter speed to be longer. This is useful when trying to get a slightly longer exposure than normal, but still allowing enough shutter speed to capture some form and shape in the motion.
I would use this in a practical sense when its less that broad daylight and I'm looking for just a slighty longer exposure to smooth out water or to get a trail with an exposure from 2 to 10 seconds.
10 Stop ND Filter - 8 sec exposure at f10. Shot on Sony A7RIII with 16-35mm f.40 at 27mm
The 10 stop ND filter is darker than the 6 stop. This gives more dramatic results with the longer exposure times, but can also leave water formless as you can “overcook” the exposure time.
In bright broad daylight, a 10 stop ND will be more effective in reducing the light coming through. Generally I will use the 10 stop ND if I'm looking to go beyond a 10 second exposure.
Polariser Filter - 2 sec exposure at f22. Shot on Sony A7RIII with 16-35mm f4 at 16mm
Polarizing filters are typically circular, allowing for easy control of the effect of polarization. By filtering out polarized light, it can enhance colours and increase contrast. I mainly use it to reduce reflections and glare in. Water and glass. There's just no other way to get the details through reflections without changing the angle of the camera, but then the perspective is different.
These filters allow the photographer to create something artistic and unique as the images can look dream like or ghostly. I use the Lee filter set and a circular variable polariser.
The Lee filter set I can use across the different lenses I have and just change the filter ring size according to the diamter of the lens (eg the Sony 16-35mm f4.0 uses a 72mm ring) The filter sets can be expensive to start with, but are a great investment in taking your photography to another level.
You will also need a sturdy tripod to keep the camera steady while shooting the long exposures and I use a remote control to not bump the camera when starting the shot. Another way around not using a remote control is to set a 5 second delay from taking the shot.