I'm new to DSLRs and am a bit confused about how to tell a good macro lens based on specs. For one, there are primes across a range of focal lengths (40, 60, 90, 105, 135, to name a few) that are macro capable. Is it safe to assume longer lenses are better at macro? Then, there are some zooms are macro capable, but does one assume primes are superior here? Also, I'm not sure I understand the implication of the magnification spec on macros. Is higher magnification better? Or is there a sweet spot?
Finally, if you could recommend the best value macro prime lens for DX, which would it be?
Thanks!
Sent from my iPhone using Tapatalk
There are quite a few technicalities involved when selecting Macro Lenses
1. Working Distance. This depends on focal length, the longer the focal length the farther away you can be from the object. This has both its advantages and disadvantages. Longer lenses will ensure that the object mostly insects will be far away from the lens and not be spooked. The down side is that longer lenses will require better flash system and will increase the chance of camera shake as small tremours will be amplified. On the other hand shorter focal lengths will give shorter distance, which is excellent for flowers, but ma spook insects. In some cases the too short working distance will obstruct natural light.
2. Chromatic aberration. For the sake of DOF, most macro shots are at high F numbers. That results in softening of the image due to diffraction. What we generally ignore is the contribution of CA. A high CA can soften the image faster, as the diffraction will have not only diffraction fringes but also CA fringes. Some lenses are known to have a high CA, very few are Apochromatic, that is the CA is practically ignorable. Apochromatic lenses cost a lot more, but will give razor sharp images upto F16, before diffraction softening starts.
3. Flat field. Most lenses have a curved field of focus. In case you are shooting planar objects - stamps, coins etc, curved field of focus will render the edges a bit soft.
4. AF. With DOF in most macro shots very thin, most of macro shooters resort to manual focusing, as AF is too iffy. So if you use the lens purely for macro AF is not necessary. But if you use it for general photography also - 105mm to 200mm macros are used a lot for portraits, then AF is a useful feature.
5. VR. Utility of VR in macro is debatable. For some it is heaven sent as VR can compensate for hand shakes and small camera vibrations, but if you are shooting with tripod or have rock steady hands, then you can dispense with VR.
Now depending on your target of macro photography here is how the lenses are stacked :-
40mm. It is a DX lens, good enough for flowers and other inanimate objects. Too short for insects.
55mm. It is MF lens.
60mm. It has flat focus field, so a must have for stamp, coin and flower shooting.
85mm. It is a DX lens. Much cheaper than the FX 105mm from Nikon.
90mm & 105mm. General purpose macro lenses, neither too long nor too short. Most popular buy. Just check various iterations, some have more CA than others. Some may not be 1:1. WHile some are MF only.
150+. Best used for insects and portraits. Again check for CA and other aberrations.
Zeiss 135mm F2 APO. Though this does not do 1:1, it is one of the finest lenses for close up photography. The practical lack of CA will give you sharper images by a long shot, compared to other macro lenses.
Beyond the current popular range lies the realm of expensive purpose built lenses from Coastal Optics and other firms specialising in Industrial lenses. You may look them up on the net.
cant be important or he would be a Nikonite 
