Askar 111F Flat-Field Quadruplet Astrograph — 111mm f/6.9 The Askar 111F Flat-Field is a 111mm aperture, 766mm focal length quadruplet APO astrograph built around Askar's proven self-flattening design philosophy. At a native f/6.9 focal ratio, it sits between the compact 91F and the larger 131F in the F Series lineup — offering meaningful aperture and a relatively fast ratio in a package that tops out under 6kg with rings and dovetail, making it compatible with a wider range of equatorial mounts than its larger sibling. The optical design uses four air-spaced elements — three in the front group and one correcting element in the rear — with one piece of ED glass to manage chromatic aberration across the full field. An internal baffle in the tube body further reduces stray light, and the system natively supports a 44mm image circle covering full-frame sensors. Like all F Series telescopes, it requires no separate field flattener and no backfocus calculation: connect your camera, achieve focus, and begin imaging. The mechanical package is comprehensive: a 3" rack-and-pinion focuser with 1:10 fine adjustment, a built-in 360° camera rotator, a retractable dew shield, two finder scope bases on the tube plus one on the handle, and a 300mm Vixen-style dovetail plate with 1/4" and 3/8" tripod screw holes. The tube body is precision CNC-machined in the signature Askar blue-and-white finish. Who Is This Product Best For? Intermediate astrophotographers stepping up from a smaller instrument who want full-frame sensor coverage with no flattener complexity. Deep-sky imagers targeting nebulae, galaxy groups, and emission regions where 111mm of aperture provides meaningful light collection advantage over sub-100mm instruments. Mount-limited users who want more aperture than the 91F but need to stay within the payload range of mounts like the Sky-Watcher HEQ5, iOptron CEM40, or equivalent. Dual-purpose users who want both astrophotography and visual observing capability in one instrument, since the 111F accepts standard 1.25" and 2" eyepieces. Budget-conscious upgraders who want a large-image-circle full-frame astrograph at a lower price point than the 131F. Why Choose the Askar 111F? Self-flattening quadruplet — no additional flattener needed, no backfocus distance to calculate. Attach your camera and shoot. 44mm full-frame image circle — covers full-frame DSLR, mirrorless, and large dedicated astronomy camera sensors. ED glass chromatic control — one ED element in the quadruplet group suppresses false colour across the entire image field. Built-in 360° camera rotator — frame your target at any angle without moving the telescope. 3" R&P focuser with 1:10 fine adjustment — large-format, low-flex focuser with fine control protective cap. Multiple finder base positions — finder scope can be repositioned between handle slot and focuser-side bases without disassembly. Lighter than the 131F — at 6.76kg gross (with rings and Vixen dovetail), compatible with a broader range of imaging mounts. 2" filter thread built-in — the photographic extension tube accepts standard 2-inch astronomy filters directly. Recommended Uses Wide-field deep-sky astrophotography (nebulae, galaxy clusters, emission regions) Full-frame DSLR and mirrorless astrophotography Dedicated astronomy camera imaging (ZWO, QHY, Player One, Touptek, etc.) Narrowband and broadband filter imaging Visual deep-sky observing with 1.25" and 2" eyepieces Moderate-payload equatorial mount imaging setups Compatibility and Accessory Notes Camera connections: Ships with M48×0.75 and M54×0.75 photographic adapters. DSLR users need a standard camera T-ring. The built-in 2" filter thread on the extension tube accepts standard astronomy filters. Most dedicated astronomy cameras with M54 or M48 nose threads connect directly. Mount compatibility: The 300mm Vixen-style dovetail plate fits any Vixen-compatible saddle. The 1/4" and 3/8" holes allow direct tripod mounting. At 6.76kg gross, mounts rated for 10–12kg imaging payload are appropriate — such as the Sky-Watcher HEQ5 Pro, iOptron CEM40, ZWO AM5, or equivalent. Optional accessories: The Askar 111F 0.74× Reducer (sold separately) drops the system to approximately f/5.1 (566mm focal length) for wider-field, faster imaging. An electronic focuser motor is available separately for remote focus control. Guiding: Two finder bases on the focuser body plus the handle slot provide three guide scope mounting positions. Compatible with Askar 52mm guide scope series and other standard guide scopes. Important Limitations f/6.9 is not ultrafast — for very faint targets in light-polluted skies, the optional 0.74× reducer (sold separately) is recommended. Not ideal for planetary or lunar imaging — optimized for wide-field deep sky, not high-magnification planetary detail. No electronic focuser included — motorized focus requires a separately purchased focuser motor. Not a beginner instrument — most appropriate for users with an equatorial mount and some astrophotography experience. Frequently Asked Questions Do I need a field flattener?No. The self-flattening quadruplet design produces a flat field natively across the 44mm image circle. Does it cover full-frame sensors?Yes. The 44mm image circle covers all current full-frame DSLR, mirrorless, and dedicated astronomy camera sensors. What mount do I need?A mount rated for 10–12kg payload is recommended for imaging. Examples: Sky-Watcher HEQ5 Pro, iOptron CEM40, ZWO AM5N, or equivalent. How does the 111F compare to the 91F?The 111F has 22% more aperture (111mm vs 91mm), a slightly faster native ratio (f/6.9 vs f/6.7), and a longer 766mm focal length vs 609mm. It is heavier (5.74kg net vs 3.92kg) and does not include eyepieces or an erecting prism in the standard package. The 91F is better for users with smaller mounts or who want a more complete visual/travel kit out of the box. How does the 111F compare to the 131F?The 131F has more aperture (131mm) and a longer focal length (983mm) but is significantly heavier (7.9kg net) and requires a heavier-duty mount. The 111F is the better choice for users with mid-weight mounts who still want full-frame coverage. Is a reducer available?Yes. The Askar 111F 0.74× Reducer (sold separately) reduces the system to f/5.1 and 566mm focal length. Our Recommendation At Ontario Telescope and Accessories, we recommend the Askar 111F Flat-Field for astrophotographers who want a meaningful aperture upgrade over a 60–91mm instrument while keeping the system weight manageable for mid-range equatorial mounts. The self-flattening design eliminates the most common source of setup complexity for newer imagers, and the full-frame image circle means the optics will not limit you as your camera equipment evolves. It is a strong all-round deep-sky imaging platform at a competitive price point in the 100–120mm aperture class. Optical Diagram Reports The following diagrams are provided for customers who wish to review the optical performance data, mechanical dimensions, and connection specifications of the Askar 111F before purchasing or setting up the instrument.
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