PlaneWave CDK12.5 Optical Tube Assembly

Starting Price: $10,000.00
Price as Configured: $10,000.00
Brand: PlaneWave Instruments / SKU: PW-125101


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Recommended Add-ons and Accessories
Product Price Quantity
PW-125150 - PlaneWave Counterweight Accessory for CDK12.5
PW-125150 - PlaneWave Counterweight Accessory for CDK12.5
About This Product
This PlaneWave counterweight accessory mounts to the dovetail bar of the CDK12.5 for critical balance in declination. The kit comes with a mounting bracket and three 0.5lb weights. Additional weights (PW-125382) can be purchased separately.The kit can also be mounted on larger telescopes (CDK17, 20, 24) with the Piggyback Dovetail & Bracket (See Related Products below).
$290.00 each
PW-125166 - PlaneWave Reducer 0.66X CDK12.5/14/17
PW-125166 - PlaneWave Reducer 0.66X CDK12.5/14/17
About This Product

This is a reducer designed specifically for flat field telescopes like the CDK. This reduces the f ratio of the CDK telescope 66%. The CDK12.5 f/8 telescope will be reduced down to f/5.3. The CDK14 will be f/4.8  and for CDK17 f/6.8 will be reduced to f/4.5

**NOTE – 125166 adapter is compatible with CDK17 that have 10.24″ back focus.   CDK17 with 8.81″ back focus will use the 200166 focal reducer. See instruction manual for details.

$1,400.00 each
PW-6009003 - PlaneWave FINDER SCOPE AND MOUNTING BRACKET
PW-6009003 - PlaneWave FINDER SCOPE AND MOUNTING BRACKET
About This Product
The finder mounting plate attaches to the back plate of the telescope and the quick-release finder bracket attaches to the mounting plate. If the telescope used in on a German Equatorial Mount, it may be convenient to purchase two finder scopes - one for the east and one for the west side of the telescope. The finder scope is a Baader 10x60 Varios with mounting rings and L-bracket. The back plate of all of the PlaneWave CDK models has four mounting positions for a finder mounting plate.
$460.00 each
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PW-125150 - PlaneWave Counterweight Accessory for CDK12.5
PW-125150 - PlaneWave Counterweight Accessory for CDK12.5
$290.00
« Back to All Add-ons
PW-125150 - PlaneWave Counterweight Accessory for CDK12.5
About This Product
This PlaneWave counterweight accessory mounts to the dovetail bar of the CDK12.5 for critical balance in declination. The kit comes with a mounting bracket and three 0.5lb weights. Additional weights (PW-125382) can be purchased separately.The kit can also be mounted on larger telescopes (CDK17, 20, 24) with the Piggyback Dovetail & Bracket (See Related Products below).
PW-125166 - PlaneWave Reducer 0.66X CDK12.5/14/17
PW-125166 - PlaneWave Reducer 0.66X CDK12.5/14/17
$1,400.00
« Back to All Add-ons
PW-125166 - PlaneWave Reducer 0.66X CDK12.5/14/17
About This Product

This is a reducer designed specifically for flat field telescopes like the CDK. This reduces the f ratio of the CDK telescope 66%. The CDK12.5 f/8 telescope will be reduced down to f/5.3. The CDK14 will be f/4.8  and for CDK17 f/6.8 will be reduced to f/4.5

**NOTE – 125166 adapter is compatible with CDK17 that have 10.24″ back focus.   CDK17 with 8.81″ back focus will use the 200166 focal reducer. See instruction manual for details.

PW-6009003 - PlaneWave FINDER SCOPE AND MOUNTING BRACKET
PW-6009003 - PlaneWave FINDER SCOPE AND MOUNTING BRACKET
$460.00
« Back to All Add-ons
PW-6009003 - PlaneWave FINDER SCOPE AND MOUNTING BRACKET
About This Product
The finder mounting plate attaches to the back plate of the telescope and the quick-release finder bracket attaches to the mounting plate. If the telescope used in on a German Equatorial Mount, it may be convenient to purchase two finder scopes - one for the east and one for the west side of the telescope. The finder scope is a Baader 10x60 Varios with mounting rings and L-bracket. The back plate of all of the PlaneWave CDK models has four mounting positions for a finder mounting plate.
PW-200368-3 - PlaneWave 2" Drawtube Spacer (L=3.3")
PW-200368-3 - PlaneWave 2" Drawtube Spacer (L=3.3")
$140.00
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PW-200368-3 - PlaneWave 2" Drawtube Spacer (L=3.3")
About This Product
This drawtube spacer allows for 2″ imaging, or visual accessories to be attached to the telescope  (accepts a standard 2" barrel). This will directly attach to the CDK12.5 Hedrick focuser without any additional adapters. If you are using the CDK14 through CDK24 Hedrick focuser, or the IRF90 rotating focuser then you will require the PW-600352 IRF90/Hedrick focuser to 2″ accessory adapter to attach this adapter to the focuser. To choose the correct spacer, the backfocus of your camera plus path length of any other accessory plus the CCD spacer to be between 4.8 and 5.8".

L = 3.3"
PW-200368-2 - PlaneWave 2" Drawtube Spacer (L=2.85")
PW-200368-2 - PlaneWave 2" Drawtube Spacer (L=2.85")
$140.00
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PW-200368-2 - PlaneWave 2" Drawtube Spacer (L=2.85")
About This Product
This drawtube spacer allows for 2″ imaging, or visual accessories to be attached to the telescope  (accepts a standard 2" barrel). This will directly attach to the CDK12.5 Hedrick focuser without any additional adapters. If you are using the CDK14 through CDK24 Hedrick focuser, or the IRF90 rotating focuser then you will require the PW-600352 IRF90/Hedrick focuser to 2″ accessory adapter to attach this adapter to the focuser. To choose the correct spacer, the backfocus of your camera plus path length of any other accessory plus the CCD spacer to be between 4.8 and 5.8".

L = 2.85"
PW-200368-1 - PlaneWave 2" Drawtube Spacer (L=3.85")
PW-200368-1 - PlaneWave 2" Drawtube Spacer (L=3.85")
$140.00
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PW-200368-1 - PlaneWave 2" Drawtube Spacer (L=3.85")
About This Product
This drawtube spacer allows for 2″ imaging, or visual accessories to be attached to the telescope  (accepts a standard 2" barrel). This will directly attach to the CDK12.5 Hedrick focuser without any additional adapters. If you are using the CDK14 through CDK24 Hedrick focuser, or the IRF90 rotating focuser then you will require the PW-600352 IRF90/Hedrick focuser to 2″ accessory adapter to attach this adapter to the focuser. To choose the correct spacer, the backfocus of your camera plus path length of any other accessory plus the CCD spacer to be between 4.8 and 5.8"

L = 3.85"
PW-125388 - PlaneWave ADAPTER, LOW PROFILE 2.75" FOCUSER TO SECUREFIT
PW-125388 - PlaneWave ADAPTER, LOW PROFILE 2.75" FOCUSER TO SECUREFIT
$185.00
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PW-125388 - PlaneWave ADAPTER, LOW PROFILE 2.75" FOCUSER TO SECUREFIT
About This Product
ADAPTER, LOW PROFILE 2.75" FOCUSER TO SECUREFIT L=0.5"
PW-125357-1 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=4.8")
PW-125357-1 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=4.8")
$250.00
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PW-125357-1 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=4.8")
About This Product
The SecureFit spacers are attached via four screws to the PlaneWave CDK12.5 Hedrick focuser. When using a PlaneWave SecureFit CCD adapter, the CCD camera is also attached via screws so there will be no slipping, movement, or falling equipment. The backfocus of the CDK12.5 is 7.2" from the fully racked Hedrick focuser.

L = 4.8"
PW-125357-2 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=3.5")
PW-125357-2 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=3.5")
$250.00
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PW-125357-2 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=3.5")
About This Product
The SecureFit spacers are attached via four screws to the PlaneWave CDK12.5 Hedrick focuser. When using a PlaneWave SecureFit CCD adapter, the CCD camera is also attached via screws so there will be no slipping, movement, or falling equipment. The backfocus of the CDK12.5 is 7.2" from the fully racked Hedrick focuser.

L = 3.5"
PW-125357-3 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=2.5")
PW-125357-3 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=2.5")
$250.00
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PW-125357-3 - PlaneWave SecureFit CCD Spacer - CDK12.5 (L=2.5")
About This Product
The SecureFit spacers are attached via four screws to the PlaneWave CDK12.5 Hedrick focuser. When using a PlaneWave SecureFit CCD adapter, the CCD camera is also attached via screws so there will be no slipping, movement, or falling equipment. The backfocus of the CDK12.5 is 7.2" from the fully racked Hedrick focuser.

L = 2.5"
PW-125915 - PlaneWave RONCHI EYEPIECE AND ADAPTER KIT FOR CDK12.5
PW-125915 - PlaneWave RONCHI EYEPIECE AND ADAPTER KIT FOR CDK12.5
$230.00
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PW-125915 - PlaneWave RONCHI EYEPIECE AND ADAPTER KIT FOR CDK12.5
About This Product
INCLUDES: 2.75" TO 2" ADAPTER FOR HEDRICK 2.75" FOCUSER, RONCHI EYEPIECE, AND RONCHI EYEPIECE SPACER
PW-DDP-8004 - PlaneWave TELEVUE - 2" 90º EVERBRITE DIAGONAL
PW-DDP-8004 - PlaneWave TELEVUE - 2" 90º EVERBRITE DIAGONAL
$320.00
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PW-DDP-8004 - PlaneWave TELEVUE - 2" 90º EVERBRITE DIAGONAL
About This Product
TELEVUE - 2" 90º EVERBRITE DIAGONAL W/2”-1¼” ADAPTER
QTY:  
Price as Configured: $10,000.00

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The PlaneWave Instruments CDK12.5 is a 12.5 inch (0.32 m) f/8 Corrected Dall-Kirkham Astrograph telescope. The telescope has a closed carbon fiber tube, with 3 cooling fans ejecting air from the back of the telescope. The CDK12.5 covers a 52 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 46 lbs and comes standard with the large capacity 2.75 inch Hedrick focuser.

The CDK (Corrected Dall-Kirkham) Optical Design is an innovative solution for unsurpassed astroimaging quality at an affordable price. The CDK telescope design provides excellent imaging with large format CCD cameras while remaining superb for visual use. The CDK design far exceeds the off-axis performance of most commercial telescope designs including the Ritchey-Chrétien design.

This no-compromise design is unique in making the optical alignment forgiving and collimation very easy. This guarantees the user the best possible performance from the telescope. The end result at the image plane of the CDK design is no off-axis coma, no off-axis astigmatism, perfectly flat field (no off-axis defocus). The CDK design will give you pinpoint stars from the center to the corner of the field of view.

TECHNOLOGY

The CDK Optical Design

The CDK [Corrected Dall-Kirkham] telescope is based on a new optical design developed by Dave Rowe. The goal of the design is to make an affordable astrographic telescope with a large enough imaging plane to take advantage of the large format CCD cameras of today. Most telescope images degrade as you move off-axis from either coma, off-axis astigmatism, or field curvature.  The CDK design suffers from none of these problems. The CDK is coma free, has no off-axis astigmatism, and has a flat field. The design is a simple and elegant solution to the problems posed above. The CDK consists of three components: an ellipsoidal primary mirror, a spherical secondary mirror and a lens group. All these components are optimized to work in concert in order to create superb pinpoint stars across the entire 52mm image plane.

Optical Performance

 Shown are two simulations showing the CDK’s stunning performance. The first is a diffraction simulation and the second is a spot diagram. In both simulations the small squares are 9×9 microns, about the size of a CCD pixel. In the diffraction simulation the star images on axis and off-axis are nearly identical. In the spot diagram 21mm off-axis the spot size is an incredible 6 microns RMS diameter. This means stars across a 52 mm image circle are going to be pinpoints as small as the atmospheric seeing will allow.

Both of the simulations take into consideration a flat field, which is a more accurate representation of how the optics would perform on a flat CCD camera chip. For visual use some amount of field curvature would be allowed since the eye is able to compensate for a curved field.  The diffraction simulation was calculated at 585nm.  The spot diagram was calculated at 720, 585, and 430nm.  Many companies show spot diagrams in only one wavelength, but you cannot see the chromatic performance with only one wavelength.

Comparison: CDK vs. Richey Chrétien

The simulations shown compares the optical performance of the CDK design to the Ritchey Chrétien (RC) design. The Ritchey design was popularized as an astroimaging telescope due to its use in many professional observatories. Although very difficult and expensive to manufacture and align, the Ritchey is successful in eliminating many of the problems that plague many other designs, namely off-axis coma. However the Ritchey does nothing to eliminate the damaging effects of off-axis astigmatism and field curvature.

The CDK design tackles the off-axis coma problem by integrating a pair of correcting lenses into a two mirror design.  The beauty is that this design also corrects for astigmatism and field curvature. Because the lenses are relatively close to the focal plane (unlike the Schmidt corrector plate found in various Schmidt Cassigrain designs), and because these lenses work together as a doublet, there is no chromatic aberration.  The CDK offers a wide aberration-free, flat field of view that allows the user to take full advantage of the very large imaging chip cameras in the market place today.

 Having an aberration free telescope design means nothing if the optics cannot be aligned properly.  Many Ritchey owners never get to take full advantage of their instrument’s performance because the Ritchey is very difficult to collimate.   Aligning the hyperbolic secondary mirror’s optical axis to the optical axis of the primary mirror is critical in the Ritchey design, and the tolerances are unforgiving.  The secondary mirror of the CDK design is spherical.  It has no optical axis and so the centering tolerance of the CDK secondary mirror is comparatively huge.  With the help of some very simple tools, the CDK user will be able to set the secondary spacing, collimate the optics and begin enjoying the full performance potential the instrument has to offer within a few minutes.

The drastic difference in performance between the CDK and the RC is apparent.  The biggest component that degrades the off-axis performance of the RC is the defocus due to field curvature.  In many diagrams shown by RC manufacturers, the diagrams look better than this because they are showing a curved field.  This is fine for visual use because the eye can compensate for some amount of curvature of field.  But CCD arrays are flat and so in order to evaluate the performance a spot diagrams and/or diffraction simulations requires a flat field as shown.