PlaneWave CDK12.5 Astrograph f/8: Following the successful introduction of the CDK 20" Astrograph from Planewave a few years ago, many amateur astronomers expressed a desire to purchase such an optical design with a smaller aperture and thus significantly more affordable. With the CDK 12.5", Planewave now presents a telescope that meets these requirements.
- Quartz glass optics modified according to Dall-Kirkham, with fully corrected image field
- 3" prism rail
- Hedrick focuser (without EFA kit), prepared for Delta T heater
The CDK optical design
The PlaneWave CDK layout is an optical design based on the classic Cassegrain design by Dall-Kirkham.
It was developed to accommodate the ever-increasing size of chips in digital and CCD cameras. With many other mirror optics, you quickly see off-axis aberrations such as coma and/or astigmatism; in addition, many systems suffer from image field curvature, which causes the images of stars to become increasingly blurred as they move away from the optical axis.
The image field is free of coma and astigmatism. In addition, the image field plane is absolutely flat and level across this diameter, so that stars are reproduced with the same sharpness across the entire field in the focal plane.
The CDK design offers a perfect solution to the problems mentioned above, with an excellent price-performance ratio and moderate delivery times.
It consists of:
- an elliptically curved primary mirror
- a spherical secondary mirror
- and a 2-lens field corrector
All three optical elements are perfectly matched to each other to achieve the incredible image quality. The image quality is largely dependent on the seeing conditions at the location.
2.75" Hedrick Focuser: Heavy-duty no-slip focuser with 1.3" of drawtube travel when fully racked out. The focus tube runs on 5 bearings and is driven by a leadscrew, so there is no chance of slipping.
The quartz glass (fused silica) used is a synthetic amorphous quartz glass of the highest purity and one of the most transparent glasses available. Due to its purity, the optical and thermal properties of quartz glass are superior to other types of glass. Its transmission and homogeneity exceed those of crystalline quartz and avoid the problems of temperature instability that crystalline quartz glasses suffer from.
Fused silica has a thermal expansion coefficient six times lower than that of borosilicate glass (Pyrex). It therefore retains its shape with a very high degree of accuracy when it cools. This results in consistent optical performance and an unchanged focal point during temperature changes.
L-Series Direct Drive Mounts
The L-Series combines versatility, simplicity and affordability by packaging proven technology, such as the CDK700 and the 1-metre PW 1000 telescope used in universities around the world, into a compact, stand-alone mount.
- The L-350, with a payload of over 45 kg, is ideal for the CDK14 and CDK12.5.
- The L-500, with a payload of over 90 kg, is ideal for the CDK17 and CDK20.
- The L-600 carries up to 136 kg and is ideal for the CDK24.
The mount is equipped with direct drives and high-precision encoders. The software is fully ASCOM-compatible and allows precise positioning and satellite tracking.
In Alt / Azimuth configuration, it is much more compact than a parallactic mount. This allows the movement radius of a larger telescope to be much smaller. This means that large instruments can be housed in small protective structures, saving a lot of money on the dome or building. Unlike parallactic mounts, there are no meridian flips and no large, protruding counterweights. The Alt/Az mode is more intuitive to use and there is no need for polar alignment.
Scope of delivery:
- telescope
- L350 mount
- Motorised 2.75" focuser. Requires the separately available EFA kit (electronic focuser)
- Built-in heating elements to prevent dew formation. The heating elements on the primary and secondary mirrors require the separately available Delta-T controller for PlaneWave telescopes with pre-installed wiring for the heating.
- Cover to protect the primary mirror and the inside of the optical tube
- Cover for the secondary mirror
- Flash drive with software and instructions for collimation and primary-secondary mirror alignment
- Tool kit
- 12V AC adaptors
- Six 3/8-16 x ¼" hexagon socket screws for screwing the mount to the column or polar wedges
- Six 3/8-16 x ¼" washers
- One extension bolt for the RA axis for polar alignment with the polar wedges
- The "EZ Saddle" 3" dovetail clamp accepts Losmandy D-dovetail rails such as those on the CDK12.5 and CDK14.
- A 4.8-metre USB cable – for connecting the mount to the observatory's control computer
- A 120V AC power cable – to power the mount
- A standard hex key set – for tightening the screws on the mount
- Flash drive – Contains the PWI4 software for controlling the mount and installation instructions
