Exposing

The light-sensitive film (or paper) contains crystals of silver halide, which is light sensitive. At this point, the film is opaque grey. When light hits the film, the silver halide crystal splits into a silver ion and a bromine atom.

Ag⁺Br^- (crystal) + hν (radiation) → Ag⁺ + Br + e^-

Then, the silver ion recombines with the free electron to give an atom of metallic silver.

Ag⁺ + e^- → Ag⁰

After exposure, there is an image on the film made from a tiny quantity of metallic silver. This is known as the latent image. It would be invisible to the eye and the film is still dull and opaque. For an individual grain of the silver halide emulsion to count as “exposed”, at least two photons must have interacted with it, to form small silver crystals consisting of two or more silver atoms.

Development

The purpose of developer is to amplify the latent image. The chemical composition of developer varies and is complicated so I won’t go into it here – other than to say that it promotes silver crystal growth where the small silver crystals already exist.

After development, the latent image has been converted to an actual image, made of metallic silver crystals. It appears black, although the film itself is still opaque.

Stopping

Even after taking the film out of the developing solution, it continues to develop (your hands are still wet after taking them out of the sink, right?) so a stop bath is used to halt development. Developing requires an alkaline environment to work, so stop bath is simply a weak acid – usually acetic acid.

The stop bath causes no other changes to the film.

Fixing

Although we have now developed the film and ended up with a black image in metallic silver, the areas of the film that were not exposed to light are still opaque, and still sensitive to light. Bathing the film in fixer dissolves the unexposed silver halide, leaving a near-transparent film backing that is not sensitive to light. At this stage, you can take the film out of the developing tank and look at it in daylight.

Toning

So far, we have ended up with either a film or a print which has an image made from metallic silver. If there’s one thing we know about silver, it’s that it tarnishes. Depending on the storage conditions, silver prints may degrade with time. Toning the image serves two purposes: it improves the longevity of the image, and it can produce the colourful sepia effects.

Various toners exist, but they all work in the same way. They react with the silver to produce silver salts, such as silver sulphide which is more stable then pure silver. It is also slightly brown in colour, hence the sepia tone.

References

• http://www.cheresources.com/photochem.shtml
• http://en.wikipedia.org/wiki/Photographic_developer
• http://en.wikipedia.org/wiki/Photographic_print_toning

Ansel Adams on a car

I think he is my favourite photographer. But why?

Composition and subject

Like Adams, I most enjoy taking photos of natural objects, landscapes or possibly man-made objects (buildings) that I find. When I look at his work, I find the subject matter most appealing. I enjoy studying his photography, and I enjoy taking photographs in that style.

He lived in a beautiful part of the world in terms of natural features, which is likely to prove a problem for me, though! There are some beautiful natural places in the South-West of England, but it’s not quite the same as the mountains of the West Coast of America.

Technical photography

Adams’s work is technically excellent. His photographs are pin-sharp and this makes for an incredibly detailed picture. Being a geek, I can relate to this, and I want to take sharp and detailed photos. I am interested in cameras and how they work, as well as how they can be used to create art. And as I already mentioned, Adams pioneered the zone system of setting the exposure of photographs to have nice highlights, deep shadows and a lot of tones in between.

This is why I collect old and interesting cameras: to see what I can make them do. It’s also worth noting that the large format cameras Adams used in the 1930s were capable of producing images equivalent in detail to a 1000 megapixel digital photo. That’s pretty cool.

Straight photography

Adams was a joint founder of a group called Group f/64. The members renounced manipulation of photographs and instead aimed to capture the beauty of the natural world as realistically and naturally as possible – a style known as straight photography. The name f/64 itself is derived from a small aperture setting on a large-format camera that would give good sharpness from very close to very distant objects – similarly to the way an observer would see the scene if they stood at the same position as the camera.

It might just be a cover for being poor at Photoshop, but I also like to take pictures that are good to look at straight from the camera – be it film or digital.

Darkroom expertise

Adams was a true expert in the darkroom. When using film, taking a photo is only part of the job – you have to process it so it can be seen by people. Of course Adams wasn’t the first person to use a darkroom, but he mastered the art of dodging and burning to mimic the range of tones in his prints that can be seen by the human eye.

I am a mere beginner in the darkroom but I find it fascinating. I want to learn more, and Adams’s book The Print is an excellent reference.

The first graph shows the different focal lengths used in the photographs. Among my lenses, I have the ability to work between 8mm and 300mm. The three large spikes to the left are apparently where I’ve taken lots of photos with my primes, at 8mm, 50mm and 90mm. The general area of bars is my 18-55mm kit lens. Finally, the spike at the far right is the 70-300mm zoom lens, which I always seem to use at full zoom. (Incidentally, the EXIF data doesn’t record whether I used my 2× teleconverter, so some of the 300mm records should be 600mm).

What can I learn from this? Maybe that I would benefit from buying a longer zoom lens, but that’s a different story.

The graph of shutter speeds is perhaps more expected. Under “normal” conditions (where normal means outdoor daylight, or indoor flash photography) the shutter mainly gets used at decent everyday handheld speeds like 1/250 – 1/30. The sudden spike at 30″ is where I’ve used my camera for long-exposure night shots, including many of the night sky. My 450D doesn’t allow for anything longer than 30″ unless in bulb mode, where continuous drive doesn’t work.

And finally, we come to apertures. Clearly the most-used aperture setting is f/5.6. This is a sensible middling value, probably giving optimum sharpness for most of my lenses. It’s the kind of thing I’d choose in manual mode, and I bet the camera would readily choose it in semi-auto mode too.

f/1.8 is slightly more common than you might expect, and is probably from shooting in low light or where I’ve tried to maximise the depth of field.

More recently, I got into printing my negatives rather than just scanning them. For printing, you need more equipment, larger equipment, and a lot of space. Our tiny bathroom wasn’t big enough, so I converted my loft into a darkroom. Here’s how.

I used the space in my loft for my darkroom. It’s quite large, and partially boarded up. I added some more boards to increase the floorspace. Luckily the loft already had a pull-down ladder, so access was easy. You can also see the extension lead I added.

The ladder

For my main work area, I used a spare dining table with two chairs against one wall. There’s no other furniture up there, although I have some boxes to keep things in.

The darkroom

There’s a standing lamp with a 100W bulb which gives reasonable illumination in the work area. The switch is in easy reach of the chair for easy blackout. I also have a clock which ticks loudly, so I can time things in the dark.

The enlarger and lamp

In a couple of areas, the boards overhang joists without reaching the next joist, and so they are unsupported. I taped these areas, and the thin trapdoor, with hazard tape to remind me not to step on them. Luckily these areas are not in the main floor area.

Hazard tape

I also attached some kitchen cupboard handles to the inside of the trapdoor, to make it easier to open from inside. Don’t want to get trapped in the loft!

The trapdoor

There’s no running water, so I bought a jerry can with a tap. This stands on a higher level than the floor, and I put a large bowl underneath the tap. The jerry can holds ten litres, which is enough to last me for several darkroom sessions. I made sure the bowl holds at least ten litres, so it will never accidentally overflow. The paler tray has some small holes at one end, so I can wash prints under running water, while submerged.

The water tank

Being in the loft, with no insulation against the outside world, the temperature can get quite low if the sun isn’t shining. I don’t personally mind being cold, but the chemicals do. I have a fan heater to boost the temperature to an acceptable working range. There’s a thermometer hanging from one of the roof supports. However, I store the chemicals in the house so they keep close to working temperature.

You can also see the safelight in the background, with a choice of three colours.

My thermometer

Also hanging from the roof supports – a drying line for wet prints. This small one only holds three or four prints, but there’s plenty more room to hang more photos.

The drying line

Of course, I’d love a larger workspace, one without roof supports, and one without fibreglass everywhere. But this will do nicely for now, and it’s all I need to develop films and make prints from my classic camera collection.

Since moving, I’ve been waiting for a clear night so I can point my camera at the sky and take in a wide view of billions of stars (as opposed to regular astronomy, where the photographer/observer focuses one one object). Last night presented just that opportunity, so I whipped out my 450D and fitted my 50mm f/1.8 prime lens.

I quickly found out that astronomic photography is a balancing act and a series of compromises. In short, the thing you are pointing the camera at is very dark, so you need to collect a lot of light to make a decent picture. There are three real ways of doing this (and one way of cheating).

1. Expose for longer. The trouble is, stars move across the sky. Exposing for 30 seconds, you see some blurring that just looks like poor focus. Exposing for 60 or 90 seconds, you can clearly see that the stars are all moving and have blurred tails. So in practice we have to keep the shutter speed faster than at least 30 seconds.
2. Open the aperture wider. The trouble is, the wider the aperture, the worse the sharpness. When taking photos of fine points of light, f/1.8 just doesn’t cut it (unless you have a fantastic lens). You need to stop down to at least f/8 to see the sharpness of the stars come through.
3. Increase your camera’s sensitivity (by increasing the ISO of your sensor or film). This effectively means you collect more light, so you can shorten your exposure, or decrease the size of your aperture. The trouble is, higher ISO means higher noise or grain in your picture. ISO1600 on your DSLR sounds great, until you see the results and find out it’s a load of speckle.
4. Fix it in Photoshop. This has the same fundamental effect as increasing the ISO, although you can be a bit more intelligent about noise reduction. I’m no whizz at Photoshop myself, and in any case I prefer to get it right in the camera.

So, we have to find a suitable compromise. The best combination I came up with was a 20-second exposure at f/6.3, and ISO400. Then I briefly altered the curve in GIMP to keep the noise down in the paler areas of the sky. The result was a pretty mediocre photo. The stars were a bit blurred (motion blur) and a bit blurred (poor sharpness) while the background was also a bit noisy. I somehow don’t think it will feature on the cover of New Scientist any time soon.

These are the two best photos out of about two dozen that I shot. It doesn’t sound much, but bear in mind that each one was exposed for anywhere between 30 and 90 seconds! I’m sure that converting them to JPEG and resizing down to this size has done them no favours at all, but never mind. In the first photo, the shutter speed is too long (90 seconds) and the stars are blurred, while in the second one I shot at ISO400 and played with the result in GIMP, so the noise is bad instead.

Stars flying by

The night sky

Some of these issues can be worked around. I’m using a standard Canon f/1.8 50mm prime lens. If I had some more pocket money, I could upgrade to an L-series lens (for example) that would probably offer better sharpness at wider apertures. I’m also using a decidedly consumerish EOS 450D. I am a consumer, after all, but an EOS 1Ds mkIII with a full-frame sensor would offer lower noise at higher ISOs. I’m not sure what can be done about the movement of the stars across the sky though, regardless of personal wealth. I suppose I could buy a sky-tracking tripod like they use for real observatories.

Next time It’s clear I’m going to try approaching this from a different angle. I’ll keep the ISO low at ISO100, and the aperture small at f/16 perhaps. To compensate I’ll expose for a “while” – perhaps five minutes. This should give me a low-noise, sharp photo of some extremely blurred stars. It’ll be like the world is spinning, and I hope it will look interesting. Watch this space*!

Finally, coming back to the issue of light pollution from sodium street lights – despite it seeming far better here in Fishponds, the images from the camera still seemed horrifically orange. I can get around this by either adjusting the colour balance, or by simply converting the images to black and white. I suppose I could also solve this one with money, by buying a house in the countryside

* Actually, watch my photo blog. I’ve said it before but I’ll say it again – this blog is for nerdy discussions about photography, while my photo blog is for showcasing the pictures that actually turned out OK.

Throughout my childhood, I’ve taken pictures of important occasions on single-use cameras. My parents would always buy me a single-use camera before a family holiday, for example. I wasn’t interested in the camera, though.

A few years ago (2005, I think) I lived in hall of residence with a guy who had a “fancy camera”. I was so uninterested in it that I have no idea what it actually was. It was digital, and it had a big lens on it. This just goes to show that I didn’t care about photography at the time.

More recently, in 2007, I had a Sony Ericsson K800i camera phone. For a phone, it had an extremely decent camera and could compete with some of the entry-level digital compacts available at the time. But I still only really used it for taking photos of things that were happening around me.

But then, my colleague Paul starting doing his photo-a-day in 2008. I became a keen follower of his photo blog, and started to take “arty” shots on my phone. I enjoyed it so much that I quickly ran into the limitations of my phone and started wondering about buying a “real” camera.

There was a decent superzoom “bridge” camera in the office so I borrowed this for a few days and had great fun with it. Then unfortunately I was involved in an accident and dislocated my shoulder. Stuck at home, bored, I bought a camera. It was a bridge camera, one mark up on the one I’d borrowed from work. I bought it primarily as a high-tech toy, and with not much interest in the art of photography.

This was the stimulus I needed, and with a powerful and versatile camera I tried all sorts of photography. Gradually I became interested in the art of taking photos, and I now try to take photos that are nice to look at, as well as fun to take.

In 2009, I was given an unwanted 35mm SLR. At first I was sceptical – how useful could film be? I bought some film and had a go. I really enjoyed using an SLR for the first time and immediately wanted a DSLR.

In 2010, I caved in and bought a DSLR. I also continued shooting film and I now have a collection of around ten cameras – all film except for the DSLR. I’m still more interested in the cameras and the techniques in using them, but I hope that my work is also pleasing to look at. Make up your own mind.

In March 2010, temptation got the better of me and I bought a Canon EOS 450D. My main concerns beforehand was the loss of the large LCD viewfinder of my Fuji S9600, and in particular, not being able to flip it out for awkward shots, and not being able to see useful information about the camera settings in the eyepiece.

Well I needn’t have worried – the 450D is of course more advanced than my AE-1 and has a small LCD under the optical viewfinder for that information. I hadn’t realised until I tried it out in the shop.

The issue of having to put my eye up to the camera still hasn’t been addressed, but it hasn’t been a problem. I just find myself lying on my belly more, or simply pressing the button and guessing about the composition.

In the two months that I’ve owned the 450D, I’ve taken over 2,000 photos^[1] and I’ve thoroughly enjoyed all of them. I feel more in control of the photos, and I can’t recommend an SLR strongly enough to anyone who is serious about photography.

I now have three EF mount lenses for this camera. Unfortunately they don’t fit the AE-1 (which uses the FD mount) but this very evening I bought a Canon EOS 300, which is a consumer-level 35mm SLR with an EF mount. You can pick up 35mm camera bodies on eBay for a fiver so I thought it might be nice to make even better use of my lenses.

If you’re actually interested in any of my camera facts and figures, you might like to look at my page of cameras. If you’re more interested in the pictures themselves, then why not browse my photo blog.

[1] That’s about 1.4 each hour I’ve owned the camera

When I traded in the S9600 for a Canon 450D, I was slightly disappointed to find that it wasn’t at all sensitive to the same range of IR and/or deep red. There are companies that will do an IR conversion, which involves taking the camera apart and removing its internal IR filter. It’s expensive, and it’s pretty much a one-way conversion.

Then I realised there was a cheap and practical alternative that had been staring me in the face the whole time. My 35mm SLR.

IR film is several times more expensive than regular film, but still vastly cheaper than digital IR photography. I bought a roll of Ilford SFX200 and it was about £8.

I read about how to correctly expose IR film and frankly it sounds confusing. Lots of people recommend using a light meter, but then you have to take into account the filter which is present on the camera but not on the light meter. It’s anybody’s guess how many stops you need to compensate for the IR filter.

It’s also a shot in the dark (no pun intended!) as to the ratio of visible light to invisible IR light. This varies with the time of day, what the light is falling upon, and about a million other things.

I wanted to shoot one or two frames, see the results, and then make sure I was doing it properly before shooting a whole film. Unfortunately that’s not easily possible, so I’m just going ahead and shooting a whole 36-exposure roll. As I write, I’m about halfway through the film.

The good news is that my Canon AE-1′s light meter appears to be sensitive to IR light. That is, with the IR filter on, the internal meter appears to work properly so I can simply use the camera as normal. I verified this with a quick back-of-the-envelope calculation to compare the meter’s behaviour with and without the IR filter. It seems about right.

So here’s hoping that this fantastic little camera will produce me 36 interesting IR photos. We will see – watch this space!

Starting on the 1st of January, 2010 will be a series of photography tutorials to help you get the best from your camera – it doesn’t matter if you have a top-of-the-range SLR or a point and shoot, there should be something for everyone here. A new tutorial will appear each Friday morning, giving information on a single technique, concept or other thinking point. I hope not to make anything too complicated, and welcome questions and comments on each post in the comments section.

So come along for the ride – I hope I will learn from you as much as you will learn from me, and we can all improve together.

Making the pinhole “lens”

Not only do pinholes have to be tiny in diameter, they should also be made through a thin material. I didn’t even attempt to make a pinhole directly in the body cap. I drilled a 10mm hole and superglued a piece of tin foil over the hole. Using a fine pin, I made a small hole.

Front of pinhole lens

Rear of pinhole lens

Uh, that’s it. Most guides I write have more steps than this, but making a pinhole “lens” for an SLR really is this easy.

What’s the f-number?

The formula for working out the f-number is pretty simple:

           focal length
f-stop = -----------------
         aperture diameter

The aperture diameter is the diameter of the pinhole, and the focal length is the distance between the film and the pinhole.

The Canon AE-1 Program has a small mark on the side to indicate the position of the film plane. The rough distance between this mark and the pinhole is 36mm. Getting a decent estimate of the pinhole is a little trickier, as I need to measure the diameter of the pinhole. The best I could come up with was to take a picture of the pinhole next to a ruler with my Fuji S9600 and a macro lens.

The pinhole

I reckon that’s approximately 0.2mm across.

          36
f-stop = ----- = 180
          0.2

So this is a pretty tiny aperture, and we are going to need long exposures to get it to make a decent picture on film.

Earlier on I pointed the camera out of my window. With the shutter set to its slowest value of 2 seconds, the meter reckoned it wanted an aperture of 8. 180 is 22 times greater than 8, so I need to make my shutter 22 times longer than 2. So we are talking 40-odd seconds for outdoor landscape photography in daylight on ISO200 film. In lower light conditions and perhaps on ISO125 film (such as my Ilford FP4) it’s easy to see that I might need to expose for 2 or 3 minutes.

Although 2 seconds is the longest my SLR can do automatically, it has a mode where the photographer can hold the shutter release for as long as necessary. Never thought I’d need a stopwatch for my photography!

My 35mm pinhole camera

The advantage of making a removable pinhole lens is that I can carry it around and easily change between lenses.

Keep an eye on my photo blog. When I’ve got this film developed I’ll scan and post the pinhole images there.

Update: I have now uploaded some of the pinhole photos.