Perché questo nuovo nome che sa di stravagante?
La risposta è nella volontà del produttore, Yuri Petrunin, CEO della Telescope Engineering Co.
“Yellow Submarine è una canzone pubblicata dai Beatles (accreditata a Lennon/McCartney)
prima nel loro settimo album Revolver e poi come singolo “Doppio Lato A” assieme a Eleanor
Rigby il 5 agosto 1966. È anche il titolo della colonna principale di quello che poi diventerà il loro
omonimo film d’animazione nel 1968.”
Grazie anche a questa canzone il titolare della Telescope Engeering Company ha avuto modo
da giovane di imparare la lingua Inglese dopo essere giunto e stabilitosi negli USA.
In onore a questo insegnamento e al successo delle sue ottiche ormai consolidate nel mondo. Come perfezionismo ottico, nonchè di fiducia verso il cliente, ha deciso di dare rilievo ad un ricordo del suo passato.

PREZZO SU RICHIESTA.

Il telescopio è caratterizzato da un design con doppietto spaziato in aria con un elemento a Fluorite CaF2 (lente posteriore) e R/F 11 per una correzione Aprocromatica superiore a quella dei tripletti F.7 della stessa apertura (vedi articolo in fondo). Di conseguenza questo telescopio risulterà molto leggero per l’apertura, con 28 libbre (12.5 Kg) di peso e 1,76 m di lunghezza. Richiederà un supporto adeguato per la sua lunghezza, tuttavia essendo così leggero risulterà facile da maneggiare. Come tutti i telescopi TEC, l’APO160FL F/11 verrà fornito con un focheggiatore standard Feathertouch da 3.5” insieme al timone, elemento ormai di serie nei rifrattori di D.160 e superiore, nella parte posteriore, che ne facilita lo spostamento. A differenza della maggior parte degli altri telescopi TEC. l’APOcromatico 160FL F/11 non richiederà anelli del tubo. La piastra a coda di rondine TEC da 12” e la maniglia per il trasporto si collegheranno direttamente alle flange del tubo.
Il tubo è divisibile in tre sezioni per facilitarne la spedizione.

RENDER DEL TUBO

SPECIFICHE

ACCESSORI A CORREDO:

1. Maniglia di trasporto
2. Piastra tipo Losmandy 3” x 12”
3. Borsa di custodia rinforzata L. 150x25x25 cm.

DAL SITO UFFICIALE

Our dedicated Planetary Refractor, the APO160FL F/11 will open the night sky to those willing to observe.

The APO160FL F/11 will feature an air-spaced apochromatic-doublet objective with a Fluorite (CaF2) inner element that will come to temperature more quickly than the APO160FL F/7 version.
The objective will be housed in an aluminum cell, providing for excellent thermoregulation properties while remaining lightweight and strong.
The optical assembly will sit in a lightweight aluminum tube that utilizes anti-reflective coating and sharp-edged baffles throughout the interior and forget about collimation – after the scope leaves TEC, no adjustment is required.
Further, the beautiful black and gold assembly projects the elegant, handcrafted quality that TEC is known for. Expect deep contrast and rich, natural color out of this compact and timeless design.
Each APO160FL F/11 will come equipped with a Starlight Instruments FTF#3545 Feather Touch Focuser that was designed in collaboration with TEC. This is Starlight Instruments’ largest rotating focuser with coarse and fine focusing 9:1 Planetary Reduction Assembly.
The 2” locking metal collet is insensitive to temperature fluctuations and holds loads with high precision and concentricity.
The APO160FL F/11 doublet will come with a 300mm plate and handle that will be directly attached to the telescope flanges. An optional plate could be used to give a larger balancing range for the telescope.
Able to accommodate a wide variety of eyepieces.
Recommended to be paired with a high capacity load mount and a stationary observation station.
TEC recommends the 10Micron GM2000 HPS, 10Micron AZ2000 HPS and the Astro-Physics 1600GTO Mounts.
In classic refractor fashion, the TEC APO160FL F/11 is a no compromise, no frills design that lets the wonders of nature speak for themselves. The TEC APO160FL F/11 price and deposit will be determined at a later date. Please know that ALL PRICES AND AVAILABILITY ARE SUBJECT TO CHANGE WITHOUT NOTICE; the price initially quoted for a telescope purchase may not be reflected in the final invoice. Wait times may also be longer than initially quoted. Rest assured that we are working diligently to complete and ship every telescope on order.

Recommended Accessories

10×60 Baader Vario Finderscope with a TEC Finder Bracket and Base for Telescope mounting.
7×50 Vixen Finderscope with a TEC Finder Bracket and Base for Telescope mounting.
Gutekunst Compact Atmospheric Dispersion Corrector (ADC) with the ADC Adapter Set.

The Yellow Submarine has surfaced. Our newly released update to the classic APO160FL will feature key design changes to optimize color correction and will be known as a “super” planetary telescope.

It will use an air-spaced doublet design and longer focal ratio to delve deeper into the skies and will shine in the night with its beautiful golden color. Yuri says, “it is about bring back the beauty of long refractors to your backyards, public clubs, school observatories, etc.”

Testing and Quality Assurance

TEC Telescopes go through rigorous testing to ensure top quality performance. Newtonian Rings are used throughout the glass production process and we then use an interferometer to correct any remaining imperfections. Every telescope is then tested vigorously to reach the most optimum Strehl ratio possible. Rest assured that your telescope has been optimized to be as optically perfect as possible. If the objective does not reach Yuri’s expectations, the telescope will not be shipped. As a strict policy, TEC will not release telescope test reports.

While the objectives are fine-tuned under interferomerical control to meet the highest optical standards, cosmetic imperfections may exist in the objective and the tube assembly. Please rest assured that any imperfection in the telescope has been determined not to affect the optical performance.

160mm TEC fluorite apo, f/11 doublet vs. f/7 triplet

The two fluorite apos offered by TEC are the top line instruments, one geared toward wider field, the other toward near-ultimate correction level (appropriately named by TEC “planetary”). How much better corrected could the long doublet be? While no specific answer to this question is possible without published prescriptions, playing with matching glasses that are in a very narrow circle of the best matches can give a good idea of it. Image below shows 160mm f/11 fluorite doublet with Ohara S-BSM14 mating glass (top), f/7 fluorite triplet using the same mating glass with all four inner radii equal (middle) and the triplet optimized by bending the mid element. Linear field is nearly identical for all three, which means that the triplet has correspondingly larger angular field. Note that the triplet is oil-spaced, so R2=R3 and R4=R5 (S-NSL36 is used as oil surogate, having similar optical properties as commonly used oils; raytracing-wise, there is little difference if the gaps are filled with air instead). The choice of mating glass was based on the quality of chromatic correction; with the doublet, slow focal ratio indicates that the mating glass is not lanthanoid, since it is not necessary, and would result in generally worse chromatic correction than the BSM14 (borosilicate medium-index crown, near-equivalent of the Schott N-SK14).

Raytrace shows that the doublet has indeed significantly better correction than the triplet with all four inner radii equal (middle; OPD graph has added individual Strehl values for the four wavelengths, except e-line, whose Strehl is shown at left, below system prescription, together with polychromatic Strehl). This is mainly caused by the latter having more of the higher-order spherical aberration residual, limiting its e-line Strehl to 0.965. Difference in chromatic correction between the two is for all practical purposes undetectable. Also, uncorrected lower-order spherical requires strong aspheric on the front surface (oblate ellisoid; front surface is preferred because aspherizing it also reduces the higher-order spherical aberration residual). Showed in the box to the right, some other combinations viable with respect to secondary spectrum correction would have better correction in the e-line, but their larger error in un-optimized wavelengths – primarily F and C – mainly cancels out that advantage when it comes to the overall correction level expressed with polychromatic Strehl ratio (nine evenly spaced wavelengths from 430nm to 670nm, photopic sensitivity).

Best result is obtained by reducing spherical aberration load bending the mid element (bottom). Usually, either the first, or second inner pair of radii generates significantly more of spherical aberration than the other one. By relaxing that pair, while at the same time making the other stronger, in order to nearly preserve longitudinal chromatic correction, at some point both pairs contribute roughly similar amount of the aberration, but the total is minimized. In this case, the front pair had to be made stronger, and the rear pair weaker. This way, it may be possible to eliminate spherical aberration entirely; it wasn’t possible here, but it allowed for a considerably less aspherised front surface, in addition to significantly lower higher-order spherical residual. The e-line Strehl is now 0.986, and the poly-Strehl is 0.954. This triplet meets both “true apo” criteria, the one requiring F and C lines be no more than 1/4 wave P-V, with g and r lines no more than 1/2 wave, as well as the poly-Strehl of 0.95, or higher. It is still behind the doublet with respect to the overall correction level limit, but both are now within the “sensibly perfect” domain. An important practical aspect are their respective fabrication/alignment tolerances.

As post scriptum, Yuri Petrunin let me know the mating glass is not the one used here, but is “very close”. It could be one of the handful of nearly identical glasses; Hoya’s BACD14 seems to have little better correction in the violet, but that’s how far guessing can go. Also, Yuri said the actual lenses are significantly thicker (17 and 22mm the doublet), due to fabrication requirements. It has no appreciable effect on the final raytrace output.

(Vladimir Sacek)