Digital Clinical Photography: Part 2 - Choosing A Digital Camera For Clinical Work
The first article in this series presented a persuasive argument for doctors to consider using digital photography in their routine clinical work. This article will focus on how to choose from the large and ever-increasing number of different models of digital cameras currently available, a task which may seem daunting to those setting out to buy their first digital camera. Almost every day new camera models are announced with more features and greater resolution while at the same time the cost for all these features and increased resolution keeps falling. The complexity of the terminology used to describe new cameras features can be baffling for novices and it is not surprising that unscrupulous salespeople persuade novices to purchase cameras inappropriate to their needs and sometimes beyond their budgets.
Here are some very simple and logical guidelines which will help to reduce the risk of buying something that isnt appropriate to your needs:
1. Intended Use
Decide first up what you want the camera to do for you or, to put it another way, decide what you want to do with the camera. If you want the camera only for clinical work in the surgery then you should choose a camera wich is especially good for closeup or macro photography. Closeup simply means getting as close as possible to the subject so that it appears magnified! Cameras which are able to focus when the front of the lens is as close as 1-3 cm from the subject may provide excellent closeup photos. However the expensive macro lenses available for digital single lens reflex (SLR) cameras can provide fantastic macro images without having to get so close to the subject. Unfortunately these cameras are quite expensive, bulky and heavy and require much more expertise to use correctly than less expensive amateur cameras which may well provide wonderful closeup photographs. Also, before you buy a digital camera for clinical photography consider whether you want the camera to work with a dermatoscope. Unfortunately only a limited number of digital cameras can be coupled with a dermatoscope. (Manufacturers of dermatoscopes now list exactly which cameras can be used with their products either directly or with an adaptor device.)
If you want a camera which can be used for a wider range of uses beyond just clinical work, eg. holiday and family snaps, there are a number of other factors which need to be considered including how compact and/or robust the camera needs to be, how much resolution (or megapixels) you want the images to have, what zoom range you want the cameras optics to have, how many pictures the cameras battery will take before it needs to be recharged, whether the camera has a built-in video function and if so, how much and what quality of video it records, and finally how much manual control of the the cameras functions you want. There are other features of a digital camera which one might consider but those just mentioned are probably the most important features. However please dont neglect the fact that the camera still has to be able to take good closeup photos if its to be of any use in the clinic!
A robust camera is always going to tolerate knocks and mishandling better than a flimsy camera but robustness comes at a price and robust cameras usually weight more than flimsy cameras. Compact cameras are easy to hold with one hand but will shake more easily than heavier cameras and closeup photography requires a very steady hand or lots of light or built-in image stabilisation.
Perhaps one of the most over-rated features of digital cameras is the number of megapixels the cameras imaging sensor has. There is a virtual megapixel war being waged with manufacturers trying to outbid one another to woo purchasers. Admittedly more megapixels does mean more resolution or detail in the photos so that it is possible to crop or trim photos to remove unwanted areas and still print out finely detailed photos. Also pictures with more megapixels enable one to zoom further and further into the picture on ones computer before the individual pixels start to enlarge and appear as blocky blobs of colour. This feature can be particularly useful in closeup photography. HOWEVER, small compact cameras generally have very small image sensors and as manufacturers cram more and more pixels or light-sensitive dots into these small sensors, each individual pixel must be smaller. This means that can therefore receive smaller numbers of light photons. Smaller pixels dont present as much surface area to receive light than larger pixels and generate more electronic noise or static than larger pixels especially when theres not much light around. This noise appears in photos as grain in darker, less illuminated areas of photos. Larger cameras such as digital SLR cameras have much bigger image sensors with bigger individual pixels and therefore the images made with these cameras have much less grain or noise in low light settings. So there is a tradeoff between resolution and graininess in digital photos and therefore a camera with 10 megapixels isnt necessarily going to take better pictures than a camera with 6 or 8 megapixels, especially in a clinical setting.
Bear in mind that more megapixels means each photograph taken at full resolution contains more information and therefore each picture takes up more space on ones computer. Admittedly digital cameras generally allow pictures to be taken at a number of different resolutions and also its possible to reduce the resolution of large digital photos after theyve been taken by using software, but this requires time which most clinicians wont have.
No matter how many megapixels a cameras image sensor has, if the optics are cheap the images may have lots of distortion or artifacts of light and colour at the edges of objects which may be most prominent at the extreme ends of the range which may include closeup work. Good optics costs money.
Automation of a digital cameras functions (focus, exposure, white-balance) is now relatively inexpensive and can allow complete novices using very cheap digital cameras to take quite good photographs. However some particular situations such as close-up photography can be particularly demanding on a digital cameras inbuilt computer with the result that photos may be poorly exposed or focussed. Therefore it is useful to choose a camera which provides manual controls for focus, light exposure (via aperture and shutter speed), light sensitivity (ISO rating) and white balance. Of course using these manual controls requires a greater understanding of photography in general and in particular how these features work and when to use them. It also comes at more expense because manual controls requires more knobs and buttons on the camera as well as much more complex internal electronics. In some situations it can also be useful to have manual controls of the cameras shutter speed and aperture which together influence how much light enters the camera and how much of the image can be in sharp focus i.e. just the object or the object and the background, and so forth.
Also consider whether you will be the only person using the camera for closeup work in your clinic or whether other colleagues or staff members will want to use it. If you intend the camera to be used by others, the choice of camera may depend a little on how competent they are with technology and photography in general. Choosing a simpler but more robust cameras with fewer controls may actually make more sense as long as it can still take good closeup photos.
Decide how much you are prepared to spend for the camera and essential accessories. It helps to have already looked around a bit to get a reality check or a realistic expectation of what it will cost to buy what you want. Just remember that good tools are usually expensive but cameras used for clinical purposes can be depreciated for taxation purposes and will ultimately cost you very little money.
3. Online Research
Do some online research by visiting some of the wonderful digital camera websites such as Steves Digicams.
These websites have highly detailed reviews on a large number of recent and older models of digital cameras and list all the specifications of cameras as well as their good and bad features. It can be difficult to interpret or understand some of the terminology but the sites listed below usually explain technical terms in ways that novices can understand.
If you have done your research on the web by reading reviews and come to a choice between a few different cameras then the deciding factor may well be how the camera feels in your hand and how easy it is to use. This is an important issue and no matter how good a cameras reviews may be, if it feels awkward or clumsy or unintuitive to use, you might not enjoy using it!
4. Camera Shops
Visit some of the larger camera shops which have on display a wide range of different models of digital cameras ranging very cheap to outrageously expensive. Once you get the attention of a salesman and mention that you are interested in clinical photography let them first know how much you are prepared to spend on a camera so that they dont try to tempt you with the most expensive gear in order to earn the best commission!
If you are allowed take some closeup photos with the camera which most tempts you and ask if you can view the images on a computer in the shop. Alternatively, if you have a laptop, take it with you and ask to view the images on your laptop. The salesperson, sniffing a sale, may become very obliging!
5. Borrow A Friends Camera
Try out other peoples digital cameras to see how well they work and how easy they are to use. This will be far less stressful and if your friends are particularly obliging you may be able to test the cameras in your own clinic, using your own computer.
6. Buyer Beware Online
Watch out for cheap bargains as you may end up with an expensive white elephant. Buying a digital camera from a camera shop should provide security for those unhappy situations when a newly-purchased camera malfunctions and needs to be repaired or replaced under warranty. However, if one buys a camera more cheaply from an online retailer there is no certainty that such a vendor will provide satisfactory backup and it may provide greater peace of mind to pay a bit more for ones purchase for this perception of support. Online vendors can only sell cameras more cheaply because they dont need to maintain expensive premises or employ salespeople. Commonly they import cameras cheaply themselves rather than buying their retail stock from distributors who will often provide repair and exchange services. Until now author has successfully resisted the temptation to save money by buying cameras from online vendors and has enjoyed excellent support from camera shop staff on those rare occasions something has needed fixing or exchange under warranty. The bottom line is pay peanuts, get monkeys.
7. Dont Look Back
Once you buy a camera, dont look back. Just accept that no matter which camera you choose, it will become obsolete the moment you buy it. Newer models which are cheaper and have better/more features than the camera youve just paid for will be announced very soon. If you look at advertisements, the camera you have just bought will soon be available for half the price you paid for it or will no longer be available at all because its been superseded by a better model. Please accept these harsh realities and just get on with enjoying your new purchase.
The author has deliberately avoided recommending any specific brands or models of cameras as being particularly good for clinical work because it is virtually impossible to keep up with the outpouring of new models of digital cameras. However during discussions with colleagues and while presenting talks on the topic of digital photography for doctors he is often asked about his personal choices of equipment for clinical photography and readers may also find this interesting. The author currently uses two digital cameras virtually every day in his clinical work - a Nikon Coolpix 4500 (solely for use with a Heine dermatoscope) and a Nikon Coolpix 5700 for general closeup work. Both cameras are fixed-lens prosumer cameras and are now several years old and therefore quite seriously obsolete. Fortunately the cameras seem unaware of this sad fact and still produce excellent digital photographs and, unlike their owner, have proven to be very robust with no obvious signs of ageing! For holidays and other recreational purposes he uses his relatively new and very bulky Canon 20D digital single lens reflex with a Canon 50mm macro lens and a Sigma 18-200mm all-purpose zoom lens.
Virtually all digital cameras store their images on removable solid-state memory cards which come in different forms, capacities and speeds with which they can be read from or written to. It is now possible to buy memory cards with 16G capacity which have the capacity to store hundreds if not thousands of high resolution photos and prices for high capacity cards seems to fall as fast as the technology develops ever-larger storage capacity. Nevertheless it is useful to have at least one spare high-capacity memory card because most digital cameras come with quite low-capacity cards.
However, if ones use of the digital camera is confined to clinical work and if clinical photos are immediately downloaded and incorporated into patient medical records then one memory card of even a modest size such as 256 MB may well be sufficient for that purpose. In fact, the author commonly uses a 32MB card to ensure that it there are not a large number of images on the card at any one time so that it takes very little time for the computer to see the images on the card (the more images on the card the longer the computer takes to see them all)!
High-Speed Memory Card Reader
A lot of time can be saved by using a high-speed memory card reader to transfer images from the cameras memory card to the computer instead of connecting the camera directly to your computer. Essentially one just removes the memory card from the camera after taking the photos and plugs it into the card reader which in turn is connected to the computer by either a USB 2 or a FireWire cable. Many cameras only have a slow USB 1 port for connecting directly to the computer. Because digital images can be quite large (up to 14MB each with 10 megapixel cameras) it can take a very long time to transfer to the computer even just a few of these big images via a USB 1 cable. By contrast, card readers commonly have either USB 2 or FireWire connections with computers and this means images can be transferred up to 40 times as fast as USB 1 transfer rates. This time saving is very useful in the context of a consultation and, unlike a doctors time, card readers are not very expensive. Of course ones computer needs to have USB 2 or Firewire ports/cards to make optimal use of a high-speed memory card reader!
Once the camera leaves the confines of the surgery it may not be possible to download images from the memory card once its full of images. So it is useful to own several memory cards. Another alternative, albeit expensive option, is to purchase a digital wallet, a generic description for a small portable device which incorporates a battery powered hard drive and one or more slots to accommodate the various formats of memory cards. This device can quickly download the images from the memory card and store them on the hard drive thereby allowing the card to be reformatted or cleared of its images so that more can be taken. The more expensive models of digital wallets have a viewing screen so that the images can be viewed, deleted, and even renamed. The images can eventually be uploaded to a computer for further use. These devices are not cheap but can be invaluable if one takes ones digital camera on an extended holiday sans computer!
Sure as Murphy had a law, as soon as one goes to take a picture of a skin lesion just before excising it, the cameras only battery is found to be as flat as a pancake and needs at least 90 minutes of charging!!! Its important to always have at least one spare battery and to keep it charged. Some cameras can use standard AA or even AAA size batteries which are available virtually anywhere. However rechargeable batteries are more environmentally friendly! There are some cameras which have non-removable built-in rechargeable batteries and with these cameras one has to become disciplined to keep the battery charged all the time to avoid disappointment. For extended holidays in the outback or other remote areas far away from powerpoints it is handy to have a battery charger which can work plugged into the cars cigarette lighter socket.
Owners of single-lens reflex cameras may choose to buy more than one lens and for clinical work a dedicated macro lens is an absolute necessity. They dont focus in as close to the subject as many of the smaller and cheaper digital cameras but take extremely high quality photos which look as if they were taken much closer to the subject than indeed they were.
External Flash Unit
Close up photography requires a good source of light. Unfortunately the built-in flash units in many digital cameras are quite useless for closeup photography because the cameras are incapable of sufficiently reducing the intensity of the flash for close-up work. In these cameras the extremely high light output from the flash reflects back from a closeup object, completely overwhelms the light sensor and makes closeup pictures of skin lesions look totally white without any detail. Some of the more expensive pro-sumer digital cameras do have a hot shoe onto which an external flash can be mounted and some internal flash units can be controlled sufficiently to reduce the intensity of the flash so as not to overwhelm the camera. Most digital single-lens reflex cameras can use a flash unit specifically designed for closeup work (eg. a ring flash) but these flash units are nearly always unreasonably expensive.
The author chooses not to use a flash unit and instead brings either a freestanding light or a cantilevered desk light closer to the patient. This has the advantage of being a cheap solution to provide adequate illumination and unlike a flash unit provides sufficient light for photographer to accurately focus on what may well be a very tiny object such as a tiny basal cell carcinoma. Unfortunately this type of light source can still be intense and uncomfortably hot when its held close to the patient.
This device can sometimes be a useful tool if one cannot maintain a steady pair of hands and if the ambient light is so low that the cameras shutter speed is too slow to prevent blurring of the image. Unfortunately tripods are slow to set up and one often has to move the patient to the tripod rather than bringing the camera to the patient!
Choose your camera wisely by doing some research in advance, then go to a camera shop to play with the small number of models youve narrowed the choice down to, and dont be bullied into buying what you dont want or need. Get extra batteries and memory cards and a fast card reader, and then go home and practice with youre new work tool. Dont look back and make sure you start saving for a better camera.
Posted in Australian eHealth