Fill Flash helps bring out details in the shadowed area of high-contrast subjects. This first 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.]
To bring out some detail, a flash was added at a reduced power output for this second image. (It’s more noticeable in an enlarged image.) Fill flash isn’t intended to light the entire image frame, but only to lighten very dark areas. [Click on image to enlarge, then click on back arrow to return.]
While there was a little more detail in the suspension and frame, raising the flash power added even more light under the fender. Again, it’s best to enlarge the image to see the effect. [Click on image to enlarge, then click on back arrow to return.]
Note that all three photographs were made at the same exposure of f/10, 1/50 second, and ISO 64. The images differ because the amount of fill flash was different. This showed the flash was supplemental or “fill” meaning flash filled in the shadows without altering the overall exposure.
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.
-1- Fill flash adds light in the shadows without affecting the overall exposure, which stays the same.
-2- You can control the amount of shadow detail you want to show by changing the output of your flash, or its flash power.
Note: This is an updated and enhanced version of a post originally made in July 2018.
After having four of the five classes canceled last year, I’m really happy to announce the return of my SAE automotive and product photography class: https://www.sae.org/learn/content/c1729/. I’m glad to be returning to the site of my first class in 2018 at the great facilities of Mecanica Scientific Services in Oxnard, CA: https://www.mecanicacorp.com/. Many thanks to John Steiner, CEO and Principal Scientist of Mecanica, for hosting this upcoming class from August 30 through September 1, 2021.
Whether your primary job is accident reconstruction, product analysis, vehicle or component testing, or other technical area, you will need consistent, quality photographs to both document and analyze your subjects. These photos need to be made regardless of ambient lighting or conditions. Your camera on Auto isn’t going to do that. [Click on image to enlarge in new window, then click back arrow to return to post.]
Not only are good photos essential for documentation and useful for analysis, they can be critical for use in lawsuits, insurance claims, recalls, and design and testing evaluations. Both in-house analysts and independent consultants will be counted on to routinely produce accurate and reliable photographs as part of their professional work. Did I mention that your camera on Auto isn’t going to do that? [Click on image to enlarge in new window, then click back arrow to return to post.]
This class is designed to give you the tools and knowledge you’ll need to consistently create professional photographs by proper use of focus, depth of field, composition, lighting, polarizers, tripods, and close-up/macro tools. You’ll see how flash is essential for capturing all the data, and how it’s not as intimidating as many believe. We’ll also cover the two types of night photography as well. [Click on image to enlarge in new window, then click back arrow to return to post.]
There will be more hands-on sessions than in previous classes, so make sure to bring your camera, lenses, polarizer, tripod, and flash. Course information and registration are available through the link in the first paragraph, but if you have any questions or need more information, please feel free to e-mail or call me directly.
For almost an hour, we talked about a wide range of topics related to tire, vehicle, and accident reconstruction photography. Among the subjects we discussed were the importance and use of a tripod, a polarizer, and flash. We also touched on both kinds of night photography and on post-processing.
I hope you will find the information we discussed useful. The interview also gives an idea of a couple of the topics which we demonstrate and discuss in depth in my SAE class which, by the way, will be resuming as in-person classes this year.
Here’s a link to that class: SAE C1729. I’ll post the dates of the new classes as soon as we finalize them.
To facilitate my tire, wheel, and product analysis and photography, I set up my Studio Lab in my basement. Although it continues to evolve, it had fortuitously been set up and in use for nine years before the COVID-19 pandemic of 2020 brought most travel and meetings to a halt. In fact, even before the pandemic, I have preferred having tires, wheels, and other products shipped to me for analysis and/or photography in my Studio Lab rather than traveling to where they might be stored.
In my Studio Lab, I have all the inspection and photography equipment I need to do a complete analysis and documentation, regardless of what I encounter. Besides, I can leave any setup in place for several days if needed. (Click on an image to enlarge it. Then click back arrow to return to this post.)
Although it is partly obscured by the support pole in the photograph above, I mount a camera on one end of the sliding arm of a Foba rolling studio stand. One of my favorite pieces of gear, a studio stand is much faster to adjust and move than a tripod. The arm rotates around, slides back and forth on, and moves up and down on a solid pole mounted to a base with three lockable wheels. These adjustments allow a camera to be brought and held in the exact position needed—both rapidly and securely.
I then mount as many lights as required on rolling light stands, floor stands, C-stands, or clamps. Having the camera and lights on rolling stands makes it quick and easy to change their positions. My large collection of reflectors and reference scales can be held in position with a variety of clamps, as needed.
I also use one of three wooden or four plastic lazy susans, depending on the size of the tire, wheel, or product. I cover the lazy susans with gray paper or cloth, and use a neutral gray background paper from a large ceiling-mounted roll.
Because tires and wheels are usually neutral in color—shades of black, gray, silver, or white—the neutral gray background neither clashes nor contaminates the subjects. With other products, I may use gray, black, or white backgrounds.
I’ve installed so many LED shop lights overhead that a couple visitors have described the area as bright as an operating room. Even with this much light, I still use a number of LED drop lights during inspections, and to assist with composition and focusing while photographing. (Click on an image to enlarge it. Then click back arrow to return to this post.)
I will describe lighting for specific items in future posts, but for tires, I generally use two Profoto B1x 500 W/s studio strobes firing into Profoto Medium Deep Silver umbrellas—both mounted on rolling light stands. A Nikon SB-910 flash affixed to the hot shoe a Nikon D850 DSLR camera triggers both studio strobes, and adds its light on the subject, too. A silver Profoto reflector bounces light onto the tread or belt surface.
If you’re wondering, I use the purple trekking pole to rotate a tire while I’m sitting on the Wen mechanic’s rolling seat behind the camera. Using that pole allows me to look at the image through the grid in Live View on the camera’s LCD while I precisely line up the position stickers on the tire with the gridlines.
The cable hanging from the camera is the remote shutter release. With this, I can trip the shutter without touching the camera to insure there is no motion blur in the photo.
I will share more of the techniques and gear I use in future posts.
In the last post, I showed some lighting solutions to use when your subject is in low light. In this post, I will briefly describe some of the supports and the lights I referred to. Flash is a big and interesting subject, and I have an entire module on flash photography in the photography class I teach for SAE (SAE C1729). Or, I should say, will resume teaching once this pandemic eases.
I will expand on each of these in future posts, but wanted to give the basics here. First and foremost is using a good tripod. There is nothing better you can do to improve your photographs than to use a tripod. I use a tripod in any kind of light for almost every image of any subject, including accident sites, vehicles, tires, and other products. A good tripod is even more essential when the light levels are low.
It used to be unusual to see someone with a tripod at an inspection. But with so many scanners now being used, tripods have become quite common. So there goes one excuse for not carrying and using one!
I have a post all about tripods in the works, but for now I’ll just mention the Really Right Stuff (RRS) TVC-24L with a RRS BH-40 ball head that I use for all inspections out of my Studio Lab. It is compact and lightweight, yet it extends quite high, which is essential. All of my tripods have LensCoat LegWraps for insulation (from both hot sun and freezing temperatures) and for comfort in carrying. (Click on image to enlarge, then click on back arrow to return to this post.)
While future posts (and classes) will discuss flash techniques in detail, in this post I will focus on the equipment I used in the previous post.
Flashes that fit in your camera’s hot shoe are generically called speedlights or flashes. In fact, Nikon calls their flashes Speedlights while Canon calls theirs Speedlites. Larger studio-type flashes are referred to as strobes. Here are some examples from the front. All are battery powered. (Click on image to enlarge, then click on back arrow to return to this post.)
And here they are from the rear. Note that the speedlight flashes can be mounted in a camera hot shoe or on a light stand. (Click on image to enlarge, then click on back arrow to return to this post.)
In the photograph of the lighting setup in the previous post, there was a Nikon SB-910 Speedlight in the camera hot shoe and two Profoto B10 strobes on Manfrotto 5002-M travel light stands. These stands are lightweight and fold up small, yet are quite sturdy. (Click on image to enlarge, then click on back arrow to return to this post.)
This final image shows a Profoto B10 mounted on a Manfrotto 5001, which is slightly smaller and slightly less sturdy (though still sufficient) than a 5002-M. (Click on image to enlarge, then click on back arrow to return to this post.)
In the previous post, the two B10’s were fired through their infrared slave sensors when they sensed light from the on-camera Nikon flash. All three flashes and the camera’s exposure settings were all manually set.
Why use strobes when you can use speedlights? Power is the answer. Mid-to-high end speedlights typically have power outputs between 60 and 150 Watt-seconds (Ws), while the Profoto B10 and B1x are 250 and 500 Ws, respectively. This means you’d need two-to-eight speedlights to equal one Profoto strobe. For example, you’d need sixteen 60 Ws mid-range flashes to equal the power output of the two 500 Ws strobes I use for tire photos in my Studio Lab. Not only would those be unwieldy to set up, but think of how many AA batteries you’d need!
Why is flash power important? Every one stop increase in exposure requires doubling of the light power. For forensic or testing photographs, you want to minimize noise by using the lowest ISO you can, and you want a deep depth of field by using a smaller (higher number) aperture. Both a lower ISO and a smaller aperture result in less light reaching the sensor. Consequently, the flash has to be powerful enough to ensure a proper exposure without raising ISO or opening up your aperture.
Future posts will go deeper into exposure both with and without flash. We will be using this equipment throughout.
Most accident reconstructionists and product liability engineers have had to photograph a vehicle, vehicle component, or other product in a dark area such as a warehouse, storage facility, lab, or even an office. Conditions can be even worse for building or fire investigators, especially if the power is out. By definition, what is missing in any of these situations is light!
But despite the lack of light, you might only get this one chance to inspect the evidence. You’ve got to come back with well-exposed, well-lit professional photographs—photos that accurately portray what you saw, represent you well to your clients, and reflect the quality standards of your work, especially during depositions and trials.
Unless you are trying to capture a low light scene as it is (which is a completely different discussion), you have several options to make a photo in low light.
One is light painting by moving a flashlight over your subject during a long exposure. This is tedious and time-consuming, especially if you have to make more than one or two images. It is also hit-and-miss, even if you are experienced with it. Of course you need a sturdy tripod for every shot, since the exposures are long. These long exposures also risk generating noise. So light painting might be good in an emergency, and it’s sometimes necessary for illuminating vehicles at nighttime accident scenes.
It can work, as shown below, but it’s not recommended for making inspection photographs. This photograph of a rental car was made at dusk with no lights on in the garage. The only light came from when I walked around the vehicle constantly moving a flashlight, painting both the car and the garage bay. Note how the long (74 second) exposure made the outdoors look brighter than it was. (Click on image to enlarge, then click back arrow to return to this post.)
Another option is use high ISO sensitivities. On all digital cameras, the higher the ISO, the more noise and less dynamic range there is. With newer cameras, neither the increased noise nor the dynamic range loss are obtrusive until the middle or higher ISO values (say ISO 800 or even 1600). Here’s an example made at ISO 200,000 and cropped from the full frame. (Click on image to enlarge, then click back arrow to return to this post.)
As a third option, continuous light sources are better than nothing, but none are bright enough to avoid having to use a long shutter speed and/or to raise your ISO. Most fluorescent lights flicker and have an undesirable color cast. Halogen shop lights get hot and have a very warm color cast. Quality LED lights have good color control, but still aren’t bright enough. Even the larger LED panels made for photo studios don’t put out enough light, plus the brighter ones are big and unwieldy to transport and setup. Again, none of them put out enough light to allow a low ISO and a shorter shutter speed.
Flash is your best option, by far. But the tiny built-in flash on a point-and-shoot, the popup flash on a DSLR or mirrorless, or even a professional flash in your camera’s hot shoe won’t always be sufficient. You’ll need additional light.
There is a learning curve to using flash, since you can’t see the effect of the light until after you’ve made the photograph. But as long as you think about where and about how much light you need, it’s something you’ll pick up with a little practice.
Since I shoot Nikon, I always carry three Nikon Speedlights (flashes) with me. (You don’t need flashes made by your camera manufacturer, but those will always work with your camera, and are usually quite robust.) One flash goes in the camera’s hot shoe, and I put the other two where needed. I usually carry two small, lightweight, travel light stands with me so I can place the lights where they will do the most good, but I will often just prop them up on something nearby. (Within the next couple days, I will write a post about the gear I mention in this post.)
Since I do a lot of tire analysis, I often need even more light than the Speedlights can put out. Besides, Speedlights can take a long time to recharge their capacitors between shots.
Especially for tires, I use Profoto B10 battery-powered studio flashes on the road and battery-powered Profoto B1x studio flashes in my Studio Lab. Again, more on these in a post later this week.
Recently, I had to inspect tires and wheels inside a semi-trailer. Even though my inspection was close to noon on a sunny day, and the trailer had a couple side doors I could open, I knew it would be pretty dark inside the trailer for photography. I set up my two Profoto B10 flashes on my travel light stands. They were fired by a Nikon SB-910 flash in my camera hot shoe. Exposure and flash powers were all set manually. (Click on image to enlarge, then click back arrow to return to this post.)
Here is a resulting image from that setup. (Click on image to enlarge, then click back arrow to return to this post.)
A single flash on the camera—even Nikon’s most powerful Speedlight—could never have provided enough light to evenly illuminate this tire and wheel. The Speedlight and battery-powered strobes not only provided nice even lighting, but allowed me to shoot at ISO 64, which is the lowest on a Nikon D850. This minimized the noise and maximized the dynamic range to show the most detail possible.
A couple posts ago, I showed examples of bringing out textures in a sponge by creating shadows using an off-camera flash. Here is an example with the type of photography subject we are more likely to encounter.
Vehicle wheels and other components are often stamped with model and serial numbers, along with with dates of manufacture. If you use a built-in flash or a flash mounted in the camera’s hot shoe, those stampings will often be invisible in your photograph. (Click on image to enlarge, then click on back arrow to return to this post.)
This photo is properly exposed, but is useless in documenting the wheel. The key is to get the light at an oblique angle so it skims across the surface to create both light and shadow, just like we did with the sponge. (Click on image to enlarge, then click on back arrow to return to this post.)
For this second photograph, I used a Profoto B10 strobe to the camera’s right, almost perpendicular to the stamping. I fired that strobe with the flash in my camera hot shoe, but I made sure the hot shoe flash did not affect the exposure. I used a B10, but could just as easily used another Nikon flash to get the exact same effect. I had already been using the B10 for other shots, so I just used that. In fact, it would have been even easier with second Nikon flash, since I could set the hot shoe flash to Master with no light output while the other flash would be set to Remote with either manual or TTL flash.
This second image is also properly exposed, but now the direction of the light makes this photo useful. Now you can see it is a 22.5 x 8.25 Accuride wheel manufactured 10/19/17.
The point is that you need to consider both the amount and direction of light to properly illuminate a subject. Light illuminates your subject, but the shadows give it definition. Shadows are essential in a 2-D depiction of a 3-D subject, especially when you need to show textures or depth.
A subject lit from any light source (natural or artificial) coming from the direction of the camera toward the subject is said to be front lit. Front lit subjects are easy to expose for since the light is flat and even. That’s why in the film days, the little paper in the box with a roll of Kodak film recommended shooting with the sun at your back. Although the result was a dull, flat, two-dimensional look, the lighting was so predictable that even using the full Auto mode would nail the exposure.
To give the impression of three dimensions in a two-dimensional medium requires a combination of light and shadows. As noted landscape photographer and teacher Chas Glatzer stresses, “Light Illuminates, Shadow Defines”.
For subjects that are not shiny, front lighting yields consistent color, but lacks texture. (Shiny subjects reflect glare with most front lighting—a subject for a future post.) For lighter colored subjects, the best way to show that texture is to have a light skim across the textured surface from the side. (Black textured objects respond differently. This will also be addressed in a future post.)
Although it’s unlikely you’ll be asked to photograph sponges, they are easily accessible subjects to use to practice bringing out textured surfaces in a photograph. I came across this demonstration in the excellent book Light: Science and Magic, 5th Ed. by Hunter, et al.
For this first image, I held the head of a Nikon SB-910 flash in Remote mode along the barrel of the lens at its bottom right. (You can tell where the flash head was placed by looking at the hard-edged shadow along the top and left side of the sponge.) That flash was triggered by another SB-910 flash mounted in the hot shoe on top of the camera’s pentaprism. It was set to Master mode with its own flash light turned off so only the remote flash fired. [Click on the image to enlarge, then click on the back arrow to return to this post.]
To make the second image, I put the remote SB-910 on a light stand to the right of the camera at a height between the end of the lens and the top of the sponge. I aimed the head of that flash across the face of the sponge. Again, the shape and location of the shadows show where the light was placed. As with the first image, that flash was triggered in Remote mode by the flash in the camera’s hot shoe set in Master mode with its own flash head turned off. [Click on the image to enlarge, then click on the back arrow to return to this post.]
Both images were made with the same manual exposure mode and with the same manual flash exposure mode. Moving the light to the side resulted in both light and shadows, giving the sponge a three-dimensional appearance in a two-dimensional photograph.
You can see similar results using a sponge and a flashlight, but it’s worth duplicating these photographs yourself to understand how to use light to emphasize or minimize any texture you encounter. Illustrating texture is all about the amount and direction of the light—which you can control.
Even when stopping down a macro lens to f/16, you often won’t have enough depth of field (DOF) to keep your entire close-up subject sharp. Fully stopping down a macro lens to, say, f/22 or smaller won’t yield a meaningful increase in DOF, but will likely make your entire image appear less sharp due to diffraction.
Here is an example photo of the rusted ends of steel belt cords made at f/16:
Some of the ends of the cords are sharp, but both the wires closer to the camera and the rubber skim coat of the belt farther away were soft. Focusing closer to the ends of the wires would make everything below them more out of focus. Focusing on the belt rubber would cause all the wire ends to be soft.
The solution is to take a series of photographs using a middle aperture (usually between f/5.6 and f/11) starting with the focus on the part of the subject closest to the camera. Focus slightly further away from the camera for each subsequent photo until you’ve focused on the part of your subject furthest from the camera. All exposure settings should be set manually and held constant for each frame; only focus should be changed.
For larger subjects including vehicles and accident sites, only two or three frames might be needed. More on that in another post. But close-up or macro images will typically need several more.
To create an image with all the belt edge wires sharp, I made thirteen photos at f/11, changing only focus. I started by focusing on the tip of the wire closest to the camera. Subsequent photos were made focusing slightly further from the camera with each frame.
All thirteen images were brought into Photoshop through Adobe Camera Raw as individual layers into a single image. All layers were auto aligned, then combined in a stack. As you can image, thirteen 45 megapixel Nikon D850 images brought into a single image resulted in a gigantic file. In fact, at five gigabites(!), it was too big to save as a PSD (Photoshop Document) file; I had to save it as a PSB (Photoshop Big) file. Of course, I flattened it, reduced its size, and saved it as a JPEG to send to my client and (even smaller) to post here:
If you look closely, there are some small artifacts around the edges of some wires. With a bit of work, these can be removed, but they are unobtrusive enough to ignore, unless an image will be used as a trial exhibit.
As alternatives to Photoshop, I also use Zerene Stacker and Helicon Focus to process stacked images. Different software processes create different artifacts, so sometimes I’ll process the stacked images in all three, then choose the best.
If you already own Photoshop, it’s well worth practicing focus stacking. It’s an effective tool that can produce images that can’t be captured in a single shot. I use it regularly for tires and products, and have even used it at accident sites on occasion (usually, as mentioned, with only two or three images stacked).
During my analysis of a failed tire, I noticed what looked like a tiny, tiny nail in one of the sidewalls. I looked inside the tire, but couldn’t see if the tip had penetrated the innerliner. I gingerly felt around the inside to detect if the tip had protruded through. It had. Now I had to document that.
Photographing the head of the nail on the outside was easy, but photographing the tiny tip on the inside was quite a challenge. It was both minuscule and inaccessible.Here is a photo of the nail made with my usual lens, the ZEISS Milvus 50 mm f/2 macro. (Click on any image to enlarge. Then click on back arrow to return to the post.)
Even with the arrow, it’s impossible to get any useful information about the nail tip from this photo.
I photographed that nail tip with several other combinations of lenses, lights, and camera supports, but couldn’t get close enough to it optically. Then I remembered my beanbag called “The Pod” (now sold as either The Red Pod or The Green Pod) to which I had added an Arca-Swiss-type quick release clamp.
To get the camera lens closer to the nail, I propped the beanbag with a mounted Nikon D850 and the Laowa 25 mm 2.5 to 5x Ultra Macro lens (which I discussed and showed in previous posts) on the opposite side bead. I removed two Nikon SB-R200 macro flashes from the R1C1 ring and placed them on either side of the nail tip. This photo shows the positions of The Pod and the flashes with the camera, lens, and on-camera SB-910 flash removed.
Below is the resulting single-shot, uncropped, full-frame image with the incredible Laowa Ultra Macro lens. A single shot was necessary because the beanbag setup was not rigid enough to allow for focus stacking of multiple images.
Compare the size of the nail tip in the the top and bottom photos, and recall both were full-frame, uncropped images. Considering there was such a significant enlargement of the subject, the detail in the bottom photo was remarkable despite the limited depth of field and the less-than-rigid support from the beanbag as opposed to a tripod. I’d say that about nailed it!