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When I choose my 5Mpixel camera for RIG04 at the end
of 2003 I did an extensive survey of all the main manufacturers of high-end
compact cameras. I have not reproduced this here because this information ages
so quickly. Rather I present here a list of areas that you should consider when
selecting a KAP Camera.
This was done specifically with 180 to 250g Compact Digital Cameras with 4 to
6 Mbyte CCD sensors, although I'm sure the headings and considerations may help
with the selection of other KAP cameras, digital and film.
A good place to start is by looking at what experienced KAPers fly, they have
been this way recently, and have experience on their side, although I'm not the
most experienced I hope this page will give you some insight into what's important
and what's not.
When you make your choice you can get some of the data required from the web,
there are numerous sites that allow you to list and compare cameras. However
some of the information you need is harder to obtain and I found myself
downloading Camera Manuals from manufacturers web-sites to get this greater detail. Finally,
even the manual didn't answer some of the questions, and I resorted to trying
the camera out in shops, asking others with similar models, e-mailing
other KAPers, and asking questions on the KAP discussion
page.
 Light, Camera, Action!
First you need to consider where you are - always a good place to start!
- Lightweight? What weight do you want to fly? 200g is a good starting point
for a Compact Digital Camera, but for dSLR or larger formats you will have a
different target.
- Camera? How many pixels? Optical quality? All the things you would
consider normally when buying a camera!
- Action - or money. How much are you prepared to pay, and how much are you prepared
to loose in a heavy landing?
So, pick your price and try to get the lightest, best camera deal you can.
Sounds simple, but before buying read on - there are a few other recommendations
in my opinion!
An interesting article I read recently
(assuming I drew the right conclusions :-) suggested that for Compact Cameras,
then 5 to 6Mpixel was as high a resolution as you could get before the quality
of the small lenses used in these cameras became the picture quality limiting
factor.
 Memory
One other cost consideration is memory cards (or film - some people use
medium format and still use film!). Different film and memory
cards all have an associated cost, which can be significant with respect to the cost of the camera. There is no
point having to keep raising and lowering the rig to put in more film or change
memory cards. For digital cameras I would recommend having at least 100 shots
available per memory card, and if possible 2 cards.
 jpeg compression
Most Digital Cameras allow a choice of image compression, and hence quality.
This is inextricably linked with the memory size. For a given memory you get
more images with higher compression, however the quality of the image suffers,
another choice...
 Aperture
Priority
I consider it essential that the camera has Aperture Priority, this allows you
to fix the aperture at maximum (minimum f setting) and force the shutter speed
as high as it will go. This will greatly improve the number of images that are critically
sharp.
Most compact cameras in AUTO
mode do not behave like this. They tend to use a low f stop until the shutter
reaches about 1/125, and camera shake is less of a problem, then they increase the f stop
to get more depth of focus. Depth of focus is not worthwhile in KAP because you
should always be at least a few meters away from the subject! This need to force
the shutter speed up will be a recurring theme, and does beg one other difficult
to answer question...
For KAP, I would recommend shutter speeds in excess of 1/500s. Once here it
wont take much more light to get you to 1/1000, which is the maximum shutter for
some cameras. When the camera reaches this point it could either:
- beep and say, "I wont take a picture right now" (like cameras do when the
flash hasn't re-charged), or
- Take the picture anyway at 1/1000 at the risk of over exposure.
With KAP, and the camera remote from you, option 1 is not what you want, an
over exposed picture is better than none at all. This is the kind of information
the manual doesn't tell you, and I have resorted to trying the camera in a shop
and taking close up pictures of light bulbs to see what happens!
 Focus
You should be able to lock the camera on infinity.
- Generally there isn't anything in the "foreground" in KAP,
- Fixing the focus reduces the time the camera takes to fire the shutter,
and
- not having the focus motor hunting saves batteries, and therefore weight.
You may even consider cameras with no automatic focus at all, although for
compact digitals, you tend to get this feature whether you want it or not.
 Flash
For all the same reasons as for FOCUS,
you don't need flash.
 EV
The camera should have a means of deliberately under or over exposing
the shot with respect to what it's automatic settings tell it.
I usually have this set to 0.3 or 0.7 stops under exposed. Often my
subject matter tends to be bold, i.e. a white lighthouse tower, and the cameras
automatic exposure in trying to find a compromise over exposes the tower. Most
cameras have more precise ways of dealing with this - e.g. changing the exposure
area, or using a half press of the shutter. These aren't really practical for KAP,
so I go for the underexpose everything option. If necessary this limited amount
of under exposure can normally be recovered in a photo editing package later.
A useful side effect however of doing this is that it will push the shutter
speed up a little, which is always good in my opinion!
 Speed
With a film camera you choose the film speed, with higher specified Digital
Cameras you can set the speed, or rather the gain of the CCD
sensor. Normally the settings vary from around 64 to 400ASA equivalent, with an
automatic mode. AUTO normally
means the camera uses the slowest setting until forced to use higher settings in
poor light, this also increases the amount of noise from the CCD
sensor.
I set the camera to the second slowest setting (100 instead of 64, 200 or 400
in my particular case), this gives a little extra gain, to allow increased shutter speed, but
isn't so sensitive as to allow the CCD
sensor noise to become a problem.
 Settings
Perhaps not essential but a USER
or MY MODE is very useful.
It allows you to store settings in a camera for quick recall. When you launch
the kite and set-up the rig you have lots of things to do, this feature greatly
simplifies the set-up of the camera, so things don't get forgotten in the chaos
of launch.
 Battery and Power
Are you going to run the rig from one battery or have separate batteries for the servos, camera, video downlink etc? Sharing saves weight, but
makes rig design more complex as the different parts tend to require different
voltages.
Another consideration is that some cameras behave differently when powered from
their battery and from the external power connector. Often in the latter case
the power saving features are disabled, so the camera uses more power anyway.
If you are going to power the camera from it's own batteries, standard
batteries (i.e. AA type) are best. Invariably they have a good power to weight
ratio (especially the new NiMH cells), and they can be easily replaced with
stand-by alkaline cells in an emergency. If your camera uses a proprietary
battery pack - make sure it's charged, or you have a spare!
Digital Camera especially are power hungry. There will be times when you fly
when you are walking about and looking for a shot, during these times you want
the camera to be in sleep mode, using as little power as possible. Being
able to vary this time is useful, too short a time is annoying, too long wastes
batteries. When
in this mode you need to be able to wake-up the camera, preferably with
the shutter control, some cameras you need to press the ON/OFF
button to wake it up, this will add weight and extra complexity if you need to
control this button remotely.
 Shutter Release
If at all possible you should consider releasing the shutter
electrically or with infra-red (IR). This reduces the mechanical complexity and the
weight of the rig. It also makes it easier to load the camera into the rig
in the field.
Cameras from the late 1990's had serial ports which could be used to control
the camera, but more recent models in the early 2000's have moved to USB, which
is much more difficult to implement control with. Maybe the next wave of
digitals will have better remote control functionality that KAP could take
advantage of?
There is a big difference between cameras in the time between pressing the
shutter and the picture being taken, this can be especially frustrating with a
constantly moving KAP suspension. Although some of the things already mentioned
will help reduce this (e.g. fixed focus reduces the work the camera has to do in
preparing to take the picture), I'd recommend you choose a camera with as short a
shutter-to-picture time as possible.
If considering IR release, make sure that you are happy with how this works
as some makes only allow a delayed release (for self portraits) rather than an
instant release. Additionally you need to look and see if the camera is woken from
sleep mode by the IR signal if you are interested in conserving batteries as discussed above.
 Video
Output
There are various schools of thought about a video downlink of the
viewfinder. Whilst digital cameras without video outputs are generally smaller
and lighter, you should carefully consider whether you should have a video
output on your list of wants even if you don't plan to use it initially, or feel
it's unnecessary.
Whilst on this subject another couple of points about the video output. Make
sure that the LCD display can be manually disabled or disables automatically
when the video connector is plugged in. The LCD monitor is one of the most
power-hungry parts of a digital camera, and you don't need it when flying! This
was another feature that was tested in a local camera shop. After engaging the
assistant, I produced a pocket TV and used the video lead that came with the
camera to see what happened when the video output was used!
Finally most cameras show a freeze-frame of the picture you have just taken -
but some do not! This is an excellent feature for KAP. Because the camera is
remote from you it is good positive feedback that a picture was taken, and your
rig is working properly.
 Blue Sky
Finally a few ideas that you may consider, but are not easily
obtainable with today's digital cameras:
- Wide angle lenses are excellent for KAP, consider obtaining lenses for
your dSLR, or making sure your compact camera goes as wide as possible,
- Failing the above, does the camera take external lenses? Nikon's compacts
do, but unfortunately they fall down in some other important areas I have
already mentioned.
- Cameras with automatic exposure bracketing can get round the exposure
difficulties already briefly discussed. Beware, this uses three times as
much film/memory, and some models require the bracketing to be re-setup
after every exposure, which is not practical with KAP!
Conclusion
That's a lot of information, I hope you found it useful. As with all cameras
there is an element of personal choice, and dependency on your other
requirements - have fun choosing your camera! Thanks to Peter Bults for
his critique of this page from his experience.
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