Rocky, steep and fairly strenuous – we worked up quite a sweat on the climb up to the Teufelsloch (Devil's hole) near Altenahr. And of course we couldn't leave home without all of our photography equipment. Alongside a single-lens reflex camera and the high speed Tamron SP 24-70mm F/2.8 Di VC USD, we also had a graduated filter in our rucksack on this trip. The graduated filter allows you to reduce high contrasts between the sky and landscape. Ideal for taking photographs on sunny days when the dynamic range of the camera is not sufficient to capture details in highlights and shadows with one single exposure.
Balancing the brightness of the image
After arriving at the top, we enjoyed the fantastic view across the wildly romantic Ahr valley for a few minutes. The view that was offered to us was essentially divided into two halves: At the top the overly bright sky and at the bottom the dark forest. Finding the optimal setting for balancing the exposure was impossible in this situation. The contrasts were simply too great to be able to capture details in both sections. The subject matter was thus ideal for trying out the graduated filter. It can be used to darken only the top half of the image, which allows you to balance the exposure of the sky and landscape. The image brightness is now evenly distributed and the contrasts significantly reduced. It is even possible to recognise this effect in the viewfinder: While the sky previously appeared almost totally white, the white clouds now stood out in front of the beautiful blue sky.
Aligning the filter with the horizon
High quality graduated filters are comprised of a finely polished plastic or glass plate. This is fixed in place in front of the lens with a compendium, although an 82mm adapter ring is required for the Tamron SP 24-70mm F/2,8 Di VC USD. One half of the filter is neutral grey, while the other side is clear. The transition between the two halves can be soft or hard depending on the type of filter. The filter can be moved or rotated until it is aligned with the horizon. These filters are available in different thicknesses, with the most popular darkening the image by about 1 or 2 aperture stops.
Using the filter is extremely simple. An exposure measurement is carried out without the graduated filter by pointing the camera downwards towards the landscape, the final image section is then selected, the filter attached and aligned to the horizon. This process provides you almost automatically with the optimal exposure level.
Alternative to a filter
The effect achieved using a graduated filter can also be simulated by editing the image on a computer. Many programmes e.g. Adobe Lightroom are equipped with corresponding functions. In order to be able to use these functions effectively, the photograph should be taken in raw format and also carefully exposed. Check the histogram and highlight warning to avoid sections of the image being too bright with no detail. If the contrast range in the image is too high, the graduated filter can also provide you with practical support in this situation. Particularly when you don't have the time or the inclination to assemble two differently exposed individual photographs into a harmonious image on the computer.
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