This double element close up lens accessory screws on to the front of the lens and changes the closest focusing distance from infinity to 500mm approx 197 from front of lens the type 500d is more suited to lenses with focal lengths from 70mm to 300mm however good results are possible using the close up lenses with focal lengths outside these prescribed ranges the close up lens is designed for canon ef lenses and canon powershot cameras note requires appropriate conversion lens adapter