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Below are answers to some of the most frequently asked
questions about the HyperStar system. Read the instruction manuals for the
HyperStar lenses on their respective
product pages.
How Does the HyperStar Lens Work?
The HyperStar lens replaces the secondary mirror at the front
of a Schmidt-Cassegrain telescope (SCT). Most SCTs operate at a focal
ratio of f/10, which is very slow photographically. This requires a long
exposure. The HyperStar lens converts the telescope to an f/1.8 optical
system (f/2.0 for a 14" scope). This allows incredibly fast images, up to
33 times faster than at f/10! In addition to shorter images, the telescope
may does not need to be polar aligned, nor is guiding necessary. Deep-sky
imaging is vastly easier than it used to be!
Why Do I Need a HyperStar Lens to Image at
the Front of the Telescope?
A Schmidt-Cassegrain telescope uses a primary mirror which
has a focal ratio of around f/2. The secondary mirror provides a 5x
magnification, yielding an overall f/10 system. Removing the secondary
mirror and placing a camera at the front of the scope allows f/2 imaging.
But without a corrective lens, the image would be awful. The primary
mirror alone suffers from spherical aberration and field curvature which is
normally minimized by the secondary mirror. The HyperStar is a
multiple-element lens which corrects the inherent aberrations in the telescope,
allowing f/1.8 imaging with a highly-corrected field of view.
Does the Corrector Plate Have to be
Removed?
No. A HyperStar-compatible telescope has a retaining
ring, like the lid of a mason jar, that you simply unthread by hand to remove
the secondary mirror. The mirror is attached to a plate with the
collimation screws on it. This lifts out of a holder in the corrector
plate (which also holds the baffle tube on the inside of the corrector plate).
The mirror is safely stored in a protective holder while outside the telescope.
The HyperStar lens attaches to the holder in the corrector plate. No tools
are required and the corrector plate never comes off the scope.
What is the Image Quality Like with
HyperStar?
Excellent. The HyperStar lens uses a sophisticated,
custom-designed optical system. There is a different HyperStar lens for
each model of telescope, not just because the physical size must be different,
but because the lenses are optimized for each telescope design. The result
is a flat field of view which is sharp from edge to edge. The star images
with HyperStar are sharper than using the same telescope at f/10, despite the
field of view being 5 times wider!
What Telescopes Are Compatible with
HyperStar?
Currently, the HyperStar system is available for Celestron
8", 11" and 14" Schmidt-Cassegrain and Meade 10" and 14" Schmidt-Cassegrain
telescopes. Some telescopes of these sizes will need to be converted to
HyperStar compatibility. HyperStar requires the telescope to have an
easily removable secondary mirror assembly. Fastar-compatible Celestron
scopes and select Meade telescopes will already be compatible. For those
which are not, Starizona offers conversion kits to retrofit non-compatible
telescopes.
Will HyperStar Work with Meade LX200R
Telescopes?
At this time, Meade LX200R telescopes are not compatible with
HyperStar lenses. Only the Schmidt-Cassegrain optical systems are
compatible.
Can I Use a Digital SLR Camera with
HyperStar?
The size of the CCD chip that can be used on the HyperStar
lens is dependent on the telescope used. The bigger the telescope, the
bigger the HyperStar lens, and thus the larger the chip which can be illuminated
by the HyperStar system. Digital SLRs are compatible with 14" HyperStar
lenses (for both Celestron and Meade), but not the smaller models.
Can I Still Use My Telescope Visually with
HyperStar?
You can easily switch between the standard f/10 (visual)
configuration and the f/1.8 HyperStar configuration. Converting from one
to the other takes less than 5 minutes. Since the secondary mirror is
removed for HyperStar imaging, viewing cannot be done simultaneously, but the
image can be viewed via the CCD camera on the computer screen. A 1-second
focus exposure will show more than your eye would ever see at the eyepiece!
This makes finding and framing objects very simple.
Do I Have to Collimate My Telescope Each
Time I Use the HyperStar Lens?
No. The secondary mirror is indexed so it goes back
into the telescope exactly the way it came out. This retains the alignment
of the optics precisely, eliminating the need to recollimate after HyperStar
imaging.
How Do You Focus the Telescope with the
HyperStar Lens Installed?
Focus is achieved using the standard focus knob on the
telescope (moving the primary mirror). The image is seen on the computer
screen via the CCD camera, so focusing is very easy. Autofocusing is also
possible using a motorized focuser such as Starizona's Wireless MicroTouch
Autofocuser. Despite focusing with the primary mirror rather than a
Crayford-type focuser, mirror shift is not an issue. Remember that the
image from the primary mirror in an SCT is normally magnified 5 times by the
secondary mirror. With HyperStar, the secondary is removed so any mirror
shift is reduced five-fold. The field of view is so wide with HyperStar
that any image shift is not an issue.
Can I Use HyperStar for Lunar and Planetary
Imaging?
HyperStar is ideal for deep-sky imaging but is not
well-suited to solar system imaging. For planetary imaging you need very
high magnification, the opposite of what the HyperStar gives. While the
moon may be framed well using the HyperStar lens, the system is so sensitive
that it will be all but impossible to avoid overexposing the moon.
Are There Any Disadvantages to Using
HyperStar?
You won't sleep anymore.


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