Hello for the 11th time,
This is obviously Part 11 of my notes and comments on digital photography for
bird-photographers.
In this part I will discuss miscellaneous accessories and a bit on digiscoping.
Add-on lenses (also know as Conversion Lenses):
A 'teleconverter' increases the magnification while a 'wide converter' gives a
wider angle of view.
As far as I know, all 'consumer' type digital cameras come with fixed lenses,
i.e., the lens cannot be removed without dismantling the camera.
So, in general terms you need to have a good idea what you plan to do with your
camera so that you get one with a suitable lens.
For bird-photographers that will mean the most powerful lens possible.
As we have already seen this class of camera has few models with what could be
called 'powerful' lenses.
The most powerful that I am aware of has a 35mm equivalent of approximately
380mm.
Most only go to around 250mm.
This is in spite of them having zoom ranges between 6x to 10x.
To increase the power of the lens it is possible, sometimes, a teleconverter
lens can be attached to the front of the lens.
I say "sometimes" because it is necessary to have a thread in the front end of
the camera lens to screw the teleconverter into.
Not all digital cameras have this thread!
My Olympus C-700 does not have this thread in the lens but uses an adapter tube
that screws into the body of the camera and covers the extended lens.
The teleconverter then screws into the front of this tube.
This adapter tube has a 55mm thread so that any accessory that has a matching
thread can be directly attached.
An old 1.4x teleconverter I had for an analogue video-camera fits this adapter
perfectly.
However 1.4x magnification is not enough for the purpose of bird-photography.
With the C-700 this gives a 35mm equivalent of approximately 530mm.
I also have a Sony Digital 8 camcorder for which I have a Sony 2x converter.
With this attached to the C-700 the 35mm equivalent is approximately 750mm.
(Note: I am only referring to the optical power of the lens and not the digital
zoom power.)
This is what I would think to be around the minimum required for
bird-photography with a 2 mega-pixel camera.
Cameras with CCDs of greater than 2 mega-pixels produce larger size images when
viewed at full size on a computer thus having the effect of increasing the power
of the lens.
Maybe a larger CCD could be considered as a substitute for a more powerful lens?
Think about that.
(Digital cameras ARE different to film cameras and require a bit of lateral
thinking to get the most out of them.)
Fitting the Sony 2x teleconverter to the C-700 wasn't as easy as it sounds, I
was just lucky.
This teleconverter is designed for a 37mm thread. Normally this would require an
unusual combination of step-down rings to adapt it to the digital camera adapter
tube. However, this teleconverter comes with a set of adapters also.
one of these adapters is for a 52mm thread which is common on video cameras
these days.
A single 55 to 52 step-down ring allows the Sony adapter to connect to the
Olympus adapter tube.
Complicated? Yes, but it works and shows what can be done with a bit of thought
and luck.
Actually the best way to do this would be to find a teleconverter with a 55mm
thread and a magnification of at least 2x.
There are such things but in Australia you may have to hunt around for them.
Try the second-hand box at your local camera shop or the pawn brokers.
A brand to investigate would be Raynox.
I believe they make a range of teleconverters in a range of thread sizes and
magnification power.
When looking for teleconverters check out ones intended for video cameras
as well as the ones for still cameras. Be aware that the quality varies.
Other brands available in other countries have magnification powers up to 8x
with some units being zoom type lenses themselves.
I would advise being cautious with how powerful a teleconverter you fit to your
digital camera.
Definitely try before you buy.
Check that the autofocus still works with the teleconverter fitted.
Also check the edges of the picture as well as the centre for correct focus .
With increased lens power comes the increased probability of chromatic
aberration, strange colours appearing in the wrong places in the picture.
Check for excessive vignetting.
(Vignette: An engraving, drawing, photograph, or the like, shading off gradually
at the edges.)
Vignetting is caused when the teleconverter is not matched correctly to the
camera lens and produces a small, round image with an obvious black border.
Generally this occurs when the zoom lens on the camera is set to the minimum.
Bird-photographers will generally be using maximum camera zoom when using the
teleconverter so don't worry if there is obvious vignetting up to about half the
zoom range.
Even a small amount of vignetting at maximum zoom could be tolerated if the
picture is sharp and clear.
The final image can be cropped to remove any dark edges.
Digital cameras don't provide a very wide-angle view at minimum zoom so for
those extra-wide shots a wide-converter could be fitted.
A substitute for this could be to take a series of overlapping shots with the
standard lens and use a computer software application to 'stitch' them into
a panorama. I will talk more about this later.
Even bird-photographers want to take some macro (close-up) shots at times.
Digital cameras usually have reasonably good macro capabilities but this can be
enhanced with close-up rings.
One problem here is that the in-camera flash will probably be useless for these
extremely close encounters. ( See also my comments on external flash units.)
Close-up rings look like normal filter rings and often come in sets.
Remember, if you have visions of wanting to add extra lenses or filters check
that the camera you are considering can accommodate.
Polarising Filter:
A polarising filter can be useful but the recommended type for digital cameras
is the circular type.
Of course, they all look circular but I am referring to the polarising pattern.
You won't be able to see this; the only way you can tell if it is a circular
filter is by the label.
The older non-circular polarising filters may upset the autofocus system.
Actually, I have tried both types on my C-700 without any apparent trouble.
Remote shutter release:
It would seem that most consumer digital cameras don't have a facility for a
remote (cable) shutter release, however, some digital camera users have
devised brackets that are attached to the camera by the tripod screw thread.
These brackets are designed to hold a cable release positioned over the shutter
button.
There are details of commercial units at:
http://www.steves-digicams.com/digi_accessories.html#flash
This is also a good place to find out more about converter lenses etc.
Digiscoping:
Digiscoping is done by attaching a digital camera to a spotting telescope.
Many bird watchers have a spotting scope in their kit so the addition
of a suitable digital camera can provide a very powerful tool for
capturing high grade bird photos.
Of course the best quality pictures are obtained with the best quality
equipment.
That is, it is best to use a very good quality scope such as the Leica Televid
APO 77 model but it is only necessary to use a 'modest' consumer digital camera
such as one of the Nikon Coolpix 9xx series.
Actually, the Nikon Coolpix 9xx series (now replaced with the 4500) were good
cameras but with only a 3x or 4x zoom lens they were not ideal for
bird-photography. The essential attribute for a digital camera intended for
digiscoping is that the lens 'matches' the eye piece of the scope.
That is, a camera with a small diameter lens is best to avoid the vignetting
mentioned above.
Also it is preferable that the lens does not move out when the camera is
activated thus maintaining a set position in relation to the eye piece of the
scope.
The Nikon Coolpix 9xx series was ideal in this regard.
I imagine the new 4500 model with its 4 mega-pixel CCD would be even better.
Other models with the same attributes should also work well.
The ideal method of mounting the camera to the scope is with a dedicated
adapter.
The combination of Leica scope and Nikon Coolpix 9xx camera is a popular one so
such an adapter is obviously available for this setup.
Unfortunately I don't have either instruments.
My experiments with the Olympus C-700 suggests that it is not an ideal camera
for digiscoping.
The lens on this camera is large and moves out when the camera is switched on
making it difficult to position correctly as well as producing excessive
vignetting.
Although a digiscoping setup such as the one described above is a far bigger and
more 'cumbersome' setup than a consumer digital camera with a powerful zoom lens
and a teleconverter it is a relatively easy and 'inexpensive' (especially if you
already have a good scope) way of obtaining a very powerful digital camera for
bird-photography.
It must be remembered, of course, that the same 'rules' apply to digiscoping as
to other forms of photography : The ratio of 'good' shots to 'not-so-good' shots
is probably 1 in 50.
Up to this point in time I have not had any personal experience with digiscoping
but some of the results others have produced show that this is a very viable
system of digital photography especially suited to bird-photography.
More information on this topic can be found by searching for 'digiscoping' on
the internet.
In the next and probably the last part of these notes I will discuss what to do
with your images.
Cheers
Bob Inglis
Woody Point
Queensland
Australia.
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
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