Focus Stacking – Something New for Me

Some of you may know that I love photographing the unique wild flowers of Western Australia, especially in the pristine bushland on our farm near Wandering, south east of Perth. We have about 400 different varieties, just on a couple of hundred hectares.

On my late mother’s birthday, 19th August, I casually glanced through the book Wildflower Country by William and Kaisa Breedon, a magnificent volume featuring one of my favourite wildflowers on the cover. I was struck by the stunning quality of the photographs in the book. They were not so forthcoming on the details of their methods, so I did a bit of online research and guessed they were using focus stacking. I resolved to try the technique for myself. [some results]

Normally, photographing a flower in the wild requires some compromises. For many years, I have resorted to flash photography, using a hand-held flash to simulate low-angle lighting that creates interesting light effects for flowers. Flash is especially useful in fading light, darker cloudy weather, or when the wind is blowing and the flower is moving, even slowly, ruling out anything but a short exposure. Here’s an example above, a rare form of patersonia on our farm. I first saw one of these about 15 years ago, and I have been looking out for another. I found this one close to sunset so flash was the only option.

Yet there limitations. To get significant depth of field, to see at least some of the flower in sharp detail, I had to use a small aperture setting with my 100 mmm macro lens, around f22. However, diffraction limits the resolution of even the best lenses at this aperture to about 5 pixels on my 3000 x 4000 pixel image sensor. My camera is a Canon EOS 80D, so the image sensor is smaller than in a full frame SLR camera.

Also, the background is often black or very dark. It’s difficult to obtain natural light in the background.

The principle behind focus stacking is to capture anywhere from 5 to 50 images of the subject, each with relatively wide aperture and rather shallow depth of field. Special image processing software combines all the images to generate a single image with far more in razor sharp focus. Typically lenses produce their best resolution at an aperture setting around f8. With a wider aperture, compromises in the lens design start to become significant and the resolution degrades. At this aperture, my 100 mm macro lens theoretically produces a resolution of about 1.5 pixels, several times better than at f22.

Here’s one result.

Below is an image of Thryptomene australis, a small tree that flowers profusely through September and October. On the left side is a single image at f8 and the blurring of much of the interesting parts of the flower is obvious. On the right is the result of merging 33 images. I could have captured more images and retained sharp focus for the entire scene had I wanted to. So in some ways, the improvement is subtle, but the enlargement beneath shows the level of detail this technique can capture.

Thryptomene Australis – left is single image, right the result of focus stacking.
Enlarged section of focus stacking result

I use two apps. Zerene Stacker is a superb purpose-built app for focus stacking and runs on my laptop. The user interface is not fancy, but it works far better than Adobe photoshop and includes a retouching studio. It automatically aligns the images before starting, matching the slight change of scale as the lens focus changes.

Bees, flies and ants love the flowers too. If they are blurred, the stacker will ignore them. But sometimes, a fly or ant will appear in sufficient focus in different parts of the flower for perhaps three or four of the images. Retouching enables me to decide whether to include her or not. Also, a slight puff of wind can distort part of the flower in a couple of images, and I can correct for that.

The other app is Camera Connect & Control (CCC Pro) on my phone with a really useful feature. Its focus control changes the lens focus by one of three fixed increments: small, medium or large. I can set up my camera where there is no way to see its built-in viewfinder, yet see the image on my phone while standing in a comfortable position, shaded from the sunlight. I set up the focus so that the nearest part of the flower is in sharp focus. The rest is blurry. I wait till the light is just right, then I capture an image and then tap the focus shift button. I repeat that 20 – 40 times, shifting the focus each time, till the rear of the flower is in focus.

Recording RAW images makes for fine results, but it takes 10 – 30 Gb of disk space after processing the RAW images to TIFF format for the stacker to work.

One other tip. I use a length of wire to stabilise the main part of the flower, minimizing any movements in the gentle puffs of wind now and then. It helps to be out just after dawn when the wind is almost dead calm, or just before sunset. Good insect repellent is essential as you need to stay anchored to the spot for 10 – 20 minutes. And a water bottle of course. I think the results make it all worthwhile. I feel so blessed to have access to such wonders of nature and sharing the images with others is part of the reward. Take a look for yourself. I still have a way to go before I can match Kaisa’s work, but the improvement on narrow aperture flash photography is remarkable. A nice birthday gift. Are you interested enough to try it for yourself?

Bill Williams – Science Education Award from University of Lisbon

I was very happy to hear that Bill has received this prestigious award for his career achievements and especially his contributions to editing the Journal of Engineering Education and the European Journal of Engineering Education in the last 6 years.

Bill convened the first international meeting to bring researchers studying engineering practice together in Madrid in 2011, and went on to be the lead editor for the book “Engineering Practice in a Global Context” with chapters developed by the participants. Bill managed to persuade his friend Etienne Wenger to come, joint originator of the well-known concept of “Communities of Practice”.

Bill and I worked together on developing our theoretical understanding on how engineers contribute commercial value from their work.

The photo reminded me how fortunate I am to be in Perth, Western Australia, where we have neither Covid-19 infections nor restrictions, except we cannot travel anywhere without a tedious process to get rarely granted permission.


I have always emphasised listening as the single most important skill for engineers to develop. It’s easy too. It’s not the same as hearing. So I was happy to come across this podcast on listening from Australia’s ABC. It’s entertaining and thought-provoking. If you want to improve your listening skills, look for an ABC podcast with a transcript. Listen to the podcast (at full speed, for just 5 minutes or so), then prepare your notes, and then compare your notes with the transcript to find how much you missed. For more see “Learning Engineering Practice”. Or buy the book “People Skills” by Robert Bolton.

Illustration Credit: Saeed Karimi at

Winners of the Global Cooling Prize announced

I rarely stay up late to watch serious TV. However, this announcement, three years in the making, was something that I just couldn’t miss.

At Close Comfort, we sincerely congratulate the Global Cooling Prize 2021 winners along with all the judges and participating teams! Everyone involved in the Prize helped develop new green technologies that can cool people around the world without warming or harming our planet.

Continue reading

A Big Question

How are we going to adapt engineering education to prepare coming generations of engineers for climate warming and the need to protect people and infrastructure? How can we prepare them to re-engineer almost our entire civilisation to eliminate greenhouse and other harmful emissions in 25 years?

As you would know, I often write about engineers and engineering, and education issues. However, I have usually stopped short of specific recommendations, relying on my books and articles to convey ideas that educators can use.

Next week I am speaking at a panel discussion at Engineers Australia Perth on Wednesday March 31, 5:30 – 8pm. Register here to join in the discussion and contribute your ideas, or if you cannot join us then, reply to this post.

Continue reading

Feeling Highly Honoured

Last Monday evening, on International Women’s Day and Begum Sarfraz Iqbal’s birthday (Samina’s mother)… if ever there was a role model for women Samina’s mother was one of them)… I was honoured by The University of Western Australia with a Chancellor’s Medal.

Thank you, Ayman Haydar, for this video of the citation by Prof. Amit Chakma, Vice Chancellor, himself an engineer and his first graduation ceremony since taking on the role last year. It was also a privilege to receive the honour in front of colleagues from the engineering school and a couple of hundred graduating engineers. One of my former students gave the occasional address: it was reassuring to feel that such a confident young woman had learned something from my teaching.

Changing notions of comfort

I am so thankful I don’t have to work all the time in an air-conditioned office building. Especially since Covid-19, our entire Close Comfort team works part of the time at home. We’re happier and feel healthier too.
Of course, I have a Close Comfort personal air conditioner with me. Our team members each have at least one at home as well.
Lee Kuan Yew, honoured as Singapore’s founding father, loved to tell everyone how air conditioning enabled today’s Singapore by providing a comfortable working and sleeping environment. However, there’s a dark side that comes with 20th-century air conditioning systems.
It is well established that people who live most of the time in constant temperature air-conditioned buildings lose their natural thermal acclimatization. As a result, they only feel comfortable at about 23 °C.
Recently I hailed a Singapore cab and climbed into the shiny black refrigerator on wheels, feeling so glad I remembered to bring a cardigan tied around my shoulders. The driver exclaimed, “Ah, it’s so hot today, la!”
“What’s the temperature?” I asked.
“33, it’s really hot, la”.
“But, yesterday it was 32”.
“Yeah, 33, it’s so hot today, la!”

Continue reading

Productivity isn’t everything, but…

No wonder Trump can easily still command rustbelt supporters. Stagnation in the US manufacturing industry is killing prospects for wage rises. Bureau of Labor Statistics data released two weeks ago shows that while productivity increased by about 3% annually from the 1980s till 2007, annual growth since has been only 0.4%. Most of that, and more, is needed for sustainability improvements like changing to clean energy.

Labor productivity depends on engineered tools, machines and materials, so engineers are the key people to restart productivity growth. While economics and labor saving solutions were the priority for engineers in the 1950s, as evidenced by the ASEE Grinter report, now that seems to have been forgotten. Our research is revealing that today’s engineers have limited understanding on how to generate commercial value.

Students need to learn the fundamental purpose of engineering. Distilled from our research on hundreds of engineers in several countries, that purpose is to enable people to be more productive.

“Engineers are people with technical knowledge and foresight who conceive, plan and organise delivery, operation and sustainment of artificial objects, processes and systems. These enable productivity improvements so people can do more with less effort, time, materials, energy, uncertainty, health risk and environmental disturbances.”

Sustainability depends on similar improvements.

As Paul Krugman wrote more than 30 years ago,

“Productivity isn’t everything, but in the long run it is almost everything. A country’s ability to improve its standard of living over time depends almost entirely on its ability to raise its output per worker.”

Economists are hoping that the digital economy will restore productivity growth. It might. But in a world where information supply is exponentially increasing, its value must be exponentially decreasing.

Continue reading

LifeBridge is seeking volunteers

I need help from engineer volunteers (employed, looking for work, or retired and willing to help). In helping us you will acquire new professional capabilities enhancing your career prospects.

LifeBridge is a voluntary, non-profit organisation I helped set up to bring students and graduates looking for internships or paid work together to work on projects under the supervision of volunteer mid-career and retired engineers. The idea is to build on engineering practice research at UWA to give young engineers a head start in their careers. We will build on this research to rapidly develop their professional skills and employability. The aim is to get as many as possible working in small project teams, developing ideas for local companies in Perth.

Click or tap here for more details and prospectus.

Click or tap here to register your interest today.

LifeBridge Institute

We need your help

With the pandemic and economic disruption, we have a couple of thousand students in Perth who have completed their degree studies but are waiting to graduate because they cannot get appropriate internships to complete their course requirements. We also have many mid-career engineers laid off from projects and even major companies. LifeBridge is a voluntary, non-profit organisation I helped set up to bring these people together with smaller businesses interested in helping out. The idea is to build on engineering practice research at UWA to give the students a head start in their careers. We will use this research to rapidly develop their professional skills and employability under the guidance of volunteer mid-career engineers. The aim is to get as many as possible working in small project teams, developing ideas for local companies in Perth. I need help from engineer volunteers (employed, looking for work themselves, or retired and willing to help). In the process they will acquire new professional capabilities that will make them more attractive for companies hiring them as project opportunities emerge. We at LifeBridge also need your help to pass the word out to students and graduates looking for paid engineering work, particularly international students who have a tough time finding internships. Click or tap here for more details and prospectus. Click or tap here to register your interest today.