Iceland Aurora Photographic

The magic cloth technique was born out of the need to get the image right in the camera but to still increase the dynamic range of a scene. Under normal circumstances, the top part of a landscape is brighter than the lower half. Even with a mirror lake the difference can be a couple of stops. In order to get the best exposure of both the land and the sky, photographers have traditionally used filters which are darker at the top and clear at the bottom. These are called Graduated Filters (grad) and although they come in different colours, the most popular are Neutral Density (ND - Grad). Neutral density adds no colour to the scene. Aside from different colours, Grad filters come in different strengths - measures in stops. They also come as soft or hard grads.

This is an extreme example to demonstrate the difference between a hard and soft grad.

Ok, so if you wanted to have graduated filters to cover every eventuality, you would have a set of around 8 filters plus a holder and adapter. If you want the quality versions, you are talking about the same price as a used car. This was my obstacle, I couldn't afford them! But while I was looking I decide to buy a decent ND filter.

An ND filter is just a filter to darken the scene. You can get silky waterfalls or nice sea movement without having to wait for it to get dark. Like Grad filters, they come in different strengths. I bought an 8 stop ND.

Magic Cloth
This technique seems so obvious to me now! It is as simple a using a cloth, sock, wallet, hat or whatever you like to allow different parts of a scene to have different exposure lengths. The basic technique is to fire the shutter while covering the front of the lens with the cloth and slowly raise the cloth to reveal more of the scene. The more slowly you raise the cloth, the higher the strength of the Grad. For example; if you expose the foreground for 30 seconds and raise the cloth very slowly to allow only 3 second on the sky, you will have a 10:1 ratio which is just over 4 stops. The more you move the cloth, the softer the grad.

Use your camera light meter and set the exposure compensation about 2 stops over. This should give you a really nice exposure on the immediate foreground.

The magic cloth technique isn't for everyone or for every scene, but it is certainly cheaper than carrying around a set of expensive glass filters.

The downside is that you need a long exposure for this to work. The longer the exposure, the more control you will have. For day-time shots, you will need a way of slowing your exposure use a combination of ND filter, small aperture f/16 - f/22, and slow iso 50-100. I have had acceptable results with 2 second exposures. The other downside is that is can involve a lot of trial and error, this can be frustrating if you are taking a very long exposure. It is not really suitable for extremely long exposures as your arms and shoulders will ache.

The upside is that is is a very cheap method and can give excellent results. Also it is dynamic, you can expose all the sky in one go to give detail to the clouds, or you can use short bursts to give the clouds extra movement. It is possible to change the exposure if the sky suddenly changes. It is possible to use a mixture of angles if one side of a scene is too bright. It is also possible to clean your lens half way through an exposure. Very useful for waterfall shots.

This shot of Skógafoss would have been very difficult because the spray was constantly soaking the lens. I was able to use the cloth to keep it dry during the exposure.

This was an extreme condition as the sky was a lot brighter than the cliffs. I gave the foreground around 10 minutes and the sky around 10 seconds in total. I exposed the sky for about 1 second every minute to give the clouds a sense of movement.