Why you need a Macro Lens…
Firstly, I’ll start by saying that, personally speaking, macro photography has never particularly interested me, always finding that I am usually more impressed by the content of a macro photo itself (whether a colourful flower or exotic insect) rather than the composition. I purchased a decent set of electronic Macro Extension Tubes years ago, purely because they would allow me to take an occasional macro shot without having to lug around an extra lens. Having got some decent shots out of them (whenever they’ve been needed), I’ve always seen them as being ample for my needs. Recently, taking on a product photography project requiring predominantly macro photography, I invested in a dedicated Macro Lens (the very popular and highly praised Canon L-series 100mm f2.8). I won’t share my thoughts on that lens itself (that should be left to a comparison between macro lenses), but will instead sum up why one would really need a Macro Lens.
A Macro Lens offers no real benefit in terms of image quality over a quality standard lens + Macro Extension Tubes; remember that the tubes are merely hollow spacers which only alter the magnification of the lens you’re using, not the quality of its glass.
That’s the reason why, with Macro Extension Tubes I’ve gotten some great, sharp, macro shots out of my Canon EF 24-70mm f/2.8L II USM.
The real benefit of a Macro Lens is the freedom of movement it gives you when focusing on an object; unlike the very restrictive focus range allowed by tubes, Macro Lenses allow you to pretty much focus from where you want, meaning that you are free to compose a shot as you wish.
If you’ve never used Macro Extension Tubes, the best way to imagine how this “feels” is to imagine shooting a portrait on a standard lens but only being able to focus when the subject is, say, between 6 to 6 ½ meters away...you’d be extremely limited in terms of composition, wouldn’t you?
Having purchased a Macro Lens specifically for studio product photography, I was keen to answer the question of whether a standard lens + tubes could have “done the job”, especially considering that I was shooting on a tripod capturing fixed perspectives of similarly sized objects. The fact is, to get shots exactly how you want, to really capture what you are photographing as effectively as possible, you have to continually adjust your position from the subject, and extension tubes simply do not allow for this. Even if I had shot the project in question using Macro Extension Tubes, using all the workarounds available (from whichever restrictive angles were possible), the extra-time this would have taken would have increased my shooting time at least tenfold. It would simply have been madness to even consider it.
Compromises for moving subjects are fine; you simply compose a shot as best you can. However, when you are shooting still objects, there should be no such compromises. Macro Extension Tubes are fantastic for travel and one off shots during a larger on location project; a Macro Lens would never replace their fabulous portability. However, for any project exclusively or significantly requiring macro photography, a dedicated Macro Lens truly is indispensable.