Fog is a popular mist - we often get confused and just term it all as fog or all as mist. It's not quite like that. It's all about the visibility, if we can see less than 1km through it then it's fog. If we can see between 1 - 2 km then it's mist. So when is the best time to catch these ground level clouds at their best? Fog forms in the late evening and can be found lying in valleys most commonly but if the conditions are right you could well get it anywhere. It lies best over water too, creating a wonderful atmosphere if you're there to capture it. Haze is often found in Summer at the end of a really hot day and is also fantastic photographically. You can use haze to capture sunsets - and use fog to highlight those sunrises. Regardless of whether you are shooting in fog, haze or mist - the photo-graphical technicalities are very similar.
Before you curse fog, look at it as a natural soft box. It diffuses light nicely and reduces contrast. The lighting is much more dimmer and this requires a longer exposure time than you would ordinarily think is needed. Fog means that the air is reflective to light which can fool your camera (if it's one of those smart types) into believing that exposure needs to be decreased. Therefore you need a healthy dose of exposure compensation. We'll talk about camera metering and exposure another day though..
So fog isn't to be despaired and cursed at. It can emphasize depth, lighting and compliment the shape of your subjects. Whether that's a long road, a bridge, a person or a statue and so on. So, as objects move further away from your camera they become smaller. And by that token, if you've got an avenue of trees you're going to lose contrast, saturation and clarity the further back they go because the mist will add extra diffusion to shape, tone and colour. Making use of this silhouette type feature that mist enhances is paramount.
As we already mentioned, fog and mist emphasize light. If you've not got natural light or artificial street lamps in your setting then try using a torch to create some rays through the mist. The effects can sometimes be amazing, especially if water is involved. Planning your vantage point will make light rays either stand out or disappear completely. You have to be in a certain position to see them. Be near to the light source so that you're at an 'off-angle' perspective - this is useful if your fog or mist is weak. If it's strong, then the light rays should be visible wherever you are and it's just up to you to compose the shot adequately to make the most of it.
The best vantage point (in my opinion) that you can take when shooting in such conditions -is to get above your mist. Get up high on a hill, hang out of an upstairs window - even, if it's really low and dense, scramble up onto the bonnet of a car and shoot downwards. There's nothing more impressive than mist and fog from above as it circles and rolls around you. If you are able to do this, then all of the above is not necessary, as you'll have put yourself far out of the conditions of fog.
Important point: Fog and mist are both wet. Be aware of condensation and the impact it can have on your camera! Also, Camera Covers (waterproof ones) are awesome and make you look ridiculous - be kind - give other photographers something to laugh about.
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