GeoLogic

Photography

Photographing fossils is more difficult than it sounds.

We often take for granted how easily our eye can capture contrast and relief, where cameras often struggle.

This guide offers a little of our expertise, gained over years of attempting to capture fossils in a scientific - or artistic - sense. We hope it will also help you photograph your fossils, whether to show them off to friends or get them identified.

What to photograph

The most important thing to have in mind at all times when photographing fossils is that your images need to capture every diagnostic feature of the fossil. The trick to good photography is in taking as few pictures as possible to illustrate all the key features.

Depending on the nature of your fossil, you may need to take photographs from anywhere from one to six angles, and perhaps at different levels of zoom. Start by taking photographs which depict the whole of the fossil, then take "close-ups" if necessary.

Be sure to capture any surface texture, and any distingishing features (such as eyes, spines, legs, etc).

To make sure you miss nothing out, it's sometimes worth drawing out a sketch of your image first - this can force you to pay attention to features you'd otherwise have missed.

It's very important to include something to give a sense of scale in each image. Best is to include a ruler, but if this isn't possible anything with a recognisable size is useful. Coins, hammers, camera lens caps and pencils are the most commonly employed markers in the field.

How to photograph

Camera

You'll get a much better image with a good camera, properly set up. Always use the highest resolution and image quality possible.

If you can, alter the aperture on your camera. You may need to set your camera to "A" mode. The aperture is denoted as an "F-stop number", typically in the range of (say) "F 2.8" to "F 12". Crank your aperture to a large number: this shrinks the aperture, allowing more of the image to be in focus. However, be wary that smaller apertures (larger F numbers) allow less light to enter the camera, and could lead to underexposed, "gloomy" shots.

This small aperture will make it easier to get all of your picture in focus. If you have it, a "macro mode", usually denoted by an image of a flower, will let you focus on items closer to the lens - mine often comes in useful. Get the image as crisp as possible before pressing the shutter!

Set-up

The final step to a clear picture is a steady hand when taking the shot. The best way to stop "camera shake" blurring your image is to use a tripod, but even something as simple as resting your camera on a shelf is preferable to having it in your hands. If you must hold the camera yourself, hold it with both hands, near to your body. Further, using a countdown timer can avoid judder caused by pressing the shutter button.

Lighting

Good lighting is what makes or breaks a successful image. Daylight is ideal for bringing out the maximum detail, and blue "daylight bulbs" are a handy alternative. It is often worth experimenting with a polariser if you have one. Never be tempted to use a flash! These give a flat light which destroys all detail.

The angle of light affects the shadows left on the fossil, which in turn help to pick out the detail of the fossil. You should generally only use one light source, to maximise the clarity of the shadows, which will make the textures easier to see. Low angle light brings out relief and fossils preserved as flat films. High angle lighting is more useful when shadows may be detrimental - for instance, when a fossil stands out clearly from the surrounding stone.

You can play around for hours adjusting the level and angle of light - and it's often worth it! Professional academics sometimes spend a full day in pursuit of the perfect photographs of difficult fossils, so as to get an image that illustrates all the features of their specimen in maximum clarity. A good quality photograph is so important that some academics employ professional photographers to snap their fossils!

Background

You should think carefully about what is behind your fossil. Ideally, use a non-reflective piece of card of a contrasting shade to your fossil - black or white are often best.

Image manipulation

Altering your photograph on a computer is a controversial area. Tweaking can make huge improvements very easily, but too much is frowned upon.

Simple software such as Google's Picasa does everything you need it to, but for a better result you may want to invest in Adobe's Photoshop, or use the free alternative, GIMP. The edits that are generally considered fair game are listed below, but always keep a copy of the original, unedited.

Cropping and straightening

Trimming empty space from the edges of an image draws focus to the fossil and removes distractions. Be careful what you cut off, though!

• In Picasa, just use the Crop and Straighten buttons on the "Basic Fixes" pallete. It's easiest to crop the picture first, remembering you'll lose the corners when you straighten.
• In Photoshop, select Image→Crop, and select the area of note. By dragging round outside the selected area, you can rotate the area. Make sure the cropped area remains rectangular, to avoid adding misleading perspective.
• In GIMP, you should straighten first, using Layer→Transform→Arbitary rotation. Then crop, using the crop tool (click on the craft knife, or press Shift-C).

Sharpening

Blurring and out of focus areas can be removed using a sharpening tool.

• In Picasa, the "sharpen" function is on the "Effects" tab. Note that it is a) not very effective; b) bug-laden. Don't click it more than once, and ideally use more advanced software, like:
• Photoshop or GIMP. You are looking for Filters→Enhance (Adobe re-arranges the menus on a regular basis, so it may be in a different place in your version!) From the list produced, the most suited to fossils is the "Unsharp mask", which sharpens areas of higher contrast. The default settings are fine, but feel free to tweak them. Always view the effects at 100% zoom, and look for unwanted artefacts along edges.

Contrast

Increasing contrast makes features clearer, but must be done with caution.

• In Picasa, use the top three sliders of the "tuning" tab. Be careful not to take any of the lighter or darker areas to total white or black, respectively, as you will lose detail. As a guide, you should typically only use the left fifth of the sliders!
• Photoshop and GIMP allow more sophisticated manipulation. The "Levels" tool (Photoshop: Ctrl-L; GIMP 2.4+: Colours→Levels) is what you need. Examine the dark curve, and if there's any space at either end, move the black and white "input" sliders to the start of the black area. You can move the middle, grey handle as you wish to adjust the darkness. For more control still, use the "Curves" tool (Photoshop: Ctrl-M; GIMP 2.4+: Colours→Curves), which allows you to increase the contrast of light or dark areas preferentially.

Focus

If you can't get all of an image in focus at once, you can take a picture at each focal level, then combine them using "CombineZM". This is difficult to explain but simple to do - details and instructions are available at their site. Note that it is rapidly improving - it's updated every couple of weeks.

Practise!

That's it! Now all there is to do is practise - try photographing fossils preserved in a range of different ways, and make a note of what works when. Good photography is a difficults skill, but one well worth having!