Endless possibilities with rectangular filter photography
The popularity and ease of photo editing software like Photoshop, Lightroom and Co might have you questioning why anyone might need to adjust or edit your subject before taking a photo. The simple answer is filters can produce stunning image results and effects that can‘t be achieved in post-editing.
Check out our guide below for a breakdown of the results you can expect to achieve with rectangular filters and when it’s worth using them.
What are rectangular filters?
A rectangular filter is an external photo filter made of glass that’s attached to your camera by a special filter holder.By placing a filter between the camera lens and your subject you can achieve different image results depending on the filter type. You can also layer several filters in the appropriate holder to create your own combinations.
There are two types of rectangular filters: ND (Neutral Density, Grey) and GND (Graduated Neutral Density) filters.
ND filter – Light reduction
Neutral density filters reduce the amount of light on the sensor of the camera, change the brightness or the colour contrast of the subject. With this filter and a larger aperture, you can limit the amount of light coming through the camera lens and you’ll see a reduction in the depth of field as a result. A dark ND filter combined with an increased shutter speed will allow you to show movement in your photos by blurring flowing water or cloud movement.
ND Rectangular Filters are available in a variety of types: classic variants include the ND8 filter with an optical density of 0.9 and an aperture stop reduction of 3 stops, the ND64 rectangular filter with an optical density of 1.8 and an iris step reduction of 6 stops, and the ND1000 with an optical density of 3.0 and an aperture reduction of 10 stops.
How to use ND rectangular filters
For ND filters with a high density and a correspondingly longer exposure time, a tripod should always be used to avoid camera shake.
ND filters are effective if you want to achieve darker images through a longer shutter speed. This is a great tool for landscape, city and travel photography. Using this type of rectangular filter, you can take images during the day when it would otherwise be too bright.
GND rectangular filters – Adjust brightness
In principle, cameras differ significantly from the perception of the human eye. Our eyes adapt well to different lighting conditions.They take in dark and bright areas individually and then piece the puzzle together to create a consistent picture.
Cameras, on the other hand, experience problems when different levels of light are present in an image because they capture the entire environment – light and dark – in a single image. This situation often leads to overexposure or underexposure. Grey gradient filters can compensate for these differences in exposure and produce a uniformly exposed photo.
There are four types of GND rectangular filters: soft, medium, hard and reverse.
Soft GND filter
The soft GND filter has a very gentle and extensive grey gradient. It’s useful when there isn’t a clear light and the differences in brightness are visible. The filter can help to merge them smoothly into one another. This is particularly good for landscape photography.
Medium GND filter
The medium GND filter has a slightly harder progression than the soft GND rectangle filter, but there is still no clear line in the image motif where you can see the contrast between light and dark. Typical applications in landscape photography include mountain ranges or treetops when the valley is much darker than the sky, or a city skyline when the buildings are darker than the horizon.
Hard GND filter
The hard GND rectangular filter can perfectly compensate for differences in brightness, with a clear horizon line, due to its clear contrast between light and dark. A classic application is photography by the sea or taking photographs of mountain landscapes with a straight horizon edge.
Reverse GND filter
The fourth variant is the reverse GND rectangular filter. With this type of filter, the grey gradient is reversed towards the middle. The filter doesn‘t turn brighter towards the centre but darkens before going into the bright area. This rectangle filter is often used for sunrise and sunset photography because most of the picture centre (the sun) is the brightest point and the upper and lower edges of the picture are a bit darker.
Practice makes perfect
Some practice working with rectangular filters will make sure you choose the best one for each subject, but once mastered, the results speak for themselves.
Images: Rollei
