Grime Doesn't Pay - Part 2

Dirt on your lens matters ... but maybe not for the reason you think.

Many people believe that a spot of dust on the lens will cause a spot on the photograph.

It won’t. You can have a spot of dust on your lens the size of a small coin and you might not notice it.

Don’t believe me? Here’s the proof ...

These two photographs were taken one after the other, with my camera lying on its back pointing up at the ceiling in the hallway of my house.

I didn’t move the camera between shots. I didn’t change the exposure. Both were taken with the diaphragm fully open, at ƒ1.4. But in one of those photos there is a small Swiss 5 cent coin lying on the lens front element ...

Which photo was taken with the coin on the lens? (Answer in the comments section).

Even if you got it right, I think you’ll agree that it was a tough one to spot.

So, what’s the point of that demonstration? That it’s okay to let your lens get dirty? Even huge chunks of grot won’t make any difference?

No. The point is that dust on your lens has a much more insidious effect which may not be easy to see. A dirty lens lacks contrast and colours in the image are washed-out. The effects occur across the whole image and are impossible to correct with image editing software. Here’s a demonstration ...

So, if you want the crispest, sharpest photographs that your lens can give, with vibrant colours, keep it clean.

How?

Step 1. Make sure that you keep a cap on your lens whenever it is not in use. One will have been supplied with the lens when you bought it. Don’t throw the thing away. And if you have lost it, buy another. Most camera shops carry a selection.

Step 2. Blow any dust particles off with that big fat rubber blower that you used to clean the camera’s exterior. Don’t forget to blow out the inside the lens cap. Dust easily gathers there, too.

Step 3. Gently wipe the surface of the lens. No, not with your shirt-tail, handkerchief or a piece of toilet paper. (You’d be surprised how many people use these things.) With your microfibre cloth. But make sure that the cloth is spotlessly clean. A tiny piece of grit trapped in its folds will play havoc with your coated lens surface. If you want to be really particular, have one cloth for the camera body and another entirely different on for the lens. Or buy some lens-cleaning tissue. Packs of it are very cheap and, unlike toilet paper or paper handkerchiefs, lens-cleaning tissue does not shed fibres. You can also use a drop of optical cleaning fluid to help the process.

Step 4. Finally, give the lens a few hefty puffs with the blower to evaporate any cleaning fluid left or remove any stubborn specks of dust.

Next on 'Grime Doesn't Pay' - Cleaning your Sensor

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Footnote:

Incidentally, I didn’t actually let my lens get dirty for the photo above. I used an old skylight filter – one of those clear ones – and coated it with fine dust. The effect is the same. Then I took one photo with the filter off and one with it on and split them down the middle to make a comparison.

Grime Doesn't Pay - Part 1

Fact: if you use your camera, it’s going to get dirty. And if you’re using it seriously it is going to get even more dirty. Photographing interiors? They’re dusty. Beaches are gritty. Flowers shed pollen.

But even if you keep your precious camera carefully wrapped up in cotton wool, the cotton wool itself is made of fibres.

There's more. Your camera is a machine, with moving parts. The shutter, just opening and closing, is going to wear releasing microscopic particles of plastic, metal, or whatever the shutter mechanism is made of.

Grime is grim, wherever it’s found. So, you wash the car, dust the house and brush the dog. But how often do you clean your camera and associated gear?

“Clean the camera myself?” you say. “No way! I’m going to end up with a massive repair bill.”

Not necessarily. Here’s a personal experience. A few years ago I took my camera to have its sensor cleaned by an authorised dealer in the UK (who, because I don’t want to get sued, shall remain nameless). The ‘cleaning’ cost me 30 quid and the camera came out worse than it went in. Since then I’ve done the sensor cleaning myself, in a three-stage process that I’ll describe later in this series.

But first, start out by cleaning the exterior. You can’t hope to get it spotless inside if the outside is dusty. This process is simple. Brush ... blow ... wipe. And here's the equipment you nedd to do the job ...

Cleaning equipment: microfibre cloth, blower, soft brush (this is a man's shaving brush), optical cleaning fluid, cotton bud.

Brush. You can get a dedicated camera brush for this, but you’ll probably pay extra for it. A large, soft make-up brush, or a man’s shaving brush (both of them unused, of course!) will do the job just as well, if not better. And will cost less. Give your camera a good brushing all over to remove surface grit and grot. Then ...

Blow. No, not with your mouth. There are two ways of doing this. Either buy a big fat bulb-type blower, that looks like a hand grenade with a pipe sticking out of the end, or use a can of compressed air. Don’t bother with those diddly little puffer and brushes combined. They’re close to useless. Use a big ‘un. Puff liberally all over the camera body and front element of the lens to shift any particles that have not been removed by brushing. Blow out the inside the lens cap too, as dust can gather there. If you’re using a can of compressed gas be a bit careful. This can spurt liquid propellant if you hold it the wrong way (like upside down). Finally ...

Wipe – using a microfibre cloth. This is a special type of tightly-woven cleaning cloth that has a unique, silky feel to it. You can buy these cloths in photo shops and or at opticians. Get a big one. You could use a well-washed piece of cotton, but cotton tends to shed fibres. In addition, microfibre cloths are good at removing greasy marks, and they prevent scratching. Just remember, you need to keep the cloth clean, too. So give it an occasional wash.

If there are stubborn greasy patches that won’t shift – and let’s be honest, your nose against the viewing screen can leave hard-to-shift marks – then use a dab of optical cleaning fluid. These liquids have been specially formulated to ensure that they don’t damage glass, plastic or coated surfaces, and they evaporate away harmlessly. But, even so, always read the instructions first. Never ever use other solvents like white spirit. Then you may well have a massive repair bill.

Clean the eyepiece of the viewfinder too. This is usually recessed and is a wonderful dust trap. A cotton bud, moistened with some optical cleaning fluid will do the job well. And, while you’re at it, check the dioptre adjustment - the little wheel or lever that sets the viewfinder to your individual vision. It can get knocked out of place during use, or your vision may have altered slightly since you last set the viewfinder. You can’t hope to take sharp photographs if you can’t view them clearly.

Cleaning the eyepiece. Check the dioptre seting at the same time.

Finally, don’t forget your camera bag. It’s no good putting your lovely clean gear back into a bag that’s been gathering dust all year. Empty it out completely, remove all the interior partitions and vacuum clean it. Make sure to get the nozzle into all the nooks and crannies, and suck dust out of the various pockets, too.

Next time round – cleaning your lenses.

Seeing straight

As you get older your vision ... the all-important sense to a photographer ... can change. But these changes can happen so slowly that you are unaware of them.

I'll never forget stepping out into the street, wearing my first pair of spectacles. I was in primary school at the time - still not very old - but even so,  my eyes had been changing. And they'd been changing so slowly that I hadn't noticed anything amiss.

But, fortunately, my mother had been keeping tabs on me, and had dragged me kicking and screaming (figuratively, that is) to the opticians for an eye test. No way did I want to wear glasses. The other kids at school called you names if you wore glasses, and they made you look 'swotty'. I didn't think I needed glasses ...

... until I stepped out into the street wearing them.

What a revelation! Everything was so sharp it was as if the town had been trimmed with a diamond-tipped saw. I could read the roadsigns. The trees had individual leaves instead of a blur of green. The clouds were sculpted and textured. Old peoples' faces had wrinkles and young kids smiled with gleaming white teeth. It was unbelievable. And the moment has stuck with me to this day.

Your vision can change at any time, and it's worth keeping a check on it. One way of doing this is to use an Amsler grid which may show changes that you wouldn't notice otherwise. You could print it, and stick it up somewhere in your kitchen so you'll remember to look at it ...

To use it:

1. Wear your glasses if you need them and hold the grid 12 to 15 inches away from your face in good light
2. Cover one eye
3. Look directly at the centre dot with the uncovered eye
4. Keep your eye on the the centre dot and note whether all lines of the grid are straight or if any areas are distorted, blurred or dark
5. Repeat this procedure with the other eye
6. If any area of the grid looks wavy, blurred or dark, contact your ophthalmologist immediately

This is not a substitute for a regular eye check by a qualified practioner, but it could pick up problems before they become too serious.

Vision is vital to a photographer.

Megapixel mania mashed

Here's an interesting development. The Canon Powershot G10, a top-of-the-range compact camera, has recently been superseded by the Canon Powershot G11.

"And what's so special about that?" do I hear you ask? "Manufacturers are upgrading their models all the time."

Yes, but get this. The G10 had a 14 megapixel sensor. The G11 has only 10.  In other words, Canon's 'development' is to reduce the number of megapixels in their upgrade.

It just goes to show that the widespread belief - much touted by salespeople - that the more megapixels the better, may not necessarily be the whole truth.

The megapixel rating of a camera does one thing, and one thing only. It tells you how big a print you can make at a certain resolution. That's all.

It tells you nothing about the quality of the image - the sharpness, the amount of 'noise' (random speckles), the colour differentiation - nothing.

Why? What is a megapixel? how does it work?

The rectangular sensor in your digital camera is made of rows and rows and rows of tiny light-sensitive dots called pixels (short for 'picture elements'). A megapixel is simply a million of these. The number is calculated in exactly the same way as you calculate the area of a rectangle, length x width.

So, if the sensor of your camera is 2000 pixels by 3000 pixels, that is 2000x3000 = 6'000'000 pixels = 6 million = 6 megapixels. Simple.

Camera sensors are different sizes. And it's pretty obvious that an ultra-compact pocketable camera is going to have a much smaller sensor that a digital single lens reflex. Here are a few sensor sizes, drawn to scale ...

It's not exactly rocket science to work out that 10 million pixels crammed into the ultra compact camera's sensor (green) are going to be squished together a whole lot more tightly than 8 million in the DSLR sensor (red).

And when pixels are squished together so tightly they begin to interfere with each other. Electronic 'noise' (not the same as sound noise), static charges, all sorts of interference, can spill over from one pixel to the next. We're talking ultra-microscopic dimensions here. As with you and me ... well, me, anyway ... given a bit more breathing space, pixels perform much better.

In other words, more pixels don't mean better. They can simply mean a worse photograph made of more dots.

And what about that bit "... megapixels tell you how big a print you can make ...".

That's right. You have to do a little bit of maths, but it's not difficult.

When you print one of your photographs, or display it on a screen, each pixel is represented by a tiny dot of colour. Look closely at a photograph in a magazine, and you'll see what I mean. The number of these pixels/dots that are squeezed into an inch (the old imperial system of measurements is still used here) determines the quality of the final image.

High-quality printed photographs use a resolution of 300 pixels per inch (ppi). Computer monitors have a lower resolution, at 72ppi.

Lets go back to our camera sensor which was 2000 pixels by 3000 pixels - 6 megapixels. In this case each pixel translates to a dot of colour when printed. So, if you're printing at 300 pixels per inch then the biggest photograph you can get is:

2000 ÷ 300 = 6.7 inches, and 3000 ÷ 300 = 10 inches.

In other words, if you go larger than 6.7 by 10 inches the image quality will start to degrade.

Is the maths making your head hurt? Don't despair. Here's a handy chart. And, notice, underneath it the authors describe several ways of 'cheating' to get larger images.

So that's why Canon dropped the megapixel rating of their latest top-of-the-range compact camera. To get a higher quality image. They ain't daft. They know that more megapixels aren't necessarily better.

Let it snow!

It's been snowing here. Masses of it.

I love the snow, it transforms everything and, for a while, makes a new world of otherwise familiar surroundings.

It also gives lots of opportunities for photography.

Mundane scenes, such as a garden rake lying against a flight of steps, become interesting graphic compositions:

Everyday scenes, such as this Swiss postman on his rounds, take on a new dimension:

Without the snow, this scene would be boring and dull. The postman, on his delivery bike, would hardly stand out against the grey of the road and background. With the snow it becomes a tiny story.

And you can get action shots, almost isolated on white. In any event, in the snow there is lots of opportunity for getting shots with  minimal background distraction.

Just remember a few points when taking shots of snow scenes:

• Set your exposure compensation to over-expose at between 0.7 - 1.0 stop ... possibly even more. The reason is that your camera is not very clever. It is expecting you to take photographs of scenes containing a whole range of tones from black to white, and so averages out the exposure setting. If you average out the exposure for a scene with a lot of bright tones in it, such as snow or beach, and you'll get the white coming out as a dirty grey.
  
  
• Make sure your sensor is clean. Snow being bright, will often require small apertures and, at small apertures, every speck of dust on your sensor shows. This is made worse by the fact that snow scenes tend to have a lot of plain colours against which dust shows up.
  
  
• When you've finished photographing snow and you go back indoors, don't be tempted to transfer all those brilliant images to your computer immediately. Keep your camera securely zipped up in its bag/case for several hours until it has warmed up to room temperature. Condensation will form on a cold camera in a warm house and, whilst condensation on the outside of the camera is pretty harmless, if moisture condenses between the lens elements, actually within the lens, you could have a big problem on your hands.

Let it snow!

Frozen Britain

One of my personal photographic mantras is 'always look for a different viewpoint'.

Which is why I'm sometimes to be seen lying on the ground with my camera, or climbing up fire escapes.

But, seeing as I can't yet afford the millions that it takes to be a space tourist, this is a viewpoint I'll never achieve ...

Photo: NASA/GSFC, MODIS Rapid Response

An historic moment

This astonishing image has to rank amongst the 100 greatest photographs of all time ...

Boulevard du Temple, Paris, eight in the morning (1838?)

by Louis-Jacques Daguerre
(Click on the image to see it larger)

It is a daguerrotype, an image recorded on a sheet of copper coated with silver and developed by mercury fumes. Ironically the hour at which it was taken is known, but the year is not. It was either 1838 or 1839.

At first glance this may seem like a rather ordinary ... even boring ... subject. And it's badly scratched too. Aren't I saying its so great, simply because its so old?

No. Look carefully to the bottom left. There you will see two human figures, a customer having his shoes polished by a bootblack. These two unknown characters were the first humans to be photographed. Their simple, everyday transaction has made them immortal.

How come there is no one else in the image? Weren't the streets of Paris busy at that time?

They were. But Daguerre would have had to use an exposure of 10-15 minutes to get this image. So all the other Parisians, bustling back and forth, have not come out.

All the commentaries on this photograph that I have read speculate that these two were probably unaware that they were being recorded. And they say that Daguerre knew neither of them. One photo-historian writes, "He (Daguerre) quite possibly didn't notice them as he focused his camera, but his plate remained true to nature, and one can imagine his delight when the mercury fumes revealed their presence during development."

I wonder.

Daguerre would have known that people moving about would not record on his plate and I have a sneaking suspicion he planted these two. Apart from anything else, who has one shoe polished for 10 to 15 minutes? Then it's a slightly odd place for a bootblack to set up business, right on a corner, close to the kerb, and directly in the path of people walking up and down the road.

Finally, these two are very conveniently placed close to the classic compositional 'thirds' position.

I think that it has been set up ... not that this detracts from the image in any way. Those two make the picture. I'm guessing that Daguerre knew a thing or two about composition as well as developing plates with mercury fumes. He knew that a 'heartbeat' would improve his image. But he couldn't just have a person or two standing motionless on the street corner. Apart from the fact that it would look odd to passers-by, it would also look odd on the image. So, get them to do something, and what more natural than a shoe shine?

In a further bizarre twist of fate, this image has been saved for us by an invention of Daguerre's rival, William Henry Fox Talbot. Fox Talbot invented the calotype which was the precursor of modern film photography. (Film photography replaced the daguerrotype process and made it obsolete.)

Whilst this daguerrotype was display in a museum in Munich, in 1937, an eminent photo-historian, Beaumont Newhall commissioned a very high-quality photograph of it ... using photographic film of course.

Subsequently, Daguerre's picture survived the bombings of Munich in 1940 but, shortly after the war, an over-zealous museum curator attempted to clean it. The mercury amalgamated to the silver was incredibly fragile - likened to the powdery scales on a butterfly's wings - and the hapless curator wiped the whole thing clean.

But Beaumont Newhall's  photograph of it survived. And a replica daguerrotype could be made.

An amazing story around a truly great photograph.