Sunday 26 October 2008

Close-up Photography of Small Objects

Welcome to Macro Photography for Beginners. In my last post I wrote about a lot of different subjects but mainly concentrated on still life and to a lesser degree product photography. Today, I am writing about a technique of photographing coins or other small objects of interest. This post is not just packed full of macro photography tips and information about photographing small objects it is also based around a story of how this particular collection began.

My eagle-eyed four year old daughter began collecting coins after taking an interest in the pictures and designs on them. She has now amassed approximately 20 of various shapes, sizes and designs. I decided to photograph and catalogue her collection to ensure that we have an accurate record of them. None of the money in this collection is valuable and mostly they have been taken from circulation. There are one or two interesting specimens that are no longer in circulation which I have donated to boost the collection. I’m sure that if we promoted her interest in collecting metal money she would soon have a lot more donations from further a field. Although her collection is not worth much in financial terms the majority of this assemblage was put together by my daughters Grandad who sadly passed away last year. As you can imagine this set of coins may not be “special” to anyone else but to my daughter they are very special indeed. So much so, that whenever anyone in our household goes to the bank to pay money in to an account my daughter has a minor “panic attack“ over the whereabouts of her collection!

I suppose we are all money collectors at some level with most of us collecting for different reasons. I’ve known a few people who refer to their hard earned money as beer tokens. If you take the time to observe more closely the contents that pass through your hands each day, you will be surprised at the variety of different designs in circulation. The main problem seems to be that there just doesn’t appear to be enough of them coming my way. So there will be little chance of any new camera equipment in the foreseeable future! Luckily, I found a simple and effective method of using my macro lens and ring-flash to photograph the entire collection. It is a great technique that I derived from information on other people’s photography websites. I wanted to take a shot of both sides of each one. To use the correct technical terminology this would be the obverse and the reverse. I try as much as possible to avoid mathematical calculations on this website but I think we can all cope with this one. (20 x 2 = 40 shots). To save as much set-up time as possible all subjects of the same (or similar) size (or type) will be photographed and catalogued at the same time. Then the camera position will be re-set so that all the compositions are full frame. There is a cropping factor to consider if you want to get the object completely full in the frame, but be careful not to allow any overlap over the edge at all because this always looks a bit strange (a bit like a car with a flat tyre).

Even the smallest radius of these objects is usually too large to photograph at 1:1 but this is not important for this type of work. The main intention here is to capture the entire subject in the frame with as much detail as possible. This means ensuring that the details are in sharp focus and easily legible in the final photograph. In older metal coins it is important to capture any damage which may be present on the specimen. There may be a few notches, surface scratches or discoloured areas. In extreme cases in very old money there may even may the occasional hole!

Why use a Ring Flash?
It is a well known fact that the ring flash has a reputation as being as useful as pair of chocolate underpants. I seem to be one of the few macro photographers prepared to stand up for this much maligned device. In my opinion it is much more useful than you could ever imagine if you are prepared to use it in an unconventional manner. In addition you may have to build some additional equipment such as a (home made) diffuser to get the most out of it. I made mine from an empty “Vitalite” margarine tub. You do not need to worry about diffusers today because this is not required for this type of photography. I will come back to this in another post if anyone wants to build a similar device. It does not take a genius to work out that in certain situations a ring-flash will direct the light to the wrong place and ruin the image. In these situations you have to detach the flash unit from the macro lens and hold it in position (most often at an angle of 45 degrees). The flash does not have to be held steady as any shake will not be picked up by the camera (unless it is extremely violent, such as an earthquake or the shutter speed is very slow).

The Pedestal Technique of Photographing Coins
This technique may sound complicated at first but in fact it is very simple and easy to accomplish. The basic principle of this technique is to isolate your subject on a small pedestal from the background. To do this you need to erect a small cylinder or tube to a height of approximately 5 ½ inches (or 14 centimetres). Ensure that the pedestal’s diameter is smaller than your object so that it will be hidden from view in the final images. Use a matt background around the base of the pedestal. The distance between the subject and the background is what makes this technique work. Set-up the camera and (macro) lens to focus on the pedestal. Use an appropriate aperture value to throw the background out of focus. Ensure that the value used keeps the entire subject (or object) sharp in the frame. See illustration in figure 1. Reflectors can be used to direct more light to the subject. Place reflective material in an appropriate position to bounce light onto the subjects surface from your light source.

Figure 1: Illustration of Tripod and Camera Set-up (Marvin Africa, 2008)

There are two way to photograph your subject using this technique. You can use one side of a ring-flash to fire a burst of light across the surface or use some type of continuous lighting. I have taken pictures using both techniques and found the ring-flash method more reliable. The only major problem with this set-up is that the subjects are often all different shapes and sizes. This equates to a lot of setting up and re-focussing the camera. Another time consuming problem is keeping track of all the heads and tails. The only reasonable method that I have come up with so far is writing down the image number (with a pencil) on a piece of scrap paper. Which is not very technical in this digital age! Another minor problem to overcome is that some of the subjects have very bright surfaces. This occurs when a coin has not been in circulation long enough to loose its surface shine. A very newly minted piece of metal will be much more reflective than an older piece that has become dull with time. Adjustments to the ring-flash or (continuous lighting if your using it instead) need to be made to accommodate this variation. Changes need to made for objects with different surface colour as this may require a different lighting set-up to get the best image. This is often a matter of changing the angle of the lighting or with the ring-flash changing the intensity of the flash. I found that for some items with silver surfaces it worked best to use both tubes at different intensities for the best results. This took a lot of trial and error and moving the ring-flash around to many different angles.

How to set the Ring-Flash to Fire one Tube
To set the ring-flash (Sigma EM-140DG) select on (you won’t get far otherwise) and then select M (Manual Mode). Once in Manual Mode you can change the intensity of the flash on both tubes. Select until the left tube’s value flashes, it will begin at full intensity. Use the (-) minus button to reduce the intensity to a lower amount, which will be displayed as 1/64, 1/32, 1/16, 1/8, 1/4, 1/2, and 1/1 (lowest to highest). To turn the tube off press (-) button again and the line that represents it on the LCD screen will disappear. This indicates that it has been disabled. I am sure that the settings are similar with other manufacturers of ring flash.

This was very much an unplanned post about a project that I ended up doing. In the end I found it so enjoyable that it became worthwhile writing a post on this subject. In addition this experience has made me more aware of the different designs on the money in circulation. My aim was to try and take a flat image of these diverse and interesting objects. This was not an artistic shoot and I did not want to make them stand out too much. All I needed was a scientific record of their existence in case they are ever lost or stolen. I recommend taking a closer look at the contents of your own pockets and see if you can find anything worth capturing this way. I’m now considering using this same technique for other small subjects including stamps. I hope you found some of the information in this post useful. Thank You for visiting my Macro Photography website.

Marvin Africa