Lighting Equipment Used for the Previous Low Light Blog Post

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.)

Really Right Stuff (RRS) TVC-24L tripod with RRS BH-40 ball head. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens. Lit with two Profoto B1x strobes firing into silver umbrellas.)

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.)

(L to R) Profoto B1x, Canon 430EX III-RT, Nikon SB-910, and Profoto B10. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens.)

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.)

(L to R) Profoto B1x, Canon 430EX III-RT, Nikon SB-910, and Profoto B10. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens.)

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.)

Manfrotto travel light stands 5002-M (top) and 5001 (bottom). (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens. Lit by two Profoto B1x strobes firing into silver umbrellas with diffusers.)

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.)

Profoto B10 on Manfrotto 5001 travel light stand. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens. Lit with two Profoto B1x strobes firing into silver umbrellas.)

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.

Making Photographs in Low Light

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.)

Light painting at f/11 and ISO 64 with shutter speed of 74 seconds. (Made using Nikon D850 with ZEISS Milvus 25 mm f/1.4 lens on RRS TVP-45 tripod.)

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.)

Crop of an image made at f/16, 1/60 sec, ISO 200,000 showing noise. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens, no flash.)

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.)

Tire and wheel inside semi-trailer. (Made using Nikon D850 with ZEISS Milvus 35 mm lens and on-camera Nikon SB-910 that also fired two Profoto B10s.)

Here is a resulting image from that setup. (Click on image to enlarge, then click back arrow to return to this post.)

Tire and wheel inside semi-trailer. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and on-camera Nikon SB-910 that also fired two Profoto B10s.)

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.

Checking Tire Pressures in Truck Tire Monitoring and Inflation and Systems

Tire pressure monitoring systems (TPMS) are required on cars, pickups, and SUVs, and can be found on some heavy trucks. A TPMS simply warns the driver that the air pressure in a tire dropped to a certain pressure, or dropped a certain percent below the programmed pressure. TPMS does not replenish the air. 

Onboard tire inflation systems, which are becoming common on air-braked trucks, semi-trailers, and buses, use the onboard air system to maintain the appropriate air pressure in each tire. Truck tire inflation systems only warn a driver if a tire loses air faster than the system can replenish it.

During routine maintenance, after a tire issue, or after an accident, you will often want to check all tire inflation pressures, even if there is a tire monitoring system or an onboard inflation system. You’ll need to ensure that either type of system was working properly. That requires checking each tire pressure individually.

With either system, how to you access the valve for each tire? Below are two examples.

First is a Stemco AirBat RF tire monitoring system on the rear tandems of a three-axle truck tractor. (Click on image to enlarge, then click on back arrow to return to this post.)

Stemco AirBat RF assembled. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Nikon SB-910 flash.)

There are two standard metal valve caps—one for each tire of the dual. Remove these caps and use a truck tire pressure gauge as you normally would. You can also add air through these valves if required. (Click on image to enlarge, then click on back arrow to return to this post.)

Stemco AirBat RF with valve caps off. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Nikon SB-910 flash.)

Make sure you know which valve goes to which tire. It’s easy to do; just trace the hose back to its associated wheel.

As an example of tire inflation systems, the Meritor Tire Inflation System by P.S.I. (MTIS) is a popular system on both new and retrofitted semi-trailers. (Click on image to enlarge, then click on back arrow to return to this post.)

MTIS by P.S.I. assembled. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Nikon SB-910 flash.)

With MTIS, twist the knurled fitting at either end of the through tee, then use your truck tire pressure gauge on the valve at the end of each hose. Again, make sure you trace which hose goes to which tire. (Click on image to enlarge, then click on back arrow to return to this post.)

MTIS by P.S.I. valve stem. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Nikon SB-910 flash.)

While these systems initially look intimidating, it is actually much easier to check tire inflation pressures with them than it is trying to get a tire gauge to fit on individual valve stems on the wheels.

Using Off-Camera Flash to Bring Out Details

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.)

Stamping in wheel flange with flash in camera hot shoe. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Nikon SB-910 flash.)

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.)

Stamping in wheel flange with flash off camera almost perpendicular to the right. (Made using Nikon D850 with ZEISS Milvus 50 mm macro lens and Profoto B10 strobe to camera right.)

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.

Effects of Flash on Retroreflective Tape, with a Surprise

Retroreflective tape is designed to reflect light directly back toward the light source. It is most effective when the light source is perpendicular to the tape. The amount of light reflected drops off as the angle between the light source and the tape becomes more oblique.

As required by Federal law, most trucks and trailers have retroreflective tape to enhance conspicuity at night. I’m sure you’ve seen the red and white pattern on the sides and rear of trailers.

Because I always use fill flash when photographing vehicles outdoors, light from the flash will reflect off the retroreflective tape even during the day. This effect can be seen on the rear of the trailers in this photo. [Click on the image to enlarge, then click on the back arrow to return to this post.]

Retroreflective tape on semi-trailer with flash. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 flash.)

Here was the surprise. Several years ago, I was inspecting a red ambulance with black stripes using my usual polarizer and fill flash. When I checked out one image on the camera’s LCD, I thought either the camera malfunctioned, or I had inadvertently changed some setting. Instead of the black stripes I was seeing on the ambulance, they appeared gold in the photo I just made. [Click on the image to enlarge, then click on the back arrow to return to this post.]

Retroreflective tape with flash on. (Nikon D810 with ZEISS Milvus 50 mm f/2 lens with Nikon SB-910 flash.)

I took a second shot, and it looked the same. Strangely, everything but the stripes looked normal in both photos, so it couldn’t be a camera setting.

I turned the flash off and made another photograph. With the fill flash turned off, the stripes looked just as I was seeing them with my eyes. [Click on the image to enlarge, then click on the back arrow to return to this post.]

Retroreflective tape with flash off (Nikon D810 with ZEISS Milvus 50 mm f/2 lens with no flash.)

Turns out it was black retroreflective tape that turned gold when light hit it. I had never seen or heard of that before. I ended up going back and making another set of images of the ambulance without flash.  I sent both sets to my client.

Two takeaways here:

-1- Always check your images before you leave an inspection site. I typically review them during my inspections, particularly if the lighting is tricky or changing. It’s also a good idea to run through all of them quickly before leaving to ensure you haven’t missed anything. This is particularly true at inspections when clients or other experts are present. It’s easy to get distracted and forget to document something.

-2- It’s often best to make two (or more) sets of images if changes in lighting dictate.

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).

Photo Composition: Too Much Wasted Space

I’m sure you’ve seen many photos like the one below. [Click on image to enlarge, then click back arrow to return to this post.]

Left front of truck with bad composition. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

What is the subject? The tire and wheel? The intruding part at the upper right (which was actually from an unrelated truck)? The gravel? Is there something important that I should be seeing in the gravel?

It was actually the tire and wheel. But if you draw a vertical line down the middle of the photo, almost the entire right half of it is unrelated to the subject.

In the image below, the tire and wheel are still featured, but now you can see how they relate to part of the truck’s frame rail and steering system, too. [Click on image to enlarge, then click back arrow to return to this post.]

Left front of truck with good composition. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

This photo makes more sense and eliminates unnecessary and confusing elements. It’s easy to pay so much attention to your subject that you forget what it looks like in the frame. Make sure you haven’t included too much empty space or too many unrelated elements that are not only distracting and confusing, but look sloppy, careless, and unprofessional.

Using a Polarizer on a Large RV

I posted an example earlier illustrating the effects of using a polarizer and a fill flash on a car in a junk yard. In this post, you’ll see the effect of a polarizer on a large, slab-sided vehicle like a trailer or an RV.

Many people believe that polarizers are only effective on sunny days, and when the sun is at a 90° to the camera lens. But as these examples will show, a polarizer is just as effective in multiple directions on a heavy overcast day.

These images will also show that, just as on sunny days, the polarizer eliminated different amounts of reflected glare depending on the angle of the camera to the RV. As you will see when you look through and rotate a polarizer, the glare effectively moves around the scene. It’s up to you to decide what is the most important part of your image, and to rotate the polarizer until you eliminate the glare or get it just where you want it.

I inspected this RV in a salvage yard in Florida on a very cloudy day. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer minimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

As with all of my vehicle photos, I used both a polarizer and a fill flash. In this image, you can see the thick overcast sky and the bright glare reflected on the side of the RV. I had the polarizer on my lens, but for illustration, I rotated it to minimize its effect. That’s what the RV looked like to the naked eye.

Keeping the camera and fill flash settings the same, I rotated the polarizer while looking through the viewfinder until I reduced the glare as I wanted. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer optimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

As you can see, there was very little glare left along the side of the RV, which allowed its true colors to show through.

Moving around toward the 3/4 right rear position, I made another pair of photographs to illustrate the effect from a different angle. First the polarizer is minimized. Again, notice the reflections and the glare. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer minimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

From this angle, I could not completely eliminate the glare regardless of how much I rotated the polarizer, so I chose the area where I wanted to eliminate the glare, and set it there. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer optimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

From the right front, the side of the RV was again partially obscured by glare. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer minimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

From this angle, I was able to rotate the polarizer into a position that eliminated the glare on both the right side and the front end. Notice how you can even see through the side windows now. [Click on the image to enlarge it, then click on the back arrow to return to the post.]

RV with polarizer optimized. (Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens and Nikon SB-910 fill flash.)

Here are the takeaways:

-1- Use a polarizer when you want to eliminate reflected glare off of vehicles.

-2- Use fill flash with a polarizer to bring out detail in vehicle photos.

-3- Polarizers are effective on overcast days when light is scattered everywhere. Polarizers are not just for sunny days.

-4- Polarizers can be effective at angles other than 90° to the light source.

-5- The only way to determine the best setting for a polarizer is to rotate it until it gives you the effect you want.

-6- Last but most important, you MUST rotate your polarizer before each shot to get the desired effects.

Another Example of Using a Polarizer at an Accident Site

In a post last year, I showed an example illustrating the importance of using a polarizing filter when photographing skidmarks at a wreck site. As you rotate a polarizer while looking through it, you can watch the glare either move or disappear entirely, depending on the subject and the angles involved.

Below is a photograph of two lanes on an Interstate that don’t appear to have any tire marks. (Click on photo to enlarge, then click back arrow to return to post.)

No polarizing filter used. Skidmarks aren’t visible. (Made with Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens.)

No tire marks were visible to the naked eye either, but they could be seen through polarized sunglasses.

Just adding a polarizer on a lens might not have any effect until it is rotated. It cannot be said enough: You must rotate a polarizer before every shot if you’ve moved the camera even a little bit.  Fortunately, the effect is easy to see looking through the filter before putting on to your lens, or through the viewfinder or when using Live View once it’s on the lens.

Here is the same view using a polarizer rotated for maximum effect (Click on photo to enlarge, then click back arrow to return to post.):

Polarizing filter rotated until glare removed from skidmarks. (Made with Nikon D850 with ZEISS Milvus 50 mm f/2 macro lens.)

In this example, if I hadn’t used a polarizer, I couldn’t have captured the skidmarks shown here. Also notice there is now enough contrast that you can see the police paint marks in the tire marks.

Most polarizers lose between one and two stops of light. Because polarizers are dark filters—like polarized sunglasses—you must compensate for that loss of light by increasing your exposure by opening your aperture (losing depth of field) or slowing your shutter speed (making it harder to handhold) or raising your ISO sensitivity (adding noise and reducing dynamic range). A one-stop polarizer costs more money, but it is money well spent—especially when light levels are low (like on overcast days and near sunrise or sunset). Note that since I always use a tripod, I always choose a slower shutter speed, since the camera will remain steady no matter how slow the shutter speed is.

Next to a camera and lens, a tripod and a polarizer are your two most important tools for outdoor photography, especially accident sites and buildings.

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.