[Editors Note: This week is Macro week here on DPE with Rob Sheppard. We'll be having a macro tip every day, make to sure to check them all out!]
I own and use macro lenses. If I also own and use extension tubes and achromatic close-up lenses, then why do I need macro lenses? I use extension tubes and apochromatic close-up lenses to allow all of my lenses to focus closer. I use macro lenses for different purposes.
A macro lens is designed to give you continuous focusing from infinity down to 1:1 or something close to that. That is a great advantage when you are working in the field and doing a lot of close-up work combined with more distant scenes. With extension tubes or achromatic close-up lenses, you have to add something to your lens in order to focus closer. With a macro lens, you just change focus and keep on getting closer.
A macro lens is also designed to have optimum sharpness up close. This often translates into excellent sharpness across a flat field of view. So if you are photographing a stamp collection, for example, which would be flat, a macro lens would give you the best results. When you’re shooting other subjects, that is not so important.
A macro lens also tends to have very high sharpness when shot wide open (at the maximum f-stop such as f/2.8). Not everyone likes the effect of extreme limited depth of field you get when you shoot a macro wide open, but for those who do, a macro lens gives a heightened sharpness that you don’t always find with other lenses used up close. Macro lens will often give better sharpness at small apertures such as f/16 or f/22, but still will be affected by diffraction effects when you get very close which can degrade the image quality.
I love to use macro lenses when photographing insects. With insects, you are constantly changing the distance to them, so a continuously focusing lens such as a macro lens can be really helpful. With both extension tubes and achromatic close-up lenses, you will have a range in which your lens will be focusable, but if you’re outside that range, you will not be able to focus without changing your set up.
I also love to explore colors, shapes, light and so forth up close when shooting with a macro lens wide open. There can be some very magical effects that happen then. Try it and you might surprise yourself with what you get!
If you are really excited about macro and close up work, then you should think about exploring the amazing life of Costa Rica. Check out my trip there this coming December 8-12 at Holbrook Travel.