In almost every workshop I put on, regardless of content I always get at least one person asking about filters; specifically solid neutral density(ND) and graduated ND. One recent question that came to me from Nico, and is a common one was: What filters do I need and when do I use what? So, based on that I thought it was time for a run down on what can be very confusing when faced with buying the right filters and what conditions to use them under.
I’m going to talk specifically about the types of Graduated ND filters and their strengths, and also how solid ND filters work to improve certain situations. First, Grad filters come in soft and hard edged, and also different stops. For example, 1 stop, 2 stops or 3 stops. Solid ND filters come in different stops as well; for example 1 stop, 2 stops, etc., up to 8. Grad filters help us achieve a balanced exposure like in image 1. By sliding a 3 stop hard edge Grad filter over the bright sky I was able to achieve a balanced exposure and have the foreground not become completely dark. When you have a relatively straight horizon, you can utilize a hard edged filter. If you have tall trees that are protruding in the sky, you’ll need a soft edged filter in order not to have a dark edge over the top half of the trees or landscape. A 3- stop soft Grad was used in image 2 to help illustrate. The soft edge grad helped tone down the exposure of the clouds while not allowing a hard line through the mountains. Had the 3 stop Grad not been used here, the clouds would have been blown out in their exposure.
Solid ND filters are probably most used to slow down water to give it that silky look. They are also used frequently to allow longer shutter speeds for landscapes and moving skies and absorption of colour, as they can reduce shutter speeds significantly. Note the cloud movement in image 3. That effect was achieved by using a 4 stop (reducing the shutter speed to 30 seconds) and also a 3 stop Grad filter for the bright sky. This is known as filter stacking.
The same filter combination was used in image 4. Here I was able to achieve a long enough shutter speed for blurred traffic to register on the sensor and also a sky that was not blown out in highlights. The results would have been much different without the use of these filters.
For my purposes I use 2 and 3 stop hard and soft edged Graduated ND filters, and a 4 stop solid ND filter. These are both ‘slide in’ filters, which means there’s a filter holder screwed on to the front element of the lens and the filters are subsequently slid into slots over the lens. The holder can be found as a ‘P’ type for most cameras. You’ll need an adapter ring that’s sized to your front element, for example, 55mm, 58, 72 or 77 (usually). These are quite affordable. Filters on the other hand can be pricey, depending on the brand. The top quality Grad ND filters, and I would recommend them, can cost around $100 – $150 mark per filter. The soft and hard edged are quite similar in price. Solid ND filters, once again for really good quality will be around the $150 range for a 4-stop solid, getting up to near $400 for a ‘vari ND’, which is a screw in filter that allows for variations of 2-8 stops.
Filters can be extremely rewarding for those looking to push their photography to the next level. If you have further questions about this column, please send them my way! For more information and to view my galleries, click here