Photography News Issue 37

Photography News | Issue 37 | absolutephoto.com

Technique

Screw-in filters

Slot-in filters

Screw-in filters are usually highly durable, being made of glass with a metal ring, and they don’t need the additional investment and space of a filter holder as they mount directly to the screw thread of the lens. They should also offer no vignetting as they sit very close to the lens, unless you stack them; filters of the same size can be screwed into one another to multiply or mix effects, but this can cause vignetting. The downside is they can get stuck if put on in a heavy-handed fashion, and you need different sizes for different lenses (or to use stepping rings), so costs increase. You can also get variable ND filters, such as Cokin’s PURE Harmonie Variable Density filter, which, with a twist of the bezel, offers a range of strengths; although these can save time, they tend to be more expensive than individual filters.

Square or rectangular slot-in

filters can be used on any lens, so long as the holder will fit, and changes in size in the lens can easily be offset with inexpensive adapter rings; you just need to find the

Above A Cokin PURE Harmonie Circular Polarising Filter CPL and a PURE Harmonie Variable Neutral Density filter, which offers a range of light blocking strengths in one unit.

one that fits your filter thread. Filters and holders vary in size, so in the Cokin range for instance, there’s A/Small, P/Medium, Z-Pro/Large and X-Pro/Extra Large. Sizes correspond to the size of the filter ring on the lens, so if you have large or wide- angle lenses, you need larger filters and holders. With grad filters, slot-in types make repositioning the effect much easier; most grads come in slot-in form for this reason. Most holders also have space for more than one filter, so you can build up the effect. Disadvantages are that if plastic or resin materials are used filters must be carefully handled to avoid scratching, while glass versions are more likely to smash than their screw-in counterparts if dropped. Arguably, they also take longer to use, but with the considered approach taken on most landscapes, that’s not necessarily a problem.

Other types

Cleaning and storage

Remember that, just like your camera and lenses, filters need to be well maintained or you’ll be in danger of compromising image quality. Cleaning using a dedicated lens cloth is advisable, so long as you make sure both it and the filter are free from grit or dust first. You can also use dedicated filter cleaning systems that come with a liquid cleaner and disposable cloths, but in many cases washing them in soap and water, then drying them with a clean, lint-free cloth can also remove grease and smears. Filters should also be stored with care, so seek out a well-padded case or wallet that’ll fit easily into your bag.

Some lens models also offer a rear filter mount, where you can slot small gelatin filters; these include the Canon EF 17-40mm f/4L and 11-24 and EF 11-24mm f/4L, EF 8-15mm f/4L Fisheye and the Nikon AF 14mm f/2.8D ED and AF DX 10.5MM f/2.8G ED Fisheye, all of which have bulbous front elements incapable of mounting regular screw-in filters or holders onto them, without modification and special adapters.

With filters (15secs at f/16, ISO 100)

Without filters (1/15sec at f/16, ISO 100)

Compare these two scenic images, one in which filters were added, and the other which was shot without. The composition is almost identical, but one looks like a ‘proper’ landscape photo and the other more like a snap you might take when out on a walk. Why? For starters, the filters used have blocked out a lot of light, forcing the shutter speed to slow, which in turn softened the water and the moving clouds on this windy evening. This longer exposure makes the scene feel less busy and also lets the detail in the rocks stand out. Then there’s the sky. In the unfiltered photo it’s quite a lot brighter than the rest of the scene, so the image looks unbalanced. But if you place the right kind of filter to cover the sky you can hold light back there, too, making it darker (but not too dark). This darker area tops off the image and stops the viewer’s eye from roaming to it, as the gaze is generally drawn to light. Far left, Mike French used filters to shoot this glorious sunset at Hallsands, Devon. See more of his work at the end of the guide.