Want a lightweight, low-cost way of getting in really close for macro-style pictures? A close-up filter may be just what you are after. In this tutorial we explain how to use them
There are lots of ways in which you can get your SLR closer to the subject, so that small areas look big in the image. The most common solution is to use a macro lens.
However, this means buying a new lens, and having another bulky thing to carry around with you, just in case.
A less expensive, and less bulky, solution is a close-up lens (also known as a close-up filter). This attaches to the front of an existing lens, and works in the same way as a magnifying glass or a pair of reading glasses.
This type of filter is available for most square filter systems (such as Cokin), but round screw types are more common.
Close-up filters are available in different strengths, measured in diopters. The higher the number, the higher the magnification, and the closer the minimum focus of the lens becomes.
These lenses are often sold in sets with a +1, +2 and +4 diopter lens in a convenient carry case. Two or more filters can be combined to increase magnification – you just add the diopter values together to get the resulting magnification (a +2 filter used with a +4 diopter gives you a +6 diopter set-up, for example).
The optical quality of these filters is not as high as a macro lens – you tend to get more softening at the edges and more colour fringing.
However, they are more than capable of giving you a different view of a miniature world. They can provide record shots of stamps, coins and jewellery, for instance – but can be used for artistic shots that show texture and detail that more distant shots fail to show.
With a close-up filter, your focusing range becomes very limited (you can no longer focus on distant subjects). However, you can still use autofocus, and as there is no light loss, automatic exposure also works perfectly.
Step-by-step how to use close-up filters
01 Magnifying glass for your lens
A close-up lens screws into the filter thread of your lens (or slots into your square filter holder). The effect of the magnification is much greater with a telephoto zoom than it is with a standard one, so a focal length of over 100mm is recommended, and one of 200mm is ideal.
02 Buy the set
The three lenses you get in close-up sets can be combined to give you more than just three levels of magnification. The cost of a set increases with its diameter. We used a 72mm set from Kood, costing £80 – a 52mm set costs £27. Other manufacturers include Hoya, Tiffen and B+W.
03 Zoom in for maximum effect
Picking the right filter, or combination of filters, to get the crop that you want is usually a matter of trial and error. The focus range with the filter in place is limited to a few inches at best, and the minimum focusing decreases as the number of diopters applied increases.
04 Focus in on the detail
As with all close-ups, depth of field gets more limited the closer you get to the subject, and can be as little as a couple of millimetres. Use a tripod for stability, and if you need to ensure as much of the image is as sharp as possible, keep the camera perpendicular to the face of the subject.
One size fits all!
Close-up filters are usually the round type that screw straight on the filter ring of your lens (rather than the rectangular filters that slot into a special adapter).
Because of this you need to make sure that you buy a filter to match the diameter of the lens you are likely to use it with. But what do you do if you have more than one lens – with different filter thread sizes?
The answer is to buy close-up filters to fit your widest lens – and then use stepping rings. These simple metal adaptors convert the filter thread size of your lens – from 77mm down to 67mm, say. SRB do a full range for £4.50/$6.82 each (www.srb-griturn.com).
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