Continuous studio light, like quartz-halogen are the cheapest to purchase and the easiest to set up but using them is to subject your human subjects to cruel and unusual punishment. Continuous studio lighting generates a great deal of heat and is therefore very hot to work under. Besides being uncomfortable for the model/subject, the increase in ambient temperature makes working in the studio uncomfortable for the photographer. Continuous studio lighting also places a greater load on the studios electrical system, raising the utility bills. Studio flash cost more initially but in the end, they will save the studio photographer money in utility costs and bulb replacement cost. Studio floods have a ridiculously short useful life, typically 6 to 10 hours. They don’t burn out in 6 to 10 hours but their color temperature changes drastically so one can’t use them for shooting pictures. Typical photoflood costs several dollars a piece so it’s very easy to spend $300 to $400 a month on bulbs and you could have bought a flash unit for that. For less then what you would spend in a year on bulbs ($3600 to $4800), if you spend 30 to 40 hours a week in the studio, you could have a decent set of studio flash units. A three flash setup can be had for less than $2500. The Dynalite RK5-2303 Kit,
comes with Two RP500 Power Packs, Three RH1015 Flash Heads, three 40” Umbrellas, a complete set of cables and a Carrying / Storage Case. This professional lighting system will give you years of service with the proper care and maintenance. The one thing that these flash heads have is built in modeling lights, which makes setting them up a snap. Whether you buy this kit or some other, make sure the flash heads have built in modeling lights. You’ll learn about modeling lights and how to use them in another tutorial. I have several other kits that I have acquired over the years and a few odd units that I picked up when I was on the road, but this one is my favorite and I recommend it to anyone as their first lighting kit. I’m digressing; the subject of this tutorial is metering studio flash for proper exposures.
To make great studio portraits using studio flash units you must go manual on both your camera and on the flash units. Most beginners find just thinking about going full manual daunting because all the rules they learned about exposure control no longer applies when you go full manual in the studio. Most books written for beginners on flash photography doesn’t cover this adequately or, if they cover it, they use formulas and language that leaves the new photographer shaking his or her head in despair. The same can be said about most online sites that offer tutorials on flash photography. This one is different; it’s written in a language everyone can understand.
Rule of Thumb
This is the most important thing that you have to remember when shooting with studio flash; you control exposure by adjusting aperture, not by adjusting shutter speed. Changing he shutter speed changes the ambient light exposure and we don’t want to do that.
Changing the Shutter Speed/Camera Sync Speed
Almost all cameras have a max flash sync speed somewhere around 1/250 second. The Nikon D40 has a max sync speed of 1/500 second, consult the users manual that came with your camera to verify the max sync speed for your camera. Knowing the max sync speed for your camera is of the utmost importance because the camera and flash units can’t sync up properly if you try shooting at a higher shutter speed. I know that this may seem slow to you but when you consider that the actual exposure is determined by the duration of the flash, which, depending on the power setting of the flash units, can be as short as 1/4000 second. That’s really fast.
Control Exposure by Changing the Apertuture
The important thing to keep in mind here that when you change the aperture you also change the depth of field. The amount of light reaching the camera sensor varies inversely with the f–stop number. The smaller the f-stop number, the larger the aperture, the greater the amount of light reaching the cameras sensor. The larger the f-stop number, the smaller the aperture, the smaller the amount of light reaching the camera sensor. The depth of field varies directly with the f-stop number. The larger the f-stops number the deeper the depth of field, the smaller the f-stops number the shallower the depth of field. If you need to control the amount of light reaching the camera sensor you are often better off moving the flash units, adjusting the flash head output power, shooting at a different ISO setting, or a combination of these adjustments rather than changing the f-stop.
To Meter or Not to MeterMany photographers will tell you that metering is essential to making great studio flash pictures but it really isn’t. Flash meters are expensive and it’s not necessary to get your exposure down to 1/10 of an f-stop. It can be calculated by using the lens focal lengths, the flash units guide numbers, and the ISO settings, but the easiest way to do it is to pick an aperture that feels right and take a sample exposure. With digital, unlike back in the film days when you had to meter or calculate because, you couldn’t see the results until after processing the film, you can pick an f-stop and take an exposure or two, then adjust your setup as needed. When you find a setup that works, sketch the light setup in a notebook and record all the pertinent settings.
We’ll talk more about exposure settings when we discuss how to set up your lights for a single light portrait.
