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Re: Lens->Telescope adapter (Help identify this equipment?)
Yes, I have several of these for different mounts. They are all 5x
multiplication. Best is with a 300mm mirror lens -- gives a very
small, light, high definition telescope for use whilst walking etc.
I use mainly elderly pre-set or broken lenses at full aperture.
Best with 200mm prime, or 80-210 zoom. Provides dirt cheap, quality,
'scope. Even better if u rig up a tripod mount
Colin
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Craig Bailey wrote:
>I'm interested in trying some close-up photography using my Canon AE-1
>Program.
>
>I have a Canon 50mm lens and wondered what the best approach would be:
>Do I need to purchase another lens? Or would extension tubes for my
>existing lens serve the same purpose?
What kind of images do *you* want to make???
Diopter supplementary lenses, reverse rings, using a short lense
(say 50mm) as a diopter by mounting it reversed in front of a
longer lense, extension tubes, bellows, tripods, focusing rails,
ring flash units, "macro" zoom lenses that can do 1:4
magnification, macro prime lenses that can do 1:1 magnification,
flat field lenses, and using enlarging lenses... are all topics
related to different kinds of photomacrography.
There is a huge difference in what to talk about if the intent
is to take pictures of very small, very flat, or 3 dimensional
items.
With a regular 50mm lense there are a few characteristics that
you'll want to know about, because they restrict what it can do.
Your 50mm lense will almost certainly need something to help it
focus closer, and either a bellows (which will put it into
manual mode only) or extension tubes (which can be either manual
or can provide automatic functions too) will work well.
Supplementary (diopter) lenses that mount like filters do not
have as much effect with shorter focal length lenses, hence only
a very strong diopter would work and of course the stronger the
diopter the more it degrades the sharpness of the lense, hence
that would probably not be as productive.
With extension tubes or a bellows, a short focal length like
50mm will have a very short working distance, but give
significant magnification. Not Good, if you want pictures of
rattle snakes, for example. And you'll be so close that most
insects will flee in terror, so that's out too.
It will not have a very flat field either. And it will probably
have a very distinct decline in sharpness if the aperture is
anywhere near either wide open or fully closed. Basically
you'll only get sharp images at f/8 and maybe f/11 or f/5.6.
That means you cannot get much depth of field for 3 dimensional
objects, and yet it isn't very versatile for flat objects
either.
Some of the limitations do have work arounds though. For fairly
large objects, such as flowers, a 50mm lense with a short
extension tube will do just fine if you can set the aperture to
f/8 and vary exposure in other ways. A tripod and focusing rail
might be handy, especially if natural light and long exposure
times are used. Or two or more flash units can be used
creatively too.
What kind of pictures do you want to take? Tell us that, and
folks will describe the easiest ways, the cheapest ways, and the
most versatile ways. All different, and probably all both fun
and productive to some degree.
--
Floyd L. Davidson
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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