Askar PHQ151 – Large-Aperture Quintuplet Flat-Field APO
The Askar PHQ151 is a flagship 151 mm f/7 quintuplet APO astrograph built for serious deep-sky imaging. With its native flat-field design, this instrument produces razor-sharp stars across full-frame and large-format sensors—no flattener required.
Key features
- Huge aperture: 151 mm of light-gathering power.
- Flat field: Petzval-inspired quintuplet design eliminates field curvature.
- Focal length: 1057 mm at f/7, perfect for galaxies and smaller nebulae.
- Superb colour correction: Multiple ED elements for chromatic control.
- Heavy-duty focuser: Large 4″ rack-and-pinion for heavy imaging trains.
- Robust build: Precision CNC machining with retractable dew shield.
Technical summary
| Optical design | Quintuplet APO with flat field |
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| Aperture | 151 mm |
| Focal length | 1057 mm |
| Focal ratio | f/7 |
| Image circle | Full-frame & large-format compatible |
| Focuser | 4″ rack-and-pinion, dual-speed |
| Weight (OTA) | ~15 kg |
| Included | OTA, rings, dovetail, adapters |
Best for
- Advanced astrophotographers using full-frame or large-format sensors
- Targets requiring high resolution: galaxies, globular clusters, small nebulae
- Permanent observatories and serious imaging rigs
Product introduction
151PHQ is a long-focal-ratio, flatfield astrograph newly launched after 130PHQ and also the biggest refractor of Sharpstar products till now. Instead of buying extra flatteners, calculating the backfocus of the flattener, or making a tedious connection to match the distance, astrophotographers can simply equip it with any possible imaging devices, make the target stay at the focus, and then the whole optical system is perfect for imaging.
151PHQ has a focal ratio of f/7 and a focal length of 1057mm. The aperture is 151mm, which is the largest of Askar refractors so far. The quadruplet lens with two ED glasses offers excellent control of chromatic and other aberrations. With its self-flattening design, 151PHQ offers strong advantages in the astronomical shooting. It supports a medium frame 60mm image circle, has a fine spot diagram with tiny distortion of the peripheral stars, and its central RMS radius is less than 2 microns.
151PHQ comes with a telescopic lens hood, a high-quality CNC machined and painted tube, and attractive decorative parts. The 3.4" R&P focuser comes with M68/M54/M48 adapters, 360°rotator and a finder base. When used with the 3" 0.7 x flat field reducer, the telescope can reach a focal ratio of f/4.9 and a focal length of 740mm, effectively reducing exposure time. The multifunctional handle comes with a central slot for attaching an M6 screw with an M6 screw hole. A standard 300mm Losmandy dovetail plate, together with a sturdy double tube ring, is perfectly suited for viewing and shooting.
Specifications
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151PHQ Illustrate in detail |
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Aperture size |
151mm |
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Focal length |
1057mm |
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Focal ratio |
f/7 |
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Objective lens |
Quadruplet air-spaced APO (including two ED glass) |
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Image circle |
60mm |
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Maximum accessory connection (with the focuser fully retreated) |
Imaging mode： 78mm（from the base of M48×0.75 male thread） |
Observing mode ： 119mm （from the end of1.25" eyepiece holder） |
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Total length |
Observing mode：930.3mm（with the dew shield contracted）1117.8mm（with the dew shield fully stretched） |
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OTA Weight |
11.6kg |
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Total Weight (Including tube ring&dovetail plate） |
13.7kg |
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Rear-end thread type |
M86×1-M68×1 |
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Four-piece photographic end adapter |
M48×0.75 |
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Standard package items |
An 151PHQ OTA，a pair of tube rings, a handle, an Askar losmandy 300mm dovetail plate, a set of 4-piece photographic adapters, an aluminum box，a manual |
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Video
Images
Mr.ZhuLiQun | Rosette Nebula | ASKAR 151PHQ+ASI 6200 | SHO 3.5hrs
