Advantage of a dedicated Macro?

Question

What are the advantages of a dedicated macro prime lens (fast lens) over a good quality zoom macro lens (which is not so fast), when for good depth of field they both have to stopped down to well below f/8 ?

Answer 1

Plain and simple:

True macro lenses get much higher magnification ratios of 1:1 over macro zoom lenses, which have ratios of 1:3 or 1:4 typically.



Because they are fixed focal length lenses, the optical designs are simpler, resulting in better contrast and sharpness at any aperture.



A dedicated macro lens is designed to have a flatter field of focus too, unlike the macro zoom. In other words, you have better sharpness on the edges.



The working distance thing varies with focal length chosen; that doesn't affect the magnification ratio. In other words, a 200mm macro lens will still get 1:1 but give you more working distance than a 60mm macro that does 1:1. That working distance can be important for lighting or not spooking your subject.

Answer 2

1. Close focusing



Dedicated macro lenses can focus much more closly than equivalent focal length non-macro lenses. This results in a higher...



2. Reproduction ratio, to be a true macro lens it should offer life size repoduction, i.e 1:1. Most cheapo telezooms that wrongly claim to be macros offer a maximum of 1:4. This means that your subject can potentially fill much more of the frame with a dedicated macro.



3. Optical design



Macro lenses being primes, are generally simpler in design with less compromises, so geometric drawing is far better, non-exsistent pincushion or barrel distortion is the norm.



4. Faster max aperture



Simpler design enables wider apertures to be used, the best macros have internal focus so that the effective aperture does not decrease with close focus lens extension as occurs on some models.



5. Usually a focus limiter, cheapo 'macro' telezooms will hunt back and forth through the enitre focal range, if you are at 300mm you may as well go and have a coffee whilst it finds focus. Most decent macro lenses have close distance or far distance limiter to speed things along.



6. Lens resolution. No not your cameras megapixels, but a measure of the amount of detail your lens can resolve before it even reaches the sensor or film. Higher is better. Dedicated macro lenses typically perform very very well, far above cheapo telezooms.



You make a fair point about depth of field. Even at f11 or f16 the subject may not be rendered entirely sharp from nearest point to farthest, this is more true if you are focused very close to the subject. Stop down below f16 and diffraction starts to sap the resolution. Other problems kick in such as subject movement or available light when you use small apertures. One way round this is to use a tilt shift lens instead.



BUT, depth of field isn't everything in the macro world, sometimes for very tiny subjects or details you only need miniscule depth of field. Sometimes the seperation helps to draw the viewers attention.



If you are serious about close up work then you need a dedicated macro. No doubt about it. And a tripod. And a manfrotto micro adjust plate. And a cable release. And some patience.



If you had told me what kind of camera you were using I could have even given you some recommendations.

Answer 3

Simple answer, there are no good quality macro zooms. Most of those all purpose type of lenses are cheaply built. And you dont have to stop the macro lens down to f/8 or f/16, I use mine wide open at f/2.8 or maybe f/4 all the time and am glad I have a dedicated macro lens because its still razor sharp. Especially if you are trying to capture moving objects, f/8-f/16 just doesnt allow enough light for the correct shutter speeds.