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Comparison of the Brunton Eterna 80mm Spotting
Scope and the Kowa TSN82 82mm fluorite lens Spotting Scope for
digiscoping
Another simple comparison: using the Brunton Eterna
80mm Spotting Scope and the Kowa TSN82 82mm fluorite lens Spotting
Scope in conjunction with a Nikon CoolPix 4500 digital camera.
The camera was handheld to the optics, which were mounted on tripods.
The poor image quality comes from handshake and slow shutter speeds
due to reduced light at higher magnifications (see shutter speeds
in each caption). Image quality can be improved by using an adapter
to mount the camera to the scope (none exists yet specifically
for this scope-camera combination) and a cable/remote shutter
release. All images are full-framed. Both scopes had vignetting
with the camera set at full wide-angle, as shown on the previous
page.
I had the scopes set up side-by-side and set both
on the same birds. I shot several shots through each scope, hoping
to use the same lighting conditions and bird posture. I was not
able to get a full set of comparable images. At first pass, the
Brunton scope seems to be quite comparable to the Kowa. It appears
that both eyepieces are of the same dimensions, so a CoolPix to
Kowa adapter may work with the Brunton.
Please do not download these images without acquiring
permission to do so. All images are copyrighted by Les Chibana.
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| Brunton Eterna at 20X |
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Kowa TSN82 at 20X |
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Field of View
Although it may not seem like it from these
shots, the fields of view seem comparable. There was substantial
wind that blew the bush around; not the best choice of subject
and conditions. I thought that I could notice about 2mm
worth of wider objective for the Kowa, but this was probably
my imagination. Both scopes set at 20X and the camera at
maximum optical zoom (4X).
Brunton exposure: ISO 200, f7.3, 1/34
Kowa exposure: ISO 200, f7.3, 1/44 |
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Brunton Eterna 80mm Spotting
Scope
Scope at 20X, camera at maximum zoom (4X).
This is a 1st-winter Golden-crowned Sparrow.
ISO 200, f7.3, 1/62 |
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Kowa TSN82 82mm Spotting
Scope
Same setup as above. The brighter image is
a result of to the changing lighting conditions from a patchy
cloud cover.
ISO 200, f7.3, 1/203 |
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Brunton Eterna 80mm Spotting
Scope
Different bird, same setup as above, unfortunately,
the camera focused on the foreground foliage.
ISO 200, f7.3, 1/155
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Kowa TSN82 82mm Spotting
Scope
Same bird and setup as above.
ISO 200, f7.3, 1/88
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Brunton Eterna 80mm Spotting
Scope
Same setup as above, focus seems to have shifted
back a bit.
ISO 200, f7.3, 1/120
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Kowa TSN82 82mm Spotting Scope
Same bird as in first two bird images and
same setup.
ISO 200, f7.3, 1/202
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Brunton Eterna 80mm Spotting
Scope
For this shot, I set the scope to 40X. Unfortunately,
the birds flew off and I couldn't get a shot on the Kowa
at 40X.
ISO 200, f6.9, 1/56 |
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Brunton Eterna 80mm Spotting
Scope
This was an attempt to test how well the scope
transmitted light in low light conditions. I aimed at a
shady spot in a tree. Scope set at 20X. The shutter speed
was very slow.
ISO 200, f6.6, 1/4
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Kowa TSN82 82mm Spotting Scope
Same test for the Kowa, also set at 20X. It's
possible that the Kowa transmitted almost twice the amount
of light as indicated by the shutter speed, but in this
range, it hardly matters. The difference in image density
could have resulted from the small amount of image processing
that I apply to all images. The comparable images have the
same processing.
ISO 200, f6.6, 1/7
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