this picture was photographed in Austria, on the way to a glacier with a Canon 5D mark II, 35mm Lens, and a variable-ND filter.
So, I have a little advice when photographing in the daylight hours with long exposure, as it can create beautiful and unique images that can really only be taken during the day at, you guessed it, a long exposure! However, using variable neutral density or (V-ND) filters can be tricky to use, as you sometimes get an “X-ing” accross your photo-exposure which can leave a bad mark-imbalance.
So, here is an example of that V-ND X-ing problem that I mentioned and I tried to correct it by turning this in to a black and white photo. So, as you will see where water is flowing in the middle, it has a black shade in the water and also in the middle-bottom of the photo, is a dark spot. This may not be too noticeable, however, in colour it is a very different story indeed. This is the original photo, out of the camera. Here is that problem, the ND filter was turned too far and created this imperfection/colour deformation. Outside it is sometimes hard to see on the back of the camera preview screen to see these little problems properly, especially when you’re so excited photographing and are in the mode. However, when you get back to the lab and load up the injection, you see that on the big screen presents this simple problem.
You can do what I have done and just turn it to a B/W photo, however, it is better to control this when out and about. There are often markings on the filter, but I suggest to find out where the max is and make little tape- or marker-markings on the filter to help you when you are on the mission and save you the frustration later-on.
I hope this helps save some photo-mistakes later on for your amazing photo/nature adventures.
Løre Danger, kicking it back in the Lab, Würzburg.