If you have ever heard of a close up diopter you may be confused as to how it works exactly or why it is important. These close up diopters are considered an additional lens that you put on the front part of the existing lens that is on the camera. In this way it acts as a sort of filter.
The main benefit of this close up diopter is the ability to actually permit a much closer focus function. This close up diopter actually allows this for whatever lens it happens to be in front of. On top of this is that it does not require any post-production enhancement of the footage with a non-linear video editing software or any kind of exposure compensation.
How to Use it
These close up diopters actually come in an increasing level of strength, which is measured numerically in a similar fashion to things like iris readings. The larger the number reading correlates to the closer distance you can focus at with your close up diopter. This means that if you need to focus very close you should get the highest number you can.
You have to also remember that the power of the close up diopter is directly correlated to over all accuracy of the image. This means that the stronger the close up diopter the less clear the image will end up being. This is similar to the balance of shutter speed when you are trying to lighten an image.
Try to combine focal length with the close up diopter to see if you can find a nice balance between the two functions. You are going to have to estimate how to use these functions as each situation is different. Use your eye to try and decide what you are going to need.
Close up diopters are referred to by a number of different names. The most common alternative name for the close up diopter is the plus diopter. Some people refer to the close up diopters Proxars after a common brand name. It is best to stick with a brand neutral name when you are trying to pick one out.