The cokin a series a102 close up 2 filter comes in different powers dioptres and works as if a magnifying glass is in front of the camera lens enabling the user to produce close up shots using this filter is one of the simplest and least expensive methods of close up photography filter powers dioptres include bull a 1 close up lens focuses lens marginally closer than original lens bull a 3 close up lens focuses closer than the 1 the maximum magnifica