Photography for Accident Reconstruction, Product Liability, and Testing Class Outline

From August 12 through 14, 2019, I will be teaching the third Photography for Accident Reconstruction, Product Liability, and Testing class for SAE. This time it will be at Southeast Toyota Technical Center in Jacksonville, FL. We’ll cover a lot of material in the three days, and you’ll come away making better quality, more professional photographs from that point on, regardless of the location or lighting conditions. After all, your photographs are at least as important as any other part of your work. You’re a professional, and your photographs should reflect that professionalism. After this class, they will.

Here’s a detailed outline of the class: SAE Forensic Photography Class Outline_2019-07.

Please contact me if you have any questions or would like more information about the class.

Laowa 25 mm f/2.8 2.5-5X Ultra Macro Lens

Wow, that’s quite a name for a great, unique lens, and the name should make sense by the time you finish reading this.

This photograph is a single shot of a 0.5 mm pencil lead at 4X magnification (4:1 reproduction ratio) made with that lens on a Nikon D850. I made it in my studio lab without using flash. The lens aperture ring was at f/11. I set the ISO at 160 and the shutter speed at 2.5 seconds. It is a full-frame image. In other words, it has not been cropped.

0.5 mm pencil lead. Made with Laowa 25 mm Ultra Macro lens on Nikon D850.

By definition, a macro lens captures an image at 1:1 or 1X or life size, which all mean the same thing: the subject will be the same size on your sensor as it is in real life. Since a full frame sensor (FX in Nikon world) is a 1″ x 1.5″ rectangle, the subject, or piece of the subject you’re showing, would have to be no more than 1.5″ wide or 1″ high.

Most macro lenses have a reproduction ratio of either 1:1 (life size) or 1:2 (half life size). These may also be referred to as a 1X or 1/2X magnification, respectively.

My 60 mm and 105 mm Nikon macro lenses (“Micro-NIKKOR” in Nikon-speak) both have a 1:1 reproduction ratio. My usual lenses are ZEISS Milvus 50 mm and 100 mm macro lenses (ZEISS calls them Makro-Planar) have maximum reproduction ratios of only 1:2, or half life size. While either 1:1 or 1:2 is just fine for much of the photography I do, I often need greater magnification for certain details—especially for tire or other product analysis photos.

If you have a camera with a high resolution sensor, you could crop the image to just the area you want to show. But by cropping, you will be throwing away pixels and restricting the size of the image you can print or project as a trial exhibit. That negates the benefit of a high resolution camera. It’s much better to capture the image full frame without cropping so you keep all the resolution your camera can deliver.

After trying all kinds of lenses and attachments, I found the Laowa 25 mm f/2.8 2.5-5X Ultra Macro lens works incredibly well. And it’s inexpensive at only $399 (http://www.venuslens.net/product/laowa-25mm-f-2-8-2-5-5x-ultra-macro-2/) or at B&H Photo Video (https://www.bhphotovideo.com/c/product/1399602-REG/venus_optics_ve2528n_laowa_25mm_f_2_8_2_5_5x.html). This lens is available in Nikon F, Canon EF, Pentax K, and Sony FE mounts. Adapters will allow it to be used on most other DSLR and mirrorless cameras.

Laowa 25 mm f-2.8 2.5 to 5x Ultra Macro on Nikon D850. Made with ZEISS Milvus 50 mm macro lens on Nikon D850.

Now, this is not a lens that you just pop on your camera and start taking incredible macro photos with. It’s a fully manual lens that does not communicate with your camera. It also doesn’t have a focus ring. So auto exposure and autofocusing are out.

Here are some considerations to keep in mind when using this lens:

-1- You need lots of light or very long shutter speeds for any kind of macro work. And the greater the magnification, the more light you need. This can be tricky with the small working distances involved.

-2- Raising your ISO won’t often be a great option because any additional noise will destroy the fine details you’re trying to capture.

-3- With high magnification, both your subject and your camera need to be perfectly still. That often means clamping down your subject and definitely means using a good, sturdy tripod for your camera.

-4- There is no focusing ring on the Laowa lens. You focus by moving the lens closer to or further away from your subject. Handholding is completely out of the question. Even with a good tripod, it can be quite tedious. You’ll really benefit from a macro focusing rail. It works best with Live View zoomed in to 100%. You’ll also want to illuminate your subject with a flashlight while you focus.

-5- You set the aperture on the lens, then adjust the ISO and shutter speed to match your lighting. You’ll need some experimentation and practice to get your exposure correct. This will become easier with experience.

-6- While stopping down your aperture increases depth of field (DOF), it also increases diffraction, which destroys the fine details you are trying to capture. The greater the magnification, the less DOF you have at any given aperture. If you can’t get adequate DOF at a given magnification, you should consider focus stacking a series of photographs. That involves taking multiple images with varying focus points, then blending them in Photoshop, Helicon Focus, or Zerene Stacker. More on focus stacking in a later blog post.

-7- To ensure the greatest DOF in a single image, or just a few images, it is best to photograph with your camera as perpendicular to your subject as possible. The greater the angle your camera is to your subject, the shallower the DOF will appear. To keep an offset subject all in focus would require multiple shots stacked in post-processing.

Suggested Gear for Accident Reconstruction, Product Liability, and Testing Photography

Even before I started teaching Accident Reconstruction, Product Liability, and Testing Photography classes, I’ve often been asked about what photo gear works the best for those areas.

In response, I’ve created two wish lists at B&H Photo Video: one for Nikon Nikon Gear Wish List and one for Canon shooters Canon Gear Wish List. I’m a Nikon shooter, so most of my direct experience is with Nikon equipment. Here are some notes on the lists:

-1- I currently use the Nikon D850. It’s arguably the best all-around camera on the market, but I recommend the Nikon D750 for Nikon shooters for several reasons:
– Its files are more manageable in size, but are still plenty large.
– It still has the manageable body size and shape, and even has the really useful flip up and down LCD screen.
– It has a built-in flash to use to trigger the Nikon 4804 R1 macro flashes.
– The built-in flash isn’t terribly powerful, and can’t be rotated or removed, but can be used in a pinch.
– Right now, it is on a fantastic sale—especially with the 24-120 mm lens. You save $1,200 instantly.
– It’s been out for a while, and is tried and true.

There are similar advantages for Canon shooters with the 6D Mk II vs. the 5D Mk IV. If you have the budget, the Nikon D850 or Canon 5D Mk IV can’t be recommended highly enough. But they are not necessary for the work we do.

-2- The lists show both the ZEISS Milvus 50 mm and either Nikon 60 mm or Canon 100 mm macro lenses. I use the ZEISS, but also have the Nikon. I use my ZEISS Milvus 50 mm lens for most of my work photography, since it has a normal perspective. I also use the ZEISS Milvus 100 mm lens when I need to fill the frame with a macro shot, but can’t get close enough.
Advantages of the ZEISS are: Precise manual focus; amazing micro contrast; and, 50 mm is accepted “normal” lens that I use for almost everything.
Disadvantages of the ZEISS are: Manual focus only (but that is my preference); and, only enlarges to 1:2 (or half life-size).
Advantages of the Nikon: 1:1 (life-size macro); autofocus (but see note below); close enough to “normal” focal length; and, less expensive.
Disadvantages of Nikon: Not as easy to manually focus.
Note: When shooting macro images, you’ll most likely have to manually focus anyway, so having a more precise manual focusing ring is a real benefit.

Speaking of ZEISS lenses, four ZEISS manual focus prime lenses make up my work kit: the classic ZEISS 25 mm f/2 Distagon; the ZEISS Milvus 35 mm f/2; the ZEISS Milvus 100 mm f/2 macro; and, the aforementioned ZEISS Milvus 50 mm f/2 macro. I use the latter for 90 percent of my work. ZEISS makes lenses for Nikon, Canon, and Sony mounts. They have unrivaled sharpness and micro-contrast, and such smooth and accurate manual focusing that you’ll forget autofocus exists! Continue reading “Suggested Gear for Accident Reconstruction, Product Liability, and Testing Photography”

Adding Light with a Reflector

Even once you get your flashes dialed in to give you the exposure you want, there may be areas where you need more detail in the shadows. You can add lights, or just use a reflector. For this example, the flash lighting illuminated the tire just as I wanted, but the tread area in the foreground was too dark. (Click on image to enlarge, then click on back arrow to return.)

Sidewall lit with studio flashes, but tread in shadow. (ZEISS Miluvs 50mm f/2 macro lens on Nikon D850.)
I could have added one or more lights to illuminate the tread, but I chose to place a simpler silver reflector at an angle next to the shadowed tread. This allowed me to redirect the spill light from the flashes back into the tire’s tread.
Sidewall lit with studio flashes, with silver reflector lighting the tread. (ZEISS Miluvs 50mm f/2 macro lens on Nikon D850.)
I used the silver side of a Profoto collapsible white/silver reflector to bounce light into the shadows. The beauty of a reflector is that it does not affect the overall exposure, so there was no need to re-meter to determine the proper exposure.

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.)
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.)
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.