On DPR, a poster asked what macro lens to get and got this reply:
I would definitely go with the Z 105/2.8. It’s better than the F mount 105/2.8 and probably even the best macro lens ever made.
This is a bit like saying that the 27mm f/5 Bio-Summagon is the best landscape lens ever made, or that the 85mm f/0.8 Apo-Sonnarcron is the best portrait lens ever made. The possible use cases for portrait and landscape lenses make picking just one best lens impossible. I think the range of macro use cases is even larger than the range of landscape or portrait uses.
Here are some of the dimensions:
Reproduction ratio. There are lots of definitions of what constitutes macro photography, and I’m going with a fairly — small c — catholic one here: between 1:10 and 10:1 reproduction ratio (the number before the colon is the size of the image on the sensor, and the number after the colon is the size of the object in the real world). No single lens is going to do more than a journeyman job across that hundred to one range. Macro lenses are often optimized for ranges like between 1:1.6 and 1: 3 (you could reverse the lens and probably get good performance at between 1:1.6:1 and 3:1). Many macro lenses made for industrial use (let’s call them process lenses) are optimized for a single reproduction ratio. The Rodenstock 105/5.6 HR Digaron macro lens has a adjustment ring that lets you optimize it for reproduction ratios between 1:3 and 3:1, which is a broad range, but you need to manually set that ring for good results.
Some macro lenses have floating elements to control aberrations as you focus. Be very careful when using those lenses in combination with extension tubes or reversed, which will defeat the optimizations designed into the lenses.
Reproduction ratio affects the maximum f-stop you should choose. If you’re going to use a lens at 1:3, f/5.6 probably fast enough, and diffraction probably won’t affect the results too much. If 3:1 is what you’re after, a faster lens would probably be sharper because of the effects of diffraction.
Subject depth. Lack of field curvature is not important for many macro applications, but is very important for things like copying flat art or digitizing negatives. Field flatness can interact with reproduction ratio. Case in point: the Fuji 120mm f/5.6 GF lens needs a 45mm extension ring to get to 1:1, but suffers from a lot of field curvature there. I happily used that lens at 1:1 for a couple of years before I tried to use it for copy work and got terrible results.
Focus bracketing. There are three ways to do focus bracketing
- Focus the lens.
- Move the sensor plane, but leave the lens fixed.
- Move the whole camera and lens assembly.
If you want to do #1, and have the bracketing take place automatically, you need a lens that the camera can control that way, which favors a native lens.
If you want to do #2, you need a view camera arrangement like the Cambo Actus. The Actus and the Cambo Ultima support the attachment of a stepper motor to the rear focus assembly to facilitate automation of this.
You can do #3 with just about any lens.
Turnkey solution or not. There are lots of macro lenses out there that use mounting arrangements that are unfamiliar to many photographers, and that have no focusing mechanism. Some of those lenses are spectacular for some uses. There are many — probably the vast majority — who have no interest in adapting those lenses to their cameras, because such adaptation would require them to MacGyver a way to attach and focus the lens, or purchase a bellows arrangement.
Autofocus. Personally, I consider autofocus to be useless for macro photography, but I know that there are many who disagree with me on that point.
Tolerance for aberrations. Especially when used outside of their optimum reproduction ratios, and especially off-axis, many macro lenses suffer from longitudinal chromatic aberration, lateral chromatic aberration, coma, and astigmatism. For some uses, these defects are highly important. For others, they are not a consideration al all.
All these variables complicate picking the right macro lens for a particular task, and make it impossible to say that any one lens is the best macro lens for all tasks.