Update on shooting IR

Having converted a Panasonic camera to shoot infrared and built a little push-on hood to hold the special filter, I had second thoughts. Part of it was looking at the work of Pierre-Louis Ferrer on Petapixel and his own website. Obviously, I’m not that good, but I liked what he was doing.

I realised that I normally use mono film, so what was my reason for not putting the IR filter directly in front of the sensor? Besides, fitting the filter inside the camera did away with the fiddly lens hood.

I also had a close look at Ferrer’s work and I think he is using a luminosity mask to do split toning. He is applying a pale khaki tone to the highlights and possibly a touch of blue to the shadows.

So for my next trick I found a useful YouTube video on creating luminosity masks in Photoshop Elements (as I’m too cheap to spring for the full version, and it does all I could want). The basic idea is to create a mask that controls where an effect works, based on the brightness of the image. So you can do something like tone the highlights a delicate shade without changing the mid-tones or shadows.

On my first attempts I realised that the highlights in my IR images were totally blown out. Back to the camera and play with the settings. IR mono scenes are very high contrast and the camera was not holding the highlights. Since I actually want the shadows to go black, I set the camera to underexpose by one stop.

Lower lake, Yorkshire Sculpture Park
Lower lake, Yorkshire Sculpture Park

I had a chance to go out for a walk in sunshine (I felt like a battery-hen on day release), so I took the remodified camera. With a dog lead round one wrist I was very glad to not be fiddling with the filter.

YSP sculpture
First go with luminosity masking

So the update is that I’ve fiddled with and adjusted the camera and learned a new technique.

Not bad for a day out.

A cheap digital light meter

I’ve been playing around trying to repair a lovely old Weston light meter (of which more anon). I also have a variety of other old light meters, all of which read slightly differently. I do have one meter that I bought new, but it’s getting to be as old as its owner. So which one is to be the reference standard against which I can test and adjust the rest?

The simple answer would be to buy a new meter. But that’s expensive and, well, easy.

Then I had a stroke of clever. Commercial illumination meters are much cheaper than photographic light meters, but they read in Lux. A quick search online found that there is a Lux to EV conversion (Lux is two to the power of EV times 2.5 – don’t panic: clever people have done the sums already). So I splashed out on a Chinese-made luxmeter for under a tenner delivered.

Amazingly, the intercontinental postal system is up and running again. What I got was a chunky gadget about the size of a TV remote.

Lux01

The meter can read from 0.1 to 200,000 Lux, which is about -4 to 16 EV. That’s a useful range. My little book of notes tells me that -4 is ‘night away from city lights or subject lit by half-moon’ and 16 is ‘subject in bright daylight on sand or snow’. EV 15 is where the sunny 16 rule applies. So basically this meter could cover everything I am likely to encounter.

My next job then was to build a Lux to EV converter. Now Lux is a logarithmic or exponential scale. We should all be familiar with exponential curves by now but what it means is that while EV 1 is only 5 Lux, EV 13 is 10,240 Lux. The meter handles this fine by switching scales but I was going to need to build a little conversion table on a card. My ideal would be a circular table like you get on an old light meter so that you can dial-up the reading and the ISO and see all the exposure combinations. The straight table to convert Lux to EV at 100 ISO is easy, as is the table that gives the options at different ISO – see lower below. The circular calculator took longer. I had to work out how many layers of disk I needed and what was on each layer. One of the scales also had to progress around the disk in the opposite direction to the others.

Lux03
Earlier versions

After a few attempts I got it right. I took a reading with the luxmeter and converted it to a shutter speed and aperture. I took a reading with my best meter, the Sekonic, at the same place and ISO. And they matched. Result! My Sonic meter is accurate, I have a tool to test the others with and I have a new digital light meter. Go me!

Lux02

I will get hold of some plastic sheet and see if I can make a better version of my wheel calculator. In the meantime it’s actually easier to print a small card with the Lux to EV conversion on one side and some common starter values for each EV and ISO on the other.

Luxtable

EVtable

Lux04

The advantage of using a card is that you can also add a rangefinder to it.

Enjoy!

PS
I did build a better version of the paper wheel.

Whel

 

 

Percussive learning

Percussive learning in a world of automation is what it says in the subtitle to this blog. What that means is me making mistakes. My old boss used to say “if you think you’re good, you’re not comparing yourself with the right people”. In my case, I think the right people have me well outnumbered. It’s been very humbling to find that stuff I have just learned is well-known to everyone else. So this blog is not instructional – I have no secrets to impart. Where I witter about something technical, try it yourself before assuming I’m right.

Oops!
Slightly uneven development, perhaps?

But one thing I have learned is that it’s ok to make mistakes. And if you accept that you will make them and that being wrong doesn’t mean you’re stupid, then you get to learn. Learning means thinking about your mistake and working out why you didn’t get what you wanted. Or maybe looking at a picture and asking yourself why you are less than delighted. What would have made it better? Then think about how to do more of that.

This means reflection. It means saying honestly to yourself “I wish this was more…” and then working out what more means. If the definition of madness is repeating something and expecting a different outcome, then reflection is the road to sanity. The aim of reflection is to not repeat the same mistakes. Many of them will be similar, but what you are hoping for is to break things differently each time. Or if not break things, then to hone in on that thing in the picture you want to do more of.

I’d like to introduce you here to another idea – that of reducing variability. Anyone involved in manufacturing will know this inside-out (see above for me being outnumbered). Every process has a natural level of variation. What the manufacturing people strive to do is understand what this natual level is and then reduce it as far as possible. Then, if the output moves outside the expected range, you know that something is wrong.

Bob Godfrey, The Enid.
Wave your hand under incandescent light and you will see the same effect

What I have learned in photography is that my methods need to be precise, so that I can understand why something went wrong or be able to repeat something that went right. Mostly this means consistent exposure and development. I always use a light meter for example. Then, by looking at my results, I learn to understand and use the light meter better. I have been a bit of a tart for different developers in the past but I’m over it now. When I started out I developed just about everything in Aculux. These days it’s Rodinal for its keeping qualities. Like the metering, I always use a thermometer to get my chemicals to the right temperature and I use the same method of development and agitation every time (unless I am deliberately using stand development). So the results are that the negatives should be correctly exposed and consistently developed. Any variations that show up were either a deliberate choice or a mistake.

Anyway – that’s the theory: reduce variability so that it’s easier to understand what happened when the unexpected occurs. And then keep trying new things to see what happens. Break things with deliberate care.

 

How to use flash

 

Not the cleaning product; the lighting one. But you knew that.

I’ve written before about my use of flash, but I’ve never written about yours. What made me think about it was an article on Emulsive, plus Em’s own opinions on the unhelpful arses who tend to answer questions on social media.

So here you go: flash 101. That said, this is not about how to light a scene with flash; this is about connecting a flashgun to your camera and getting the exposure about right. You can then learn how to use flash lighting by trying stuff out.

We’re talking here about electronic flash. There may still be the odd bulb or Magicube  around, but they must be rarer than free beer.
Electronic flash – let’s just call it flash – is a very brief and intense pulse of light. Packing even the small amount of energy from a battery into a very short pulse means that the flash can be very bright – the candle that burns half as long burns twice as bright, as they didn’t say in Blade Runner.

Your camera has a connection or method for triggering the flash just at the point the shutter is fully open. Most cameras have a ‘shoe’ bracket that the flash clips into, called a hot shoe because it has an electric contact in it to trigger the flash. Older cameras have a variety of fittings. Without the contact (a cold shoe) or without the shoe, you need to find a little round socket that a flash cable can plug into. Some older flashguns will take a cable connection, some even have a cable fitted, or you can find adapters that take a cable feed into a hotshoe fitting. If you need to find the cable port on your camera, it looks like a miniature version of an old coaxial TV socket. It can be set flush in the camera body or be on the side of the lens like a short stub of pipe. If it is labelled or there are several, use the one marked X or PC. If it’s on the lens, there may be a pointer with X, V and M symbols. Set this to X. Some old Russian cameras have a setting around the shutter speed dial for M or X. Again, set it to X. The X setting fires the flash when the shutter is fully open. The other settings are for flashbulbs. If your camera has a hotshoe and none of this other nonsense, it’s already set up to use flash.

Flash 1

In reading order: cold shoe; hot shoe; cable socket on lens; flash setting on lens; cable sockets in body; flash setting on shutter speed dial. The last one also shows an X on the speed dial, which is the fastest capable speed for flash, in this case 1/30.

A word about putting old film-era flashguns onto digital cameras: care. I’ve heard that some old flashguns can send voltage back down to the connection that triggered them. I hear tell that this can damage some modern digital cameras. If you are worried, buy a cheapo Chinese radio trigger to fire the flash with.

Triggers
Cheapo radio triggers. Ignore the large plug – I use this on a different type of flash.



So, now what?

Rule 0 – get your hands on at least one flashgun. Ignore the ones that are dedicated to a particular camera. Even ignore the ones that are automatic or have sensors, although they are handy. Old manual flashguns are unloved and cheap. Get some.

Flashes
Old manual flashes. They have exposure calculators on the back.



Rule 1 – you control the exposure of the flash using the lens aperture. The flash pulse is much shorter than even your fastest shutter speed, so the shutter speed can’t reduce the amount of flash light. In fact you may need a slow shutter speed. Both curtains of a focal plane shutter have to be out of the way, and sometimes this only happens at speeds slower than 1/125 or even 1/60. Check on your shutter speed dial for a speed that’s a different colour or a setting marked X. You should only use this speed or slower.

Rule 2 – the flashgun has a way of telling you what aperture to use. Some flashguns have a distance vs aperture calculator on the back. Or you can try to find the Guide Number (GN) in the manual or online. The GN will be a distance and an ISO, so something like 12 metres (100 ISO) would be typical. If you were shooting at 100 ISO, focus on your subject and read-off the distance. Divide your GN by your subject distance (in the same units) and that’s your aperture. So if my subject was at 3m, with this flashgun I should use 12/3 = f4 as the aperture. At 400 ISO I could close-down by two stops, so f8.

Rule 3 – surfaces. Flashlight bounces and fills like a torch beam. If you are shooting indoors, you might get smoother and rounder light by bouncing the flash off a wall or ceiling rather than pointing it directly at the subject. This is where you really need an automatic or sensor flashgun, as they can sense the right amount of light rather than trying to use the GN.
Be aware that flash bounced off a green wall will light the subject in green.

Autos
These have an auto mode, where the flash can control its output to match a defined aperture.



Rule 4 – triggers.  These are little sensors that (usually) clip to the hotshoe fitting of a flashgun. They sense the brief pulse of a flash going off and trigger the flashgun they are attached to. They can do this fast enough that your camera sees both flashes. This is great for any old flashguns you can find (rule 0) – put a trigger cell on them, maybe some coloured cellophane over the light and put them round the back or side of your subject. Or in the next room to shine through the door. Or inside a car or house you are shooting from the outside. Now you get to play with your light balance. To start with, unless you are after an effect, make sure the GN and subject/ backdrop distance for your slave flashes needs a wider aperture than your main flash. Then they will throw less light. Some flashguns will let you reduce their output. Or you can tape a tissue over the light. If you don’t want to set the triggers off with a flash on the camera, fire one of them with a radio trigger or a long cable.
A trigger cell also lets you fire separate flashguns from a simple point and shoot. Tape a bit of tissue over the camera flash if you need to tone it down.

Slaves

Trigger cells

Rule 5 – fill-in. It’s possible to balance the light from a flash with the daylight on your subject so that the flash fills-in the shadows. Measure your subject distance, refer to your GN and set the aperture one stop smaller/ darker to underexpose the flash. Then adjust the shutter speed to expose the scene correctly as though the flash was absent. If the shutter speed you need is faster than you can use for flash, you need more flash power or to get closer. Cameras with the shutter in the lens can usually work with flash at any shutter speed, so are good at fill-in lighting.
Get this right and it looks like you have used a reflector to fill the shadows (without needing an extra pair of arms). You could also underexpose the background for drama. Or put a blue filter on the lens and a yellow one on the flash to make the background go day-for-night blue.

Rule 6 – play. Flash freezes motion, so follow a moving subject with the shutter held open on B then trigger a flash just before you lift your finger. Try multiple flashes for a strobe effect. Try a flash from one side through an orange filter and one from the other side through blue, to get that modern orange and teal look. Put a flash on the end of a selfie stick, fire it with a trigger and you have instant side-lighting. Get a chum to point a flashgun at the back of a subject at night and fire it with a radio trigger to get backlighting. Put the camera on a tripod at night, lock the shutter open and walk around your subject firing a flash at it. Have fun.

Cable
The last resort – a long cable



Want more? Read the Strobist.

See? Nary a snarky comment made. It can be done.

Back to the fumble

Have you ever been in the situation where you thought you were good at something, and then discovered that you knew nothing? You could say it’s like having your box prised open. It happened to me on my recent big diving holiday. I thought I had it down pretty good: I had a qualification and everything; I was even good enough to be in charge of other people underwater. Then we jumped into some warm water and casually went deeper than I had ever been before. I was a total rookie – I had strapped on just about all the kit I owned, treating a warm-water shore dive the same as a cold-water, far from shore, boat dive. I was a long way from streamlined, so had to put much more effort in to swimming. I was carrying too much weight, as I’d never dived without at least a very thick wetsuit. I was a bit anxious, so was breathing more than I would if I was relaxed. So I gulped through my air in no time. Far from being an experienced professional, I acted like a nervous beginner.

Have I done the same thing photographically? Oh yes! Many times I’ve thought I knew what I was doing, only to be proved wrong. I can develop film, until it comes out blank. I can do exposure, until I can’t. I can work this camera, and then it locks up. I can do flash portraits, until the pictures are totally underexposed. But these tend to be small and single events with an obvious solution. A quick self-applied slap on the head and we’re back in business. I’ve also been dumb on a motorbike – see photo for details. That was an externally applied slap on the head.

No, what I’m thinking about is the realisation that you are totally ignorant or borderline incompetent. People talk about imposter syndrome, but what if you realised that you really were an imposter? I know I have a lot to be humble about, but this is truly humbling.

It could be totally crushing: why not just give up and admit you can’t do it? If everyone else is so much better than you, why keep being the fool? Or you could treat it like the first stage in some imaginary ten-step programme. The first step is to admit to yourself that you are at the first step.

The second step might be to realise that you can learn. The good thing about acknowledging you are wrong is that you can become righter. There is a body of knowledge in lean manufacturing that says it’s better to do something the right way, even if you are bad at it, than it is to do the wrong thing efficiently. You do not want to become even better at doing the wrong thing. So you are better off learning from a position of incompetence than doing the wrong thing righter. Nobody is a total eejit – you will have done things and achieved things. It’s just that you have learned that you have more to learn. This should be a happy place – you can grow. Some lyrics and music just dropped into my head – anyone remember the Dylan song in Easy Rider? “He who not busy being born is busy dying” (“It’s alright, ma” for the curious. Brilliant lyrics but a protracted dirge of a song.). So come on, be more Bob (learning, not droning).

Admitting that you need to learn is a huge release. If you can let go of that defensive pride, you are ready to learn what you don’t know or can’t do. And if you add what you learn to what you already know, you can get better at what you do. Sounds a bit New Age inspirational, doesn’t it? This isn’t supposed to be a pep-talk or the start of a new philosophy. I just know that, for me, trying to defend what I know when it is obvious that I don’t know enough is pointless. The world can’t hear my excuse: events will find-out the truth. And as an ex-boss used to say “if you think you’re good, you are not comparing yourself with the right people” (thanks for your support, John!).

So in diving terms I removed the excess weights, stripped the kit I didn’t need, focused on my breathing and used a larger tank. Photographically – I have re-read the manual and practised using certain set-ups or combinations of kit. I have owned my digital SLR for more than ten years, and I still read the manual for a couple of the features that I know it has but I rarely use. I have bought a new (to me) underwater camera, so I’m taking lots of pictures of small objects using flash until I learn how to use it. These aren’t really the same as discovering you are ignorant though – they are ways of avoiding the collision with ignorance. The real pain comes from the realisation that you don’t know enough. Humility hurts. It’s that feeling of pride leaving the body.

What we need around us is people who understand that knowledge and ability are but sparks in the void, and there is more that nobody knows than we do. Recognising that someone has admitted to themselves that they don’t know or can’t do a thing is supportive. There’s no need to be an arse about someone knowing less than you: just be aware that your time will come. So perhaps the golden rule of learning is to help someone as you would like to be helped yourself? And be more Bob.

No more heroes any more

I wanted to love the Legend but I can’t. It’s not that I discovered my hero had feet of clay: it was more that we didn’t get on. It may well be the most competent camera in the world, but it doesn’t do what I need. I find myself saying “it’s not you, it’s me”, and it’s true.

What the Nikonos V does is rugged and sharp film photography underwater. It has a dedicated flash with off-the-film metering. Mine also has a close-up lens with a frame-finder. You don’t even have to look through the viewfinder – just place the prongs either side of the subject and shoot. Which would be perfect if I was shooting things that kept still and didn’t mind being surrounded by metal prongs.

However, this is not what I do. What I need is a camera that can do macro work and general context scenery. I need a zoom so that I can frame subjects that would flee if I got closer. I need autofocus that will allow me to lock on the subject and reframe. I need a screen on the back of the camera so that I can operate it at arm’s length, so that I don’t scare the critters or I can get the camera into small and awkward places.

Flabellina Affinis. Nudibranch, Gozo
I need to be able to do macro (this is about the size of my thumbnail)

I did get carried away with the romantic notion of shooting film in a classic camera. And then I realised I would be spending so much attention working the camera I was likely to ignore things like my dive buddy or my own safety.

The telling thing is that I took the Nikonos on a diving holiday and never used it. I didn’t want to struggle with it getting in and out of the water. Underwater, I didn’t want the restrictions of either fixed-distance macro or having to remove and stow the close-up lens to do general pictures. Basically, it was going to be too difficult and too restrictive, so what was the point?

Comino caves, Gozo. 7th October 2019
And general context shots

I’m not alone – Martin Edge talks about using Nikonos gear in his book The Underwater Photographer. And then he says he switched completely as soon as cameras with autofocus became available.

Comino Caves, Gozo. 7th October 2019
To accurately-framed shots at mid-distance

On my recent diving trip, instead of the Nikonos I used an old and cheap Canon Ixus 750 in a housing. It has many limitations, but it is small and moves easily between macro and scenic work and takes reasonable pictures. To be fair, it took great pictures. What it lacked are things that I now know I really do need: not the fancy gadgets and features they list in the adverts, but the things you find yourself wishing the camera could do better. So I will be replacing the Canon with something that has more of what I want and saying goodbye to the Nikonos that doesn’t really do anything I need underwater. I could keep the Nikonos for surface use I suppose, but I have better and lighter cameras. So the legend will be leaving.

I did manage to buy it at a good price, so I should hopefully get more for it than I paid. The surplus will go towards a more capable digital camera plus housing that has a better ISO range, hopefully some image stabilisation and higher resolution.

So mark this one up to experience.

So, was my dream shattered by reality? No: it turned out that my reality was different to my dream. The dream is still a valid and highly capable camera system. My reality is needing something more flexible.

Awkward focus

How do you focus a camera that doesn’t tell you when it’s in focus? That’s really awkward.

If you can learn how to do this trick, there are loads of interesting old cameras that you could use. They can be reasonably cheap too, as people do prefer things you can focus. And yet, you may have heard the pundits talking about magical solutions like zone focussing or hyperfocal distances. What’s a poor boy to do when you thought zones were something to do with exposure and hyperfocals were what old people went to opticians to get?

Focusing a lens means moving it nearer or closer to the film or sensor, so that the light from your chosen subject is brought to the least fuzzy point. There was some stuff about it here. Many lenses have a built-in screw thread so that turning them moves them in and out, without letting light leak past. Other arrangements are possible, but they mostly all do the in and out thing.

Now, our eyes are not perfect and there is a lower limit to the size of things we can see. As you get older, that might be grandchildren. Grant me though, that we can’t see atoms, or even molecules. So when an image is projected onto the film or sensor by a lens, there will be a range of distances where everything appears sharp. If you could look closer, perhaps with a microscope, you could see that that amount that was truly sharp was less than it appeared to the eye. This is why small prints or pictures often look sharper than they are when you make them bigger.

But for practical purposes, there is a range of distances in front of the camera between which stuff looks sharp. This is the depth of field. Where this zone falls and how deep it is depends on several things. Let’s assume for now though that these things are outside your fine control: you can make a basic choice like the camera you are using, but you can’t change the lens on it. Let’s also assume that your camera might have one of the two forms of focusing: controlled and guess, where guess includes fixed and not adjustable. If your camera provides accurate and adjustable focusing and that is what you want, then move along – there is nothing to see here. But there can be good reasons why you might want to use your adjustable camera as though it was not. The main one is often speed of use. Focusing takes time.

So, how do you make best use of either what you are stuck with or what you choose to adopt? According to type is the answer. Guessed focusing comes in three forms: fixed, zone and scale.

Fixed is where there is no adjustment possible. It’s not autofocus – it means the focus of the lens is fixed and you do your best to put the subject in the sharp zone. If you are lucky you may be able to find out from the manual or t’interweb where the focus distance is, or what the depth of field is. I have a fixed-focus camera, and the manual lists the range of sharp(ish) distances for each aperture setting. Without this information you may have to find out, or just live with it. It’s a fair assumption that a fixed-focus camera will be set to somewhere around the distance where you can get an adult in the frame, around mid-length. My own fixed-focus camera is set for about 8 feet. You could leave it at that and just work with it, or use a bit of film in testing. What you need is a long fence or railings that you can shot at an oblique angle so that your picture shows it from close to far. Before you shoot, pace out some distances and mark them with chalk or a stone. Then examine the developed image to see where it is sharp and how far away that is. Then get someone to stand that far away and look at them using the camera, to get an idea of what that distance looks like. Or make a simple version of the card rangefinder. Then shoot everything at the sharp distance.

Fence

Next up is zone focusing. This is where the lens offers a set of symbols for where it will focus. These are usually head and shoulders, group, mountains. Again, you can work with it or do the fence test to get an idea of what each setting does.

Zone focus

In the case of my camera, head and shoulders works out around 1.5 metres or a bit less than 5 feet. Groups fall at around 5 metres/ 15 feet.

Cameras like this can be very quick to use – pick the type of picture you are making, set the symbol for focus and go. Providing the aperture is around f8, you are likely to have enough depth of field to not have to worry.

Scale focusing is like using the symbols, but without the symbols. This is where the lens is marked with real distances, but you have to guess or measure the distance of your subject and adjust the lens accordingly. The lens on the camera above has both a distance scale and symbols. It sounds dreadful – how will you ever be able to estimate the distance accurately? Use some basic rules:

  • A head and shoulders is around 5 feet, or a bit less.
  • An adult, shot vertical on 35mm with a 50mm lens, just about fills the frame at 10 feet (3m).
  • A group will be around 15 feet, or 5m.

Then use a reasonably small aperture like f8 and it will mostly work. If you are picky or nervous, make yourself a card rangefinder. It will easily fit in the camera case or your wallet.

You can even use a ‘proper’ camera with scale focusing. The street photographers do this for speed. You need to have a lens that has depth of field marking on it.

DoF

If I set this lens to f8, then everything between 2.5 and about 5m will be sharp. If that’s the most likely distance for stuff I want to take pictures of, I can set the lens and aperture and use the camera like a point and shoot. It would let me do slightly wide head and shoulders shots through to slightly tight groups without having to adjust a thing. This is what news photographers used to do, to give them the reaction time they might need to get the decisive moment (as legend would have it).

Then we come to the secret weapon of landscape photographers: the hyperfocal distance. Given a particular aperture, the hyperfocal distance is the point you focus the lens at that gives a depth of field spanning from half that distance out to infinity. It sounds like magic, and the actual point you need to focus on varies with the film or sensor size, the lens and the aperture. You don’t have enough fingers and toes to do the maths. So you either use an online resource or an app to calculate it for you, or use the depth of field markings that the lens maker gave you.

Say I’m using the lens in the above photo and I want both a group of people and the mountains in the background to be sharp. So I want a depth of field from say 4m out to infinity. I twist the lens to find a pair of aperture markings that put infinity on one side and my closest distance at the other. Then set the aperture to match the marks – the point of focus is already set correctly. Job done.

Hyper

In this case I need f11 and my closest sharp distance is perhaps 3.5m. The actual point of focus of the lens is 6m, but I don’t care.

This also works well if you are taking pictures of things that occur a bit further away, but variable. Some sports or activities, for example. Set the depth of field to cover the area of the action and concentrate on taking pictures.

So there you are – sharpness made simples, and a way to make use of the cheap end of the camera market.

In perspective

Want to start a fight? Ask a few photographers what effect the choice of lens has on perspective. Perhaps not a fight, but you will get a lot of hearsay rules and theories. But, as we know, a proper theory is one that can be falsified and makes testable predictions.

So a camera is basically a pinhole sitting at some distance from a sensor or film. The angle of view is set by the size of the sensor and how far away it is from the hole. A big sensor further away from the hole can have the same field of view as a smaller sensor closer to the hole.

Angle of view

Since the distance between sensor and hole is basically the focal length, this explains why different sizes of film or sensor need different focal length lenses to get the same angle of view. For example, a 50mm lens would be a telephoto (narrow angle of view) on an APS-C sensor, a normal lens on 35mm and a wide angle on medium format. Or, to put it the other way round, a standard lens on a small sensor would have a shorter focal length than one for a larger sensor – see A and B in the diagram above.

Let’s ignore the sensor size for now and just look at the angle of view of the lens.

Angle 1

The lens we have fitted has a wide enough angle of view to take in both the person in the foreground and the building in the background. If I stay in the same position and fit a lens with a narrower angle of view, it gets just the person’s face and a small section of the background.

Angle 2

What you will notice though, is that the relative sizes of the person and the building do not change, you just get a narrower slice of the wider version. You can test this by taking the same picture from the same position on both a wide and a narrow angle lens. Or use a zoom. Enlarge the wide-angle shot so that the central portion matches the narrow-angle picture and you will find that they match perfectly. This is the falsifiable test. This means that perspective, in the sense of the relative sizes of objects in the frame, does not change with your choice of lens if you stay in the same position. All that changes is how much stuff you get in the frame.

So what does a wide-angle lens change? If you get close to the subject, it changes the relative sizes of the nearby subject and the distant background.

Angle 3

In this diagram I shoot a head and shoulders with a narrow-angle lens (the dotted lines). It can see a narrow section of the background, so the background looks quite large in relation to the subject. If I get close to the subject with a wide-angle lens, so that I still get a head and shoulders (the solid lines in the diagram), the subject is the same size but I see more of the background and it looks smaller in relation to the subject. What changes is called the diminuition – the rate at which objects get smaller as they get further away.

This is why we usually avoid shooting portraits with wide-angle lenses. If we get close enough to fill the frame, the relative size of things near and further from the camera changes. These could be the nose or an arm or leg. But we do use wide angle lenses for landscapes, where we want to give prominence to a foreground object (like a Joe Cornish rock).

So there you have it – the angle of view of the lens only controls how much you can fit into the picture, providing you stay in the same place. You can use the angle of view of the lens to control how big the background is in relation to the subject, but only if you move nearer or closer to the subject.

What does this mean? That perspective is controlled by position, not the field of view of the lens.

Making a card rangefinder

I have referred to this a few times, with links out to pages on t’interweb where these things are spoken of. The drawback is that the web resources seem to use maths, when what we want is simplicity. So here’s my version.

What you need is a bit of card (I know, the title was a spoiler). Anything from credit card to an index card will do (ask your parents what a card index was). The main thing is that the card has one good right-angled corner. You also need a tape measure and a second scrap of card or paper.

Find a nice vertical line – a door frame or the edge of a wall. Measure a distance of say six feet from it and stand facing the target line with your toes at the distance mark. I say feet, but you might also measure the distance in meters. Use whatever units your camera lens is marked in.

Hold the card out in one hand at arm’s length. Choose the hand you will be using when you do this for real with a camera. If you are likely to be holding the camera in your right hand and using the rangefinder in your left, then hold it out in your left hand. Let’s assume you will be using your left hand. Close your left eye and line-up the edge of the card with the vertical target. Without moving the card, close your right eye and open the the left. Hopefully the vertical target will appear to move along the card, away from the edge that was originally lined-up. If it moves the wrong way, swap eyes.

That second scrap of paper is used to mark where the vertical edge appears to move to. Pinch it against the main rangefinder card and slide it sideways until your distant mark appears to consistently move to the same place. Keeping the rangefinder card and the scrap of paper pinched together, mark on the rangefinder card a line for that distance. In this example, six feet. Change the distance and repeat.

Card rangefinder
Left picture is what you see with your right eye open. Right picture is with left eye open – mark the measured distance where the yellow card joins the white one.

You can now throw away the scrap of paper and keep the rangefinder. You have built a rangefinder that works for you and your eyes and will measure close distances with enough accuracy to focus lenses using their marked distance scale.

Card
Here’s one I made earlier. Marked in meters and made to be held in the right hand (which is why the distances come in from the left).

Go ahead and make copies of the card so that you can keep one with each camera. Laminate them. Print the scale on the back of your business cards. Get the lines tattooed on your finger or mark them with a pen before you go out.

The only time you will need to change the card is if the length of your arm changes, or the distance between your eyes. Or you decide to become a pirate.

Are you sitting comfortably?

If you recognise that phrase you could be as old as me, although the programme ran until 1982 so you might equally be a spring chicken.

What’s the story? Or, to poke another meme, “I’ll tell you a story, about Jack a Nory…”.

We, as a species, love story-telling. I believe this because Yuval Noah Harari says so and so do Mssrs Stuart and Cohen in The Science of Discworld II. Their argument is that it was the cohesive power of a shared story that taught us to collaborate across family and tribal borders. It also led to religion, but that’s another story.

So what the Darwin has this got to do with photography? Narrative has power and people look for a story. Even in the absence of an available story, people will make one.

The desire for a compelling tale is so strong that we will choose the embellished story over the plain and more likely one. See Kahnemann and Tversky’s Linda experiment for further details.

The expression of this in photography is when people tell you what they see in an image. I’ve heard photographers talking about people telling them what their picture is about, in terms and directions that were a great surprise to the person who actually made the image.

Fish on grass

So why should you care? Well, your pictures will tell a story whether you like it or not. If you have a particular story in mind, you should either make it very clear or add words. If you do not, the viewer will make their own story, and it may not be the one you intended. If you care, you need to make your story more clear. But if you think of how many times you see an image without a caption or description though,you might believe that the story should be in the image.

You might also think that what matters is not the story you are telling, but that there is potential in the picture for people to make-up their own story. Obviously this doesn’t apply to news photographers, social documentary and so on – these people really do have a story to tell and will work hard to do it. For me though, I can try to add elements to my picture that will lead the viewer to make a story. So I can try to show a relationship, or show someone’s doing something interesting that will make the viewer ask themselves what is going on.

Waiting for the man...

Perhaps this is the second Golden Question – the first was ‘what do I see?’. This one is ‘what does it say?’.

Does every picture have to tell a story? No. But that leads to the third Golden Question of ‘why should I care?’ Which is the realm of landscape photography.