Focus Stacking Close-up Images

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.

SAE Photography Class December 5-7, 2023, in Irvine, CA

I will be teaching Photography for Accident Reconstruction, Product Liability, and Testing – C1729 in Irvine, CA, on December 5-7, 2023. Please check out this link for more information or to register:  https://www.sae.org/learn/content/c1729/.

Night photo of intersection with traffic light. (Made with ZEISS Milvus 50 mm f/2 macro lens on Nikon D850, at f/6.3, 1/60 second, ISO 1600.)

[Click on photo to enlarge, then click on back arrow to return to this post.]

In addition to the class presentations and materials, I will be bringing various tripods, tripod heads, and accessories, along with a lot of Godox flashes that we’ll use to practice multi-flash and off-camera flash techniques.

Please contact me if you have any questions about the class.

New SAE Photography Class Scheduled October 17-19, 2023!

SAE International has just added another of my photography classes (Photography for Accident Reconstruction, Product Liability, and Testing – C1729) at their excellent training center in Troy, MI, for October 17-19, 2023. Please check out this link for more information or to register:  https://www.sae.org/learn/content/c1729/.

Melted aluminum on lug stud. (Nikon D850 with ZEISS Milvus 100 mm f/2 macro lens.)

[Click on photo to enlarge, then click on back arrow to return to this post.]

In addition to the class presentations and materials, I will be bringing various tripods, tripod heads, and accessories, along with a lot of Godox flashes that we’ll use to practice multi-flash and off-camera flash techniques.

Mid-October is still a great time to be in Troy, with daytime highs about 60° and lows about 42°.  The SAE Troy facility is just off I-75 at W Big Beaver and is surrounded by hotels and restaurants, so is quite convenient.

Please contact me if you have any questions at all.

SAE Automotive Forensic Photography Class – April 2023

SAE International has scheduled my next Photography for Accident Reconstruction, Product Liability, and Testing (C1729) class at their excellent Troy, MI facility from April 4-6, 2023: https://www.sae.org/learn/content/c1729/

It’s a great facility and is quite easy to access on W Big Beaver Rd just off I-75. It’s about 45 minutes from the Detroit airport. There are plenty of hotels and a lot of great restaurants in every price range.

The link above provides a detailed course outline. We’ll also get hands-on time to practice with exposure, flash, polarizers, tripod use, and more.

If you have any questions or would like more details, please feel free to email or call.

I look forward to seeing you there!

SAE Photography Class — July 12-14, 2022

With live classes now returning to SAE, I’m excited to announce that my next Photography for Accident Reconstruction, Product Liability, and Testing class will be July 12-14, 2022 at Mecanica Scientific Services’s fantastic classroom facilities in Oxnard, CA. Special thanks to Mecanica’s John Steiner for hosting this class for the third time!

Here’s a link for more information and to register: SAE Photography Class July 2022.

The class has ten major subject modules that build upon each other. We’ll explore in-depth about gear, light, camera fundamentals, settings, post-processing, and much, much more. You’ll come away not just knowing about, but actually understanding how to make better, more consistent, and more useful photographs during all your inspections and analyses, regardless of lighting conditions.

Please call or e-mail me directly if you have any questions or need more information.

I hope to see you there!

New SAE Photography for Accident Reconstruction, Product Liability, and Testing Class Scheduled!

After having four of the five classes canceled last year, I’m really happy to announce the return of my SAE automotive and product photography class: https://www.sae.org/learn/content/c1729/. I’m glad to be returning to the site of my first class in 2018 at the great facilities of Mecanica Scientific Services in Oxnard, CA:  https://www.mecanicacorp.com/. Many thanks to John Steiner, CEO and Principal Scientist of Mecanica, for hosting this upcoming class from August 30 through September 1, 2021.

Important note: This class is an elective choice for the SAE Accident Reconstruction Certification (https://www.sae.org/learn/professional-development/certifications/accident-reconstruction-certificate/courses). It also qualifies for PE continuting educational requirements and ACTAR credits. Best of all, what you learn in this class can be applied immediately, and every single time you’re doing an inspection afterward.

Whether your primary job is accident reconstruction, product analysis, vehicle or component testing, or other technical area, you will need consistent, quality photographs to both document and analyze your subjects. These photos need to be made regardless of ambient lighting or conditions. Your camera on Auto isn’t going to do that. [Click on image to enlarge in new window, then click back arrow to return to post.]

Photo made by panning with vehicle moving at 55 mph during tire testing. (Made with Nikon 300 mm f/2.8 lens on Nikon D800E at f/6.3, 1/640 sec, ISO 400.)

Not only are good photos essential for documentation and useful for analysis, they can be critical for use in lawsuits, insurance claims, recalls, and design and testing evaluations. Both in-house analysts and independent consultants will be counted on to routinely produce accurate and reliable photographs as part of their professional work. Did I mention that your camera on Auto isn’t going to do that? [Click on image to enlarge in new window, then click back arrow to return to post.]

BMW in sun at tow yard. Fill flash and polarizer. (Nikon 24-70 mm f/2.8G lens on Nikon D810. Exposure: f/10, 1/60 sec, ISO 160.)

This class is designed to give you the tools and knowledge you’ll need to consistently create professional photographs by proper use of focus, depth of field, composition, lighting, polarizers, tripods, and close-up/macro tools. You’ll see how flash is essential for capturing all the data, and how it’s not as intimidating as many believe. We’ll also cover the two types of night photography as well. [Click on image to enlarge in new window, then click back arrow to return to post.]

Night photo of intersection with traffic light. (Made with ZEISS Milvus 50 mm f/2 macro lens on Nikon D850, at f/6.3, 1/60 second, ISO 1600.)

There will be more hands-on sessions than in previous classes, so make sure to bring your camera, lenses, polarizer, tripod, and flash. Course information and registration are available through the link in the first paragraph, but if you have any questions or need more information, please feel free to e-mail or call me directly.

Be Careful When Processing a Photo

1989 Toyota 4Runner photo from print ad. (Click on image to enlarge, then back arrow to return to post.)

In 2016, I bought a Toyota 4Runner TRD Pro. Almost four years later, if I had it to do all over again, I’d buy the exact same one. You can’t ask for anything more when buying a vehicle. It’s great on and off the road, and is the perfect size inside and out for everyday use, my personal landscape photography trips, and for traveling for work. About the only thing I use my beloved F-150 for now is to haul tires and wheels between my warehouse and my Studio Lab in my home office.

When I was researching the history of the 4Runner, I came across this photo that was used in a print ad by Toyota for a first generation model in 1989. While it is a nice image, right away I noticed something was wrong.

If the 4Runner was moving with its tires rotating, its body could only have stayed sharp if the photographer panned the camera with the vehicle as the shutter was clicked. But then the foreground and background would have blurred as the camera moved along with the vehicle. If they were rotating fast enough, the tires could still have shown up as rotating blurs, but there would likely have been streaks behind them.

If the 4Runner was moving and the photographer used a high enough shutter speed, all motion—including rotating wheels—could have been frozen. Here, the 4Runner was not moving in relation to the foreground or background, yet the right side wheels and tires appear to be spinning. If the tires were spinning but the vehicle was not moving, the tires should have been kicking up dirt, which they are not.

More importantly, on closer inspection you can also see that neither left side tire is rotating.  It’s obvious the vehicle was not moving when the photograph was made, but a radial blur filter was applied to the right side wheels and tires in post-processing.

Unlike advertising creatives, project testing engineers and litigation consultants must make only real photographs using proper camera settings.  Never attempt to submit modified images as actual photographs.

That being said, modified photographs can be quite useful for demonstrative exhibits for a trial or to illustrate behavior during testing conditions, but they must be presented as such. Any modifications should be kept as layers in Photoshop, and both the modified and original photos should be presented .

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.

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”

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.