General considerations with technical notes
Brief synoptic guide
When you buy a digital camera
Hints on learning a new digital camera
Advanced hints for digital photography
Glossary for digital photography
Genus/Species-Specific Fungus Photography
Woody Desert Fungi
Mushroom photographs, like any others, are judged for their intrinsic interest, uniqueness and aesthetic appeal. If successful, they meet all the conventional standards of composition, focus, true color and detail. In addition, mushroom photographs for identification purposes must explicitly record specific features, depending upon the genus and/or species.
This article consists of three parts. The original guide was compiled in 1986 by Mariana Bornholdt with the help of Pacific Northwest Key Council member specialists, before digital photography was available. Many current photographers find that film cameras still give the best results. 35mm slides are particularly popular. For an excellent introduction, see Pam Kaminski’s article on MushroomExpert.Com. http://www.mushroomexpert.com/photography.html
The next two sections, by Ian Gibson, tell what he has learned in switching from film to digital photography with a variety of cameras. The information is not limited to mushroom photography, but reflects his interests which include photographing mushrooms.
The third part, on Advanced hints for digital photography, is written by an accomplished digital nature photographer, Rich Mably, whose photographs were viewable in 2007 at http://www3.telus.net/public/richm3/Small_World/index.html
(Mariana Bornholdt & Harley Barnhart)
Most of the following instructions assume that you will be making color photos or slides. If photographing in black and white, make written notes concerning color characteristics from the fresh specimens at the same time you photograph. In many cases, even with color photographs, supplemental written notes will be helpful, especially if the identification is to be made by someone else. It is suggested that the same film and lighting conditions be used for all photos of a given genus. It is usually desirable to arrange the subject showing a variety of views in one frame, photograph cut specimens, and /or show a developmental series if specimens are available.
If you don't have detailed instructions with you when you photograph, some common sense general rules will cover most situations:
A useful technique, but one to be approached cautiously, is the introduction into the photograph of nearby foliage (leaves, needles, cones, etc.) to show mycorrhizal relationship. If the mushroom is identified and its mycorrhizal affiliate known, the foliage bits will add to the value of the photograph as a recognition aid, especially if field notes get separated from your photos. In some cases, the relationship may be deduced with reasonable certainty from the location of the fungi and from the scarcity of possible other trees or shrubs as partners. In other cases, with well-mixed woods and a photographer who doesn't know a five-needle pine from a spruce, the introduced foliage could be disastrously misleading. If foliage is brought back to the lab for a studio-type photo, care should be taken to avoid mixing with foliate intended for shots of other fungi and to keep the greenery fresh. A moist paper towel around cut ends will help, especially if these are then inserted into a plastic sandwich bag, wrapped snugly and secured with tape or a rubber band.
If the photograph is strictly for identification, consider the inclusion of a short ruler, to show scale. Place this near the plane of focus. Rulers or other objects such as coins are not often accepted fro field guides or other publications. If you have both purposes in mind, take the "natural" arrangement first, and then set up the display.
Bracket exposures (by at least half a stop over and under the calculated value), and use a reflector or flash to fill in any dense shadows, whether these shadows are produced by sunlight or by the primary flash. This is especially important when the subject has considerable innate contrast, such as a dark cap and a white stipe. "Washed out" highlight areas will not show details useful for identification, such as pale hues and surface textures.
Don't take long time exposures (1 second or over) with transparency films, such as Kodachrome, unless you understand the phenomenon of reciprocity failure, the limitations this may impose on your particular film, and the corrective measures possible with filters. Overly long exposures will adversely affect accurate color rendition and exposure calculations.
Identification photography of mushrooms presents a special challenge. The skills developed in identification photography are sure grounding for successful and beautiful mushroom pictures.
For the photographer who doesn't want to bother with detailed notes in the field AND for the photographer who forgets his notes. Either of these will fit into your camera case.
BASIC LIST A (Kit Scates-Barnhart)
Baby bottom - An entire button, with base toward camera, to show veil remnants, entire base and it coloring, shape, and mycelium, etc.
Complete caps - One cut off and upside down to show gill spacing or pores
Inside Information - Vertically cut section to show texture, staining, gill attachment, etc. - should be laid at an angle to show bottom of cap
Sideways Stature - In addition to basic stature type, will show stem features
Habit and Habitat
BASIC LIST B (Harley Barnhart)
Immature and Mature
Top of cap
Bottom of cap
Note that, in several cases, arrangement of the subject, cut specimens, a series of photographs, and field notes are specified.
AGARICUS (Margaret Dilly)
AGROCYBE (Carl Hermanson)
AMANITA (Don Goetz)
BOLETES (Kit Scates-Barnhart)
CANTHARELLACEAE (Tina Gospodnetich)
Suggestion: Bisect one sporocarp, display cut side up, cut side down, whole sporocarp with ruler and foliage. Include metric scale.
CLITOCYBE (George Rafanelli / Bob Maguire)
COLLYBIA AND COLLYBIOID GENERA (Helena Kirkwood)
CYSTODERMA (Reynaldine Sandahl)
GEOGLOSSACEAE (Dick Sieger)
These species are difficult to identify macroscopically.
They are so small that everything to be seen will show in any photograph.
HEBELOMA (Coleman Leuthy)
HELVELLACEAE (Herold A. Treibs)
The following should show in the photograph or photographs. It might be better to take two or three photos to show all of these features, but one crowded photo is better than none at all:
LEPIOTA (Dick Sieger)
LEPISTA (Clitocybe, Section Vemuculosae) (Gene Butler)
LEUCOPAXILLUS (Arthur R. Fick)
LIMACELLA (Kit Scates-Barnhart)
In addition to Basics listed earlier, emphasize:
LYCOPERDALES (9 Genera) (Robert W. Ramsey)
MARASMIUS AND ALLIES (Mariana D. Bornholdt)
MYCENA (Amy Miller)
NIDULARIACEAE (Margaret E. Fay)
OMPHALINOID (Dorothy Tarr)
PAXILLUS (Lorelei Norvell)
PEZIZALES (Harold Larsen)
PHAEOCOLLYBIA (Christel Goetz)
If possible, record information on taste, odor, habitat and tree associations.
PHOLIOTA (Kit Scates-Barnhart)
In addition to Basics listed on Page 3 (Basics List A), emphasize:
PHYLLOPORUS (Lorelei Norvell)
PLUTEUS (Gene Butler)
RAMARIA (Kit Scates-Barnhart)
One young (half-grown) specimen - with its ENTIRE BASE - cut in half vertically. One half showing inside and the other half outside of specimen will cover most needs.
One mature specimen and one button helpful if available.
RUSSULA (Ben Woo)
Photograph to show the following characteristics:
Christine Roberts adds (2007) to show separation of cutis, to show gill shape and cavitation of the stipe with a longitudinal section of a young and mature specimen, and to record taste, colour of spore print and trees in the habitat.
SCLERODERMAS (Robert W. Ramsey)
TRICHOLOMA (Charles D. Volz)
Characters to show in photographs:
TRICHOLOMOPSIS (Elsie Coulter)
VOLVARIELLA (Gene Butler)
WOODY DESERT FUNGI (Marie and Leeds Bailey)
Genera: - Battarrea, Chlamydopus, Endoptychum, Longia, Montagnea, Phellorina, Podaxis, and Tulostoma
XEROMPHALINA (Dorothy Tarr)
1. Do some research by asking friends or looking on the Internet. You can do without this, but your questions will be better if you do. One review sites available in 2011 was http://www.dpreview.com, but entering "digital camera reviews" in a search engine brings up a host of others.
2. Decide on price range. You can get very good photographs with low end cameras now. More expensive cameras are worthwhile if you want to make print enlargements (higher Megapixels and better lenses and sensors), if you take wildlife photos (higher zoom) or very close close-ups (macro features), or if you want really good color accuracy. Get a single lens reflex camera if you can afford it: you can exactly the photos you want in a wider range of conditions1. An accessory flash gives more flexibility with lighting and avoids the red pupil problem in pictures of people. In considering price range, remember you will need a high capacity memory card and a case to protect the camera, and these are not usually included.
3. How small to do want the camera to be? Pocket size cameras are readily available, but you need to protect them with a case. They are not bump-proof, drop-proof, or water-proof. How would you be carrying the camera?
4. How large do you need the screen on the back of the camera to be? Is the screen easy to see (especially in bright light) and does it look sharp? The brightness can often be turned up, but that uses more battery power. Is there an option to swivel it (useful for low shots of mushrooms)?
5. Do you want to be able to use standard AA batteries? You may lose something in the number of photos you can take between recharges, when compared with specialized batteries.
6. Let the salesperson know whether it is more important to keep it simple or to have lots of options. Some cameras have better menu systems and manuals than others.
7. If you want to take close-up photographs (flowers, mushrooms, or insects, for instance), how much does the camera enlarge small objects and how well does it work in low light. Try it out in a dim area of the store, with the flash off. Notice particularly how much of your subject is in focus.
8. If you want to take distance photographs (animals or birds for instance), what is the optical zoom? (Disregard digital zoom which is a gimmick for something you can do on the computer later anyway)2. 12x optical zoom will give you enough magnification for most purposes, but note that this is not 12x the "normal view" but 12x the view from the widest angle3. Make sure that it functions close enough to you at maximum magnification for small objects like birds (try it out in the store). The telephoto lenses differ in light-gathering power, so ideally you would try it out where the lighting conditions approximate those that would prevail when you are taking photos.
9. If you want to take photos of mycologists indoors, take a photo 25 feet away and 5 feet away, preferably in fairly dim conditions. Take photos in each case with flash and without flash (the salesperson can turn the flash on and off for you). Is the flash strong enough to provide light at a distance and how much does it wash out the close shot? How well can you see without the flash? How accurate is the color of the faces, and how sharp does the picture look? Some of these factors can be improved by settings on the camera, but if the photo salesperson can’t make the adjustments, you may not be able to either. A useful feature is a light that is beamed out in low light to help the camera focus, and it is absent from even some expensive cameras.
10. How long is the guarantee and how long does it take to get a camera repaired? Digital cameras are not as reliable as film cameras used to be. How often are the cameras sent in for repair by customers?
11. Once you decide on a camera, make sure you can take it home, try it out, and return it without charge if you are not satisfied. You need to look at the photos on a computer before you can really decide if the sharpness and color is what you want. (Remember that both of these also depend on your computer: you may even want to make some prints at the photo store.) Look up the model on the Internet or have someone do it for you.
It helps to have an organized approach. Unfortunately most instruction manuals are intimidating, and people tend not to read them anyway. You need to ask the person selling your camera how to do the basic operations. All photographers need to know how to:
1. Turn the camera off and on.
2. Press the shutter release to take a photo.
3. Zoom in and out.
4. Review the photo and possibly delete it.
5. Transfer the photos to a computer.
6. Erase those photos from the camera to make room for new ones.
7. Recharge batteries.
You can take lots of good photos with only these operations. Eventually you may want to deal with the following situations.
9. Faraway objects such as animals
10. Low light
11. Moving objects
12. Focus problems
13. Back light
14. Bright light
15. Red eye
16. Processing on your computer
17. Aids to Recording Information about Specimens
I will deal with each of these in turn.
1. Turn the camera off and on.
This is seldom a problem. Be aware, though, that the camera will usually turn itself off after a time period to save the batteries. If the camera is on, but the screen at the camera is not lit, you may have hit a button that switches between the viewfinder that you look through and the screen on the back of the camera.
2. Press the shutter release to take a photo.
Take your photos horizontally if you plan to view them on a computer screen. The shutter release is an obvious button. On most cameras, you can press it partway down to fix the focus, then all the way down to take the actual photo. This is important in two situations. One is taking photos of mycologists when you want to snap the photo at the time of the right smile. If the photo is not already focused, the camera will take a short time to focus before taking the picture. Remember that if the person moves closer or farther away, you will need to refocus. The other situation occurs when you want an object in focus that is not in the center of the photo. In that case, you point the camera at the object you want in focus, press the button halfway down, recompose the photo, and press the shutter release.
3. Zoom in and out
There will be a button on the camera that you press one way for W (wide angle, which gets more in the picture, sometimes indicated by a magnifying glass with a minus in it) and the other for T (telephoto, which brings a distant scene closer, sometimes indicated by a magnifying glass with a plus in it). There are two types of zoom: optical and digital. The optical zoom takes its information from a smaller area of what you are photographing and works like a telephoto lens. 5X optical zoom is roughly like a 150 mm lens for a film camera. Digital zoom just magnifies the information the camera has from the optical zoom and is better done later on the computer (for an exception see footnote in When you Buy a Digital Camera above). Many people turn digital zoom off.
4. Review and erase individual photos
There is always a Playback mode, and usually this is controlled by a button with a triangle pointing right surrounded by a rectangle. This will show your most recent photo. On most cameras there is a left and right control (often on a ring with a button in the center, and the control can respond up or down as well). Use the left to go to previous pictures. Once you are looking at one of your photos, you can usually use the zoom control to look closer and see if it is roughly in focus. The left, right, top, and bottom controls will then move you to a different part of the photo, and you will have to experiment to go back to the place where left and right will take you to the previous or next picture. If all else fails, just press the Playback mode button off and start again.
There is usually no need to erase individual photos right after you take them. This is better done later on the computer. You may want to erase photos if your camera fills up and you still want to take more pictures. While you are looking at a photo, press a button that has a garbage can on it, or DEL.
5. Transfer photos to a computer
You will need to set up the program that comes with the camera on your computer first. The best programs will then allow you to connect your camera to the computer via a cable to a USB connection (or connect its memory card directly if your computer has a compatible card reader), then click on a button on the computer to make a new folder and transfer all the images on the camera to the computer. While this is straightforward for people who use computers a lot, others should get the photo shop salesman or a helpful friend to show them how to do this. A few programs do not automatically make a new folder and you have to do it manually. If you have a previous digital camera, you can often use the same software without installing the program that comes with the new camera.
6. Erase all photos
Transferring your photos to the computer will generally not take them off the camera. You need to remove them as soon as you know that the transfer is successful for two reasons. The first is that you need the space on the camera for new photos. The second is the transfer would take longer next time and more hard disc space will be used on your computer because of transferring those photos twice.
You definitely need to ask the photo shop salesman how to do this, especially if you don’t like to read manuals. (Of course in the latter case you may not be reading this either.) Because the camera designers don’t want you to do this by accident, they make it hard to do, which is okay, but then it’s hard to do. There are two general ways, one is a menu item to format the disc, and one is an Erase All instruction.
7. Recharge batteries
Rechargeable batteries designed for the camera will last longer than AA alkaline batteries, although with some cameras you can use the latter in a pinch. Disposable batteries are not ecological. Ask your camera salesman whether it matters if you don’t remove them soon after they have finished charging, and whether it matters if you charge them when partially charged.
8. Close-up (Zoom, Macro Setting, Controlling the flash)
You can use the zoom to make your photo of a small object larger. Note that the largest photo of a small object may require moving all the way to W on the zoom, but may be partway toward the T. This is because the W allows you to go closer but also makes everything on the screen look smaller. You can experiment or ask the photo shop salesman, or sometimes the information will be in the manual.
Most cameras have a macro setting (usually with a tulip symbol). This allows you to get closer and have a larger photo of a smaller object. Be careful to turn it off when you go back to distant objects, or they may all be out of focus. Be aware also that if you are very close to an object, less of the object will be in focus, and there will be a distortion in which the closer part of the object will be larger (look at a people’s noses after you take a close-up of their faces).
Another problem with close-ups is that the flash will wash everything out and needs to be turned off. (The flash is set to work best for a medium distance). Usually there is a button or setting on the outside of the camera that cycles between Flash Auto, Flash Off, and Flash On. If turning the flash off makes too dark a picture, you may need to partially block the light from the flash. This can be done with a finger, but thin white tissue paper provides more even light without the color distortion reflecting off the finger.
9. Faraway objects such as animals
Zoom in to the T end of the Zoom Control (sometimes marked with a plus sign inside a magnifying glass). More expensive cameras have special lenses, but these are not required for most people.
If you have changed your cameras settings to allow more photographs to fit on the memory card, it is worthwhile to increase the size (back from 3 Megapixels to 7 Megapixels for instance). This gives better detail in enlargements later. It is also worthwhile to use the highest quality, which is usually an independent setting.
An optional refinement here is to turn off the digital zoom. Cameras will come with a certain amount of optical zoom (performed by the lens), usually marked 3x, 5x, 12x, etc. This can be extended in some cameras with digital zoom (performed by the software), but you do not really get any more information in your picture and the manipulation is better done later on the computer. If you don’t turn it off, you may get a false sense of how good your photo will be, because you lose quality as the software pushes the magnification.
The flash that comes with the camera will typically not work beyond 15-25 feet.
10. Low light
In low light, there are four main problems: camera movement, narrow depth of field, dark photographs, and failure to focus. The camera will try to slow down the shutter speed (which increases camera movement), make the opening that admits light wider (making the range of distances that are in focus smaller), and sometimes lighten the photograph (which causes distortion of color and detail).
For camera movement, the best option is a tripod, but although this stops the camera from moving, it doesn’t stop your subject from moving or being blown by the wind. When not using a tripod, hold the camera in two hands and keep your elbows at your side, or stabilize the camera against a non-moving surface. Squeeze the shutter release between your thumb at the bottom of the camera and your finger on the shutter release, rather than pushing with your finger.
Camera movement is also reduced by a fast SHUTTER SPEED, and this is the reason that it is a problem in low light, when the shutter speed would normally be slower to allow in more light.
Depth of field is wider when the opening is smaller (APERTURE has a larger number), but this is the reason that it is a problem in low light, because the smaller opening lets in less light.
Dark photographs can be remedied partly by the camera by increasing its sensitivity to light (ISO), but that causes some deterioration in quality.
When you take a picture in low light there is a compromise among the factors shutter speed, aperture, and ISO. The automatic settings try to compromise between shutter speed and aperture, but you can optionally control all three factors yourself, depending on which of reduced movement, wider depth of field, and best quality are the higher priorities.
On the automatic setting, the camera will set shutter speed and aperture for you. Optionally, you can choose a programmable automatic setting (often P), aperture priority (often A), shutter speed priority (often S), or manual settings (often M). In addition there is usually an ISO setting, which asks the camera to admit more light, at the expense of some deterioration in quality.
Use aperture priority (A) when you want a wide depth of field more than reduced movement, and shutter speed priority (S) when you want reduced movement more than you want a wide depth of field.
The M setting allows you to set each independently, but you will then be guessing at the correct exposure. It may be useful if what you are photographing is very dark or very light, as the automatic settings, A, and S will all tend to produce a more neutrally colored photo. You can use an automatic setting to read on the cameras display what aperture and speed it will use, and then set it manually slightly differently to compensate. (Many cameras will have another way of compensating for a dark or a light picture with Exposure Compensation.)
The problem of the camera’s being able to focus in low light is an issue when you are buying the camera, and sometimes cheaper cameras perform better than expensive ones. The camera will be better able to focus if you focus it on an object with lots of contrast. As always with focusing, beware of objects in the foreground (sticks in front of a flower or mushroom for instance) that cause the camera to focus too close.
11. Moving Objects
Moving objects need a fast shutter speed, or and increased sensitivity of the camera to light (ISO). Often there will be an optional scene setting for moving objects, which sets a fast shutter speed. There will be some loss of depth of field but this is normally only a problem for close objects. You can also choose shutter priority (often S) which will do roughly the same thing. Increasing the ISO number will allow a faster shutter speed at the expense of some quality.
12. Focus Problems
In bright light the main pitfall occurs when the camera focuses on a different object from the one you have in mind. On automatic mode, the camera will select an area emphasizing the center of the scene to focus on. There are usually optional ways to change the size or shape of the focus area. Beware of objects in the foreground (sticks in front of a flower or mushroom for instance) that cause the camera to focus too close. If the area you want in focus is not in the center of the picture, you can usually fix the focus by pressing the shutter release partway down, and then recomposing your photo.
Focus is particularly a problem in low light (see above).
13. Back light
If you are shooting into the sun, you will tend to get silhouette-like pictures with a dark foreground, because the camera sets itself for the average amount of light. You can compensate for that with a scene setting designed for backlit subjects or an Exposure Compensation setting.
You can also force the Flash to be on to light up the foreground. (Because of the bright light in the background, it would normally be off). Usually there is a button or setting on the outside of the camera that cycles between Flash Auto, Flash Off, and Flash On.
14. Bright light
Bright sunshine produces too much contrast for the subtle rich colors that you want to see in faces, flowers, and mushrooms, for instance. The best solution is to shade the subject.
You can use a large reflector such as white cardboard to bounce some light back onto the dark side of the subject. There are often optional settings to turn down the contrast on the camera, and this may be done to a certain extent on the computer with a photo editing program.
Another bright light situation occurs with scenes containing snow, white sand, or brightly lit water. The extra brightness or glare deceived the camera into making the photo too dark. Use a special scene setting, an Exposure Compensation setting, or set the exposure manually.
When you take photographs of people, a flash on your camera will bounce off the red retina in the back of people’s eyes, causing their pupils to appear red. A setting on the camera reduces this by flashing a bright light to reduce the size of the pupil before the photo is taken. The problem is the delay may cause you to miss the ideal expression. Red-eye can be dealt with on the computer with a photo editing program as well. More expensive accessory flashes that work from away from the camera solve this problem and allow more lighting options, but are beyond the budget of many people.
16. Processing on your computer
What you do here will depend on the kind of photo processing software you have on your computer. If you plan only to print them through a photo dealer, you can just choose some and burn them to a CD to take to the photo dealer. If you want to send them to someone by e-mail, or post them on a website, you need to do at least the following steps: a) change the size to a good size for viewing on a computer, about 600-800 pixels in length, b) check the contrast, color, and focus and correct them if necessary, and c) save them as .jpg files for the Web. For more sophisticated processing, see the next section.
17. Aids to Recording Information about Specimens
Remember to record information that cannot be seen: odor, taste, surface feel, consistency, weather conditions, and nearby trees.
A ruler can be placed in the photograph, preferably at the bottom so that can be cropped away if desired later. Another option is to place a coin in the picture to indicate scale.
Christine Roberts makes a suggestion that is appropriate to many genera for digital photography particularly - to make a colour correction bar to include at the edge of your pictures (so it can be trimmed off for any publications). This allows you to correct for colour balance. To make one use fade-proof opaque pigment colours in 2-3 reds, blues, greens, yellows and browns, painted onto thick, white, acid-free paper. If these are made in bands 1 cm thick, it doubles as a ruler. Seal it both sides with matte acrylic spray sealer (e.g. Krylon). Cut it in half and keep one half taped to your computer or printer and one half for use in the field. This would be in addition to a white card used for white balance.
Martin Osis says when considering accessories for fungal photography, consider the following in order of priority.
a) a good tripod. A good tripod is one that allows you to take good quality photos in low light conditions. The tripod should above all else be stable, even when it is windy. It should allow the versatility to get your camera close to the subject. Consider a tripod with a horizontal arm for this features.
b) a remote shutter trigger. When using a tripod this allows you to snap the photo without jostling the camera.
c) a detachable flash. A detachable flash allows you to position the flash in an assortment of positions for different results. You can fully light the underside of a mushroom to avoid shadows that can occur or eliminate other shadows falling across the subject. You can position it at an angle so you do not get the full effect of the flash directly on the subject. Another consideration is the ability to put a defuser over the light (like a white sock of sorts) to avoid over-exposing the subject at short distances.
d) a macro lens. This is a wonderful accessory if you can afford it to get minute details.
Know the camera (and other gear). Read the manual. Understand the histogram. Ask for help (manufacturers, vendors, clubs, friends, web sites) if necessary.
Study the technique of processing images on the computer (post-processing). Aim to capture images so as to minimise degradation of image quality in post-processing.
Go through the camera settings via the menus, and set them for maximum image quality.
Carry lots of memory, so that you will be able to take multiple exposures, and afterwards select the best.
Carry enough battery power, for the flash as well as for the camera, if you use a flash.
Lower ambient temperatures tend to decrease sensor noise; higher ambient temperatures tend to increase battery output.
Use a semi-automatic exposure program (aperture priority, shutter priority), or metered manual, rather than the fully automatic program mode. These modes give you the most control. Avoid built-in picture modes on the camera that don’t allow you to adjust parameters.
Use an appropriate metering method: matrix metering for complex scenes where the subject occupies much of the frame away from the centre; centre-weighted where the subject is predominantly in the centre of the frame (for which matrix often works fine, too); or spot metering for very unevenly lit scenes (meter an appropriate spot).
Apply exposure compensation if necessary. Or set both shutter speed and aperture manually.
Bracket exposure if in doubt about the correct exposure. Some cameras can be set to do this automatically.
Check the histogram, and review the captured image for blown highlights (featureless white) or blocked shadows (featureless black). If you camera offers it, turn on flashing indication of clipping (overexposed highlights or underexposed shadows). Specular highlights are OK to be clipped; any other clipping represents a loss of image data.
In desperation, you can push exposure just as with film. This means deliberately underexposing, and then compensating for the under-exposure in post-processing. The cost of this is typically some difficulty with colour, or digital artifacts (noise and clipping, particularly). Likewise, you can pull exposure by compensating for over-exposure in post-processing.
If photographing by available light, use manual white balance, if possible. Carry a white card with which to calibrate white balance in close-up photos. Don’t use a gray card, since some gray cards are not neutral in colour.
Bracket white balance if in doubt and your camera has the ability to do that.
Review the image on the LCD after capture, to check the white balance. Even if you cannot correct it in the field, you can compare it to the actual specimen to note what correction to apply in post-processing.
Focus and Depth of Field
If the camera isn’t focusing on what you want, specify which autofocus points or modes (e.g., wide, spot) to use, if your camera allows that.
Focus manually if the camera can’t lock autofocus, or does not focus where you want it to.
Depth of field depends only on aperture and magnification, for a given image size. Magnification is determined by focal length and distance from the subject; a greater focal length at a greater distance from the subject produces the same magnification as a smaller focal length at a lesser distance, so depth of field is the same in both cases, other things being equal. Smaller magnification and smaller apertures (higher f-numbers) produce greater depth of field. Remember that the depth of field is roughly about twice as far behind the focus point as in front, so the focus point should be nearer to the front of the range that you want to be in focus.
If you are using a zoom lens, and the situation offers you flexibility in the distance from your subject, you might choose a focal length at which the optical characteristics (e.g., distortion, sharpness, chromatic aberration, etc.) of the lens are better. Similarly, lenses are often optically best about two stops down from wide open, as a rule of thumb.
Review the image on the LCD after capture, to check the focus and depth of field. Zoom in to check the focus.
In order to minimise noise in the image, set your camera to the minimum ISO (sensitivity). This will require greater exposure; so if using available light, you may need to use a tripod. There are inexpensive, compact, lightweight tripods that let the camera be positioned low to the ground, good for many fungus specimens.
The camera can also be stabilised for longish exposures without a tripod by resting it on the ground or against a solid object.
To minimise noise, maximise the exposure without introducing highlight clipping (in other words, maximise the signal-to-noise ratio). Of course, you wouldn’t want to do this for a low-key image.
If your camera has noise reduction for long exposures (such as dark frame subtraction), turn it on if it is beneficial (some noise reduction algorithms significantly reduce image detail).
Noise is generally less visible with lower in-camera sharpening settings (this doesn’t apply to raw format). Noise that hasn’t been sharpened in the camera can be effectively reduced in post-processing, and then more sharpening can be applied to the image without rendering noise more visible.
Other Digital Artifacts (pixelation, quantisation, clipping, compression)
To maximise detail and avoid pixelation artifacts, capture the maximum number of pixels at the minimum compression (often expressed as an image quality level) that your camera allows, and do not resize images in the camera.
Depending upon the intended use of the picture, capture it in raw format if possible, and if you are willing and able to post-process; all the more so if the exposure or white balance is challenging. Raw format typically saves greater colour depth than JPEG or TIFF formats (quantisation is finer), and offers more flexibility and latitude to adjust the image at leisure in post-processing (and while using a large monitor under controlled conditions, rather than a relatively small screen on the camera, in field conditions). Raw format does not introduce artifacts through lossy compression, as JPEG does.
Avoid channel clipping through careful attention to exposure and in-camera processing. Even if the luminance histogram appears correct, individual colour channels could be clipped where colours are strong or contrast is high in the scene. Set contrast and saturation to low on the camera in order to avoid channel clipping; adjust contrast and saturation in post-processing.
Ignore "digital zoom". Better results can be achieved via cropping and resizing in post-processing.
Review Images on Camera
As already stated, review captured images on the camera’s LCD screen to check for desired composition, exposure (view histogram), focus, and colour.
Post-process on the Computer
Keep a read-only master copy of the original image, straight from the camera. Work only on a non-master copy.
Use a colour-managed workflow to reproduce colours most faithfully.
Save working files in a non-lossy format, such as that of your image editor, or TIFF, PNG, BMP, or lossless JPEG 2000. Do not save working files in JPEG format, since every time you save in this format, some degradation of the image occurs, due to loss of information via compression.
To avoid colour banding, work in 48-bit colour.
Use good image processing software to: reduce noise; adjust white balance; adjust tonality (the relative contributions of different colors); adjust saturation; sharpen or blur; retouch; rotate; resize; crop; and save in a desired format.
Aperture – the size of the opening that admits light through the lens, specified by the f-stop. The f-stop indicates the size of the opening for light to go through the lens (the size of the aperture). Higher numbers means a smaller hole, less light, and a greater depth of field. The actual number is the focal length of the lens divided by the diameter of the lens. At f8, an 80mm lens will have a 10mm diameter (8 = 80/10). The f-stop is usually given as one of a series, each step of which admits double the light of the one before (and each is arithmetically the previous number divided by 1.4): f22, f16, f11, f8, f5.6, f4, f2.8. If you move the f-stop one step to a higher number, you will need the shutter open for double the time, i.e. f22 at 1/250 second gives the same amount of light as f16 at 1/500 second.
Bracketing – In case the exposure is not exactly right, extra photos can be taken slightly underexposed and slightly overexposed. One of them is likely to be the ideal exposure. Other variables, such as white balance, may also be bracketed
Chromatic aberration – colour fringing caused by the lens not focusing different wavelengths (colors) of light to the same degree or magnifying the wavelengths differently.
Channel clipping – refers to clipping that occurs more in one color channel (red, green, or blue for instance) than another.
Clipping – Clipping of an image happens when shadows are underexposed and featureless or highlights are overexposed and featureless. The exposure is adjusted to eliminate this phenomenon.
Colour-managed workflow – a system of inter-relating the colors used by the image file, the computer’s memory, and its peripheral devices such as scanners and printers
Colour space – A color space is a way of relating the numbers associated with each pixel to the colors produced, and defines which colors are produced and which are not. sRGB is the most commonly used on computer monitors and in digital cameras, but some cameras give the option to used Adobe color space, which has advantages for printing. A photo taken in Adobe color space will appear flat on a normal monitor. The term "color space" may also be used to specify how many bits (0s and 1s) are used to specify each color.
Compression – The files that contain the complete information picked up by the cameras sensor are very large, which fills up the memory card quickly. Various methods can be used to make a compressed file which contains almost the same information in a smaller file. As a rough way of understanding this, if all the pixels are blue the file could say "blue, blue, blue, blue, blue…" or it could say "20,000 blue pixels" The most popular compressed formats for camera photos and for computers as well are the .jpg or .jpeg formats. When the compression results in loss of information this is called "lossy compression". Uncompressed files are called raw files. A 2M photo can be compressed more or less (allowing more or less photos to be stored) and this is usually given as an Image Quality option. Generally the rule it to choose the least compression that will give you enough photos on the card. Having a card with higher capacity (1Gb instead of 250Mb for instance) will allow more photos for the same quality or higher quality for the same number of photos. The issue of quality is not critical for e-mailed photos, somewhat more important for photos displayed on computers, and very important for enlargements.
Dark frame subtraction – At slow shutter exposures, hot spots will be produced in similar areas of the photograph. Dark frame subtraction involves taking a black photo (like one with the lens cap on) and subtracting that from the original image.
Depth of field – how much in front of and behind the subject is in focus. It is determined by the f-stop, the focal length of the lens, and other characteristics of the lens. (See also discussion under Focus and Depth of Field above.)
Exposure compensation – If the cameras suggested exposure is not quite appropriate, you can apply exposure compensation to make the exposure somewhat lighter or somewhat darker than the one suggested. For instance a backlit subject, light colored subject, or subject showing glare from snow, sand, or water can fool the camera into suggesting a lower exposure than you want. You could apply a positive exposure compensation to correct for this. A dark-colored subject might need negative exposure compensation.
F-stop – see aperture.
Histogram – a graph from dark to light showing how much of the photo is at each light level. A well-exposed photograph looks something like a bell-curve with lower values at dark and light. There should not be high values at the dark end unless there is a black area, because that implies loss of shadow detail. There should not be high values at the light end unless there is a white area, because that implies loss of highlight detail. If there is nothing at the dark and light ends, the photo lacks contrast.
Image Quality – see Compression. In addition to compression, the number of Megapixels is directly related to quality (see that heading also).
ISO – This stands for International Standards Organization but in a photography context indicates the sensitivity of the camera to light. A higher number means greater sensitivity to light. The best image quality is produced by the lowest ISO available on a camera, but in low light this will require a slow shutter speed or a wide aperture, both of which have disadvantages. Typically the camera will automatically choose the best setting, but it can often be set manually to override the automatic choice.
Matrix metering – a way of reading the light coming into the camera from various points of the subject being viewed, and combining them to arrive at a suggested exposure setting.
Megapixels – Each photograph made by the camera consists of color values for each of many points of light. At its maximum, a 4M camera will have a rectangular array of points of light (pixels) 2400 pixels wide and 1600 pixels high = 3,840,000 total pixels or approximately 4 Million.
A computer monitor display also consists of pixels A 4M photo at 2400 x 1600 pixels will be too large for the computer screen at a typical 1024 x 768 pixel resolution unless something is done to shrink the image. Depending on how you view the image on the computer, the shrinking may be done automatically but the file size will not change. When you send this photo by e-mail it will take a long time to send, and when you post it on a website, it will use a lot of space and take a long time to download. It is generally better in those cases to shrink the image in an image editing program.
A 4M camera can make smaller photos with less pixels (2M for example) and there is a setting to allow you to do this. The photos will then be smaller on a computer. The advantage of the smaller photos would be 1) more photos fit on a given size of memory card, and 2) the ability to send the photos via e-mail or post them on websites without shrinking them. On the other hand, there is less information to improve in a photo editing program, or to make an enlargement.
A card with higher capacity (1Gb instead of 250Mb for instance) will allow more photos for the same size or a larger size for the same number of photos.
Noise – The sensor that received light in the camera is part of an electrical circuit, which produces some noise (unwanted errors in the signal). This appears in digital photos as graininess or specks of false color and is particularly a problem in low light. Noise reduction can often be turned on to process some of these (or turns on automatically at slow shutter speeds), but it will usually take longer for the photo to be written to the memory card. During that time you will be unable to take the next photograph.
Pixelation – Each image is made up of spots of light called pixels. If there are many pixels in an image, these will not be visible, but as the image is enlarged they become more visible.
Quantization – Quantization is the assignment of numbers to the heights of a wave at various points. A light wave is quantized when it is converted to numbers in a digital image. Quantization error is the difference between the analog wave and its digital representation.
Saturation – described the intensity of colors in an image. An over-saturated image has colors that are too intense.
Shutter speed – the amount of time that the shutter is open to admit light when you press the shutter release. Generally speaking shutter speed slower than 1/30 second will introduce blurriness due to camera movement (unless the camera is on a tripod). If you zoom to 8X, this figure would be 1/ (30 x 8) or 1/240 second.
Specular highlights – mirror images of a light source seen as a reflection on the surface of the subject, which may be diffused into a sheen or shine.
White balance – Different lighting conditions produce different color tones which our eyes compensate for automatically. The digital camera tries to do this automatically, but many cameras provide a way of setting the white balance manually. You take a picture of something pure white such as a white card and the camera adjusts to that. If you change lighting or setting of course, you have to go back to the automatic setting or redo the white balance manually.
(1) A single lens reflex allows you to compose through the same lens that takes the photograph. In addition to the exact framing and easier focusing, single lens reflex cameras tend to have a larger sensor size. For a given number of Megapixels, each pixel usually gathers more light if its size is larger, leading to less trouble with low light exposures.
(2) An exception with some cameras occurs when using less than the largest image size. In those cameras, the entire image sensor can be used to zoom digitally without losing image quality.
(3) For 35mm film cameras a 50mm lens (focal length of 50mm) gives approximately a normal view without magnification, (and a 400mm lens would give about 8X normal view). A 3X zoom from 35 to 105mm gives almost the same magnification power as a 4X zoom from 28 to 112mm. One 12X digital zoom camera has a focal length from 6mm to 72mm, and this is equivalent to 36mm to 432mm in a lens for 35mm film. This lens therefore goes up to about 8X normal view. Usually cameras specifications will give a 35mm equivalent and this is the easiest way to work how much magnification it gives in relation to the “normal” view.
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