What is a macro lens? What if my zoom lens has a "Macro" designation, are they the same?
Today I am going to chat a little about my experience with a macro lens, and what other situations it can be used for. This is not going to be a macro photography tutorial, but more of a chit chat about macro lenses regardless of the brand. Hit the jump for more.
Macro photography can be defined as close-up photography of usually very small subjects. If you ever try shooting objects from a close distance using your non-macro zoom or prime lens, you will find that after getting close for a certain distance, the lens would refuse to focus any closer, this is what defines the magnification factor.
A lens' magnification factor is defined by the physical size of the subject in focus in relation to the sensor size, in other terms, if we assume a 1:1 magnification ratio for a certain lens, this means that it can focus on a subject that would fill the same area of the sensor as its physical size in real life. Imagine a metal coin, now imagine taking a picture of it so close that the coin's image on the sensor is physically the same size as the coin itself. This is called 1:1 magnification, sometimes it is referred to as 1x magnification. True macro lenses can usually achieve 1x magnification, and there are unique macro lenses that can go to as close as 5x magnification.
Now back to the opening question, can your zoom lens (that says "Macro") be a true macro lens? It depends, if we take the saying that true macro lenses are of 1x or greater magnification, then the answer is no, they are not true macros. However, there are some zoom lenses that can focus quite close to the subjects, they usually have around 0.3x to 0.5x magnification at the long end of the zoom, this is actually pretty respectable, check this picture taken with the Canon EF-S 55-250 lens at 0.31x magnification. This picture was taken by dpreview member Charles Durrant, you can see his full gallery here.
|0.31x Magnification, Uncropped Image - Click to see a larger version.|
Most manufacturers offer macro lenses that are primes (i.e. no zoom), they feature something called a floating lens element that helps them focus at close distances. You will find that Canon and Nikon offer very similar macro lenses, both have 60mm f/2.8 macro (Nikon calls it Micro) lenses, they also both have 100mm f/2.8 macro lenses (Nikon is 105mm). They all offer 1x or 1:1 magnification ratios. Canon also has a less known 50mm f/2.8 macro lens that offers only 0.5x magnification.
WHY DID I GET ONE?
I bought the Canon EF-S 60mm f/2.8 Macro USM for several reasons:
- When I decided to upgrade my standard zoom lens and I decided to buy the Canon EF-S 15-85 f/3.5-5.6 IS USM instead of the Canon EF-S 17-55 f/2.8 IS USM, that saved me a difference of almost $400, so when I started looking for lenses that cost this amount of money I found this lens.
- I was also looking for a better replacement for my cheap EF 50mm f/1.8 II, so I thought that since the focal lengths are close, and that I never use my 50mm wider than f/2.8 I might as well replace it with a lens that is/has:
- Eextremely sharp.
- Can focus much closer.
- Internal focusing (i.e. the front element doesn't move or rotate).
- Much faster/silent USM focusing.
- Better colors and contrast.
- Better bokeh.
The benefit of the longer focal lengths in macro lenses is the MWD (minimum working distance), if we take my 60mm lens, the MWD is 9cm from the front of the lens, this means that in order to get 1:1 magnification I need to bring the front element of the lens just 9cm close to my subject, imagine trying to get this close to a skittish or a dangerous insect, in contrast the 100mm macro lens has a MWD of 15cm and the 180mm has a MWD of 24cm, I know that these numbers all sound tiny but the difference between 9cm and 15cm while shooting insects could make all the difference.
On the other hand, the side effect of the longer focal lengths is that you need higher shutter speeds to get a blur-free image. Canon has another version of the 100mm f/2.8 macro lens with built-in image stabilization (not usual in primes with this focal length) and the "L" designation, but it is quite expensive.
You would imagine that using a macro lens is the same as using a normal lens, and you would be right except that with a macro lens when you get close to 1x magnification, you start losing light. My 60mm for example starts losing light at close ranges until it reaches 2 stops of light loss at 1x magnification, this means that the effective aperture is f/5.6 instead of f/2.8 (regarding light quantity entering, not DoF). If you are using auto modes on the camera like aperture priority or using flash in TTL mode then the camera will auto compensate for the light loss, but if you're metering light manually you need to take it into account, Canon has included a table in the user manual with the light loss values at each magnification level.
There are several ways to light your subjects, available light is always there if you can get acceptable shutter speeds or use a tripod. You can also use the camera's flash or an external flash to light your subject, but sometimes they are not good because you are so close to the subject that the flash has no direct line of sight between it and the subject, that's why there are dedicated macro flashes that are mounted very close to your subject.
A good way to light your subject is by using soft diffused light, this can be achieved using a light source that is larger than your subject, and since we are talking very small subjects, this light source doesn't need to be an octabank or an umbrella, check cheap ways of getting diffused light here and here. You can also go sophisticated with studio strobes like Alex Kolskov here, he's one of my favorite product photographers.
I use myself two different methods, either a flash diffuser mounted on my lens using the camera's pop-up flash (when I need to be discrete) or I use one or two external flashes with very small inflatable softboxes.
P.S. Excuse the quality of the first photo, I had to use my mobile phone.
|Cheap Flash Diffuser - Click to see a larger version|
|Inflatable Softbox - Click to see a larger version|
Now we come to the fun part, shooting macro with this lens, I will show you some examples and talk a little about each one, you have to keep in mind that at close focusing distances the depth of field becomes in the order of millimeters, here's an example, at 1x magnification using the 60mm lens, the DoF at f/22 is 6.7 millimeters! So you will occasionally find yourself shooting at small apertures to get as much DoF as you can. Add the 2 light loss stops to that and you will see how it quickly becomes hard to light your subject, I once had my 580EX firing at full power in the inflatable softbox and not producing enough light.
The picture below is shot hand held at f/11 using the pop-up flash and the diffuser, there was good ambient light and the flash was used as a fill.
|Climbing Ant - Click to see a larger version (f/11 - 1/60 sec - ISO 200)|
The following pictures are all shot using room lights and long shutter speeds, I used a mini tripod for stabilization, check the 100% crops in the first two pictures by clicking on them to see how much detail is available at 1:1 magnification.
|Needle & Thread - Click to see a 100% crop (f/4.5 - 4 sec - ISO 100)|
|Pen - Click to see a 100% crop (f/4.5 - 5 sec - ISO 100)|
|Lock - Click to see a larger version (f/5.6 - 13 sec - ISO 100)|
|Carpet - Click to see a larger version (f/2.8 - 1.3 sec - ISO 100)|
This last example shows you what can be done hand held in dim light, you have to use a high ISO.
|Curtains - Click to see a larger version (f/2.8 - 1/50 sec - ISO 1600)|
PORTRAIT & GENERAL SHOOTING
I told you that I bought this lens to replace my 50mm f/1.8 II, which is one of my most used lenses, it is a little long (85mm equivalent) for indoor use or for shooting groups but I use it a lot because of it's size and weight and that it is the perfect focal length for portraits. All the coming pictures are shot hand held using available light except the last one with the white seamless background.
|Baby in Her Chair - Click to see a larger version (f/2.8 - 1/100 sec - ISO 1600)|
|Crayons - Click to see a larger version (f/2.8 - 1/250 sec - ISO 400)|
|Colored Slides - Click to see a larger version (f/4 - 1/2000 sec - ISO 400)|
|Indoors Portrait - Click to see a larger version (f/2.8 - 1/80 sec - ISO 200)|
|Outdoors Portrait - Click to see a larger version (f/2.8 - 1/1250 sec - ISO 100)|
|White Seamless Portrait - Click to see a larger version (f/6.3 - 1/160 sec - ISO 400)|
As you can see, the sharpness wide open is just staggering, and by stopping down a little it becomes crazy sharp, this is my favorite go to lens when I'm shooting portraits or product shots.
I hope you have enjoyed the article, if you have any feedback please let me know.
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