Enjoy Very Long Exposures With Will Cheung And MPB

Thinking about it


Time for an update: I still use film, though. Not vast quantities, but I have a darkroom, and I'm not afraid to use it.

I enjoy every image I take: I hope you'll enjoy looking at them.
...Read More

Thinking about it

28 Mar 2021 10:35AM   Views : 547 Unique : 388


Many years ago, I reported to a maths graduate from Cambridge University at work. He is one of the most straightforward people I’ve ever met, and I learned a lot from him, professionally and generally. He believed in thinking about problems, carefully, ruthlessly, and checking every fact and assumption. When I left our mutual employer, I brought home a few outdated documents he’d written, and they are models of clarity and also of intellectual honesty.

What’s this got to do with photography, you may ask. Well, it’s the fact that Mike believed that it is always possible to solve a problem by getting sufficient data about it, and thinking hard. Actually, you begin by thinking, so that you can gather data that is likely to be relevant; and later on you may conclude that you need more data before you can continue with the thinking.

So, if you want to solve a photographic problem – shall we say, decide the likely correct exposure for the moon – you start from what you know. What light source is illuminating the moon? Yes – the sun. And you already know a lot about the strength of sunlight 93 million miles from the sun. Combining this with the fact that the moon is made of rock, a first approximation for exposure would, therefore, be 1/125 second at somewhere between f/11 and f/16 at 100 ISO.

At this point, more data – try it and see what happens. In practice, you will need a shorter shutter speed with a very long lens, but you can either open the aperture or raise the ISO to compensate. And then you can fine-tune things.

How about that phenomenon called ‘rolling shutter’ that you’re supposed to get when you use an electronic shutter – the ‘silent shutter’ mode that many mirrorless cameras have. I was wondering about it as I went for my morning walk yesterday, and decided that step 1 was to get real data for myself, by taking a picture of a moving object with an electronic shutter.

So I engaged silent mode on my camera, and got the result you see at the top. Definitely noticeable distortion (this with the car moving at around 30mph, and a shutter speed of 1/400), uneven across the frame, so that a simple skew correction won’t sort it, which surprised me (anyone who can explain why, please do so!)

I wonder if turning the camera upside down would make the car lean forward in a Looney Toons sort of a way? I don’t do enough action photography to be very interested in taking this further, and shutter noise isn’t relevant to motorsport: but if I photographed wildlife, I’d be doing more experiments in very short order, and possibly queuing up for Sony’s new Alpha 1, which apparently minimises the effect, as well as offering 30fps. As one frame every couple of seconds will do for what I shoot, you can have my place in the queue.

So, if there’s a particular photographic issue worrying you, think about it. Decide whether there are any practical experiments you can carry out to get more data. And consider looking in a traditional photographic textbook, as well as on the interwebs… Or ask here at EPZ – though you’d be well advised to do as Mike would have done, and check the thinking behind anything other people tell you. Even me.


Recent blogs by dudler

Focus scales

If you’ve been taking pictures since before autofocus arrived, you’ll be very familiar with focus scales – they are one of the primary controls on an old-school camera, and just one more of the things that you really needed to get right. With autof...

Posted: 27 Dec 2022 7:01AM

Porcelain processing

People commented on the look in my last post and it seems like a good idea to share the secrets for Christmas. I learned the technique several years ago: a model’s boyfriend told me about it, and a website that described it in detail: I tried it, l...

Posted: 23 Dec 2022 10:47AM

You develop your own films don’t you?

If you have your own darkroom, or if you use film cameras regularly, there are always a few people who mention the attic. As in ‘Grandpa’s cameras are in the attic. I don’t even know if they have film in them!’ This leads me to ask if I can have a l...

Posted: 16 Aug 2022 11:17AM

Choose your pond

There’s an old saying about being a big fish and a little pond. Do you want to be the most important person in a small organisation, or are you content being a relatively small cog in a big machine? It’s the same in photography. With relatively mo...

Posted: 3 Jun 2022 2:25PM

Graduated filters

This is for Hannah, and anyone else who has come across the casual way that a lot of togs talk about one or two types of filter that landscaper photographers use a lot: graduated filters and neutral density filters. A graduated filter is one that i...

Posted: 25 Apr 2022 12:18PM


dudler Avatar
dudler Plus
20 2.2k 2063 England
28 Mar 2021 10:38AM
The last paragraph reminds me... Mike's job, when I worked for him, was partly to check what I'd done, and he did it as rigorously as he did everything else. What may surprise you is how he reacted on the occasion that I demonstrated, with evidence, that a conclusion he'd reached six months earlier was wrong.

He smiled, and thanked me.

The quizzical look at the bottom of the blog is from French Chloe.
whatriveristhis Avatar
28 Mar 2021 12:00PM
"He smiled, and thanked me."

Surely that would be the normal reaction from any intelligent and reasonable person without serious confidence or self image issues.

Though you are of course at liberty to contradict me on that point... WinkWink
Acancarter Avatar
28 Mar 2021 12:05PM
Thanks John, very good thoughts. Think about the problem and you can probably solve it! As to rolling shutter, I'd assumed this was due to the sequential serial read out of the data from the sensor line by line, so I'd be surprised if it wasn't a uniform skew. Maybe the background would look so odd (ie reverse skewed) if you deskewed the image it would throw the eye. try it! Also try side ways and upside down. Your blog reminds me of the differences between Physicists and Engineers (I transitioned)... give both the problem of removing a nail hammered fully into a bit of wood... they both solve it.... then give them the same problem but with the nail half hammered into the wood... the Engineer just removes it, but the Physicist hammers it fully in, then removes it. When asked why, he replies ... well I've solved that problem already!
dudler Avatar
dudler Plus
20 2.2k 2063 England
28 Mar 2021 12:45PM
Alan - just so. I cannot contradict you. Though I would add that there are a lot of people with serious confidence and self image issues in the world. So many that to be otherwise is regarded as eccentric...

Andy - I like that. I shall repeat it to my family, one of whom is an engineer with significant respect for physics.
ZenTony Avatar
ZenTony Plus
7 31 7 United Kingdom
28 Mar 2021 2:24PM
As an Engineer (civil ) I recount this sad story of how the Engineers' brains work:

Two engineering students were biking across a university campus when one said, "Where did you get such a great bike?"
The second engineer replied, "Well, I was walking along yesterday, minding my own business, when a beautiful woman rode up on this bike, threw it to the ground, took off all her clothes and said, "Take what you want."
The first engineer nodded approvingly and said, "Good choice: The clothes probably wouldn't have fit you anyway."
dudler Avatar
dudler Plus
20 2.2k 2063 England
28 Mar 2021 5:50PM
A close friend went to the University of British Columbia in, I think, 1970. He told me what the prize in the engineering undergraduates' Christmas raffle was: or, rather, who... So maybe it's different in Canada.
JuBarney Avatar
JuBarney Plus
12 36 7 United Kingdom
28 Mar 2021 6:19PM
No wonder French Chloe looks quizzical with a tap growing out of her head!!! No doubt for SS Wink
philtaylorphoto Avatar
philtaylorphoto 22 334 2
28 Mar 2021 6:41PM
Possibly also a function of a vertical run shutter as seen here.
dudler Avatar
dudler Plus
20 2.2k 2063 England
30 Mar 2021 10:56AM
Andy (Acancarter) has found an interesting and relevant bit of measurement of how the silent shutter in the previous Alpha 7R works, HERE. Or, more exactly, how fast the electronic shutter works. It's not as simple as you might have thought...

You must be a member to leave a comment.

ePHOTOzine, the web's friendliest photography community.

Join for free

Upload photos, chat with photographers, win prizes and much more.