Lighting for Texture

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.]

Made with Nikon D850 with ZEISS 50 mm f/2 macro lens at f/10, 1/200 sec, ISO 64. Remote Nikon SB-910 flash head at lower right of lens barrel, fired by deactivated Master SB-910 in camera hot shoe.

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.]

Made with Nikon D850 with ZEISS 50 mm f/2 macro lens at f/10, 1/200 sec, ISO 64. Remote Nikon SB-910 flash head low and well off to the right of lens, fired by deactivated Master SB-910 in camera hot shoe.

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.

Remember to Think Light (and Shadow).

Focus Stacking Close-up Images

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:

Broken steel belt edges – single shot at f/16. (Made with Nikon D850 with Nikon 60 mm macro lens.) Click on image to enlarge, then click on back arrow to return to post.

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:

Broken steel belt edges – thirteen stacked images f/11. (Made with Nikon D850 with Nikon 60 mm macro lens.) Click on image to enlarge, then click on back arrow to return to post.

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.

Nailing an Ultra Macro Photo

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.)

Arrow highlights point of tiny nail through tire innerliner. (ZEISS Milvus 50 mm f/2 macro lens on Nikon D850.)

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.

The Pod beanbag with Arca-Swiss style quick release clamp. (ZEISS Milvus 50 mm f/2 macro lens on Nikon D850.)

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.

Setup for tiny nail end using The Pod and two Nikon SB-R200 flash units. Laowa 25 mm 2.5 to 5x Ultra Macro lens on Nikon D850 removed from The Pod to show setup. (ZEISS Milvus 50 mm f/2 macro lens on Nikon D850.)

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.

Full frame, uncropped close-up of tiny nail. (Laowa 25 mm 2.5 to 5x Ultra Macro lens on Nikon D850.)

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!

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.