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.
You may be aware that light (whether ambient, flash, or a continuous light source) reflecting off a colored ceiling or wall will reflect that color into your photograph. Likewise, color reflections from a background will adversely cause your subject to take on a tint that isn’t actually present.
In the best case scenario, you may only have to explain why your photos of a subject have erroneous colors. In the worst cases, those erroneous color tints can lead to erroneous conclusions. For example, a tire photographed on a blue background will likely take on a blue color cast. This could be mistakenly interpreted as evidence that the tire or tire piece exhibited signs of high heat, which includes the “bluing” of certain surfaces in the tire.
Setting a custom white balance (WB) with a calibrated white or gray target won’t remove the unwanted background color casts because the target is usually placed between the light source(s) and the subject. In that position, it would yield a proper WB for the light falling on the target, but it wouldn’t receive the tinted reflections of light from the background. As custom WB is designed to do, it would properly render the actual reflected color cast on the subject—even if is unwanted.
But if the WB target was in position to receive background reflected light, the custom WB function would try to neutralize that color cast, which would adversely affect every other color. That would be the worst of both worlds.
Let’s see how different color backgrounds work in practice.
For these examples, I photographed a manual tire spreader on different solid color backgrounds in my Studio Lab. [Click on photo below to enlarge, then click on back arrow to return to this post.]
Tire spreader on background paper lit by two Godox TT685IIN flashes triggered by another Godox TT685IIN on a Nikon Z 8 with a ZEISS Milvus 50 mm f/2 macro lens. Note: the on-camera flash was used only as a trigger for the two remote flashes, but did not add any light to the subject itself.
The tire spreader was made from uniformly-colored cast metal. It had no paint or other color applied to it. Before making any of the photographs below, I set a custom WB using a Calibrite gray WB target.
Made with Nikon Z 8 with ZEISS Milvus 50 mm macro lens & two Godox TT685IIN flashes. f/16, 1/200 sec, ISO 64.
Here is the resulting photograph with the blue background paper. It’s easy to see the blue cast in the vertical surfaces, but even the horizontal surfaces have picked up an unwanted and incorrect blue tint. [Click on photo above to enlarge, then click on back arrow to return to this post.]
Made with Nikon Z 8 with ZEISS Milvus 50 mm macro lens & two Godox TT685IIN flashes. f/16, 1/200 sec, ISO 64.
Replacing the blue background paper with red changed the improper color cast from blue to red. Again, the tint was most evident in the vertical surfaces, but was also noticeably visible on the more textured horizontal surfaces—especially when compared with those same surfaces in the blue background photo. [Click on photo above to enlarge, then click on back arrow to return to this post.]
Made with Nikon Z 8 with ZEISS Milvus 50 mm macro lens & two Godox TT685IIN flashes. f/16, 1/200 sec, ISO 64.
Replacing the red background paper with white removed the color cast, but now the vertical surfaces were significantly brighter than the horizontal surfaces. This was not what the spreader looked like if you held it in your hands. [Click on photo above to enlarge, then click on back arrow to return to this post.]
Made with Nikon Z 8 with ZEISS Milvus 50 mm macro lens & two Godox TT685IIN flashes. f/16, 1/200 sec, ISO 64.
Changing to a black background paper retained the neutrality of the white paper, but now the shadows were darker than they appear to the naked eye. In fact, black cards or black reflectors are often specifically used to absorb light and create deeper shadows. [Click on photo above to enlarge, then click on back arrow to return to this post.]
Made with Nikon Z 8 with ZEISS Milvus 50 mm macro lens & two Godox TT685IIN flashes. f/16, 1/200 sec, ISO 64.
A neutral gray background paper added no color cast, nor did it overemphasize highlights or shadows. In conjunction with a custom white balance, a neutral gray background provides the most natural and true colors, textures, and shapes of your subject. [Click on photo above to enlarge, then click on back arrow to return to this post.]
After testing and measuring numerous gray background papers, I found Superior Seamless #4 Neutral Gray Seamless Paper to be the most neutral gray background paper available. I’ve been using it ever since. Here’s a link to that paper: https://superspec.com/product/neutral-gray-seamless-paper/
Takeaways:
-1- Non-neutral background colors negatively affect the accurate rendition of your subject in a photograph.
-2- Colored backgrounds impart their colors onto your subject.
-3- Setting a custom white balance (WB) with a calibrated white or gray target won’t remove the color cast, but will accurately capture the actual reflected color. This is as it should be since capturing accurate actual color is the purpose of setting a custom WB.
-4- Although black and white are neutral tones, black overemphasizes shadows while white overemphasizes highlights.
-5- A neutral gray background gives the most natural and true colors, textures, and shapes of your subject. It’s all I ever use for any forensic photography.
(Note: This post incorporates several important fundamentals along with the discussion of controlling sun stars. As always, it’s all summarized in the Takeaways at the end.)
A previous post illustrated how the number of aperture blades affected the number of rays produced in a sun star. As discussed, sun stars are created from bright spots of light in an image when the lens aperture is stopped down. While prominent sun stars might be desirable for landscape or creative photographs, they are usually unwanted in forensic photos. In fact, there have been instances where photographs with distinctive sun stars have been limited or disallowed. Here’s how to control—or even eliminate—their prominence.
There were three small, distinct bright light sources in the following night scene. A series of images was made at every whole aperture from f/16 through f/2. (As a reminder, there are six stops up from f/16: f/11, f/8, f/5.6, f/4, f/2.8, f/2.) Only four of the seven total images—each two stops apart—will be shown below. The other three intermittent images fit in the progression as you’d expect from what you’ll see below.
This first image was made with the aperture stopped down to f/16. As expected, the sun star rays were most distinct at this aperture. [Click on image to enlarge, then click on back arrow to return to this post.]
Sun Stars at f/16 made with Nikon Z 8 with Nikkor Z 50 mm f/1.2 S lens at f/16, 2.5 sec, ISO 64.
Opening up two stops to f/8 noticeably reduced the sun star effect. [Click on image to enlarge, then click on back arrow to return to this post.]
Sun Stars at f/8 made with Nikon Z 8 with Nikkor Z 50 mm f/1.2 S lens at f/8, 0.6 sec, ISO 64.
Opening up two more stops to f/4 almost completely eliminated the sun star effect. This should be acceptable for any foreseeable use. [Click on image to enlarge, then click on back arrow to return to this post.]
Sun Stars at f/4 made with Nikon Z 8 with Nikkor Z 50 mm f/1.2 S lens at f/4, 1/6 sec, ISO 64.
Finally, opening up yet two more stops to f/2 eliminated any trace of sun star rays. [Click on image to enlarge, then click on back arrow to return to this post.]
Sun Stars at f/2 made with Nikon Z 8 with Nikkor Z 50 mm f/1.2 S lens at f/2, 1/25 sec, ISO 64.
As you can see, the wider open the aperture (which means the lower the f-number), the less pronounced are the sun stars. But you can’t just adjust your aperture to either intensify or to eliminate sun stars. Whether it is daytime or nighttime photography, changing your aperture affects your image in two main ways: exposure and depth of field (DOF).
Recall that the smaller the f-number, the larger the lens opening. Just like 1/2 of a pie is twice as large as a 1/4 of a pie, a lens aperture of f/2 is twice the diameter of f/4. Here’s how changing aperture changes exposure and DOF:
Exposure: Opening the lens aperture lets in more light, which brightens the exposure. To keep the overall exposure the same, you must compensate by the same number of stops by using a faster shutter speed, lowering your ISO, or using a combination of both. Since all the above images were already at my Nikon Z 8’s lowest ISO of 64, my only option was to select a correspondingly faster shutter speed every time I opened up the aperture.
This means that for this series of four images, every time I opened up the lens aperture by two stops, I had to use a shutter speed that was two stops faster. As you can see from the captions under the images, at a constant ISO 64, the f/16 image required a 2.5 second exposure. Opening the aperture two stops to f/8 required a shutter speed of 0.6 seconds, which is two stops faster. Likewise, f/4 required 1/6 second and f/2 needed 1/25 second to keep the same overall exposure. Each were two stop increments of aperture and shutter speed.
As a side note, since the camera remained on a tripod throughout all the photographs, the shutter speed had no effect on the sharpness of the images. But changing shutter speeds will definitely affect the appearance of any moving elements in the image frame.
Depth of Field (DOF): DOF is how much of the scene—from near to far—is in acceptable focus for a given focus point. DOF is controlled by aperture. The more open the aperture, the less DOF. Conversely, stopping down the lens aperture increases DOF.
A deeper DOF is more critical in daytime photographs where almost everything is visible and, in most forensic photography, should be acceptably sharp. At night, a more shallow DOF can be perfectly acceptable, especially if the background and foreground are mostly black, as in the photos above.
As you can see on the enlargements by clicking on the photos above, f/4 would likely produce acceptable DOF. Depending on your case, even f/2 (or an aperture between f/2 and f/4) might give you all the DOF you need. As the photographer, you need to (and you get to!) decide on the tradeoff between DOF and sun star prominence.
Takeaways:
-1- You can control the prominence of sun stars from small, bright light sources (day or night) by your choice of aperture. The more stopped down your aperture, the longer and more prominent the rays. Opening up the aperture will shrink the rays until they essentially disappear at the most open apertures.
-2- Opening up or stopping down your aperture will also affect the DOF in your image. You must decide how much DOF you will need. That amount would likely be different for daylight versus night photos—even of the exact same scene.
-3- Just like with any other photography, opening up or stopping down the aperture will require that you correspondingly adjust your shutter speed, ISO, or a combination of both, to maintain the same overall exposure. Make sure your shutter speed is sufficient for your image, especially if there are moving objects in your frame. Also, setting your ISO as low as possible minimizes noise and maximizes dynamic range, both of which are even more important in night photography.
Many lenses have an odd number of aperture blades, but several have an even number. For most photography, there is little to no noticeable effect.
There is, however, a noticeable difference if you have a “sun star” in your image. A “sun star” is the name given to noticeable rays—day or night—emanating from the sun or from an artificial light source. A sun star is created when the lens is stopped down. The more the lens is stopped down, the larger the rays of the sun star.
An even number of aperture blades results in the same number of sun star rays. As the image below shows, a lens with ten blades (the TTArtisan 50 mm f/2 lens), stopped down to f/16, resulted in ten pronounced rays from a street light at night. [Click on image to enlarge, then click back arrow to return to this post.]
Made with Nikon Z 8 with TTArtisan 50 mm lens at f/16, 3.0 sec, ISO 64.
An odd number of blades results in twice the number of rays. Using the same camera as above, but switching to a lens with nine aperture blades (the Nikkor Z 50 mm f/1.2 S lens), also stopped down to f/16, resulted in eighteen sun star rays. [Click on image to enlarge, then click back arrow to return to this post.]
Made with Nikon Z 8 with Nikkor Z 50 mm f/1.2 S lens at f/16, 2.5 sec, ISO 64.
Takeaways:
-1- Day or night, “sun stars” are often created from small, bright light sources in a photograph when lenses are stopped down.
-2- An even number of lens aperture blades creates the same number of sun star rays. An odd number of blades results in double the number of rays.
-3- An even number of blades creates more pronounced rays than does an odd number of blades.
-4- Sun stars are usually undesirable in forensic photographs. A future post will describe how to control the prominence of those rays. But if you must stop down for depth of field, an odd number of lens aperture blades will create more rays, but they will be less obtrusive.
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.
One kind of forensic night photography requires you to accurately capture the appearance of a scene as closely as possible under lighting conditions similar to what they were at the time of an incident. Of course that results in an overall image that appears dark since, after all, it is a night scene.
Using fully automatic exposure modes will result in the scene being significantly (and obviously) overexposed. This is because the camera is trying to record the scene as a mid-tone (frequently referred to as “middle gray” even when the subject isn’t gray). This automatic brightening of night scenes usually results in noisy, overexposed images that don’t resemble the actual scene at all.
Almost all consumer and prosumer cameras have a fully automatic exposure mode denoted by a green camera icon with or without the word “Auto”. The image below shows the full Auto mode icon on a Nikon D5600 and Canon T7i. (Professional cameras like my Nikon Z 8’s often do not have this mode.) [Click on the image to enlarge. Then click on back arrow to return to this post.]
Made with Nikon D850 and ZEISS Milvus 100 mm macro lens.
In Auto mode, the camera sets the aperture, shutter speed, and ISO, and you cannot change or override any of them! Because the photographer cannot affect exposure in any way in full Auto mode, when teaching I refer to it as the “Green Mode of Shame” to drive home the point that you as the photographer are left without any ability to control your exposure (or a number of other important settings). While this mode might work for ideal lighting during the day, it just doesn’t—and can’t—work for ambient light night photographs. (Note: Semi-automatic exposure modes Program, Aperture Priority, and Shutter Priority will be addressed in a future post.)
I made the following two images in a lighted parking lot that had a white, a black, and a silver vehicle in the scene. (Note: both images were captured in the camera’s raw NEF format.)
For this first image, I used a Nikon Z 5 in Auto mode (its Green Mode of Shame). As discussed above, the camera tried to create a mid-tone image, and I couldn’t do anything about it. [Click on the image to enlarge. Then click on back arrow to return to this post.]
Auto exposure mode with Auto ISO. Made with Nikon Z 5 with Nikkor Z 24-70 mm f/4 lens at 49 mm in raw mode. f/4, 1/50 sec, ISO 25,600.
Note the camera chose a wide open aperture to let in as much light as possible (f4 on that lens), and an ISO of 25,600(!), while setting the shutter speed to 1/50 of a second. (A shutter speed of 1/50 of a second is considered handholdable with a near 50 mm focal length. The thinking is that if someone is going to use a camera in Auto mode, the camera will most likely be handheld. Consequently, the camera will open the aperture and boost the ISO to keep the shutter speed handholdable. But as usual, I had this camera on a tripod, like I almost always do in any light. )
Even though the original image is quite noisy (the great reduction in size and the JPEG compression of this posted image reduced the appearance of noise from the original raw), that’s not the biggest issue with it. The real problem is the scene was nowhere near this bright; it didn’t look anything like this at the time I made this image.
For the image below, I switched to manual exposure mode (the only exposure mode I ever use). I kept the aperture at f/4, but then set the ISO to the camera’s minimum of 100 to minimize the image noise. Because the camera was on a tripod, I wasn’t too concerned about shutter speed as long as it stayed within reason. [Click on the image to enlarge. Then click on back arrow to return to this post.]
Manual exposure mode with ISO set at 100. Made with Nikon Z 5 with Nikkor Z 24-70 mm f/4 lens at 49 mm in raw mode. f/4, 1/3 sec, ISO 100.
With the aperture and ISO set, I adjusted the shutter speed until the image on the back of the LCD looked like what I was seeing with my naked eye. As it turns out, the Auto image was four stops lighter than this more accurate one.
Note 1: By default, I have the camera’s Picture Control set to Neutral with reduced contrast and saturation so the LCD closely matches my computer monitor.
Note 2: For an actual night photograph case, I start by tethering my camera to a laptop that is calibrated to match my desktop monitor. There’s much more to the actual process than I did for this demo, but it’s close enough to illustrate the point that you need to take manual control of the camera.
While this second image is close to showing the scene as I saw it, to view it properly, you would need to view it with a black surround in a darkened room with your monitor brightness set to 140 cd/m² to match what I see. Regardless of these technicalities, comparing the two images—in whatever light you’re in or computer you’re on—it is obvious that the upper Auto exposure image doesn’t look anything like the more accurate lower manual exposure mode image.
In a number of cases where I’ve done both the night photography and explained why photographs submitted by other experts or photographers were improper and misleading, all of those inaccurate photographs have been stricken and disallowed by the judge.
While it’s a little bit off-topic, being able to explain how and why photographs were made and why they accurately represent what they purport to show—and why other ones don’t—is critical in almost all ambient light night photography cases.
Takeaways:
-1- Fully automatic exposure modes (like Auto) are not designed to—and cannot—accurately capture ambient light night images.
-2- You need to shoot night photographs using manual exposure mode with a low ISO to minimize noise, with the appropriate aperture for the depth of field you need, and with the shutter speed set to match what the scene looks like to the naked eye. There’s much more to the whole process, but that’s the essence of it.
-3- While the lower photo looks much closer to what the parking lot looked like when I made the photographs, it was not made with the procedure I use for case work. It is close enough to make a quick demo comparison against a demonstrably incorrect Auto method that yielded a demonstrably incorrect image.
This tire was photographed in the afternoon on a sunny day. [Click on the image to enlarge. Then click on back arrow to return to this post.]
Mounted tire on wheel outdoors with no flash. (Made with Nikon Z 8 and ZEISS Milvus 50 mm macro on Nikon FTZ II adapter at f/16, 1/10 sec, ISO 64.)
Despite being properly exposed, there are almost no details in the shadows of the tire sidewall or the wheel. Brightening the exposure would have shifted the brightest parts of both the wheel and tire into blown out highlights and all detail there would have been permanently lost. While not essential to the tire or wheel, the brighter spots on the concrete driveway would also have blown out. This would result in a less professional looking image.
Fortunately, the overall exposure itself can remain, and flashes can be used to bring out details in the shadows. [Click on the image to enlarge. Then click on back arrow to return to this post.]
Mounted tire on wheel outdoors with both on-camera flash and second flash at lower right. (Made with Nikon Z 8 and ZEISS Milvus 50 mm macro on Nikon FTZ II adapter. Godox TT685N II in camera hot shoe and Godox AD200 Pro at lower right at f/16, 1/10 sec, ISO 64.)
While keeping the identical exposure, a Godox TT685N II speedlight was slid into the camera’s hot shoe and aimed towards the shadows inside the wheel and on the left side of the tire sidewall. A second Godox flash—an AD200 Pro—was handheld at the lower right, and angled upwards toward the right side where the tread used to be.
These two flashes balanced the natural light and added much-needed detail in the shadows. The result was both a professional appearing image and one where details were not blocked up in dark shadows or blown out in the highlights.
Of course, like almost every photograph I make, both of these images were made with the camera on a tripod. I used a five-second self-timer so I could move over and get the handheld flash at the lower right into position.
Takeaways:
-1- On bright sunny days, there is often too much contrast to capture detail in both the highlights and the shadows.
-2- Increasing the exposure will lighten the shadows, but will cause the highlights to blow out and permanently lose all data and detail there.
-3- Adding one or more flashes to fill in shadows where needed results in more detail in the shadows without losing detail in the highlights.
-4- You may have to make a couple different images with the flashes to get the proper amount of light and the proper angle of light for what you want. When I make more than one image, I only keep the one that shows the details I intended. If you feel you must keep all the images you make, no problem. Only use the best one in reports or as an exhibit.
-5- More good news! The more often you practice with one or more flashes, the more quickly and intuitively you will be able to get both the amount and direction of light that you want.
I needed to document the bolt holes on a wheel that came off the front of a pickup to show whether or not the wheel had been loose on its studs.
After making overall photos of the wheel and tire assembly, I made close-ups of the mounting surface and bolt holes from the back of the wheel. But on the outside of the wheel, the bolt holes were too deeply recessed to use a standard macro lens.
It was important to photograph the lug nut mating surface at the bottom of each recess, but it was nearly impossible both to get light down each recess and to fill the image frame with each hole. I wanted to get sharp, detailed, full frame images of the mating surface—not images cropped from a larger view.
The solution was the unique Laowa Probe lens. (I have previously discussed another unique Laowa super macro lens. I’ve found Laowa lenses to be well made and optically excellent.)
As the photo below shows, the Probe is a 16-inch long tube with a small diameter 24 mm lens surrounded by tiny LED lights at its end. You use a small USB power brick to power those LED lights. Laowa supplies a USB cable with a built-in dimmer switch, but you must supply the power brick. [Click on photo to enlarge, then click on back arrow to return to this post.]
Nikon D850 with Laowa 24mm f/14 2X Macro Probe macro lens made with Nikon Z 7II with Nikon Z 24-70 mm f/2.8 lens and two Profoto B1x studio flashes. f/16, 1/200 sec, ISO 200.
Laowa offers the Probe with several different mounts for many popular DSLR and mirrorless cameras. I used the Nikon F-mount version of the Probe lens on my Nikon D850. Note that all versions of the Probe require manual focusing and exposure; there are no electronic connections between the Probe and any camera.
Fortunately, the lens barrel fit perfectly into the recessed bolt hole, allowing me to get a full frame image of the mounting surface at the bottom. All I had to do was to adjust the intensity of the LEDs, adjust the exposure, and click the shutter. [Click on photo to enlarge, then click on back arrow to return to this post.]
Nikon D850 with Laowa 24mm f/14 2X Macro Probe macro lens made with Nikon Z 7II with Nikon Z 24-70 mm f/2.8 lens and two Profoto B1x studio flashes. f/16, 1/200 sec, ISO 200.
To steady the lens, manually focus, and keep the lens perpendicular to the bottom of the recess, I had the camera mounted on my rolling studio camera stand, which acted like an easily-adjusted tripod on wheels.
As you’ll see, the next two images made with the Probe lens required 0.5 and 0.3 second exposure times, respectively. That range of shutter speeds required that the camera be secured on a tripod to eliminate camera shake. Raising ISO to get handholdable shutter speeds would introduce noise, reduce detail, and reduce dynamic range. That would defeat the whole purpose of using the Probe to get sharp, detailed full frame images.
The first image I made for each paired hole (the wheel was drilled for two bolt patterns) was to show the bolt hole pair, while concentrating on the appropriate bolt hole. [Click on photo to enlarge, then click on back arrow to return to this post.]
Nikon D850 with Laowa 24mm f/14 2X Macro Probe. f/unrecorded, 0.5 sec, ISO 64.
I then slid the end of the Probe deeper into the recess to fill the frame with details of the mounting surface. [Click on photo to enlarge, then click on back arrow to return to this post.]
Nikon D850 with Laowa 24mm f/14 2X Macro Probe. f/unrecorded, 0.3 sec, ISO 64.
I know of no other way to have attained this image without significant cropping and the inherent loss of detail and resolution.
Although it’s not a lens I use all that often, I’ve found the Probe unmatched for photographing inaccessible labels, fasteners, or other components, too. The built-in LED lights around the lens make it a really useful tool.
-1- The Laowa Probe (along with the more recent Peri-Probe) lens is a unique, specialized macro lens that can allow you to photograph areas that are otherwise inaccessible.
-2- The Laowa Probe lens allows you to capture all the resolution and detail of full frame images that would be lost with a significant crop.
-3- If you are stymied about how to photograph a challenging subject, you might be able to find a commercially available specialized solution.
-4- While it is preferable to have specialized lenses at your disposal, you can always rent lenses (or other photography gear) for infrequently encountered situations. Of course, you might find yourself using even seemingly specialized lenses more often if you own them and have them readily available.
Often, evidence is stored in plastic bags or containers with shiny surfaces that result in reflective glare when photographed. This glare can obscure both the content and any markings on the bag or container.
As an example, a small piece of the bead toe from a tire was placed in a plastic bag, which was labeled with a black magic marker. (The writing on the bags in the images below has been intentionally altered to preserve anonymity.)
This first image was made in my Studio Lab using just the overhead LED lights. [Click on image to enlarge, then click on left arrow to return to this post.]
Plastic Evidence Bag without Flashes (Made with ZEISS Milvus 50 mm f/2 Macro lens on Nikon D850 at f/16, 1 sec, ISO 64.)
Even though the image is properly exposed, the overhead LED lights resulted in so much glare that it is difficult to make out the tiny tire piece inside or the writing on the outside of the bag.
To show both the contents and the writing, I kept the overhead LED lights on, but added a Profoto B1x studio flash on the right and on the left side of the bag. (Note: any remote flashes or speedlights can be used for the same effect.) [Click on image to enlarge, then click on left arrow to return to this post.]
Plastic Evidence Bag with Flashes (Made with ZEISS Milvus 50 mm f/2 Macro lens on Nikon D850 at f/16, 1/200 sec, ISO 64. One Profoto B1x strobe to each side triggered by a Godox TT685N II flash in the camera’s hot shoe.)
Wait, how did adding even more light eliminate the glare? Two things combined to make that work.
First, the added light from the flashes allowed me to significantly reduce the overall exposure. In this case, for both images I kept the aperture at f/16 for depth of field, and the ISO at 64 for lowest noise/highest dynamic range.
In the original image using the overhead LED lights only, the shutter speed was 1 second. When I added the flashes, I reduced the shutter speed down to 1/200 second. This faster shutter speed prevented the overhead LED lights—and their reflections—from recording at all. If I turned off the flashes, the image would have been black, even though the overhead LED lights were on.
Second, the light that reflected from each flash bounced away from its respective flash, and not into the camera lens. Hence, their reflections were not recorded by the camera.
Takeaways:
-1- To reduce or eliminate glare from overhead lights, reduce the exposure enough to cause the image to go black, or nearly so.
-2- Add one or more flashes positioned (usually to the sides) such that any reflections bounce away from the lens, not into it.
-3- Adjust the power of the flash(es) to properly light the subject at the new exposure.
-4- Note: With curved or irregularly shaped objects (like plastic bags), some localized reflections may remain. These may or may not be moved or eliminated by changing the positions of the camera or the flash(es).
