It is of course a personal judgment but I suggest using a long lens in order to maximise the effect of tonal recession. It also draws the foreground and background closer together. The light in a thick fog can often be diminished, so use a tripod particularly if you do opt to use a long lens. But do not overlook the opportunities for taking great shots using a basic camera. Some photographers keep a cheap camera in the car permanently, just in case they encounter interesting weather conditions. Also, that which can be captured using a humble mobile phone can often prove quite illuminating.
If you have good foreground interest, then use it. This is where a standard or wide-angle lens becomes useful. The sky in mist often appears quite featureless, so it might serve you better to point your camera downward in order to minimise it.
Look for a sequence of regular objects that recede into the distance. A line of trees, buildings or telegraph poles assume a strange and unifying beauty when shot in mist. Using a telephoto lens will compress the effect, although equally interesting photographs can be had by using a wide-angle lens as well.
It is good practise to always attach a UV filter to your lens, but this will prove particularly beneficial when photographing in fog. Ideally, keep your lens cap on for as long as needed or moisture will build up on the filter, thus reducing the clarity of the final image. Carrying a microfibre cloth in your camera bag really is essential.
Mists and fog are notoriously ephemeral and can very easily disappear within an hour, particularly in the morning. There is often little point looking for photographic opportunities during a period of fog as it will probably have disappeared by the time you find a suitable landscape. It is far better to seek out possible locations prior to the anticipated fog, so that you can go there directly once one emerges.
The biggest problem you are likely to encounter is underexposure. The metering system in your camera is programmed to capture a notional 18 per cent grey, which often means that your shots in fog are underexposed. The easiest solution is to select the Manual Mode , then set the camera to overexpose by between 1/2 - 1 stop. Your image might appear a tad bright in the monitor, but far better err on the side of lightness if you want to capture the right mood.
Rising or descending mist
While we all want the fog or mist to last as long as possible, there are great photographic opportunities to be had either when the fog starts to rise (usually in the morning) or when it begins to descend, (most likely in the early evening). Essentially, a fog or mist is just a very low stratus cloud so, if you are close to high ground, the visual effects can be spectacular. Mountains can be particularly prone to rising or falling mists. The photograph below, of an abandoned farm, was taken in the evening, when a descending mist began to accumulate over the lower parts of the landscape as the land increasingly cooled.
Photographing Landscape Whatever the Weather by Tony Worobiec offers a comprehensive guide to assist photographers of all abilities. The book was selected by the Royal Photographic Society as one of its Top 10 books of the year 2016.