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Astro-Tech TMB-92 Light 92mm Signature Series f/5.5 Apo Triplet Refractor

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Price:
$897.00
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Product Description

This TMB Optical TMB-92L refractor has:

• 92mm f/5.5 apochromatic triplet optics using FPL-53 ED glass
• 2" dual-speed Crayford focuser
• compact 15.25" tube length 
• rotating eyepiece holder for quick camera/eyepiece orientation 
• 2" and 1.25" compression ring eyepiece holders 
• retractable dew shield, dust covers, and hard case 
• sales limited to 100 scopes per year to maintain the value of your investment 
• normally available from stock – with no multi-year waiting list

    When Sky & Telescope named this TMB-92L a Hot Product for 2010, they said “The TMB-92 Signature Series Refractor got such a rave review in our March 2009 issue, page 36, that we could not help but take note when the company introduced a new "light" version costing hundreds of dollars less. Featuring the same 92-mm f/5.5 triplet objective as the original, the light version has a smaller-diameter tube and premium Feather Touch focuser has been replaced with a conventional dual-speed 2-inch focuser. Same great views; new lower price."

 

 
    Astronomy named the TMB-92L a Star Product for 2010, saying “the heart of this little powerhouse – a 3.6-inch f/5.5 triple objective – is optically superb, while the dual-speed 2" Crayford focuser brings everything into razor-sharp view."

    The TMB-92L Signature Series 92mm f/5.5 triplet apo is a refractor for the serious observer who values the performance of first-class apochromatic optics. The TMB-92L takes the manifest optical virtues of the original TMB-92 – a scope whose visual performance one customer said, “defies the laws of physics" – and puts them in a lighter one-piece 15.25" tube that many observers will find more convenient for spur-of-the-moment observing. The TMB-92L optically fills the void left by the discontinued 90mm f/5 Astro-Physics Stowaway (a legendary scope that sells for up to $6000 on the used market).

    The TMB-92L is an exceptional grab and go scope for observing and imaging – both within the solar system and out to the furthest reaches of infinity. Its images of subtle low-contrast lunar and planetary details are razor-sharp, with realistic and highly saturated color. Those images are free from chromatic aberration of any type, thanks to the ED (Extra-low Dispersion FPL-53 glass) element in the scope’s air-spaced triplet optics.

    The latest antireflection multicoatings and knife-edge internal baffles assure the maximum image contrast possible. Image excellence is limited only by the seeing conditions, not by any aberration or short-coming in the telescope.

    The original TMB-92 was chosen a readers’ choice “Gear of the Year" product by a vote of the members of the forums on Cloudy Nights. With the same optics, a lighter weight, and a lower price, the new TMB-92L is sure to be the choice of even more astute astronomers.

    An extended four-page test report in the March 2009 edition of Sky & Telescope magazine gave the original TMB-92 (with the exact same optics as the TMB-92L) ratings of 4½ stars out of 5 for optics, 5 stars for mechanics, and a 4½ star overall rating. The review compared the 92mm f/5.5 TMB-92 against a later model 90mm f/7 Astro-Physics Stowaway, rather than the Stowaway’s original f/5 version. (A longer focal length scope should have intrinsically better correction than a shorter f/ratio version of the same scope, all other things being equal, leading to a perhaps not exactly “apples to apples" comparison of the f/5.5 TMB optics to the f/7 A-P optics.) Nonetheless, the review said “The new TMB fared very well indeed against this remarkable Astro-Physics apo. The TMB-92 presented images of bright stars and planets that were as free of chromatic aberration (false color) as the Stowaway. It’s fair to say that the TMB had no visible chromatic aberration, stunning for such a fast instrument . . . If I were to rate the Stowaway with 5 stars for optical perfection, then the TMB-92 earns 4½. Considering that the Stowaways have been known to command $5,000 to $6,000 on the used market, $2,000 for a new TMB-92 is an excellent bargain.

    “All in all," the Sky & Telescope report concluded, “I’m impressed with this new telescope from TMB. It combines superb optics with solid, well-crafted mechanics for a versatile, compact instrument. What more could an apo-lover want?"

This Telescope’s Optical and Mechanical Systems . . .

  • Apochromatic triplet ED refractor optics: 3.6" (92mm) aperture, 506mm focal length, f/5.5 triplet lens. It uses an FPL-53 ED (Extra-low Dispersion) glass element for a sharp and flat field and images that are high in contrast and free from spurious color (chromatic aberration).

     

  • Multicoated optics: Fully multicoated on all surfaces with the latest antireflection materials for exceptionally high light transmission and excellent contrast. Light transmission is so high that the optics seem to virtually disappear when viewed from head on.

     

  • Internal light baffles: Contrast-enhancing knife-edge light baffles in the dew shield and optical tube and anti-reflection threading in the focuser drawtube provide truly dark sky backgrounds and high terrestrial contrast. In addition, the edges of the objective lens are blackened to eliminate contrast-reducing stray internal reflections.

     

  • Retractable dew shield: The self-storing retractable dew shield/lens shade slows the formation of dew on the lens to extend your undisturbed observing time. It also improves visual and photographic contrast by shielding the lens from off-axis ambient light (the neighbor’s yard light, moonlight, etc.)

     

  • Dual-speed Crayford focuser: The precision-made no-backlash gearless focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during very high magnification visual observing, and during critical DSLR or CCD imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather.

     

  • Rotating eyepiece holder: A knob on the top of the focuser allows you to rotate the focuser a full 360°. This lets you rotate the focuser to line up a camera in either a landscape or portrait orientation (or any orientation in between), as well as put a star diagonal and eyepiece into the most comfortable observing position, and then temporarily lock the focuser in that position.

     

  • Focusing scale: The long 80mm (3.1") travel focuser drawtube allows both visual and photographic use while still keeping the overall scope length as short as practicable for convenient travel and storage. The drawtube has a scale marked in centimeters subdivided in 1mm increments. This lets you note individual focuser positions for easy return to the correct focus when switching between visual use and photography. A knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads, as well as firmly lock in a photographic focus.

     

  • Compression ring eyepiece holders: The focuser drawtube ends in a 2" eyepiece holder that uses a non-marring soft brass compression ring to hold a 2" star diagonal and accessories in place. The compression ring won’t scratch the barrel of your star diagonal and accessories as an ordinary thumbscrew can. Also supplied is a 1.25" eyepiece holder that slips into the 2" compression ring holder to let you use a 1.25" star diagonal or image erecting diagonal. Like the 2" eyepiece holder on the eyepiece holder rotation mechanism, the 1.25" adapter also uses a non-marring soft brass compression ring to hold 1.25" star diagonals and accessories in place.

     

  • Finderscope mounting point: There is no finderscope provided with the TMB-92L, but a threaded hole on the upper left side of the focuser permits the installation of an optional multiple reticle red dot finder (#ATF). The finder mounting hole is sealed with a slotted-head threaded insert to prevent the entrance of dust into the scope when no finder is installed.

     

  • Tube finish: The 90mm o.d. optical tube is finished in a durable baked-on automotive white paint with a black-anodized focuser and trim.

     

  • Shipping/storage case: The TMB-92L comes standard in an 22.25" x 12.75" x 8" aluminum frame locking hard case with a carry handle for transportation and general protection purposes. TMB Optical is one of the very few manufacturers to provide a case at no charge for protection during shipping and as a storage convenience when the scope is not in use. Unfortunately, FedEx, UPS, and the Postal Service are very good at treating packages roughly. Occasionally, your scope can arrive in perfect condition, but with the walls of the shipping case dented in transit from rough handling, or the aluminum frame sprung, rendering the appearance of the case less than pristine. Damage to the shipping case in such instances is not covered by warranty.

     

  • Other supplied accessories: A slip-on metal dust cap is standard. As mentioned previously, a threaded hole for installing a finderscope bracket is located on the upper left side of the focuser body.

     

  • Two year warranty: As an expression of the confidence TMB Optical has in the quality of their products, the TMB-92L is protected by a two-year limited warranty against flaws in materials and workmanship (shipping case excluded).

 


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