Number 4 Photographing your Maps Compiled by Hans Kok
|
|
|
|
|
|
|
|
|
|
|
|
A few years ago, when this series of leaflets was conceived, it seemed that photographing was all we needed to cover. However, with new techniques available and computer-driven capabilities growing around us, the scope of this leaflet has been expanded, though the title remains as forecast.
A. Reasons
Recording for commercial use and institutional collections is beyond the scope of this leaflet, but there are various reasons for the map collector to have his collection recorded:
Generally the choice is between:
Note: When selecting any of these systems, do not forget to consider long term, compatibility of hardware, software and storage, and display medium (e.g. will a CD-Rom disk still be read in twenty years' time, or can data be easily transposed to more modern media when the time comes?)
Storing prints and slides is easy; no direct light, preferably in the dark, normal home temperatures and humidity are acceptable. Insertion of separation sheets between prints is recommended, as photos may stick together and be damaged when pulled apart. A second set as back-up is a good idea, to insure against calamaties. For prints, storing the negatives is adequate. The second set should be kept in a separate location.
Storage of digital data has different requirements. Digital data require back-up. Theft, fire, heat, magnetism (floppy disc and magnetic tape), computer virus/crash and inaccurate keyboarding all pose a hazard. CD-Rom and DVD disc are most suitable for data storage. To transmit data physically, e.g. by mail or courier, you require equipment to "write" data instead of only reading it. In view of the amount of data per map, a CD writer or zip-drive is required.
Scanned at an acceptable resolution, a CD Rom disk holds only 10 to 12 maps (up to 45 MB each). A DVD disc will accommodate about 100 maps on a 6GB disk. Higher resolution means increasingly more data for the same size map; larger maps naturally generate more data at the same resolution, leading to fewer maps on the same disk. Data compression (JPEG protocol) reduces required storage by an average factor of ten.
Professional photographers may have equipment set up in their studios; this means you will have to take your maps there. With very large or framed maps, this may be risky, complicated or even impossible. Professional firms usually have their own crates, boxes and vehicles to transport your maps, when you cannot do this yourself. Having the photographer in your home may be easier, if there is adequate space available to set set up the equipment. This is only cost-effective if a large number of maps are to be photographed (say, 80 or so).
Note: The photographer will be able to work faster if the maps are sequenced according to size (small to large or large to small). This avoids major changes in camera position and setting and reduces lens changes.
Use of the camera as a recording device requires a choice between professional operator or "do it yourself". If a professional is selected, a commercial (general) photographer is a better choice than a portrait photographer who will be less experienced with flat-surface work (repography). Ask if they will work at your home, and what the price difference would be. Working at your home, it should be possible to shoot about 100 maps a day. Installation of the equipment takes time (about two hours) but the actual photography is quick, especially if you are willing to lend a hand. If you are satisfied with less than 100 per cent professional quality and have the necessary equipment you can try it yourself.
Siting: Taking the shorts in the open air is possible, with the advantage of daylight quality. This is, however, often impractical due to rain and wind, and potential damage to the maps. Take care in the handling, and avoid your shadow obscuring the map, or relections from the tripod or stand or clouds. Keep pets well away. Framed maps should not be photographed outside, because it is impossible to avoid reflection of the glass/plexiglass. Working inside the house requires large windows, and the reflection problem may remain. The advantages of natural light are the low set-up time, the evenness of the light source, use of a camera light meter to determine exposure time, and use of daylight film (ASA 100).
Lighting: the most important rule in photographing maps is that the light on the maps should be even from corner to corner and without shadows and reflections. Never use ordinary fluorescent light tubes, they have a discontinuous light spectrum. This means that no matter how much you filter the light, the colour of the maps will not be reproduced faithfully. Red may be good, but blue comes out as green.
Artificial light sources must be balanced for the film used. Electronic flash is matched to ordinary (daylight) films, but halogen and tungsten lights are matched to artificial light film. This type of film is a specialised product, available in photographic shops. It is possible to combine daylight film with halogen lights, provided a blue filter is used on the camera lens (type 80A or 80B). If your camera has a "through-the-lens" metering system, it will automatically compensate for the filter; if it has not, give approximately one stop extra exposure to compensate for the blue filter. Never use a combination of flash and artificial light source, as the "colour" of the light cannot be properly corrected.
It is always necessary to use two lights or two flash units. The flash units need to be synchronised. Using twin flash units, make sure the units are identical; buy a camera adaptor plug; one plug goes into the camera and allows two flash leads to be connected. Extension flash leads will be required. Another possibility is to buy a flash "slave unit" to be attached to the flash unit and not the camera. When the camera flash goes off, the slave unit ensures that the second flash will fire automatically and instantaneously. Flash light has the added advantage of not heating during use.
Note: If you know a hobby-photographer, you may be able to borrow his photo-lights.
Standard SLR (single lens reflex) cameras need normally to be set at 1/60th of a second shutter time for the flash mode, adjusting the aperture only (f11,f8 etc). Select the manual mode on both flash units or chose the same power ratio (if selection is available). In the auto-function of the unit the first unit will be influenced by the second flash and this may result in uneven exposure across the map.
The disadvantage of flash light is the difficulty of obtaining even light across the map, as the flash is hard to see. Use of a (relatively expensive) flash-meter is essential; alternatively take and develop test shots before starting on the whole collection. Professional flash units (expensive) use a "modelling-light" to determine exposure; these systems are not discussed here.
Note: A low-priced solution for map photography would be to purchase two identical halogen lights at a "Do-it-Yourself" shop of the type used in the construction business or in home security systems. 200 to 500 watt lights are adequate.
Film type: For daylight film, regular ASA 100 fine grain
film is good; more sensitive film has a coarser grain and is less suitable
for enlargement. Standard film format may be used, but may not always
yield a field-of-view matching map size. The real professional might
use a plate camera, suitable for non-standard format film. The 24x36
mm format provides good resolution; cameras accommodating 4x5 inch format
are even better.
Note: For the same resolution, large maps require larger
format.
Set-up: Mount the lights or flash units on some form of tripod, equidistant from the centre of the map, angle the lamps downward towards the opposite edge of the map. The height of the lamps above the ground should be the same and each should subtend an angle to the centre of the map of approximately 45 degrees. In order to avoid reflections of the lamps if the map is framed, the lights should be positioned at sufficient distance from the sides of the frame (assuming the camera to be exactly above map-centre). The lights must always light the map evenly, hence the need to place them at equal height and distance from map-centre.
To prevent reflection of the camera in the glass and your own reflection, cover any shining parts of the camera etc. with matt black tape or cloth and use a cable shutter release. The camera light meter can be used with halogen lamps; for flash units, see above.
Note: A lateral arm can be bought which will attach to a tripod. Consider the necessity of a counter-weight to one of the tripod legs, when cameras and/or lights are mounted off-centre.
Supply a background for the map, catering for the largest map to be photographed. A matt black carton/board will be fine, so is a white or off-white one. Beware of room carpets, flowery textiles and wallpaper, reflecting glass in cupboards and mirrors. Maps in passe partout and framed maps may be moved to match field of view; for loose maps I recommend moving the background board rather than the map itself.
It makes good sense to save up a number of maps to photograph in one session. A repro-stand has to be made (make-shift will do) to speed up the process and achieve consistent results. It is important that the lens be above the centre of the map; otherwise a rectangular map will turn out trapezoid.
A camera where the viewer uses the camera lens is best to determine the cut-out to be photographed. An independent viewer lens may introduce parallax; the field of view, as marked in the viewer, is only valid for one distance between camera and map in this case. It is thus easy to miss a border, plate-mark or paper margin intended to be included in the photograph.
The camera must be parallel to the map; use a spirit level to check that both the camera and the map are perfectly level or vertical as the case may be. A framed map is less likely to be completely horizontal or vertical due to the hanging fixtures mounted on the rear. Two halves of a clothes-peg or a wedge-shaped door-stopper are perfect to correct in both axes, when the floor is used for the map, with the camera overhead. If the map is placed upright make sure it is absolutely vertical, and remains in this position, with the camera absolutely vertical in front of it. If the map is placed at an angle against a wall the camera should be adjusted accordingly (not easy to do).
Marking the background board with a centre point and a grid of, say,
three cm intervals is very helpful, as it makes it easier to judge how
much the map should be moved to fit the field of view. This is particularly
useful when the repro-stand requires you to bend a lot or climb steps in
order to look through the view finder.
Camera distance from the map should be adjustable to obtain the correct
cut-out. Changing to a wide-angle lens map help. A lens with
zoom capability is very useful.
All in all, it is important to give the repro-stand careful thought beforehand, as a good stand will expedite the photography and help avoid frustration. If you plan to shoot a large number of maps, it pays to have a few trial shots developed initially, so as to spot problems at an early stage.
When the work is completed the decision remains to produce slides as uncut positives or mounted with or without glass. Glass mounts protect better, should be free of Newton rings, prevent focus changing under projector heat, but may damage slides if the glass breaks (e.g. during mailing).
Note 1: Both prints and slides need to be organised for
retrieval and link-up with the original map and/or its specific notes or
description, perhaps in a database.
Note 2: It may be worth considering taking two shots of
each map, to prepare a back-up set (for transparencies). For positives,
two prints can be made from each negative, or the negatives themselves
can serve as back-up.
Note 3: Colour slides are easily stored on disk by a photo
shop and can then be read into a computer. Photo shop resolution
is subject to data compression. Kodak photodisks store at four levels
of resolutions, for use of "thumb-nail" prints to full size.
Digital cameras are being improved all the time. Cameras with less than one million pixels are of insufficient resolution and are not suitable for our purpose. The storage media have not yet been standardised; pictures taken may eventually end up as prints or in computer storage. However, camera storage media all suffer from limited capacity. For small collections and where no more than postcard size is required, they may possibly be adequate (1999 technology). Adequate cameras do exist but their price is prohibitive.
Present-day home scanners are not usable for map recording, being restricted to A4 size; also resolution may be insufficient. Commercial firms exist which reduce industrial or institutional archives to manageable size. Scanning cost are currently approximately $10-$15 per map.
Maps which are too large to be scanned will be handled by using a slide as intermediate step. Such a slide will be read into a computer by a dedicated slide-scanner. Sizes up to 55x75 cm can be scanned without restriction; some scanners can handle larger material. The intermediate step can also be used for framed maps, without the need to remove the frame.
In general, good recording of your maps means recording in the highest possible resolution. An average coloured map may run to 45MB of data; a black and white map would be considerably less, but the white would be very white indeed. I recommend recording monochrome (uncoloured) maps as if they were coloured, so conserving the paper tone as well. Using a lower resolution would reduce the number of disks required to storage, but would limit available detail later. This might be acceptable for collection overview, insurance and internet use.
Scanner firms offer an alternative. They scan the maps at maximum resolution; data so collected will be stored and delivered to you as TIFF-file on CD-Rom disc. Scanned data will also be stored after data-compression (according to JPEG protocol), resulting in a second set of CD-Rom disks (fewer disks, more maps per disk). The TIFF-files could be kept away safely, to serve as a master back-up or used only when full resolution is required. The JPEG disks would be adequate for most day-to-day purposes.
Note: TIFF-files can be used to produce JPEG-files; the other way round is not possible.
Before chosing a system, ask yourself the following questions:
When your collection needs to be recorded, you will need a duplicate set of records, one to work with and one as back-up to be kept in a safe and separate place.
Colour slides will be most versatile, as your photo shop can easily combine and store them on CD disk, ready to be printed, should you wish. Colour slides can be read into a computer, using a dedicated slide scanner. Colour slides may be projected on screen or wall. You can make colour slides yourself.
In terms of quality, a video camera "still" is the least desirable, slightly better is the digital camera (with at least one million pixels), followed by your own colour slides. Next best is the professional photographer with optional scan-in. Top choice would be a professional scan with parallel colour slides to make the system more versatile. The computer adept may want photo-software with printer and a CD writer or zip-drive to "write" data.
Caution:
All the above is fun and serves to conserve your precious maps.
As such, it is extremely useful, but nothing is more enjoyable to the real
map-lover than cautiously handling and studing his own maps, where memories,
scent and touch add the final flavour to map collecting.