Zoetrope Update

During Lockdown 1.0 I made a zoetrope and shot a number of time-lapses and animations with my 35mm SLR to go in it. Below is an update on this project, but first here are the links to the earlier posts about it, in case you missed them:

Although the zoetrope itself turned out very nicely – all the more surprising because I’m terrible at DIY – the content did not. I concluded that any future efforts needed to be very simple, bold and high-contrast.

Recently I got around to shooting a couple of new animations. This time, instead of detailed, complex or subtle efforts like sunlight moving across rotting apples or Lego minifigs passing each other in the street, I went back to basics. Inspired by typical animations supplied with zoetropes in the Victorian era, I created loops of a figure walking and running.

First of all I drew out the 18 frames of each cycle using online reference material. I wanted to shoot in natural light so I rigged a black backdrop outside on the patio. Dressed in my lightest-toned clothes, I adopted the 18 positions of the walk cycle one by one as my flatmate clicked my Pentax P30t’s shutter. Then I went through the run cycle in the same way to complete the roll of 36 exposures. We used Ilford Delta 3200 film, one second of exposure time and a pinhole (purely so I could say I had made and exhibited a motion picture without ever using a lens). By the time we finished, the light had fallen off a stop or two.

When I got the material into the darkroom I under-exposed the contact prints (making them lighter) because I had learnt that a spinning zoetrope darkens the image considerably. After all, you are only viewing it through tiny slots; what you’re mostly looking at is the opaque outside of the drum. I always print on multigrade paper which means that the contrast can be adjusted using a special set of colour filters. In this case I used the 4½ filter (on a scale where 0 produces the softest contrast and 5 the hardest) to get the boldest possible look. The resulting prints still looked very milky, especially the running one which I’d had to brighten more to compensate for the light falling off, but that was what I knew I needed.

When I got home and tried them in the zoetrope, the running animation just didn’t have enough contrast in it to work. The walking animation works better but still isn’t as good as I’d hoped. I think that what’s really required is strong studio lighting absolutely blasting the subject, a completely white outfit, and a backdrop with all light flagged off it.

The learning process continues!

The results look better in this video than they actually are, because the phone I shot it on conducted its own process of reducing the motion into discrete frames for your device and brain to reassemble.

Zoetrope Update

Luna 3: Photographing the Far Side of the Moon without Digital Technology

The far side of the moon (frame 29) as shot by Luna 3

It is 1959. Just two years have passed since the launch of the USSR’s Sputnik 1 satellite blew the starting whistle for the Space Race. Sputnik 2, carrying poor Laika the dog, and the American satellite Explorer 1 swiftly followed. Crewed spaceflight is still a couple of years away, but already the eyes of the world’s superpowers have turned to Earth’s nearest neighbour: the moon.

Early attempts at sending probes to the moon were disastrous, with the first three of America’s Pioneer craft crashing back to Earth, while a trio of Soviet attempts exploded on launch. Finally the USSR’s Luna 1 – intended to crash-land on the surface – at least managed a fly-by. Luna 2 reached its target, becoming the first man-made object on the moon in September 1959.

The stage is now set for Luna 3. Its mission: to photograph the far side of the moon.

Luna 3

Our planet and its natural satellite are in a state known as tidal locking, meaning that the moon takes the same length of time to circle the earth as it does to rotate around its own axis. The result is that the same side of the moon always faces us here on Earth. Throughout all of human history, the far side has been hidden to us.

But how do you take a photograph a quarter of a million miles away and return that image to Earth with 1950s technology?

At this point in time, television has been around for twenty years or so. But the images are transient, each frame dancing across the tube of a TV camera at, say, Alexandra Palace, oscillating through the air as VHF waves, zapping down a wire from an aerial, and ultimately driving the deflecting coils of a viewer’s cathode ray tube to paint that image on the phosphorescent screen for a 50th of a second. And then it’s gone forever.

For a probe on the far side of the moon, with 74 million million million tonnes of rock between it and the earthbound receiving station, live transmission is not an option. The image must somehow be captured and stored.

Video tape recorders have been invented by 1959, but the machines are enormous and expensive. At the BBC, most non-live programmes are still recorded by pointing a film camera at a live TV monitor.

And it is film that will make Luna 3’s mission possible. Enemy film in fact, which the USSR recovered, unexposed, from a CIA spy balloon. Resistant to radiation and extremes of temperature, the 35mm isochromatic stock is chosen by Soviet scientists to be loaded into Luna 3’s AFA-Ye1 camera, part of its Yenisey-2 imaging system.

Luna 3 launches on October 4th, 1959 from Baikonur Cosmodrome in what will one day be Kazakhstan. A modified R-7 rocket inserts the probe into a highly elliptical Earth orbit which, after some over-heating and communications issues are resolved, brings it within range of the moon three days later.

The mission has been timed so that the far side of the moon is in sunlight when Luna 3 reaches it. A pioneering three-axis stabilisation system points the craft (and thus the camera, which cannot pan independently) at the side of the moon which no-one has seen before. A photocell detects the bright surface and triggers the Yenisey-2 system. Alternating between 200mm f/5.6 and 500mm f/9.5 lenses, the camera exposes 29 photographs on the ex-CIA film.

The AFA-Ye1 camera

Next that film must be processed, and Luna 3 can’t exactly drop it off at Snappy Snaps. In fact, the Yenisey-2 system contains a fully automated photo lab which develops, fixes and dries the film, all inside a 1.3x1m cylinder tumbling through the vacuum of space at thousands of miles per hour.

Now what? Returning a spacecraft safely to Earth is beyond human ability in 1959, though the following year’s Vostok missions will change all that. Once Luna 3 has swung around the moon and has line of sight to the receiving stations on Earth, the photographic negatives must be converted to radio broadcasts.

To that end, Yenisey-2 incorporates a cathode ray tube which projects a beam of light through the negative, scanning it at a 1,000-line resolution. A photocell on the other side receives the beam, producing a voltage inversely proportional to the density of the negative. This voltage frequency-modulates a radio signal in the same way that fax machines use frequency-modulated audio to send images along phone lines.

Attempts to transmit the photographs begin on October 8th, and after several failures, 17 images are eventually reconstructed by the receiving stations in Crimea and Kamchatka. They are noisy, they are blocky, they are monochromatic, but they show a sight that has been hidden from human eyes since the dawn of time. Featuring many more craters and mountains and many fewer “seas” than the side we’re used to, Luna 3’s pictures prompt a complete rethink of the moon’s history.

Its mission accomplished, the probe spirals in a decaying orbit until it finally burns up in Earth’s atmosphere. In 1961, Yuri Gagarin’s historic flight will capture the public imagination, and unmanned space missions will suddenly seem much less interesting.

But next time you effortlessly WhatsApp a photo to a friend, spare a thought for the remarkable engineering that one day sent never-before-seen photographs across the gulf of space without the aid of digital imaging.

One of the 500mm exposures
Luna 3: Photographing the Far Side of the Moon without Digital Technology

Making a 35mm Zoetrope: The Results

In the early days of lockdown, I blogged about my intentions to build a zoetrope, a Victorian optical device that creates the illusion of a moving image inside a spinning drum. I even provided instructions for building your own, sized like mine to accommodate 18 looping frames of contact-printed 35mm photographs. Well, last week I was finally able to hire my usual darkoom, develop and print the image sequences I had shot over the last five months, and see whether my low-tech motion picture system worked.

 

Making Mini Movies

Shooting “Sundial”

Before I get to the results, let me say a little about the image sequences themselves and how they were created. Because I was shooting on an SLR, the fastest frame rate I could ever hope to record at was about 1fps, so I was limited to time-lapses or stop motion animation.

Regular readers may recall that the very first sequence I captured was a time-lapse of the cherry tree in my front garden blossoming. I went on to shoot two more time-lapses, shorter-term ones showing sunlight moving across objects during a single day: a circle of rotting apples in a birdbath (which I call Sundial), and a collection of props from my flatmate’s fantasy films (which I call Barrels). I recorded all the time-lapses with the pinhole I made in 2018.

Filming “Social Distance”

The remaining six sequences were all animations, lensed on 28mm, 50mm or 135mm SMC Pentax-Asahi glass. I had no signficant prior experience of this artform, but I certainly had great fun creating some animated responses to the Covid-19 pandemic. My childish raw materials ranged from Blue Peter-esque toilet roll tubes, through Play-Doh to Lego. Orbit features the earth circling a giant Covid-19, and The Sneeze sees a toilet roll person sternutating into their elbow. Happy Birthday shows a pair of rubber glove hands washing themselves, while Avoidance depicts two Lego pedestrians keeping their distance. 360° is a pan of a room in which I am variously sitting, standing and lying as I contemplate lockdown, and finally Social Distance tracks along with a pair of shoes as they walk past coronavirus signage.

The replacement faces for the toilet paper star of “The Sneeze”

By the time I finished shooting all these, I had already learnt a few things about viewing sequences in a zoetrope, by drawing a simple animation of a man walking. Firstly I discovered that the slots in my device – initially 3mm in width – were too large. I therefore retrofitted the drum with 1mm slots, resulting in reduced motion blur but a darker image, much like reducing the shutter angle on a movie camera. I initially made the mistake of putting my eye right up to the drum when viewing the animation, but this destroys the shuttering effect of the slots. Instead the best results seem to be obtained with a viewing distance of about 30cm (1ft).

I could already see where I might have made mistakes with my photographed sequences. The hand-drawn man was bold and simple; it looked best in good light, by a window or outdoors, but it was clear enough to be made out even if the light was a bit poor and there was too much motion blur. Would the same be said of my 35mm sequences?

 

Postproduction

I contact-printed the nine photographic sequences in the usual way, each one producing three rows of six frames on a single sheet of 8×10″ Ilford MG RC paper. In theory, all that was left was to cut out these rows and glue them together.

In practice, I had managed to screw up a few of the sequences by fogging the start of the film, shooting a frame with bad exposure, or some other act of shameful incompetence. In such cases I had to edit much like filmmakers did before the invention of digital NLEs – by cutting the strips of images, excising the rotten frames and taping them back together. I even printed some of the sequences twice so that I could splice in duplicate frames, where my errors had left a sequence lacking the full 18 images. (This was effectively step-printing, the obsolete optical process by which a shot captured at 24fps could be converted to slow motion by printing each frame twice.)

"Blossom"

Once the sequences were edited, I glued them into loops and could at last view them in the zoetrope. The results were mixed.

Barrels fails because the moving sunlight is too subtle to be discerned through the spinning slots. The same is partly true of Sundial, but the transient glare caused by the sun reflecting off the water at its zenith gives a better sense of motion. Blossom shows movement but I don’t think an uninitiated viewer would know what they were looking at, so small and detailed is the image. Orbit suffers from smallness too, with the earth and Covid-19 unrecognisable. (These last two sequences would have benefitted from colour, undoubtedly.)

The planet Covid-19 (as seen by my phone camera) made from Play-Doh and cloves

I’m very pleased with the animation of Social Distance, though I need to reprint it brighter for it to be truly effective. You can just about make out that there are two people passing each other in Avoidance, but I don’t think it’s at all clear that one is stepping into the road to maintain a safe distance from the other. Happy Birthday is a bit hard to make out too. Similarly, you can tell that 360° is a pan of a room, but that’s about it.

Perhaps the most successful sequence is The Sneeze, with its bold, white toilet roll man against a plain black background.

"Happy Birthday"

 

Conclusions

Any future zoetrope movies need to be bold, high in contrast and low in detail. I need to take more care to choose colours that read as very different tones when captured in black and white.

Despite the underwhelming results, I had a great time doing this project. It was nice to be doing something hands-on that didn’t involve sitting at a screen, and it’s always good to get more practice at exposing film correctly. I don’t think I’ll ever make an animator though – 18 frames is about the limit of my patience.

My light meter lies beside my animation chart for the walking feet in “Social Distance”.

 

Making a 35mm Zoetrope: The Results

Making an Analogue Print

This is the latest in my series about analogue photography. Previously, I’ve covered the science behind film capture, and how to develop your own black-and-white film. Now we’ll proceed to the next step: taking your negative and producing a print from it. Along the way we’ll discover the analogue origins of Photoshop’s dodge and burn tools.

 

Contact printing

35mm contact sheet

To briefly summarise my earlier posts, we’ve seen that photographic emulsion – with the exception of colour slide film – turns black when exposed to light, and remains transparent when not. This is how we end up with a negative, in which dark areas correspond to the highlights in the scene, and light areas correspond with the shadows.

The simplest way to make a positive print from a negative is contact-printing, so called because the negative is placed in direct contact with the photographic printing paper. This is typically done in a spring-loaded contact printing frame, the top of which is made of glass. You shine light through the glass, usually from an enlarger – see below – for a measured period of time, determined by trial and error. Where the negative is dark (highlights) the light can’t get through, and the photographic emulsion on the paper remains transparent, allowing the white paper base to show through. Where the negative is transparent (shadows) the light passes through, and the emulsion – once developed and fixed in the same way as the original film – turns black. Thus a positive image is produced.

Normally you would contact-print multiple strips of negative at the same time, perhaps an entire roll of film’s worth, if your paper is large enough to fit them all. Then you can examine them through a loupe to decide which ones are worth enlarging. You have probably seen contact sheets, complete with circled images, stars and arrows indicating which frames the photographer or picture editor likes, where they might crop it, and which areas need doctoring. In fact, contact sheets are so aesthetically pleasing that it’s not uncommon these days for graphic designers to create fake digital ones.

The correct exposure time for a contact print can be found by exposing the whole sheet for, say, ten seconds, then covering a third of it with a piece of card, exposing it for another ten seconds, then covering that same third plus another third and exposing it for ten seconds more. Once developed, you can decide which exposure you like best, or try another set of timings.

120 contact sheet

 

Making an enlargement

Contact prints are all well and good, but they’re always the same size as the camera negative, which usually isn’t big enough for a finished product, especially with 35mm. This is where an enlarger comes in.

An enlarger is essentially a projector mounted on a stand. You place the negative of your chosen image into a drawer called the negative carrier. Above this is a bulb, and below it is a lens. When the bulb is turned on, light shines through the negative, and the lens focuses the image (upside-down of course) onto the paper below. By adjusting the height of the enlarger’s stand, you can alter the size of the projected image.

Just like a camera lens, an enlarger’s lens has adjustable focus and aperture. You can scrutinise the projected image using a loupe; if you can see the grain of the film, you know that the image is sharply focused.

The aperture is marked in f-stops as you would expect, and just like when shooting, you can trade off the iris size against the exposure time. For example, a print exposed for 30 seconds at f/8 will have the same brightness as one exposed for 15 seconds at f/5.6. (Opening from f/8 to f/5.6 doubles the light, or increases exposure by one stop, while halving the time cuts the light back to its original value.)

 

Dodging and burning

As with contact-printing, the optimum exposure for an enlargement can be found by test-printing strips for different lengths of time. This brings us to dodging and burning, which are respectively methods of decreasing or increasing the exposure time of specific parts of the image.

Remember that the printing paper starts off bright white, and turns black with exposure, so to brighten part of the image you need to reduce its exposure. This can be achieved by placing anything opaque between the projector lens and the paper for part of the exposure time. Typically a circle of cardboard on a piece of wire is used; this is known as a dodger. That’s the “lollipop” you see in the Photoshop icon. It’s important to keep the dodger moving during the exposure, otherwise you’ll end up with a sharply-defined bright area (not to mention a visible line where the wire handle was) rather than something subtle.

I dodged the robin in this image, to help him stand out.

Let me just say that dodging is a joyful thing to do. It’s such a primitive-looking tool, but you feel like a child with a magic wand when you’re using it, and it can improve an image no end. It’s common practice today for digital colourists to power-window a face and increase its luminance to draw the eye to it; photographers have been doing this for decades and decades.

Burning is of couse the opposite of dodging, i.e. increasing the exposure time of part of the picture to make it darker. One common application is to bring back detail in a bright sky. To do this you would first of all expose the entire image in such a way that the land will look good. Then, before developing, you would use a piece of card to cover the land, and expose the sky for maybe five or ten seconds more. Again, you would keep the card in constant motion to blend the edges of the effect.

To burn a smaller area, you would cut a hole in a piece of card, or simply form your hands into a rough hole, as depicted in the Photoshop icon.

 

Requirements of a darkroom

The crucial thing which I haven’t yet mentioned is that all of the above needs to take place in near-darkness. Black-and-white photographic paper is less sensitive to the red end of the spectrum, so a dim red lamp known as a safe-light can be used to see what you’re doing. Anything brighter – even your phone’s screen – will fog your photographic paper as soon as you take it out of its lightproof box.

Once your print is exposed, you need to agitate it in a tray of diluted developer for a couple of minutes, then dip it in a tray of water, then place it in a tray of diluted fixer. Only then can you turn on the main lights, but you must still fix the image for five minutes, then leave it in running water for ten minutes before drying it. (This all assumes you’re using resin-coated paper.)

Because you need an enlarger, which is fairly bulky, and space for the trays of chemicals, and running water, all in a room that is one hundred per cent lightproof, printing is a difficult thing to do at home. Fortunately there are a number of darkrooms available for hire around the country, so why not search for a local one and give analogue printing a go?

Some enlargements from 35mm on 8×10″ paper

 

Making an Analogue Print

How to Process Black-and-White Film

A few weeks ago, I came very close to investing in an Ilford/Paterson Starter Kit so that I could process film at home. I have four exposed rolls of 35mm HP5+ sitting on my shelf, and I thought that developing them at home might be a nice way to kill a bit of lockdown time. However, I still wouldn’t be able to print them, due to the difficulties of creating a darkroom in my flat. And with lockdown now easing, it probably won’t be long until I can get to Holborn Studios and hire their darkroom as usual.

So in this article I’ll talk through the process of developing a roll of black-and-white 35mm, as I would do it in the Holborn darkoom. If you haven’t already, you might want to read my post about how film works first.

 

You will need

 

Loading the developing tank

Holborn Studios’ darkroom, run by Bill Ling, displays this handy reminder.

The first step is to transfer the exposed film from its cassette – which is of course light-proof – into the Paterson tank, which is designed to admit the developing chemicals but not light. This transfer must take place in complete darkness, to avoid fogging the film. I’ve always done this using a changing bag, which is a black bag with a double seal and elasticated arm-holes.

Start by putting the following items into the bag: the film cassette, scissors and the various components of the Paterson tank, including the spiral. It’s wise to put in an empty film canister too, in case something goes wrong, and if the tail of your film isn’t sticking out of the cassette then you’ll need a can opener as well.

Seal the bag, put your arms in, and pull all the film out of the cassette. It’s important NOT to remove your arms from the bag now, until the film is safely inside the closed tank, otherwise light can get in through the arm-holes and fog the film.

Use the scissors to cut the end of the film from the cassette, and to trim the tongue (narrower part) off the head of the film.

Paterson Universal Developing Tank components, clockwise from the white items: developing reels or spirals, tank, light-proof lid, waterproof cap, and agitator – which I never use. In the centre is the core.

Now we come to the most difficult part, the part which always has me sweating and swearing and regretting all my life choices: loading the film onto the spiral. I have practised this with dead film many times, but when I’m fumbling around in the dark of the changing bag it’s a hundred times harder.

It’s hard to describe loading the spiral verbally, but this blog post by Chris Waller is very clear and even includes pictures. (Chris recommends cutting a slight chamfer onto the leading corners of the film, which I shall certainly try next time, as well as using your thumbs to keep the film flat on its approach to the reel.)

If you’re working with 120 film, the loading process is very slightly different, and this video describes it well.

Once the spiral is loaded, you can thread it onto the core, place the core inside the tank, and then put the lid on. It is now safe to open the bag.

 

Developing

Developing time info displayed at Holborn Studios

Holborn Studios’ darkroom is stocked with a working solution of Kodak HC-110 developer, but if you don’t have this luxury, or you’re not using the Ilford Simplicity packs, then you’ll need to make up a working solution yourself by diluting the developer according to the manufacturer’s instructions. For HC-110 dilution B, which is what Holborn uses, it’s 1+31, i.e.one part concentrated developer to 31 parts water. The working solution has a limited shelf life, so again consult the manufacturer’s instructions.

Further dilution is required at the point of development, at a ratio of 1+7 in this case, but once more this may vary depending on the chemicals you choose. For one roll of 35mm, you need 37.5ml of the HC-110 dilution B, and 262.5ml of water for a total of 300ml.

The developing time depends on the type of film stock, the speed you rated it at, the type of developer and its dilution, and the temperature of the chemicals. Digital Truth has all the figures you need to find the right development time.

Agitating

I was taught to ensure my water is always at 20°C before mixing it with the developer, to keep the timing calculations a little simpler. At this temperature, a roll of Ilford HP5+ rated at its box speed of ISO 400 needs five minutes to develop in HC-110 dilution B. Ilford Delta, on the other hand, needs a whopping 14.5 minutes to process at its box speed of 3200.

Once your diluted developer is ready, pour it into the Paterson tank and put on the cap. It is now necessary to agitate the chemicals in order to distribute them evenly around the film. My technique is inversion, i.e. turning the tank upside-down and back again. Do this continuously for the first 30 seconds, then for 10 seconds every minute after that.

Inside the tank, your latent image is being transformed into an image proper, wherein every exposed silver halide crystal is now black metallic silver.

 

Fixing

Once the developing time is up, remove the cap from the tank, and pour away the developer immediately. At this point some people will say you need to use a stop bath to put a firm halt to the developing process, but I was taught simply to rinse the tank out with tap water and then proceed straight to fixing. This method has always worked fine for me.

After rinsing the tank, pour in enough fix solution (again prepared to the manufacturer’s instructions) to fill it completely. Put the cap back on, agitate it for 30 seconds, then leave it for ten minutes.

During this time, the fixer renders the film’s unexposed crystals inactive and water soluble. When the ten minutes is up, pour the fixer back into its container (it’s reuseable) and leave the tank under running water for a further ten minutes. This washes away the unused silver halide crystals, leaving only the exposed black silver corresponding with light areas of the scene, and just the transparent plastic base corresponding with the dark areas.

Squirt a little diluted washing-up liquid into the tank to prevent drying rings, then drain it. You can now open the tank and see your negative for the first time.

 

Drying

Remove the film from the developing spiral, taking care to only touch the ends and the edges. Squeegee the top part of the film, dry your hands, then squeegee the rest. This removes droplets which can otherwise mark the negative.

Now attach two hooks to the film, a light one at the top to hang it from, and a heavy one at the bottom to stop the film curling as it dries. Holborn Studios is equipped with a heated drying cabinet, but with patience you can hang a film to dry in any dust-free area.

When your film is dry, you can cut it into strips of six frames and insert them into a negative storage sheet.

You can now scan your negatives, or better still print them photo-chemically, as I’ll describe in a future post.

How to Process Black-and-White Film

How Digital Sensors Work

Last week I delved into the science of how film captures an image. This time we’ll investigate the very different means by which electronic sensors achieve the same result.

 

CCD

In the twentieth century, the most common type of electronic imaging sensor was the charge-coupled device or CCD. A CCD is made up of metal-oxide-semiconductor (MOS) capacitors, invented by Bell Labs in the late fifties. Photons striking a MOS capacitor give it a charge proportional to the intensity of the light. The charges are passed down the line through adjacent capacitors to be read off by outputs at the edges of the sensor. This techniques limits the speed at which data can be output.

My first camcorder, an early nineties analogue 8mm video device by Sanyo, contained a single CCD. Professional cameras of that time had three: one sensor each for red, green and blue. Prisms and dichroic filters would split the image from the lens onto these three CCDs, resulting in high colour fidelity.

A CCD alternates between phases of capture and read-out, similar to how the film in a traditional movie camera pauses to record the image, then moves on through the gate while the shutter is closed. CCD sensors therefore have a global shutter, meaning that the whole of the image is recorded at the same time.

CCDs are still used today in scientific applications, but their slow data output, higher cost and greater power consumption have seen them fall by the wayside in entertainment imaging, in favour of CMOS.

 

CMOS

Complementary metal-oxide-semiconductor sensors (a.k.a. APS or active-pixel sensors) have been around just as long as their CCD cousins, but until the turn of the millennium they were not capable of the same imaging quality.

Each pixel of a typical CMOS sensors consists of a pinned photodiode, to detect the light, and a metal-oxide-semiconductor field-effect transistor. This MOSFET is an amplifier – putting the “active” into the name “active-pixel sensor” – which reduces noise and converts the photodiode’s charge to a voltage. Other image processing technology can be built into the sensor too.

The primary disadvantage of CMOS sensors is their rolling shutter. Because they capture an image row by row, top to bottom, rather than all at once, fast-moving subjects will appear distorted. Classic examples include vertical pillars bending as a camera pans quickly over them, or a photographer’s flash only lighting up half of the frame. (See the video below for another example, shot an iPhone.) The best CMOS sensors read the rows quickly, reducing this distortion but not eliminating it.

Today, all the major cinema cameras use CMOS sensors, from Blackmagics to Alexas. Medium format stills cameras clung on to CCD technology longest for that higher image quality, but even these are now CMOS.

CMOS sensors are cheaper, less power-hungry, and not suspectible to the highlight blooming or smearing of CCDs. They are also faster in terms of data output, and in recent years their low-light sensitivity has surpassed CCD technology too.

 

Beyond the Sensor

The analogue voltages from the sensor, be it CCD or CMOS, are next passed to an analogue-to-digital convertor (ADC) and thence to the digital signal processor (DSP). How much work the DSP does depends whether you’re recording in RAW or not, but it could include things like correcting the gamma and colour balance, and converting linear values to log. Debayering the image is a very important task for the DSP, and I’ve covered this in detail in my article on how colour works.

After the DSP, the signal is sent to the monitor outputs and the storage media, but that’s another story.

How Digital Sensors Work

How Analogue Photography Can Make You a Better Cinematographer

With many of us looking for new hobbies to see us through the zombie apocalypse Covid-19 lockdown, analogue photography may be the perfect one for an out-of-work DP. While few of us may get to experience the magic and discipline of shooting motion picture film, stills film is accessible to all. With a range of stocks on the market, bargain second-hand cameras on eBay, seemingly no end of vintage glass, and even home starter kits for processing your own images, there’s nothing to stop you giving it a go.

Since taking them up again In 2018, I’ve found that 35mm and 120 photography have had a positive impact on my digital cinematography. Here are five ways in which I think celluloid photography can help you too sharpen your filmmaking skills.

 

1. Thinking before you click

When you only have 36 shots on your roll and that roll cost you money, you suddenly have a different attitude to clicking the shutter. Is this image worthy of a place amongst those 36? If you’re shooting medium or large-format then the effect is multiplied. In fact, given that we all carry phone cameras with us everywhere we go, there has to be a pretty compelling reason to lug an SLR or view camera around. That’s bound to raise your game, making you think longer and harder about composition and content, to make every frame of celluloid a minor work of art.

 

2. Judging exposure

I know a gaffer who can step outside and tell you what f-stop the light is, using only his naked eye. This is largely because he is a keen analogue photographer. You can expose film by relying on your camera’s built-in TTL (through the lens) meter, but since you can’t see the results until the film is processed, analogue photographers tend to use other methods as well, or instead, to ensure a well-exposed negative. Rules like “Sunny Sixteen” (on a sunny day, set the aperture to f/16 and the shutter speed reciprocal to match the ISO, e.g. 1/200th of a second at ISO 200) and the use of handheld incident meters make you more aware of the light levels around you. A DP with this experience can get their lighting right more quickly.

 

3. Pre-visualising results

We digital DPs can fall into the habit of not looking at things with our eyes, always going straight to the viewfinder or the monitor to judge how things look. Since the optical viewfinder of an analogue camera tells you little more than the framing, you tend to spend less time looking through the camera and more using your eye and your mind to visualise how the image will look. This is especially true when it comes to white balance, exposure and the distribution of tones across a finished print, none of which are revealed by an analogue viewfinder. Exercising your mind like this gives you better intuition and increases your ability to plan a shoot, through storyboarding, for example.

 

4. Grading

If you take your analogue ethic through to post production by processing and printing your own photographs, there is even more to learn. Although detailed manipulation of motion pictures in post is relatively new, people have been doctoring still photos pretty much since the birth of the medium in the mid-19th century. Discovering the low-tech origins of Photoshop’s dodge and burn tools to adjust highlights and shadows is a pure joy, like waving a magic wand over your prints. More importantly, although the printing process is quick, it’s not instantaneous like Resolve or Baselight, so you do need to look carefully at your print, visualise the changes you’d like to make, and then execute them. As a DP, this makes you more critical of your own work and as a colourist, it enables you to work more efficiently by quickly identifying how a shot can be improved.

 

5. Understanding

Finally, working with the medium which digital was designed to imitate gives you a better understanding of that imitation. It was only when I learnt about push- and pull-processing – varying the development time of a film to alter the brightness of the final image – that my understanding of digital ISO really clicked. Indeed, some argue that electronic cameras don’t really have ISO, that it’s just a simulation to help users from an analogue background to understand what’s going on. If all you’ve ever used is the simulation (digital), then you’re unlikely to grasp the concepts in the same way that you would if you’ve tried the original (analogue).

How Analogue Photography Can Make You a Better Cinematographer

How to Make a Zoetrope for 35mm Contact Prints

Are you an analogue photographer looking for a different way to present your images? Have you ever thought about shooting a sequence of stills and reanimating them in a zoetrope, an optical device from the Victorian era that pre-figured cinema? That is exactly what I decided to do as a project to occupy myself during the zombie apocalypse Covid-19 lockdown. Contact prints are aesthetically pleasing in themselves, and I wanted to tap into the history of the zoetrope by creating a movie-like continuous filmstrip of sequential images and bringing them to life.

In the first part of my blog about this project, I covered the background and setting up a time-lapse of my cherry tree as content for the device. This weekend I shot the final image of the time-lapse, the last of the blossom having dropped. No-one stole my camera while it sat in my front garden for three weeks, and I was blessed with consistently sunny weather until the very last few days, when I was forced to adjust the exposure time to give me one or two extra stops. I’ll be interested to see how the images have come out, once I can get into the darkroom.

Meanwhile, I’ve been constructing the zoetrope itself, following this excellent article on Reframing Photography. Based on this, I’ve put together my own instructions specifically for making a device that holds 18 frames of contact-printed 35mm film. I chose a frame count of 18 for a few reasons:

  1. The resultant diameter, 220mm, seemed like a comfortable size, similar to a table lamp.
  2. Two image series of 18 frames fit neatly onto a 36 exposure film.
  3. Negatives are commonly cut into strips of six frames for storage and contact-printing, so a number divisible by six makes constructing the image loop a little more convenient.

 

You Will Need

  • Contact sheet containing 18 sequential 35mm images across three rows
  • A1 sheet of 300gsm card, ideally black
  • PVA glue
  • Ruler (the longer the better)
  • Set square
  • Compass
  • Pencil & eraser
  • Scissors
  • Craft knife or stanley knife
  • Paper clips or clothes pegs for clamping while glue dries
  • Rotating stand like a lazy susan or record player

 

Making the image loop

First, cut out the three rows of contact prints, leaving a bit of blank paper at one end of each row for overlap. Now glue them together into one long strip of 18 sequential images. The strip should measure 684mm plus overlap, because a 35mm negative or contact print measures 38mm in width including the border on one side: 38×18=684.

Glue the strip together into a loop with the images on the inside. This loop should have a diameter of 218mm. Note that we must make our zoetrope’s drum to a slightly bigger diameter, or the image loop won’t fit inside it. We’ll use our image loop to check the size of the drum; that’s why we’ve made it first. (If you don’t have your images ready yet, use an old contact sheet – as I did – or any strip of paper or light card of the correct size, 35mmx684mm.)

 

Making the side wall

Cut a strip of the black card measuring 723x90mm. This will be the side wall of your drum. Wrap this strip around your image loop, as tightly as you can without distorting the circular shape of the image loop. Mark where the card strip overlaps itself to find the circumference of the drum, which will be slightly bigger than the 684mm circumference of the image loop. In my case the drum circumference was 688mm – as illustrated in the diagram above. (You can click on it to enlarge it.)

Now we can measure and cut out the slots, one per image. Reframing Photography recommends a 1/8″ width, and initially I went with this, rounding it to 3mm. As with making a pinhole, a smaller slot means a sharper but darker image, while a bigger slot means a brighter but blurrier one. Once my zoetrope was complete, I felt that there was too much motion blur, so I retrofitted it with 1mm slots.

Let’s stick with 3x35mm (the same height as the images) for our slot size. How far apart should the slots be? They need to be evenly spaced around the circumference, so in my case 688÷18=38.2mm, i.e. a gap of 35.2mm between each slot and then 3mm for the slot itself. If your drum circumference is different to mine, you’ll have to do your own maths to work out the spacing.

(It was impossible to measure 38.2mm accurately, but I made a spreadsheet to give me values for the cumulative slot positions to the nearest millimetre: 38, 76, 115, 153, 191, 229, 268, 306, 344, 382, 420, 459, 497, 535, 573, 612, 650 and 688.)

Mark out your 18 slots, positioning them 15mm from the top of the side wall and 40mm from the bottom, then cut them out carefully using a knife and a ruler.

Now you can glue your side wall into a loop, using paper clips or clothes peg to hold it while the glue dries. I recommend double-checking your image loop fits inside beforehand. (Do not glue your image loop into the drum; this way you can swap it out for another image series whenever you like.)

 

Making the connector

The connector, as the name suggests, will connect the side wall to the base of the drum. (When I made a prototype, I tried skipping this stage, simply building the connecting teeth into the side wall, but this made it much harder to keep the drum a neat circle.)

Go back to your black card and cut another strip measuring 725x60mm. Score it all the way along the middle (i.e. 30mm from the edge) so that it can be folded in two, long-ways. Now cut triangular teeth into one half of the strip. Each triangle should have a 30mm base along the scored line.

As with the side wall, you should check the circumference of the connector to ensure that it will fit around the side wall and image loop, and adjust it if necessary. My connector’s circumference, as shown on the diagram above, was 690mm.

Glue the strip into a loop, clamping it with clips or pegs while it dries. Again, it doesn’t hurt to double-check that it still fits around the side wall first.

 

Making the base

Use a compass to draw a circle of 220mm in diameter on your remaining card, and cut it out. (If your connector is signficantly different in circumference to mine, divide that circumference by pi [3.14] to find the diameter that will work for you.)

Now you can glue the connector to the base. I suggest starting with a single tooth, putting a bottle of water or something heavy on it to keep it in place while it dries, then do the tooth directly opposite. Once that’s dry, do the ones at 90° and so on. This way you should prevent distortions creeping into the shape of the circle as you go around.

When that’s all dry, apply glue all around the inside of the upright section of the connector. Squish your side wall into a kidney bean shape to fit it inside the connector, then allow it to expand to its usual shape. If you have made it a tight enough fit, it will naturally press against the glue and the connector.

 

Making it Spin

The critical part of your zoetrope, the drum, is now complete. But to animate the images, you need to make it spin. There are a few ways you can do this:

  • Mount it on an old record player, making a hole in the centre of the base for the centre spindle.
  • Mount it on a rotating cake decoration stand or lazy susan.
  • Make your own custom stand.

I chose the latter, ordering some plywood discs cut to size, an unfinished candlestick and a lazy susan bearing, then assembling and varnishing them before gluing my drum to the top.

How to Make a Zoetrope for 35mm Contact Prints

Shooting a Time-lapse for a Zoetrope

Two years ago I made Stasis, a series of photographs that explored the confluence of time, space and light. Ever since then I’ve been meaning to follow it up with another photography project along similar lines, but haven’t got around to it. Well, with Covid-19 there’s not much excuse for not getting around to things any more.

Example of a zoetrope

So I’ve decided to make a zoetrope – a Victorian optical device which produces animation inside a spinning drum. The user looks through slits in the side of the drum to one of a series of images around the inside. When the drum is set spinning – usually by hand – the images appear to become one single moving picture. The slits passing rapidly through the user’s vision serve the same purpose as a shutter in a film projector, intermittently blanking out the image so that the persistence of vision effect kicks in.

Typically zoetropes contain drawn images, but they have been known to contain photographed images too. Eadward Muybridge, the father of cinema, reanimated some of his groundbreaking image series using zoetropes (though he favoured his proprietary zoopraxiscope) in the late nineteenth century. The device is thus rich with history and a direct antecedent of all movie projectors and the myriad devices capable of displaying moving images today.

This history, its relevance to my profession, and the looping nature of the animation all struck a chord with me. Stasis was to some extent about history repeating, so a zoetrope project seemed like it would sit well alongside it. Here though, history would repeat on a very small scale. Such a time loop, in which nothing can ever progress, feels very relevant under Covid-19 lockdown!

With that in mind, I decided that the first sequence I would shoot for the zoetrope would be a time-lapse of the cherry tree outside my window.  I chose a camera position at the opposite end of the garden, looking back at my window and front door – my lockdown “prison” – through the branches of the tree. (The tree was just about to start blooming.)

The plan is to shoot one exposure every day for at least the next 18 days, maybe more if necessary to capture the full life of the blossom. Ideally I want to record the blossom falling so that my sequence will loop neatly, although the emergence of leaves may interfere with that.

To make the whole thing a little more fun and primitive, I decided to shoot using the pinhole I made a couple of years ago. Since I plan to mount contact prints inside the zoetrope rather than enlargements, that’ll mean I’ve created and exhibited a motion picture without ever once putting the image through a lens.

I’m shooting on Ilford HP5+, a black-and-white stock with a published ISO of 400. My girlfriend bought me five roles for Christmas, which means I can potentially make ten 18-frame zoetrope inserts. I won’t be able to develop or print any of them until the lockdown ends, but that’s okay.

My first image was shot last Wednesday, a sunny day. The Sunny 16 rule tells me that at f/16 on a sunny day, my exposure should be equal to my ISO, i.e. 1/400th of a second for ISO 400. My pinhole has an aperture of f/365, which I calculated when I made it, so it’s about nine stops slower than f/16. Therefore I need to multiply that 1/400th of a second exposure time by two to the power of nine, which is 1.28 – call it one second for simplicity. ( I used my Sekonic incidence/reflectance meter to check the exposure, because it’s always wise to be sure when you haven’t got the fall-back of a digital monitor.)

One second is the longest exposure my Pentax P30t can shoot without switching to Bulb mode and timing it manually. It’s also about the longest exposure that HP5+ can do without the dreaded reciprocity failure kicking in. So all round, one second was a good exposure time to aim for.

The camera is facing roughly south, meaning that the tree is backlit and the wall of the house (which fills the background) is in shadow. This should make the tree stand out nicely. Every day may not be as sunny as today, so the light will inevitably change from frame to frame of the animation. I figured that maintaining a consistent exposure on the background wall would make the changes less jarring than trying to keep the tree’s exposure consistent.

I’ve been taking spot readings every day, and keeping the wall three-and-a-half stops under key, while the blossoms are about one stop over. I may well push the film – i.e. give it extra development time – if I end up with a lot of cloudy days where the blossoms are under key, but so far I’ve managed to catch the sun every time.

All this exposure stuff is great practice for the day when I finally get to shoot real motion picture film, should that day ever come, and it’s pretty useful for digital cinematography too.

Meanwhile, I’ve also made a rough prototype of the zoetrope itself, but more on that in a future post. Watch this space.

Shooting a Time-lapse for a Zoetrope

Pinhole Results

In my last couple of posts I described making and shooting with a pinhole attachment for my 35mm Pentax P30t SLR. Well, the scans are now back from the lab and I’m very pleased with them. They were shot on Fujifilm Superia Xtra 400.

As suspected, the 0.7mm pinhole was far too big, and the results are super-blurry:

See how contemptuous Spike is of this image. Or maybe that’s just Resting Cat Face.

The 0.125mm hole produced much better results, as you can see below. My f/stop calculations (f/365) seem to have been pretty close to the mark, although, as is often the case with film, the occasions where I gave it an extra stop of exposure produced even richer images. Exposure times for these varied between 2 and 16 seconds. Click to see them at higher resolution.

I love the ethereal, haunting quality of all these pictures, which recalls the fragility of Victorian photographs. It’s given me several ideas for new photography projects…

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Pinhole Results