About Ritchey-Chretien Telescopes…
In 1910, American optician & astronomer George Willis Ritchey & French astronomer Henri Chretien designed a specialized Cassegrain that would later become the telescope of choice for many observatories and professionals around the world. The Ritchey-Chretien astrograph has many benefits that make this design appealing to anyone who is serious about astro-photography or imaging. Here are a few of those benefits:
- Good-bye Coma: An RC has virtually no coma (stars look like little comets around the edges of the field), which means there will be greater image quality across a wider field of view.
- No Chromatic Aberration: Because a Ritchey-Chretien does not use lenses or corrector plates, the design does not suffer from chromatic aberrations, or false color. If you've ever looked through an achromatic refractor (non-APO), you will have seen chromatic aberration.
- No Spherical Aberration: The use of hyperbolic mirrors for both the primary and secondary removes the problem of spherical aberration from this optical system, an optical effect caused when light rays do not all come to focus at the same point, resulting in an image that is not in perfect focus.
14" f/8 Ritchey-Chretien Truss Tube Astrograph Highlights…
Optical Highlights: This Third Planet Optics (TPO) Ritchey Chretien telescope has 14" (355.6mm) of aperture and a focal length of 2845mm . The concave hyperbolic primary and convex hyperbolic secondary are made from low expansion quartz, and finished with a scratch-resistant highly reflective 99% dielectric coating for great contrast. The primary mirror is fixed in place in a metal mirror cell, and the secondary resides in a metal housing that can be collimated.
Carbon Fiber Truss Tube Design:
Lightweight yet strong carbon fiber truss tubes have low thermal expansion characteristics. Shifts in focus due to temperature changes are minimized because of this design. The trusses are also designed to flex equally, keeping the optics in collimation regardless of the position of the telescope.
Cooling Fans: The 14" Ritchey has three small cooling fans in the rear cell that help cool the inside of the tube down and bring it to ambient temperature so that you can start imaging sooner! The fans are powered by an external battery pack. This battery holder accepts 8-AA batteries (sold separately).
A Fixed Primary Eliminates Image Shift Schmidt-Cassegrain & Mak-Cassegrain telescopes achieve focus by moving the primary mirror back and forth inside the optical tube assembly, and this movement can cause image shift. While manufacturers have done a pretty good job of minimizing image shift on their telescopes, a moveable mirror makes it almost impossible to eliminate it completely. The Ritchey-Chretien has a primary that is fixed in place, removing the possibility of image shift and also the job of collimating the primary.
Two D Style Losmandy Dovetails Included Talk about versatility! Two Losmandy-style dovetails are attached to the truss tube support rings so that they ride at the top of the scope as well as at the bottom.
TPO 3" Focuser A 3" dual-speed linear-bearing Crayford-style focuser rounds out this package. The ridged focusing knobs are easy to turn, even with gloves on, and the 10:1 microfocusing dial allows for very small changes, or tweaks, in focus. It takes ten turns of the microfocusing knob to equal just one turn of the larger knob. There is also a little knob on the bottom of the focuser that controls the tension, so that you can make adjustments depending on the weight or distribution of your load. The 3" opening steps down to a 2" compression ring adapter, and you will receive 1.25" compression ring adapter so that you can make use of all your eyepieces. Two 25mm and one 50mm extension tube is also included to help you match the back-focus requirements of your imaging equipment. This is one nice focuser, and due to its steel drive rail and other upgrades, you will find that it suffers from very little flexure, even under heavier imaging payloads.
Long Back Focus of 288mm allows you to mount lots of imaging gear!
- Additional Information
SKU OS-14RC-TT Manufacturer TPO Telescope Series TPO Ritchey-Chretien Optical Design Ritchey-Chretien Mount Type None - Optical Tube Only Warranty 2 Year Warranty Telescope Aperture 14 in. Telescope Focal Length 2845mm Telescope Focal Ratio f/8 Tube Color or Finish Carbon Fiber
- Questions & Answers
Product QuestionsI interested this OTA, and i will use take a picture. and so, i will add moto focuser, Is this possible before with puchaseQuestion by: cheol-gyoonm.bae on Jun 27, 2016 9:21:00 PMwhat is the difference between the Astro-Tech 14" f/8 truss tube Ritchey–Chrétien optical tube and the TPO 14" f/8 RC Truss Tube OTA ? Also can a optec 2icnch tcf focuser be used with either item?
jimQuestion by: jim boardman on Jan 19, 2016 1:53:00 PMBoth scopes can be used with a TCFS or TCFSi. Depending if you are putting a big camera on the back of the scope, It may be worth considering a TCFS3.
The main difference between these scopes is the rigidity of the tubes and the TPO having a built in tip-tilt adapter on the back of the scope. The tip-tilt adapter will allow the user to account for any sensor tilt in the imaging train. You can purchase a tip-tilt adapter for an Astrotech 14" tube, but it will be an additional expense. The TPO truss tube, hard mounted Losmandy dovetails bars are going much more rigid than a steel tube with thin dovetail bars. Flexure, in this case, could cause errors in your pointing model and tracking.
The Truss tube is a little be heavier even though it is made out of carbon fiber, but it it well worth it for the rigidity.Answer by: Jonathan Cheek (Admin) on Jan 19, 2016 5:32:00 PMQuestion by: Glenn Newell on May 27, 2015 3:29:00 PMCameras up to 30mm diagonal (APS-C format) can be used without correctors before field curvature intrudes, but with the optional Teleskop Service RC corrector (TS-RCKORREKTOR - $309), the image circle is increased to 45mm and will work with full 35mm format cameras.Answer by: Chris Hendren (Admin) on Jun 2, 2015 3:20:00 PMDo you have a focal reducer and/or field flattener available for this telescope? If so, what are the prices?Question by: Don Reed on Oct 21, 2016 12:36:00 PMWe do offer several options of reducers and flatteners for this telescope and all of them are at various price points. To determine which one would best match your equipment, Please give a call at 1-800/483-6287 or email us at firstname.lastname@example.orgAnswer by: Jonathan Cheek (Admin) on Oct 31, 2016 9:05:00 AMQuestion by: Russ Dilley on May 25, 2016 9:56:00 AMWith a base weight on this scope of approximately 65 lbs and a typical imaging load including camera, filter wheel, focuser, extensions and accessories of approximately 80-85 lbs, we would generally only recommend mounts with stated capacities of at least 100 lbs. Many manufacturers offer suitable mounts such as Losmandy (Titan), Software Bisque (MX+ or MEII), and Astro-Physics (AP1100 and AP1600), among others. The lowest cost mount that would meet this criteria would be the Orion HDX110. The Celestron CGE Pro and Meade LX850 are on the cusp and would only be recommended for lighter camera loads and no piggybacked scopes on top of the 14" RC.Answer by: Chris Hendren (Admin) on May 26, 2016 4:57:00 PMWhat is the useful magnification? How is the image quality compared the commercial SCT's made by Meade and Celestron>Question by: Greg on Sep 15, 2016 11:46:00 AMThe useful magnification depends on seeing, but using the 50x per inch rule you could theoretically use up to 700x magnification. Air turbulence will usually limit you to 200-400x, depending on the night and conditions.
This telescope is an RC astrograph, with optics very well corrected for imaging. The visual image will be very sharp, but the contrast may be lower than some other scopes due to the larger central obstruction (for better imaging illumination with a camera). On a scope this large, the seeing and accuracy of your collimation will be the determining factors, but it will hold its own with any comparable scope by any brand.Answer by: Chris Hendren (Admin) on Sep 15, 2016 4:00:00 PMIn thinking thru imaging with this scope I imagine the combined weight of the imaging train will require weights at the front of the tube to get correct balance. Is this assessment correct? Do you sell these weights?Question by: Don Reed on Dec 27, 2016 9:36:00 AMIn most cases, additional declination weights are not needed with the 14RC-TT because the center of balance stays over the dovetail as long as you don't add more than about 15-20 lbs to the rear of the scope. The smaller smaller 10" RC might need Losmandy or ADM D-series weights, but the larger scopes typically don't.Answer by: Chris Hendren (Admin) on Dec 27, 2016 5:30:00 PMI need more details to decide whether to purchase 12" or 14" TPO Truss Tube OTA: (i) physical dimension comparison to determine whether 14" will fit in ShyShed POD; (ii) does 12" also include built in tip-tilt adapter; (iii) apples-to-apples weight comparison.Question by: Fritz Stafford on Jun 22, 2016 10:05:00 AMThe 14" is 20.5" across at the rear ring (21.5" including dovetails) and 39" long with no focuser or threaded attachment. It weighs 65 lbs in this configuration.
The 12" is 17.5"/18.5" at the rear ring and just a bit over 33" long. The base weight of the scope is 51 lbs with no focuser or rear attachments.
Both scopes have 288mm of back focus, and both have the tip-tilt plate on the rear of the scope.Answer by: Chris Hendren (Admin) on Jun 22, 2016 2:32:00 PMQuestion by: Marcelo Domingues on Nov 26, 2015 5:35:00 PM
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