CN FORUMS ARCHIVE Telescope Reviews: Testing methods in Polish tests of the binoculars

Hi!

As I promised I post here the comprehensive description of
out testing methods. I appologize for ma poor English but
I hope you will understand what I want to say

Our methods are quite simple because we wanted to
make it in easiest way, which can be followed by other
astronomy amateurs even without sophisticated equipment.

Our tests are made by the group of people connected with the Polish
Comets and Meteors Workshop (CMW), Nicolaus Copernicus Astronomical
Center in Warsaw and Warsaw University Observatory. The people belonging
to this group are: Michal Jurek, Lukasz Kowalski, Krzysztof Mularczyk,
Arkadiusz Olech, Andrzej Skoczewski, Konrad Szaruga Mariusz Wisniewski,
Kamil Zloczewski and Przemyslaw Zoladek. The typical test is made by
5-7 persons and their marks are averaged.

The tests are performed in the following categories:

OPTICAL PERFORMANCE (15 points) - It is measured using the three
methods. The first one make use of Mintorn CCTV camera with integration
of frames option, which is connected to the eyepiece and records the
view of Pleiades. Then the limiting magnitude is computed to get the
transmission/optical performace. The second method make use of diode
which is photographed in the same conditions using each binocular
connected with digital SLR. Next, the aperture photometry is made. In
the third method we project the image of the Sun onto the partially
shadowed screen. The distance of the screen from the binocular is
changed to have equal surface brightness of the Sun's image and of the
screen directly illuminated by the Sun. The ratio between obtained area
of the Sun's image and the true area of the objective is the optical
performance. Often we made several measurements for each binocular, and
from averaging, we estimate the accuracy of our determination up to 3-5%.

CHROMATIC ABERRATION (10 points) - It is measured using the projection
of the image of the Sun onto the shadowed screen. Such an image was
photographed using high resolution digital camera. The photo was then
analyzed by measuring the size of the color rim around the disc of the
Sun in respect to the size of the whole disc. This test measures only
the in axis chromatic aberration and the maximal number of points for
this part of the category was 8. Additionally, we also measured the
off-axis chromatic aberration looking through each binocular at the
sharp edge of the dark roof in front of the bright and blue sky. The
edge of the roof was observed in the edge of the field of view of each
binocular. For this part of the test the binocular could obtain from
-2 to +2 points.

ASTIGMATISM (10 points) - We measured it trying to obtain most
point-like images of the stars and then defocussing them slightly. We
estimated the quality of the in focus point-like images of the stars and
measured horizontal and vertical deviations from the spherical symmetry
of the out of focus images.

DISTORTION (10 points) - The binoculars were mounted on the tripod and
put less than 10 meters from the wall with large area covered by the
millimeter grid. The testers determined independently the distance of the
first curved line from the center of the field of view. The results were
scaled using the true radius of the field of view. The points we
distributed as follows: <= 15% - 0 points, 16-23% - 1 point, 24-30% - 2
points, 31-37% - 3 points, 38-44% - 4 points, 45-51% - 5 points, 52-58%
- 6 points, 59-65% - 7 points, 66-72% - 8 points, 73-79% - 9 points,
>=80% - 10 points

COMA (10 points) - We measured it moving the star to the edge of the
field of view and estimating how fast the star is distorted into a
"coma" and how big is this effect.

SHARPNESS AT THE EDGE (10 points) - The binoculars were mounted on the
tripod and put less than 10 meters from the wall with large area covered
by the millimeter grid. The testers determined independently the true
field of view and tried to find the place where the image becomes fuzzy.
The points we distributed as follows: for 97-100% of sharp field 10
points, 93-96% - 9 points, 89-92% - 8 points, 85-88% - 7 points, 81-84%
- 6 points, 77-80% - 5 points, 73-76% - 4 points, 69-72% - 3 points,
65-68% - 2 points, 61-64 - 1 point, 0-60% - 0 points

EYEPIECES (10 points) - Multiplying the true magnification by the true
field of view we obtain the true field of view of the binocular's
eyepieces. The points we distributed as follows: >=75 deg is 10 points,
70-74 is 9 points, 65-69 is 8 points, 60-64 is 7 points, 55-59 is 6
points, 50-54 is 5 points, 45-49 is 4 points, 40-44 is 3 points, 35-39
is 2 points, 30-34 is 1 point and field below 30 deg is 0 points

BODY QUALITY (8 points) - What kind of material is used for making the
body of the binocular? Is the usage comfortable? Are the eye cups
comfortable and ergonomic?

FIELD OF VIEW (8 points) - We checked if the field of view given by the
manufacturer is true. The binoculars were mounted on the tripod and put
less than 10 meters from the wall covered by the millimeter grid. The
testers persons determined independently the true field of view. The
accuracy of such measurements was 0.02-0.03 deg. If the difference
between measured field of view and that given by manufacturer was less
than 2% the binocular obtained 5 points, for up to 4% - 4 points, up to
6% - 3 points, up to 8% - 2 points, up to 10% - 1 points, over 10% - 0
points. Additional 2 points were given to these binoculars with
especially large field in their class of magnification, and one
additional point was added for true field larger than given by the
manufacturer.

OBJECTIVE DIAMETER (8 points) - We checked if the objective diameter
given by the manufacturer is true. The testers determined the diameter
of each objective using the calipers. The results were then averaged
and thus the final value had an error of 0.05 mm. Each of the objectives
could obtain four points. If the difference between data of the
manufacturer and true diameter was less than 0.1 mm the objective
obtained 4 points, for 0.1-0.3 mm - 3.5 points, 0.3-0.5 mm - 3.0 points,
0.5-0.7 mm - 2.5 points, 0.7-0.9 mm - 2.0 points, 0.9-1.1 mm - 1.5
points, 1.1-1.3 mm - 1.0 points, 1.3-1.5 mm - 0.5 points, for more than
1.5 mm - 0 points.

VIGNETTING AND QUALITY OF THE PRISMS (8 + 8 points) - We measured how
much of the light gathered by the objective is cut off by small or
badly placed prisms. We checked the glass type of the prisms (BaK-4 or
Bk7) and its quality. The measurements were made by photographing the
exit pupils of the binoculars and measuring their deviations from the
ideal circle and determining the darkened area.

GUARANTEE (6 points) - The points we distributed as follows: 0 points
for guarantee less than one year, 1 point for one year, 2 points for
two years, 3 points for 3-5 years, 4 points for 5-10 years, 5 points for
10-30 years and 6 points for life-time guarantee.

EYEPIECES SPACING (6 points) - We measured minimal and maximal spacing
of the eyepieces. The marks for the maximal spacing were as follows:
>=74 mm - 5 points, 73 mm - 4 points, 72 mm - 3 points, 71 mm - 2
points, 70 mm - 1 point, <=69 mm - 0 points. One additional point was
given to these binoculars which had minimal eyepieces spacing smaller
than 50 mm. One point we removed those of the binoculars which had
minimal eyepieces spacing larger than 59 mm.

COLLIMATION (5 points) - It was checked by putting a bright star into
the center of the field of view and slowly moving away the binocular
from the eyes of the observer (up to 20 cm). Maximal mark was given to
these binoculars in which the image of the star did not become double.

BLACKENING AND DUST INSIDE (5 points) - A beam of bright light was used
to look inside the objective and estimate the quality of blackening and
amount of dust. We looked for the presence of white glue, dust,
scratches on the prisms, shining elements, etc.

INTERNAL REFLECTIONS (5 points) - We photographed the exit pupil and
its vicinity while the binocular was placed in the dark room and was
pointed at the illuminated white wall. The maximal mark was given for
the pupil with the dark vicinity.

FOCUSING (5 points) - We estimated how smooth the eyepieces are moving.
We checked if there are any irregularities in their movement or is it
possible to defocus the binocular by pressing the eyepieces.

WHITENESS OF THE IMAGE (5 points) - We observed a white wall through
all the binos and checked how they change the color.

DARKENING AT THE EDGE (5 points) - We measured it moving the star to the
edge of the field of view and estimating how fast the brightness of the
star is decreasing.

ANTI-REFLECTION COATINGS (5 points) - We estimated the quality and number
of air-to-glass surfaces covered by anti-reflection coatings.

MAGNIFICATION (3 points) - Using a digital camera we photographed the
exit pupil and measured its size. Knowing the true diameter of the
objective we were able to determine the magnification of the binocular
with accuracy of 0.2-0.3 times. If the difference between data of the
manufacturer and true magnification was less than 5% the binocular
obtained 3 points, for less than 7% - 2.5 points, for less than

MININAL DISTANCE FROM WHICH THE VIEW IS STILL SHARP (2 points) -
It is estimated by looking at the milimeter grid.

--------------------
Megrez I 80/480, Minolta Activa 10x50

Post Extras