With some cameras, like the digital Fuji F30 above, there is a special mode which allows photos to be taken continuously if the shutter button is held down. The camera is used in 'shutter priority' mode and set to 1/1000th second and ISO 100-400 for use on sunny days. The above camera will produce 340 best quality images on a 1GB card in about 10 minutes. Ideally, the camera should have a lens with a maximum aperture of f2.8.
Cameras that do not have a 'shutter priority' mode can be set to the 'sports' or other high speed shutter option instead e.g. Pentax Optio E35 and the Pentax cameras listed below.
For most situations where we cannot select a specific shutter speed (using Optios E35/W60 and Fuji F100fd), we usually choose an ISO setting of 200 or 400. With high ISO settings, you are always trading off image quality, with the ability to take photos at a high speed (camera 'shake' versus noise). A camera that can take relatively low noise images at ISO400 is recommended and image stabilisation (not to be confused with cameras that simply choose a high ISO) is an added bonus. The Optio E35 produces noisy images at ISO 400.
Many cameras set the exposure and focus at the initial press of the button, so have the camera pointing at something the same brightness and distance as the subject that you want to photograph. We normally pre-set our visible spectrum cameras to infinity for aerial shots.
Normally, it is advisable to set the camera's exposure compensation to minus 1/3 or 2/3 of a stop, so highlights are not lost. When working in the near infra-red, exposure compensation is essential and minus 2/3 of a stop may not be enough, minus 2 is not unusual. It is easier to pull details out of a dark image at the processing stage than one where the highlights have been burned out.
As an alternative to using a clamp, a cable-tie (or elastic band) can be used to hold down the shutter button. The smaller loop is slid forwards along the larger one (see above) to hold the shutter button down. The small loop can also be placed over the button by sliding the large loop along the camera. Variations in the cable-tie configuration are appropriate for different cameras. If access to any buttons is restricted a plastic toothpick can be useful.
This continuous shooting technique is also useful if you want to take pictures using the camera on a conventional monopod (or long telescopic or sectional pole). Alternatively, you can take a single shot on a shutter-delay setting. See here.
This is a simple alternative to wireless control and can also be used in conjunction with a 10 second delay. We no longer use radio-triggered SLRs.
The easiest technique is to use a camera which has an interval (time-lapse) mode, giving user control over a sequence of shots eg Pentax Optio W60. Such cameras are less common and usually more expensive than many with a continuous shooting mode. The Optio W60 is now our preferred camera for normal KAP and PAP.
Another non-wireless approach is auto-KAP. One of the advantages of using an LED trigger, over the continuous shooting mode, is that the exposure is re-set for each shot.
A Premier Power Sled 24 or HQ 1.7 is suitable for compact cameras and a Power Sled 36 for SLRs, or compact cameras in a light wind. Sleds smaller than the 1.7 and of a simpler design, can be very unstable.
The Power Sled 24 was our routine choice for KAP (Rosie, John and Jim), but we now use other kites including a Sutton FF16, Becotized FF16, HQ FF2.0 & FF4.0, Large Longbottom Delta Sled and Dan Leigh Deltas (Jim) and others. For use in strong winds we also had a Nighthawk Delta which lasted for two full days of continuous use, flown tethered in harsh conditions.
Rosie with a Premier Power Sled 36
We find the drogue operates more efficiently if attached with a swivel but we prefer a fuzzy tail.
The rig can be a very cheap DIY job, as shown at the top of this page (and below), or the Brooxes Simplex can be bought (~£30) from the KAPshop. If you are based in north America, you can order the Simplex directly from Brooks Leffler. We have one of these and it is a good choice if you are new to KAP and do not want to construct one yourself.
The primary requirement for archaeological work is that the camera can be pointed vertically downwards. A low distortion lens is desirable, although software corrections can be applied to digital images. The free program GIMP has an easy to use correction tool (via Filters>Distorts>Lens Distortion). Simply take a calibration photo of a brick wall, or for more accuracy a grid, and apply the correction tool to the image, making a note of the settings needed to correct any distortion. Then apply the same correction to any other image. The correction needed will depend on the focal length used, but in most cases this should be your widest setting i.e. shortest focal length. Unless specifically stated, our images are not corrected for lens distortion. See also (1), (2), (3) and the free Agisoft Lens.
Threading the picavet line is much easier than it may first appear:
Published with the kind permission of David Hunt ( http://www.kaper.us/basics/BASICS_picavet.html )
© David Hunt
The threading sequence is: R1-Rc-A-R2-Rc-C-R1-D-R2-B-R1
Flying a simple rig will give the experience to decide if a more sophisticated set-up is needed and what system may be appropriate for the intended application. A visit to the website of our local KAP specialist, James Gentles, is recommended.
Update Summer 2008
Small modifications have been made to our original setup. The larger cross (our preferred choice) can now be packed flat.
N.B. Here the camera is attached to the rig at three points, base screw, strap and cable-tie.
A later modification to the Optio E35