William Optics Fluorostar 91 (aka FLT-91) RD / red OTA (SKU: T-FLT-91RD-RP33) refractors opinie

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William Optics Fluorostar 91 (aka FLT-91) RD / red OTA (SKU: T-FLT-91RD-RP33)
Availability: In stock, can be sent within 24 hours

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2276 EUR
price w/o VAT: 1850 EUR

William Optics Fluorostar 91 (aka FLT-91)  RD / red OTA (SKU: T-FLT-91RD-RP33)
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William Optics Fluorostar 91 is an optical instrument designed for the needs of astrophotography, guaranteeing an amazing image quality free from most optical defects occurring in other telescopes of this type. Designers and engineers of William Optics, through the selection of the best materials and exemplary precision of workmanship, created a refractor of unsurpassed optical quality, as evidenced by the Strehl coefficient of> 0.95

The optical system of this refractor is an apochromatic triplet, lenses of which are made of high quality including FPL-53, produced by the Japanese company Ohara. It has a very high Abbe number of 94.49, which means that it is an extremely low dispersion material. Additional multi-layer anti-reflective coating of all lenses guarantees a sharp image with high contrast.

Due to the large diameter of the illumination disc, this refractor is an ideal device for use with cameras and SLR cameras equipped with a full-frame sensor and an APS-C matrix.

The most important features of the William Optics Fluorostar 91 refractor

• apochromatic triplet with elements made of FPL-53 glass covered with a multi-layer anti-reflective coating
• fasteners made in CNC technology
• William Optics patented Bahtin mask design with handle
• full illumination circle guaranteeing complete coverage of the full-frame matrix

Technical specifications

• optical system: ED-APO apochromatic triplet
• Objective diameter: 91 mm
• focal length: 540 mm
• lighted: f / 5.9
• lens material: including FPL-53 glass (Ohara, Japan)
• anti-reflective coating: full multi-layer coating (FMC)
• Strehl's coefficient:> 0.95
• Full illumination circle diameter: full coverage of a full frame
• Compatible sensor sizes: APS-C, full frame
• compatible photographic systems (via interchangeable T-rings): Canon EF, Nikon F, Sony E, Pentax, Micro 4/3, Fuji FX
• fokuser: 3.3 "
• type of eyepiece: rack & pinion, dual speed
• recommended flatteners: WO Flat 6A III x0.8, WO FLAT 68 III x1.0 (unique compatibility - allows for full illumination of the corners of full-format matrices)
• finder foot: Vixen
• tube length (folded): 441 mm
• tube length (extended): 510 mm
• tube weight: 4.2 kg (total weight 5.5 kg)
• tube finish: red

Kit components

• William Optics Fluorostar 91 refractor
• Vixen mounting plate
• Bahtinov's mask with its mount
• mounting bracket
• transport bag
• spacer tube


24 months

Diagrams and distances

(above: technical drawing William Optics Fluorostar 91 (aka FLT-91) + WO 6AIII; configuration recommended for APS-C)

(above: technical drawing William Optics Fluorostar 91 (aka FLT-91) + WO P-FLAT68III; this is a new, unique functionality that allows to install such a large equalizer in this relatively small lens. for using full frame matrices and full illumination of matrix corners)

(above: technical drawing William Optics Fluorostar 91 (aka FLT-91) + extender included with the tube)

The first light (April 2021, col. Paweł T.)

The Lion triplet (NGC 3628 and surroundings), WO 91, dedicated 0.8x Flat 6A III flattener / reducer, ZWO ASI 2600 MC-P, Bortle 6.

(click to enlarge)

Identification of the area: