Friday, May 4, 2007

Macro Technique

Edit: 29 January 2016: My how time flies! Seems like only yesterday I wrote this piece and here I am roughly nine years later laughing at some of my mistakes ;) I'm gonna edit this piece without changing the original content by putting my changes in brackets with the word "Edit".

I’ve been asked a couple of times to do a tutorial on macro photography, and I’ve given a few "quick and dirty" explanations on various forums. But it’s easier to write about it formally in an article and just point someone to a link. Unfortunately the web site that I had this article on initially has recently died. So here is my first ever article on macro photography –and if it’s well received it won’t be the last ;)

Disclaimer: I am not the last word, nor in my humble opinion is anyone the last word, on any photographic discipline! There are many different ways to take a photo, and I really don’t think that any technique is inherently wrong -just different. In this article I’m going to explain how I shoot macro and hopefully there will be something that you can use. The important thing to remember is that my technique was developed based on my experience with a camera -and the things that I do may be detrimental to you! So take my technique, experiment with it, and adapt it to your own style of shooting. Don’t let anyone tell you that you have to have a certain piece of equipment for a particular type of photography -think outside the box! If I listened to the conventional wisdom concerning macro photography I’d be chasing fast moving insects with a camera on a tripod and only have a handful of usable images...

Using Natural Light

When I’m out shooting there is one basic question that governs how I’m going to set up the camera: "Is there enough natural light for the shot?". If the answer is yes then I set my camera to shutter priority -I know, most would use aperture priority instead. But here’s my logic (you get to decide if it makes sense): I normally shoot insects that don’t sit still for long, and I’m going to use the flash as a fill light. Since I’m hand holding the camera and the subject isn’t going to give me enough time to set up a tripod, I need to shoot at the fastest possible speed to avoid camera shake and still get the shutter to synchronize with the flash. I don’t want to go higher than the sync speed of the flash since I’ll start losing depth of field as the Fstop gets lower. With my current camera (the Canon Xti) that’s 1/200 of a second. [Edit: That paragraph applies more to closeup photography than to macro. At 1x and higher magnification there is so little light reflecting off of the subject that you're probably going to be using a tripod if natural light is the primary light source.]

The down side to being in shutter priority mode is that the camera is going to adjust the exposure by shifting the aperture, and if the available light is low that means taking a photo with a narrow depth of field. But you can use a narrow depth of field to draw the viewer’s attention to an area where you want them to look, and as long as the insect’s eyes are in sharp focus the image as a whole will work. Another benefit that I noticed about shooting in shutter priority mode is that my images all have a different look and feel to them -shoot at F11 all the time and you’ll start to think that every image looks the same. It’s also easier to isolate the subject with a large aperture (small Fstop) because there will be little or no detail in the background. If the aperture becomes too large to give you enough depth of field for the photo you can always increase the ISO -but you’ll also increase the noise in the final image.

Along with setting the camera to shutter priority I also set the exposure compensation from -1/3 to -2/3. The sensor in a digital camera reacts to under exposure in that same way as color positive slide film -colors saturate in post processing when you bring the exposure up. You’ll also get an increase in Fstop (a smaller aperture) with the camera in shutter priority mode (or an increase in shutter speed if you are shooting in aperture priority). The only "gotcha" is the ISO speed: at higher ISO settings under exposing can increase the amount of noise (or grain) in the final image. So be careful under exposing above ISO 200. [Edit: You can take the ISO higher, it just depends on how noisy your sensor is and how much detail are you willing to lose to the noise.]

I use to have my camera set to ISO 200 because the difference in image quality compared to ISO 100 is insignificant (with the 20D) and shooting at ISO 200 gives me a full stop advantage on the aperture setting that the camera selects. If the sky is a little overcast, or the subject is in an area that’s partially shaded, I’ll go up to ISO 400 -maybe. Most of the time if the light isn’t good enough to give me an aperture around F5.6 then I’ll shift to manual mode and take full control of the light (more on that later on in the article). [Edit: Currently shooting with a Canon 70D and wouldn't hesitate to use ISO 400 if I needed to.]

Using Flash with Natural Light

Now we get to the fun part -setting up the flash. If you’re shooting with natural light you don’t necessarily need a flash and for shooting some subjects, like butterflies, flash might not be a good idea since they are very light sensitive and prone to jumping when they see the E-TTL pre-flash fire. But I like to use a flash to give me a little more detail in the area of the subject that would normally be in shadow. Shooting dragonflies last summer convinced me that using a flash was a must for getting images with maximum detail. With the sun providing the primary source of the light that you need you don’t want to use the flash at full power. If you do the background will be correctly exposed, but the colors of the insect that you’re shooting will be blown out. So set the flash to under expose by at least 2 stops (adjust the flash to -2 FEC) and then adjust from there. Most of my shots were taken with the flash set to -2 1/3 FEC.

The type of flash that you use, and to some extent where the flash is mounted, doesn’t matter [Edit: ...when using the flash only for a fill light with some distance between you and the subject. Applies more to closeup photography.]. But the quality of the light that your flash produces is very important! I started out with a Canon 430 EX flash camera mounted with a Lumiquest Min Soft Box and got good results with it. I’ve even cut a slit in a ping pong ball and put it over the camera’s built in flash for a cheap and easy diffuser. After the 430EX I switched to using Canon’s MT-24 ring flash and ran into trouble because the light it produces is very harsh. I ended up using a set of Sto-Fen diffusers stuffed with cotton [Edit: Current diffuser.]. I’ve since realized, thanks to Mark Plonsky, that using ratio control with the MT-24 was a mistake. It’s better to leave the flash heads at equal power and just use the position of the flash heads to control shadows. I typically set the flash heads 90 degrees apart and the light does not look flat. [Edit: With one flash head at the top acting as a key light, and the other at about 3 O'clock acting as a fill. The same kind of lighting setup that a lot of portrait photographers use.]

I’ve also used an MR-14 EX ring flash and it works extremely well right out of the box! The flash heads have better diffusers than the MT-24 and the quality of light that the MR-14 produces is "warm". I’ve gone back to using the MT-24 because I’m now shooting with the MPE-65 and the MT-24 takes up less room at the front of the lens than the MR-14. Both flash units are excellent for macro photography and I can easily recommend both of them! [Edit: It's at this point where I'm gonna eat a lot of crow :) I don't recommend ring flashes for macro photography anymore, and I'll explain why further on. Also because the light from a ring flash is firing straight out they don't work well when shooting above 3x with the MP-E 65mm -the light is firing over the subject.]

A word on Canon’s ring flashes: They DO NOT produce flat light -unless you configure them to! You can set one flash head to be brighter than the other (it’s called ratio control) or you can turn one flash head off completely. I normally set my MR-14EX ring flash to a 4:1 ratio with the brighter flash toward the top of the lens and the weaker one toward the bottom. [Edit: ...and that will work, kinda. The problem is that the flash heads cover about 170 degrees each, for a total of about 340 degrees out of a 360 degree circle. No matter what you do the shadows are going to look odd because they will only fall directly underneath the subject, but the light will be striking head on instead of from the top where you'd normally expect the light for that kind of straight down shadow. Even if you turn one flash head off the shadows are going to look strange. Also the stronger flash head is pretty much gonna blow out the specular highlight that it creates. So ratio control has a lot of disadvantages.]. For the MT-24 I set the heads 90 degrees apart on the flash holder. If you read that ring flashes produce flat light then know that either the person has never used one (and are just repeating what they’ve read) or they had a ring flash but didn’t read the manual that comes with it... [Edit: Ouch :) Ring flashes do produce flat light for the most part, or at least light that looks odd due to the shadows on either side of the subject getting washed out by a 340 degree light source. Just say no...]

I’m going to tell you something that sounds counter intuitive; the further your flash is from the subject the more harsh the light will be, since the flash has to pump out more power to provide a correct exposure [Edit: Wrong, it looks more harsh due to the size of the diffuser being relative to the subject. See the Apparent Light Size Article at Strobist.] . So if you’re having problems with the flash giving you a harsh light then get the flash closer to your subject… [Edit: ...because the diffuser will seem bigger relative to the subject, and getting the diffuser/flash as close to the subject as possible helps to keep the duration of the flash to a minimum making it easier to freeze motion and get a sharper image when the flash is the primary light source.]

Brace Yourself

The trick to getting sharp hand held macro shots using natural light is to find a way to brace the camera. If you can’t find something to lean against then tuck your elbows into your chest and breathe normally. When you’re ready to press the shutter release do it slowly -don’t jerk the camera. If the subject is low enough to the ground you can use the "knee pod": Go down on one knee with your left knee on the ground, and have your right knee bent. Place your right elbow on your right knee and remember to tuck in your left elbow. [Edit: Nothing wrong with that paragraph, but I rarely use natural light as the primary light source these days.]

There are a few specialty devices that can help you steady a camera without a tripod. I used a BushHawk camera mount for several months in 2006, and I’m currently using a Novoflex Chest Pod that’s even better at helping me keep the gear steady. I know of a couple of people who use a bean pole by holding on to the poll with the same hand they use to hold the camera. There are lots of different ways to avoid camera shake -be inventive and practice, lots of practice... [Edit: I'm currently using the Left Hand Brace Technique.]

Using Flash as Your Primary Light Source

Sometimes there just isn’t enough natural light to take the shot, so it’s time to set the camera to manual mode and take control of the light with a flash. Sounds simple, but there is no hard and fast rule as to how to do it. But I’ll cover a couple of the ways that I’ve done it and hopefully give you a starting point.

Taking Full Control of the Light

On days when it’s very over cast you can set your camera to manual mode, the shutter at the maximum sync speed for your flash, and the aperture set to F8 to F11 [Edit: ...or higher]. Set the ISO to 100 and your flash to 0 EV. Take a few test shots and adjust the flash until you get the exposure that you want without getting a lot of glare. The advantage to this technique is that your shutter speed doesn’t really matter because the speed at which the flash fires becomes your shutter speed. Let me explain...

If you set your camera to ISO 100, the shutter to 1/200 of a second, and your aperture to F11 and shoot indoors, or outside on a cloudy day, odds are the image will be completely black if you’re not using a flash. In low light, at those settings, there just aren’t enough photons coming through the lens to be registered by the sensor in your camera (or on film). The photo receptors in your cameras sensor are like buckets for light. Not enough light and the bucket doesn’t get full (under exposure). Too much light and the bucket overflows (over exposure). At ISO 100, F11, and 1/200 of a second there just isn’t enough natural light coming through the lens to fill the light buckets in the sensor –unless you use a flash.

So the flash is really the only light that the camera is going to record, and on average the flashes that I use emit light for 1/1200 of a second. So even though the shutter is staying open for 1/200 of a second it’s only during the 1/1200 of a second that the flash fires that an image is recorded by the camera. Ever wonder how people take photos of water drops and freeze them in mid bounce? Now you know... [Edit: Also it's a good idea to get your flash as close to the subject as possible to keep the duration of your flash to a minimum. One of the misconceptions about flash photography is that most people assume that the duration of the flash, no matter how long, is always going to be short enough to freeze motion. It's not true. Although not as obvious as freezing a balloon in mid pop or a bullet as it passes through an apple macro photography is the same -if you're using the flash as the primary light source then you're using it to freeze motion. Motion as little as half the width of a pixel is enough to rob you of a lot of detail and it will amplify the image softening effects of diffraction.]

Taking Partial Control of the Light

This one is a little bit trickier. If you’re setting your camera so that the flash is the only light source odds are the subject of your photo will be correctly exposed but the background is going to be completely black. Personally I don’t really like images with completely black backgrounds, even though I’ve taken a few of them. I like to see the insect, flower, whatever in context -I want to see what environment it’s in. There is a way to do it on overcast days, I’ll call it "partial flash", and here’s how.

The trick is to set your shutter speed, ISO, and aperture to get an exposure that’s within about 2 stops of the ambient exposure. So you might dial in, for example, 1/200 of a second, F5.6, and ISO 200 and adjust the aperture or ISO until the exposure meter hovering around -2. Set your flash to 0 FEC, take a shot, and adjust if necessary. The goal is to get the subject correctly exposed, and to be able to see something in the background. Tricky because the available light is going to dictate what your camera settings are -and you’ll have to experiment a little. Camera shake can be a problem when you are shooting with partial flash, but one way to make your images a little sharper is to set your flash to second curtain sync. That way the strongest light to reach the sensor is the last one that went into the lens... [Edit: See Mixing Natural Light and Flash for a better explanation.]

Keep in mind that shooting close to the ambient exposure can cause a lot of problems with white balance. If your images are consistently looking “overcast” or grey then you might want to switch to using the flash as your only light source. Sometimes adjusting the white balance it post processing does not work…

Go Forth and Photograph Small Things

I hope you’ve gained something form this primer -but now it’s time to stop reading and go out and practice shooting!

[Edit: I'm going to leave this piece as is for now, with my ugly edits until I decide if I want to revise it or write a completely new one. Also so you know that I'm not trying to "cover my tracks" on some issues. I had to eat so much crow over ring flashes that I'll be picking feathers out of my teeth for weeks ;) ].
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