Macro lens considerations

I've been asked by a Picasa Web friend for a little help in the decision-making when shopping for a macro lens. He was looking at the 100mm Tokina lens and asked me what I think. I looked up that lens, and it's not stabilized. (you know, that thing that prevents blurriness of the image due to camera shake; Nikon calls it VR, Canon calls it IS, Sigma calls it OS, and so on - the most amazing part is probably how each vendor came up with his own two-letter acronym:-)

There's just one question, really: do you want to take images handheld? If yes, get a stabilized lens. And as of this writing, there's not really a lot of stabilized macro lenses in the 100mm focal range available with a Nikon F-mount. Actually, there's just one if I'm not mistaken: Nikon's own 105mm AF-S Micro Nikkor (IF-ED G VR something blabla.)

EDIT: I just remembered that Nikon does have another stabilized macro lens: the AF-S DX Micro Nikkor with 85mm focal length. So if you're on a budget (see the paragraph below the 2nd picture please) and/or using DX sensor cameras only, anyway, you should definitely consider this alternative. The test site photozone.de has an English test of the lens on a DX camera.

Why is stabilization so important in a macro lens? Because you get so damn close to your subject. If you get very close to your subject, you have a very short so-called "distance to (the) focus (plane)". The smaller the distance to focus is, the smaller is the depth of field. For a macro that's not just some abstract with a hair thin focal plane that is actually sharp (photos like that can be highly attractive of course!), you need more depth of field. And for more depth of field, you need to stop down the lens. But if you stop down the lens, you lose light. And less light means longer exposure times.

How long can an exposure time be so that you can make the photo hand held? The rule of thumb for a safe handheld exposure is 1/(focal length * crop factor). For a 100mm macro lens on an APS-C sensor camera, that means 1/150s (the real-world exposure time that is available on cameras is 1/160s second then). On a full frame camera, it means 1/100s. Now let's have a look at a photo.


"Yellow Day-Lily" // Nikon D700 @ ISO200, AF-S VR Micro Nikkor 105mm @ f/16, 1/60s handheld

That was morning light, the bright sun was illuminating this Lily directly from behind, and I was looking into the Lily with my 105mm macro lens. The lens was stopped down to f/16. Have a look at the limited depth of field! At the base ISO of my camera, it would have required a good amount of luck, or a very steady hand to get this photo sharp at 1/60s handheld. And I don't know about you, but I for one have quite a hard time holding the camera steady when I'm kneeling on the lawn in front of a flower in some odd angle while focusing manually (because auto focus will drive you insane sooner or later, I promise.)

To be fair and cover the crop factor: the same depth of field would have been achieved on an APS-C camera with f/11, which is exactly the 1-stop advantage you need to get to 1/100s - but on the crop sensor, you need at least 1/150s to be safe. It just doesn't get any better. :)

Of course, with modern cameras it's no problem to just raise the ISO by one or two stops and still get a very good result... but remember, the photo above was taken in bright sunlight. You don't always have or even want these conditions. A great many times, you just don't have too much light when you're making macro photos. These two tiny mushrooms on a fallen tree are in the shade of the forest and the exposure settings where quite dramatic: 1/30s at ISO6400. An extreme example, and I should have probably used a tripod, of course (except that I didn't have it with me.) But I think I made my point that a stabilized macro lens is a must have if you want to make handheld macros.


"Mushrooms" // Nikon D700 @ ISO6400, AF-S VR Micro Nikkor 105mm @ f/5.6, 1/30s handheld

And finally... sigh... let's talk about money. Because of course, the Tokina 100mm macro lens is only half as expensive as the stabilized Nikkor - about $400 vs $800 as of writing this. Is that really worth it? I'm not going to argue about that, it's an individual decision... and a $400 difference might be a lot of money for a little macro fun.

But maybe we should think about it differently: It's got an F-mount. That thing will probably fit on a lot more cameras to come. The warranty time for Nikkor lenses is 5 years, so let's use that. 5 years are 60 months. Which means the $400 difference is a $6.66 difference per month. Doesn't sound so bad anymore, does it?

Last not least: if you're interested in a couple of first steps into the macro world, try an old prime (that has an aperture ring) with a retro adapter ring. Or use a close-up lens that you attach to a normal lens like a filter (hint: Canon has a good selection of these, they're called "500D" and are available in many common filter thread diameters.)