Is Spring, good timing for flower photos. Friends told me they can’t get too close to the flowers because the camera cannot focus. There is a very simple answer for point and shoot users since most P&S cameras come with macro function. However, for SLR camera, you may need to get a new lens.
Macro lenses are for focusing on things very close up like a few inches away. The lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, which means, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances.
Example from Macro Lens
The Images you see above are from a Sigma Macro Lens. I believe the Sigma Macro 70mm really did a good job for flowers. It has 1:1 Maximum Magnification and the minimum focusing distance is 25.7cm which make it perfect for this situation. Around $400.00 and you can click the link below to check pricing.
Sigma 70mm F/2.8 EX DG Macro Lens for Canon
Sigma 70mm F/2.8 EX DG Macro Lens for Nikon
If spending too much on a new lens is not an option for you, there are two other options.
You can get closer to the object by adding an extension tube between your lens and the body of the camera. Since there are no optics added, it wont reduce the image quality but you lose the infinity focus while it is being mount on the camera. Usually, it's between $70.00 to $150.00 and should able to get the job done. Following photo is how it will look like.
Close Up Lens
Personally, I don’t recommend close up lens as a solution, because in most cases it will reduce the image quality a lot. However, some of the close up lens a very cheap and is still fun if you are tight on cash. Since close up lens is being mount on the front of the Lens, you need to make sure it match with the filter size of the lens you are going to mount it on. The following link may be able to help you.
Search for Close Up Lens