Designing a Macro Bracket, pt.4
Continued from Part 1, Part 2, and Part 3
I still have a few minor things to overcome with the bracket — the raised post on the end comes off, but the screw is too long to mount anything to without it. I’m considering a few possible ways to work around this, but I’ve spent a lot of time talking about the bracket, and I’d like to move on. I’ll definitely mention what I’ve got when I have a final solution.
So, the next phase is lighting. This is the whole point of the macro rig: dump enough light on the subject to get a good exposure, and dump it in an aesthetically appealing way. There are over-the-counter macro lighting solutions that work quite well, some of them better than what I’m making here. The MT-14EX ring light and MT-24EX twin light are quite good, but they’re really, really expensive. I love macro photography, and as long as there’s something to shoot at 1:1 my 100mm macro lens doesn’t really come off the camera, but I can’t justify spending hundreds of dollars on something I can only use for macro. So I use traditional flash units, which are less expensive and very versatile.
I already have a Vivitar 285HV, a cheap and popular manual-only flash. I’m considering upgrading it, if budget allows, but that’s not certain yet. The ideal flash for this rig is lightweight, for obvious reasons, with enough power to get a fast flash pulse, and has TTL metering. A flash will give you hard, ugly light, so it also needs a diffuser of some kind.
The flash pulse is important for freezing motion: I shoot a lot of bugs, which are very active and very fast. Basically the lighting scenario I’m in most often is one where I’m shooting with a shutter speed close to my camera’s fastest sync speed, or around 1/250, with an aperture of at least f/8, and usually f/11 to f/14, on an ISO of 100 to 200; the flash fires at 1/16th power, because it’s so close to the subject. Without a flash, these settings would give you an unexposed black frame, except on the brightest of days.
So imagine, in slow-motion, what happens as you press the shutter with these settings: For a long 1/250th of a second, almost no light is falling on the sensor. Then, the flash fires a burst of light, and for the 1/16,000th of a second that it’s pulsing, light floods into the camera and the sensor records that image, which by itself is a full exposure. The flash turns off, and the sensor is no longer receiving any light. At the end of that 1/250th of a second, the shutter closes, and the sensor sends its data — all of it recorded in that 1/16,000th of a second — to the camera’s image processor.
The pulse duration of a powerful flash on a low setting is going to be much better at freezing motion than the fastest shutter speed your camera can do. Unfortunately, Canon doesn’t release its speedlites’ flash pulse duration, and even for the third-party companies that do, there are different ways of measuring it. So there’s a bit of guesswork here; I think the only real thing we can do is assume that any moderately powerful flash is going to be fast enough, and choose between them on other grounds. It probably rules out small low-power flashes, and it definitely rules out constant light sources like LED lamps.
TTL isn’t critical, and I don’t feel like I need it at all for my non-macro stuff. It would be nice so I don’t have to adjust the power level if I’m shooting a little further back, or decide to use a circular polarizer, for example. E-TTL 2 can make finer adjustments than just the one-stop power levels of the Vivitar 285HV. It also offers rear-curtain sync — that would let me slow the shutter speed down to let more ambient in, and capture motion trails to show movement. These are generally convenience things, but I’d like to have them.
Two things I don’t care about: Electronic zoom heads are a complete non-factor for me. High-speed sync is actually something I want to avoid using. It sounds like a great idea, using ambient as the main light, and high-speed sync as fill, but the way it works is to use thousands of low-power pulses through the entire exposure; when the subject is a fast-moving insect, that’ll give a blurred picture — like a strobe effect, but probably too close together to look cool.
Considering these things, I’d like to upgrade to the 430EX II if I can afford it. I go back and forth on the Yongnuo YN-465 and YN-467; I’d like to see a comparison to an official Canon flash in terms of build quality and reliability. Considering they cost less than half as much as the 430EX II, I’m willing to cut them a little slack, but I want good odds of getting more than a single season out of them before I drop money on one. Really it’s the international shipping that gets me: if there were a supplier in the US who would handle replacements under warranty, I’d be much more likely to buy one. This all depends on my job situation, too, which is either seriously improving or completely disappearing in the next few weeks, and I don’t have any idea which yet. No new toys if I’m unemployed. Fortunately for me, the flash I have works fine — this is an entirely optional upgrade for me. (I wouldn’t get the Vivitar as a macro flash if I were doing it again, though: it’s too heavy, it has a beveled head that’s hard to mount things on, and it’s expensive compared to more modern competitors. On a super-tight budget, I’d go with the manual YN-460 or YN-460 II as a first flash, or on one of the E-TTL flashes I mentioned above.)
As for the diffuser, that’s important for controlling the quality of the light. If you’re already familiar with Strobist-style lighting, you know this already, and it’s true for macro as well. The diffuser — basically a small softbox — is important because it makes the light bigger. The greater the angular size of the light source, the softer the shadows it makes. It also ‘spreads out’ the intensity of the lighting, so you can capture more detail in reflective surfaces without getting blown-out highlights. The plastic caps, like the Gary Fong-type diffusers, are no good here. They’re designed for indoor use, and send light out in every direction to bounce back onto the subject. Outside, with nothing to bounce light off of at macro scales, they’re just sending perfectly good light off into the void.
Right now I’m using the DIY flash diffusers described here on Myrmecos, albeit using a larger yogurt cup for my larger flash. It may be a bit too large, so I might remake it soon to be a bit shorter, but I’m getting great light from it. I’m using translucent vellum paper ($0.25 per sheet at my local stationary store) as the diffusion material, though Roscoe makes some professional materials for this exact purpose. That would be more durable, and more heat resistant as well — though the general idea is to get the diffusion surface far enough away from the flash head to catch light from a wide area, so I’m not too concerned about the heat.