How to make a close up filter for your lens in under one dollar

In photography, a close-up filter, close-up lens or macro filter is a simple secondary lens used to enable macro photography without requiring a specialised primary lens. They work identically to reading glasses, allowing any primary lens to focus more closely. Close-up lenses typically mount on the filter thread of the primary lens, and are manufactured and sold by suppliers of photographic filters. Some manufacturers refer to their close-up lenses as diopters, after the unit of measurement of their optical power. While some single-element close-up lenses produce images with severe aberrations, there are also high-quality close-up lenses composed as achromatic doublets which are capable of producing excellent images, with fairly low loss of sharpness.

We will build a high quality close up filter, in this case based on a 52mm filter. (the lenses come in different size and you may use filters of higher diameter also depending on your requirement.)

Tools we might need for this project

Tweezer
Plier
Carborundum Stone

The lens we use is a convex lens of the power +2 (reading glass bought from a spectacle store) which cost Rs 40 = a little less than a dollar. 1$ = 48 Rs. presently.

reading glass convex lens of power +2 used to make close up filter

The next thing we need is an old filter, we can make use of any broken or damaged filter because we only need the thread and not the glass.

ultra violet (uv) filter we used to make our closeup filter

Some filters have a ring which screws on to the filter to hold the glass and others have a metal ring. This one we chose has a metal ring so carefully lift the ring inorder to remove the glass from the filter.

ultraviolet filter uv removing the uv glass to make close up filter

The lens that we bought is slightly larger than the 58 mm filter and we need to make this lens fit into a 52 mm filter so we will start the grinding process. Our technique of carefully grinding the glass with a cutting plier is a job which requires some amout of practice so if you are feeling adventurous go ahead and try, else skip this step. We do it this way because it makes the job a whole lot easier. Always wear safety glasses if you are planning on trying it out this way. Make sure you collect all glass pieces on to a paper or something and dispose it off safely.

close up lens making grinding the lens with a plier

Now our lens is approximately the same size as of our 52 mm filter and is now ready for grinding using a carborundum stone.

close up lens filter making grinding the glass with a plier

Another view of the lens

When you are grinding the lens using a carborundum stone make sure you wet the stone regularly, it is better to do this under running water. First grind the sides of the lens at a 45 degree angle and then the center part.