Photographing Testing Personnel

While working so intensely together to conduct testing for publication, it is worth taking the time to make photographs of all those who participated. The photos can be useful for a report, any paper presentations, and the websites of the participants. (Click on image below to enlarge, then click on back arrow to return.)

Three testing partners with tractor trailer (ZEISS 50 mm f/2 macro lens on Nikon D810.)
From left to right are truck and truck ECM guru Greg Wilcoxson (Wilcoxson Consulting, LLC), truck, data acquisition, and, well, everything else guru Wes Grimes (Wes Grimes, Collision Engineering Associates), and me. In an earlier post, you’ll find a link to the papers we wrote together from this testing.

Even with my hat, I was hardly in their league. We did have fun in the evenings when I would walk into a restaurant first, and tell the hostess or host that I was their bodyguard, and needed to get them a good table. We should have recorded their reactions.

A photograph of something as long as a tractor trailer is often best presented in a panoramic format (much wider than tall). This focuses attention on the subject by eliminating excessive sky and foreground.

Benefits of Fill Flash

While may seem counterintuitive, adding fill flash even on a bright, sunny day brings out details that better document your subject, which can make your photos even more useful. In this first image, the car and measurement rod were properly exposed, but the high contrast from bright sun resulted in little detail in the deep, dark shadows. (Click to enlarge image, then back arrow to return.)

High contrast from bright sun with no fill flash. (ZEISS Milvus 50 mm Macro lens on Nikon D850.)
Adding light from a flash resulted in a more balanced image, with details now visible even in components on the frame, suspension, and under the hood. The car and measuring rod remain properly exposed.
Excessive contrast reduced with fill flash. (ZEISS Milvus 50 mm Macro lens on Nikon D850 with Nikon SB-910 flash.)
Determining the amount of fill flash needed will be a topic for future posts. In the meantime, it’s worth experimenting with both manual and TTL flash settings until it becomes second nature.

Focus on Your Subject

Especially when handholding a camera, autofocus points might land on an object closer or farther away from your intended subject. This can result in an unimportant element in sharp focus, while your subject isn’t sharp.

There are three main ways to avoid this:
-1- Use manual focus. This allows you to choose what will be sharpest in your image, even if you recompose or your camera moves, as long as you remain the same distance from your subject.
-2- Put camera on a tripod, then move your autofocusing point until it’s on your intended subject.
-3- If handholding, autofocus on your intended subject, press your focus lock button, and recompose.

Your intended subject should be in focus. For this pair of photographs, the camera was on a tripod. In this first image, the autofocus point latched onto the black cable shield in the foreground. This caused the axle and wrapped tire behind it to be soft. (Click on image to enlarge, then back arrow to return.)

Focus on black cable wrap in foreground, not on axle or wrapped tire. (Nikon 24-70 mm f/2.8E lens at 50 mm on Nikon D850.)
For this second image, the focus point was moved off the cable wrap and onto the axle and wrapped tire.
Focus on axle and wrapped tire, not black cable wrap in foreground. (Nikon 24-70 mm f/2.8E lens at 50 mm on Nikon D850.)
Which photograph is correct? Depends on whether the subject is the black cable wrap or the tire and axle. Make sure you focus where you intend.

More on Fill Flash

Fill Flash helps bring out details in the shadowed area of high-contrast subjects. This photo of the left front of a truck tractor without flash doesn’t have much detail under the fender. (Click on image to enlarge, then click on back arrow to return.)

Left Front of Truck with No Flash (ZEISS Milvus 50 mm macro lens on Nikon D850.)
To bring out some detail, a flash was added at a reduced power output. Fill flash isn’t intended to light the entire image frame, but only to lighten very dark areas.
Left Front of Truck with Medium Fill Flash (ZEISS Milvus 50 mm macro lens on Nikon D850 with Nikon SB-910 flash.)
While there was a little more detail in the suspension and frame, raising the flash power added even more light under the fender.
Left Front of Truck with More Fill Flash (ZEISS Milvus 50 mm macro lens on Nikon D850 with Nikon SB-910 flash.)
Before you make any photograph, look for areas that are too dark to show details you may want. By varying the power of the flash, you can bring out as much detail as you choose, without affecting the overall exposure.

Fill Flash Adds Details

Fill flash helps bring out details in vehicle photos, especially under high-contrast lighting situations. As an example, the damage to the right front of this black car does not show up well when no flash is used. With the sun behind the car, the damaged area was in shadow. (Click on image to enlarge, then on back arrow to return.)

Front end damage with no flash used. (ZEISS Milvus 50 mm macro lens on Nikon D850. Exposure: f/11, 1/160 sec, ISO 100.)

Obviously, this car couldn’t have been driven to a more favorable spot, and it was not possible to have it moved. Besides, even if the car was moved to get better light on the right front, then the light wouldn’t have been good from other angles.

Like everything else photographically, the solution is to think about the light. Where is it? (Fairly high, and coming from the other side.) Where do you need it? (Good top light, but need light in the foreground, too.) How can you get light where you need it? (Use flash to fill in the shadows.) This is called “fill flash”. The term fill flash means that flash isn’t the only light source illuminating the subject, but light from the flash just fills in the shadows as desired.

Here’s the same vehicle in the same location with the same light, but with an on-camera flash used to partially fill in the shadows.

Front end damage with fill flash used. (ZEISS Milvus 50 mm macro lens on Nikon D850 with Nikon SB-910 flash. Exposure: f/11, 1/60 sec, ISO 100.)

You can see the light on the background stayed the same, but light from the fill flash now shows details in the shadows.

While at first flash may seem too complicated and unpredictable, learning to use it correctly is probably the best way to improve your vehicle, product liability, and testing photographs. Learning to use flash will be a big part of my SAE photography class: SAE Photography for Accident Reconstruction, Product Liability, and Testing.

Flash versus No Flash – Updated

You can make photographs—without using flash—regardless of the light that’s available. But not using flash has three major limitations:

-1- You can’t change the relative brightness between elements in the image. Any change in exposure will raise or lower the brightness of all elements equally. Flash lets you emphasize any element in relation to any other.
-2- You won’t always be able to properly expose for every important part of the photo. If you properly expose to show details in the shadows, brighter areas can be blown out with no details. If you expose for highlight details, shadows can be blocked up with no detail and with digital noise. Flash lets you add light in the shadows to balance the image.
-3- You can’t handhold the camera with long shutter speeds. The less ambient light there is, the more exposure you need. Exposures requiring longer shutter speeds require a tripod, or the photos will end up blurry. Flash can add enough light so you can get a shutter speed you can handhold.

Except for accident sites, I use flash for almost every shot I make. I always use flash with tires and wheels, and with almost every vehicle or vehicle component—indoors or out. The only exceptions are for certain reflections, for close-ups of certain marks, and occasionally for light bulbs.

In my previous post, I described how to photograph a small wear gauge in place on a rim flange. All those photos were made in using flashes in my studio lab. Since I do many of my tire and wheel inspections there, I installed a bunch of bright LED shop lights overhead. They make the area really bright to the eye, but it’s still dark enough to require flash for most images. Here is a photo of the rim wear gauge setup using only the ambient LED shop lights. (Click on image to enlarge, then click on back arrow to return.)

Using Wimberley The Plamp II to hold Alcoa Rim Wear Gauge in place for photography with no flash. (Made with ZEISS Milvus 50 mm macro lens on Nikon D850 with no flash.)
Exposure settings for this image were f/16 for 1.0 second at ISO 64. A camera could not have been handheld for 1.0 second.

Now, from the previous post, here’s the setup shot using flash.

Using Wimberley The Plamp II to hold Alcoa Rim Wear Gauge in place for photography, with flash. (Made with ZEISS Milvus 50 mm macro lens on Nikon D850 with flashes.)
Exposure settings for this image were f/14 for 1/60 second at ISO 64. Adding flash to the subject required a faster shutter speed to keep it properly exposed. If necessary, the camera could have been handheld at 1/60 second.

While the differences in these photos are relatively subtle, there is more detail the photo with flash. You can see more detail in the lug bolt holes and more depth to the wheel itself in the image with flash. (Differences are harder to see in these compressed images on the web.) But more importantly for most circumstances, the shutter speed without flash was six stops less than with flash. (The total exposure was 5 2/3 stops different because the aperture was opened 1/3 stop in the flash image.) While both images were made using a studio stand (like a rolling tripod), the image without flash with its 1.0 second shutter speed certainly could not have been handheld. Higher shutter speeds also helps freeze the frame if there is any motion from loose parts or from wind.

Eliminating Glare When Photographing Light Bulbs

Glare on the glass globes can obscure the filaments when photographing light bulbs. This first photo shows the effects of overhead lights reflecting on the bulb. (LO refers to Left Outside taillight bulb.) (Click on image to enlarge, then click on back arrow to return.)

Bulb reflecting overhead lights. (ZEISS Milvus 100mm Macro lens on Nikon D850.)
Below is the setup that was used to create that photo.
Setup for bulb with reflections on globe. (ZEISS Otus 55mm f/1.4 lens on Nikon D850.)
The bulb was held in place with a Wimberley The Plamp II, and the camera was locked down on a studio camera stand. The white cabinet door was used as the background. Note that the flash was not used.

All the glare from the overhead lights was eliminated by placing a translucent umbrella on a small light stand above the bulb. That umbrella was lowered and moved around until all of the glare from the overhead lights was gone. Here’s what the setup looked like with that simple change.

Setup for photographing bulb with no reflections on globe. (ZEISS Milvus 35mm f/1.4 lens on Nikon D850.)
As you can see below, the resulting photograph had no glare, and clearly showed the filaments and the posts.
Taillight bulb with no reflections on globe under translucent umbrella. (ZEISS Milvus 100mm Macro lens on Nikon D850.)
Translucent umbrellas have the advantages of being inexpensive (well, except for this one by Profoto), lightweight, and compact. So this setup can be used anywhere outdoors or indoors, with a tripod replacing the studio stand. When using outdoors, typically you’ll just have one source of glare from the sun. Many times, you’ll be able to just prop the umbrella on the vehicle or ground without needing a light stand or some other holder. If it’s dark or shaded, you might need supplemental lighting (flash, LED, or other light sources). These can be fired through the translucent umbrella to prevent glare from them. That will be the subject of a future post.

Accurately Photographing Scales

Including a scale in a photograph is an excellent way to document dimensions. But it’s essential to properly position the camera to record an accurate measurement.

One of the most common mistakes made when photographing scales or rulers is making the photo from an angle. The camera lens must be perpendicular to the scale, both vertically and horizontally. A camera positioned too low or too high, and correspondingly tilted up or down, will result in parallax distortion. Worse is a horizontal offset that results in misleading measurements due to the angle of the camera to the scale markings.

Take this example made to show how far a mirror protruded from the side of a van. The first photo was taken at the proper scale height, but was at an angle to the scale. Note how different the reading appears in the second image with the camera perpendicular to the scale. The latter accurately showed the measurement. (Click on image to enlarge, then click on back arrow to return.)

Photographed at angle to scale. (Made with ZEISS 50mm f/2 macro lens on Nikon D850 with fill flash.)
Photographed perpendicular to scale. (Made with ZEISS 50mm f/2 macro lens on Nikon D850 with fill flash.)
Making an accurate photograph requires several steps:
-1- Make sure the pocket rod is parallel with the ground. Use something like a Wimberley Plamp clamped onto the upper mirror support arm to hold it at the proper height. Place the other end of the pocket rod firmly against the ground with enough pressure to hold the rod in proper position and angle.
-2- With the camera on a tripod, make sure the center of the lens is vertically level with the pocket rod.
-3- Move the tripod until the center of the lens is centered on pocket rod horizontally.
-4- Use a hot shoe bubble level or the in-camera level to make sure camera is level.
-5- Manually focus, or make sure your autofocus point is directly on the scale.
-6- Use a normal (50mm) or longer focal length to eliminate wide angle lens distortion. Macro lenses are ideal because of their flat field and edge-to-edge sharpness.
-7- Use fill flash to balance image, despite abundant sunshine.

Use scales, but take care to get the camera in position to show them accurately. Fortunately, you can check the results on your camera’s LCD (zoom the view if necessary) to make sure the dimension in the photograph matches the measurement you made. Fairly close isn’t accurate, and is misleading. A deceptive photo is worse than no photo at all.

Controlling Backgrounds Using Flash – Updated

When using flash, you can control how bright or dark the background by controlling your ambient exposure. A lot of people are afraid of flash, but it’s just another source of light. And it’s light you control.

As an example, while you’d never choose this busy background, let’s assume you need to shoot a light bulb indoors with a window in the background. Start with an ambient light shot like this. (Click on image to enlarge, then click on back arrow to return.)

Bulb in ambient light with no flash. Exposure f/14, 2.0 sec, ISO 64. (Made with ZEISS 50mm macro on Nikon D850.)
The scene out the window in the background is bright, but properly exposed. As a result, the bulb is almost in silhouette.

To bring out detail in the bulb, add a flash at 1/8 power in manual mode off camera to the right. Note this is the same exposure as the first image. The only change is the added fill flash.

Bulb with flash at 1/8 power. Exposure f/14, 2.0 sec, ISO 64. (Made with ZEISS 50mm macro on Nikon D850 with Nikon SB-910.)
This brings out details in the bulb, but the bright background remains distracting.

To darken the background, keep the flash setting (1/8 power), the ISO (64), and the aperture (f/14) constant. Then reduce the shutter speed to reduce ambient light. Here, the shutter speed was reduced from 2.0 seconds to 1/250 second.

Bulb with flash at 1/8 power. Exposure f/14, 1/250 sec, ISO 64. (Made with ZEISS 50mm macro on Nikon D850 with SB-910.)
Now, the ambient exposure is so low that most of the background light won’t register. Keeping a consistent amount of flash light on the bulb keeps the exposure constant on the bulb, but darkens the background almost to black.

Again, while you’d never choose such a background as this, this example shows that you can control the brightness of any background simply by using flash and changing shutter speed.

To Flash or Not To Flash

That is the question you’ll have to answer before making each vehicle, product, or component photograph.

To minimize noise and maximize dynamic range for any image, use the camera’s minimum ISO (it’s ISO 64 on my Nikon D850). For most tire, product, and vehicle component photos, you’ll also want to optimize depth of field (DOF). That requires stopping down the aperture to somewhere between f/11 and f/16. (Stopping down to f/22 or smaller will give you more DOF, but may result in softening due to diffraction.)

Exposure consists of aperture, shutter speed, and ISO. With minimum ISO and a small aperture already chosen, that leaves only shutter speed. The shutter speed will depend on how much light is available. To get enough light for a proper exposure, you can use all ambient light, flash only, or a combination of ambient and flash (often called fill flash).

Flash allows you to add the light you need to get a proper exposure, while maintaining a reasonable shutter speed. This is particularly important if you are handholding the camera. Way too many photographs are blurry because the shutter speed was too low. This can be true even with the image stabilization built into many cameras or lenses. Image stabilization helps some, but many times, component or even vehicle photos have to be made where light is insufficient for handholding.

For tires and other vehicle components, getting enough light to handhold a camera usually requires the use of flash. The alternative is putting the camera on a tripod to keep it steady during a long shutter speed.

You can get the same overall exposure using a long shutter speed with ambient light only, using a combination of ambient light and flash, or using 100 percent flash. But the resulting image will look different. (Click on image to enlarge, then click on back arrow to return.)

Valve Stem Ambient Light (No Flash). Exposure: f/16, 2.5 sec, ISO 64. (ZEISS 100 mm f/2 macro lens on Nikon D850.)
Valve Stem with Flash. Exposure: f/16, 1/60 sec, ISO 64. (ZEISS 100 mm f/2 macro lens on Nikon D850.)
In my studio lab, I have so many bright white LED shop lights some have said it looks like an operating room. Even with all that apparent light, I still either have to use flash or a very long shutter speed to properly expose an image.

Above are two images of a rubber valve stem. They were both made using my incredibly sharp ZEISS Milvus 100mm macro lens mounted on my Nikon D850, which was mounted on my rolling studio stand. I focused the ZEISS manual focus lens using Live View at 100 percent.

Both images were made at ISO 64 at an aperture of f/16. The image without the flash required a shutter speed of 2.5 seconds, which was obviously not handholdable. With an image completely illuminated by flash, the shutter speed doesn’t contribute to the exposure. (Shutter speed does contribute if the image is a combination of ambient and flash.) In the flash image below, the shutter speed was 1/60 second.

Both images are properly exposed, but they look very different. The image with flash has more contrast, which gives more of a three-dimensional appearance, where the ambient (no flash) image has more even light. When sharp and properly exposed, there’s no right or wrong to flash versus ambient light, but be aware there can be a profound difference between them.