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Download the raw, full-frame FITS files from
this
folder. Absolutely no processing has been done to
the files. They are the raw, unaltered images. Ask manufacturers
for raw, full-frame files. Otherwise the shape of the stars can
be misleading because they've either cropped in, loosing field
coverage and not showing the actual performance you'll obtain,
or they have processed the images (also not showing you the actual
performance). Real-world performance can only be judged from
full-frame raw, unaltered images. |
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The telescope is mounted on an equatorial mount, which is far
more mechanically demanding on the mechanics of the optical system
than an alt/az mounted telescope test. If you plan to mount the
telescope EQ, make sure the sample images you're being shown
were taken on an EQ mount. |
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Focus position was not touched during these tests. Focus on this
gen II, 16" f3.75 Dream Astrograph design is sensitive to
+/-8µm from the optimal focus midpoint. Move outside this
16µm window and off-axis stars will go comatic. Dream is
the industry leader in actual high-stiffness and high installed
performance opto-mechanical systems because from day one Dream
has engineered for highly consistent CFSC™
structures that chase stiffness, not strength. If an optical
system requires focus, to compensate for errors that can be seen
as the telescope angle changes, it means mechanical bending of
the structures is occurring. Adjusted focus images are not a
true indication of real-world, installed performance. Ask a manufacturer
for raw images where focus and collimation are not touched at
all during testing. |
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An initial image is taken quickly after slewing to a different
portion of the sky. Then an additional image is taken 10 minutes
later at the same location to show that Dream has unmatched stiffness;
no focus shift due to sky location (slew to and immediately image)
and no settling affect either. Because of Dream's market-leading
high stiffness and athermal nature of our carbon fiber mirror
mounts, backplates and main telescope tubes, as well as our highly
engineered zeroDELTA™
lightweight mirrors, our opto-mechanical systems are at the cutting
edge of both mechanical and thermal performance - by design. |
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The CCD used is a KAI-11002
chip: 9 microns square, 4008 x 2672 (full-format, 42mm diagonal). |
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Collimation of this and
all of the Dream Astrograph telescopes is achieved by using the
custom tools provided to our customers. They are used during
the day and only once. Collimation was accomplished on the
first day with this telescope, then it was not touched
again. |
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The ambient temperature was -7C (19F, +/-5F)
during these all-sky tests. Dream has tested this telescope design
over as much as a 20°F temperature change and still not detected
degradation of the off-axis quality, all while leaving the focus
position untouched. No other manufacturer is delivering this
level of performance. |
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Dream's gen
V, 16" f3.5 Dream Hypergraph will take this to a new
level by producing telescopes with both higher quality optical
surfaces and an optical design that also has far higher quality
than we've ever offered. |
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Use the file number and descriptions below as a quick
reference to know what direction the telescope was pointing for
that given image. |
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2660: Zenith, OTA on east side of mount. |
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2661: North field. |
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2662: same as above but ~10 minutes later. |
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2665: West field. |
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2666: same as above but ~10 minutes
later. |
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2670: South, SW field. |
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2672: same as above but ~10 minutes
later. |
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2673: Zenith but OTA now on west side of
mount. |
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2675: same as above but ~10 minutes later. |
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2677: North field. |
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2678: same as above but ~10 minutes later. |
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2679: East field. |
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2681: same as above but ~10 minutes later. |
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2682: Southern field. |
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2683: same as above but ~10 minutes later. |
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You can look at data from two
additional telescopes on this web page. |
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