In my previous post, I showed the difference in photographing tire marks at a wreck site with and without a polarizer. In this post, I’ll show nine more comparison pairs illustrating other subjects we’ll cover in my SAE C1729 Photography for Accident Reconstruction, Product Liability, and Testing class: https://www.sae.org/learn/content/c1729/.
Tracking a Vehicle During Testing
Tracking by panning with Nikon D800E with 300 mm f/2.8 lens at f/6.3, 1/640 sec, ISO 400. [Click on image to enlarge, then click on back arrow to return to this post.]Using Fill Flash to Show Details in Shadows
Both with Nikon D850 and ZEISS Milvus 50 mm f/2 macro lens. Left side: No flash at f/10, 1/60 sec, ISO 64. Right side: Fill flash at f/11, 1/80 sec, ISO 64. [Click on image to enlarge, then click on back arrow to return to this post.]Showing Depths of Abrasions and Damage Using Two Flashes vs Ambient
Left side: Ambient only; Right side: One Profoto B1x strobe on either side of tread. Both with Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens at f/16, ISO 100, 4.0 sec left & 1/200 sec right. [Click on image to enlarge, then click on back arrow to return to this post.]Controlling Background Brightness while Keeping Flash the Same
Both made with Nikon D850 and ZEISS Milvus 50 mm f/2 macro lens at f/14, ISO 64 with flash in hot shoe. Left side: 2.0 second exposure for bright background. Right side: 1/250 sec exposure for dark background. Background itself didn’t change. [Click on image to enlarge, then click on back arrow to return to this post.]Keeping Background Brightness the Same while Adding Fill Flash
Left side: Ambient light only. Right side: Same ambient light with added fill flash. Both with Nikon Z 8 with ZEISS Milvus 50 mm f/2 macro lens at f/16, 1/25 sec, ISO 64. [Click on image to enlarge, then click on back arrow to return to this post.]Using Macro Flashes vs On-Camera Flash for Recessed Subjects
Left side: flash in hot shoe (Godox TT685IIN) with head tilted -7°; Right side: one small macro flash (Godox MF-12) on either side of lens—no light from hot shoe flash. Both with Nikon D850 with ZEISS Distagon 25 mm f/2 lens at f/16, 1/200 sec, ISO 64. [Click on image to enlarge, then click on back arrow to return to this post.]Unintended Deception from Camera Position, Even with Same Lens
Both made with Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens with fill flash. Left side: f/13, 1/40 sec, ISO 125. Right side: f/16, 1/30 sec, ISO 200. [Click on image to enlarge, then click on back arrow to return to this post.]Eliminating Glare on Plastic Evidence Bag Using Two Flashes
Both made with Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens. Left side: Ambient only (f/16, 1.0 sec, ISO 16). Right side: Ambient with one flash at right and one at left (f/16, 1/200 sec, ISO 64). [Click on image to enlarge, then click on back arrow to return to this post.]Using Tripod, Manual Exposure, & Manual Flash to Ensure Consistent Images for Demonstrating Function of Subject
Using a tripod, manual exposure, and manual flash ensure consistency between images. Both made with Nikon D850 and ZEISS Milvus 50 mm f/2 macro lens at f/16, 1/40 sec, ISO 64 plus flash. [Click on image to enlarge, then click on back arrow to return to this post.]Some of you may have noticed that—except for the Explorer testing, the Trailblazer, and the onboard tire inflation system images—each pair of images had the same exact composition. Only the lighting changed. This was only possible by using a tripod. Tripod use will be another area of concentration and practice in the class. Hopefully, you’ll learn to love using your tripod like I love using mine.
I’ll post another set of photograph pairs later to illustrate additional areas we’ll cover in the class.
In the meantime, please don’t hesitate to contact me by e-mail or phone if you have any questions or would like more information. I look forward to seeing you in Reston, VA, in December. Again, here is the link for the class: https://www.sae.org/learn/content/c1729/.
Both 1/80 sec, ISO 200 made using Nikon D3s with Nikon 24-70 mm f/2.8 lens at 50 mm. Left without polarizer f/14. Right with polarizer f/11.
[Click on image to enlarge, then click back arrow to return to this post.]
SAE will once again be hosting my class C1729 entitled Photography for Accident Reconstruction, Product Liability, and Testing from March 18-20, 2025. This time it will be in Peoria, AZ.
We will start with the basics of camera setup, menus, exposure, and gear (especially flashes, tripods, and polarizers). We will build on that with composition and focusing. There will be plenty of comparison images between bad and good images so we can see how and why images can be improved to show more detail and become more useful.
We will also discuss the special requirements and procedures for macro (close-up) and night photography, along with the importance of proper perspective. Finally, we will review file handling and post-processing.
We will have extended hands-on sessions to apply what we’ve learned to real world situations. As always, I will be bringing additional flashes, tripods, and polarizers for those who don’t have them, or who don’t have good ones, or who want to try new equipment.
The closer you get to your subject, the less depth of field (DOF) you have. As you can imagine, when you photograph close-up or macro or micro subjects, you get progressively even less DOF.
In close-up—or closer—shots, even stopping down to your smallest aperture won’t give you enough DOF to make much of a difference. Besides, if you fully stop down your aperture, any small gain in DOF will likely be negated by diffraction, which softens the entire image.
Focus stacking blends multiple images with increasingly further focus points into a single image. This allows you to create an image with the specific DOF you want for your subject . You might not need everything in the foreground or background sharp, but you control what is or isn’t in focus by how many images (called slices) you use.
For this example, I wanted the entire broken lug stud in focus, but wasn’t concerned about the hub surrounding it. As shown below, even stopping down to f/16 didn’t give sufficient DOF to show the entire fracture surface. [Click on image to enlarge, then click on back arrow to return to this post.]
Single image at f/16 made with Nikon Z 8 with Nikon Z 50 mm MC macro lens. One Profoto B1x studio strobe on either side with Godox T365N II flash mid-left. f/16, 1/200 sec, ISO 64.
Notice how the focus quickly falls off toward the farther end of the broken lug stud fracture surface. Both the foreground and background of the hub are out of focus, but that’s okay since they’re not the subject of the photograph.
To get the entire lug stud to be in focus, I made nine separate photographs of the fracture surface with each one focused slightly further from the camera. [Click on image to enlarge, then click on back arrow to return to this post.]
Each individual image from closest focus upper left to farthest focus lower right, each made with Nikon Z 8 with Nikon Z 50 mm MC macro lens. One Profoto B1x studio strobe on either side with Godox T365N II flash mid-left. Each component image f/16, 1/200 sec, ISO 64.
In Photoshop, I brought all of the raw frames (slices) into a single image as separate layers. I aligned the layers, then stacked them using Auto-Blend Layers. As shown below, using layer masks, this function blocked the out of focus areas on each slice. Only the sharpest parts of each layer, or slice, remained. [Click on image to enlarge, then click on back arrow to return to this post.]
Screenshot of Photoshop layers with their focus stacking masks.
I cropped the image back to its original size and saved it with all its layers as a PSB Photoshop Big) file. With ten 45 megapixel layers, the file was over 2 GB, which is larger than can be saved as a PSD (Photoshop Document) file. I then flattened the image, resized it, output sharpened it, and saved it as JPEG. Note: I still always keep the PSB file with the layers and layer masks to be able to show what I did, if asked.
Below is the result of the focus stack blending of the nine layers shown above. [Click on image to enlarge, then click on back arrow to return to this post.]
Focus stacked in Photoshop from nine images, each made with Nikon Z 8 with Nikon Z 50 mm MC macro lens. One Profoto B1x studio strobe on either side with Godox T365N II flash mid-left. Each component image f/16, 1/200 sec, ISO 64.
Note how the entire face of the fracture surface is now in focus. Note: I used to also use Zerene Stacker and Helicon Focus for focus stacking—and both are excellent—but now I almost exclusively use Photoshop.
Takeaways:
-1- The closer your camera is to your subject, the less depth of field (DOF) you will have.
-2- Most forensic images require the entire subject to be in focus to show all its details.
-3- Even stopping your lens down to its minimum aperture won’t give you sufficient DOF, plus you risk losing detail from diffraction.
-4- Focus stacking requires a series of photographs (slices) be made with the focus increasingly distant from the camera. These slices are blended into a single image where only the sharpest elements of each slice will be kept by the software.
-5- Only combining images through focus stacking allows you to get sufficient DOF for many close-up, macro, and micro images.
-6- The closer the subject, the more slices (individual images) you need. For some micro images, more than 1,000 slices need to be blended through focus stacking.
-7- Focus stacking can also be used for large subjects including landscapes, buildings, accident scenes, and vehicles. Those larger subjects require fewer slices—often only two or three.
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, long 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.)
Tire analysis setup includes camera with flash on studio stand, two studio strobes into silver umbrellas, silver reflector, and gray background paper with tire on lazy susan. (Made with ZEISS Milvus 25 mm f/1.4 lens on Nikon D850 with SB-910 flash firing the two studio strobes, f/16, 0.5 sec, ISO 64.)
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 handheld LED 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.)
Tire analysis setup includes camera with flash on studio stand, two studio strobes into silver umbrellas, silver reflector, and gray background paper with tire on largest lazy susan. (Made with ZEISS Milvus 25 mm f/1.4 lens on Nikon D850 with SB-910 flash, f/16, 0.6 sec, ISO 160.)
I will describe lighting for specific items in future posts, but for tires, I generally use two Profoto Pro-B3 750 W/s studio strobes—both mounted on rolling light stands.(For tires, I now use the strobes without umbrellas to get even more contrast and details.) A Godox TT685IIN flash affixed to the hot shoe a Nikon Z 8 mirrorless camera triggers both studio strobes, along with supplemental remote Godox TT685IIN’s and/or Godox MF-12 macro flashes, if required. 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 on the camera’s rear 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.
1989 Toyota 4Runner photo from print ad. (Click on image to enlarge, then back arrow to return to post.)
In 2016, I bought a Toyota 4Runner TRD Pro. Almost four years later, if I had it to do all over again, I’d buy the exact same one. You can’t ask for anything more when buying a vehicle. It’s great on and off the road, and is the perfect size inside and out for everyday use, my personal landscape photography trips, and for traveling for work. About the only thing I use my beloved F-150 for now is to haul tires and wheels between my warehouse and my Studio Lab in my home office.
When I was researching the history of the 4Runner, I came across this photo that was used in a print ad by Toyota for a first generation model in 1989. While it is a nice image, right away I noticed something was wrong.
If the 4Runner was moving with its tires rotating, its body could only have stayed sharp if the photographer panned the camera with the vehicle as the shutter was clicked. But then the foreground and background would have blurred as the camera moved along with the vehicle. If they were rotating fast enough, the tires could still have shown up as rotating blurs, but there would likely have been streaks behind them.
If the 4Runner was moving and the photographer used a high enough shutter speed, all motion—including rotating wheels—could have been frozen. Here, the 4Runner was not moving in relation to the foreground or background, yet the right side wheels and tires appear to be spinning. If the tires were spinning but the vehicle was not moving, the tires should have been kicking up dirt, which they are not.
More importantly, on closer inspection you can also see that neither left side tire is rotating.It’s obvious the vehicle was not moving when the photograph was made, but a radial blur filter was applied to the right side wheels and tires in post-processing.
Unlike advertising creatives, project testing engineers and litigation consultants must make only real photographs using proper camera settings. Never attempt to submit modified images as actual photographs.
That being said, modified photographs can be quite useful for demonstrative exhibits for a trial or to illustrate behavior during testing conditions, but they must be presented as such. Any modifications should be kept as layers in Photoshop, and both the modified and original photos should be presented .
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.
