Modern-day astrophotography increasingly favors compact, fast optical systems that reduce setup complexity while maintaining field quality. The new Askar 50P has been launched as a dedicated imaging astrograph built with a quadruplet Petzval architecture. The design integrates field correction within the optical tube and aims to deliver a flat imaging plane at the native focal length.

This telescope has a 50 mm aperture and a focal length of 190 mm. This configuration produces a focal ratio of f/3.8. Such a fast system targets wide-field deep-sky imaging rather than high-magnification work. The optical layout includes one SD glass element to suppress chromatic aberration, which becomes more critical as focal ratios decrease.

Quadruplet petzval design and field correction

One of the defining features of the Askar 50P is its quadruplet Petzval configuration. In classical refractor systems, field curvature often requires an external flattener to maintain star shape across the sensor. However, the Petzval concept places corrective elements within the optical path. This produces a naturally flatter field at the design focal distance.

Askar’s implementation uses four optical elements arranged to maintain correction across the supported image circle. The inclusion of SD glass indicates an effort to control secondary spectrum, especially important in fast systems where color errors can become visible near the field edge.

Because the field flattener is internal, the telescope operates at its native focal length without additional optics. This has several practical consequences. First, it reduces the number of threaded interfaces in the imaging train. Second, it minimizes spacing uncertainty. Third, it improves mechanical rigidity compared to add-on correctors.

The fast f/3.8 focal ratio is central to the system’s identity. At this speed, extended nebulae and narrowband targets reach useful signal levels more quickly. While total integration time still governs final image quality, the shorter focal ratio improves photon efficiency per exposure.

Mechanical structure and physical configuration

Askar designed the 50P with portability in mind. The optical tube measures 147 mm in length with the dew shield retracted. When extended, the length increases to 182 mm. These compact dimensions place the telescope firmly in the travel-friendly category.

The manufacturer lists the total weight as approximately 1.4 kg, including the tube rings and dovetail plate. This weight keeps the telescope compatible with lightweight equatorial mounts and many star trackers. It also reduces the overall load on harmonic drive mounts that prioritize compact payloads.

The retractable dew shield contributes to the short storage length. For astrophotographers who transport equipment frequently, this detail has practical value. A shorter tube fits more easily into airline-safe cases and small field bags.

At the rear, the telescope uses an M48 interface with M48×0.75 filter threading. This choice aligns with current astrophotography standards. Many CMOS cameras, filter drawers, and filter wheels already support M48 connections. As a result, users can integrate the telescope into existing imaging systems without unusual adapters.

The recommended backfocus distance is 55 mm, with an acceptable range between 50 mm and 65 mm. This tolerance provides some flexibility when inserting filters or tilt adjusters. However, users should still aim for precise spacing to obtain optimal edge performance.

Sensor coverage and imaging considerations

Askar states that the 50P supports APS-C sensors while optimizing the optical performance around 1-inch formats. This wording deserves careful interpretation. Optimization typically indicates where the optical system performs at its highest level. Support indicates the usable limit of the corrected field.

Practically speaking, 1-inch square sensors should fall comfortably within the well-corrected region. APS-C sensors extend closer to the edge of the image circle. Users working with larger sensors may need to pay closer attention to tilt, spacing, and mechanical alignment.

The short focal length of 190 mm defines the telescope’s imaging role. It captures large sky regions in a single frame. Wide emission nebulae, extended hydrogen-alpha complexes, and dense Milky Way star fields fit naturally within this focal length.

The fast focal ratio also benefits narrowband imaging. At f/3.8, the system collects photons quickly from extended sources. This can help reduce individual sub-exposure times under light-polluted conditions. It also suits portable imaging sessions where the total available time is limited.

However, the focal length limits angular resolution for small targets. Compact galaxies and planetary nebulae will appear small on most sensors. The 50P functions best as part of a multi-scope imaging strategy rather than a single-instrument solution.

Key specifications, price, and availability

Here is a glance at some of the key specifications of the Askar 50P astrograph:

Aperture size	50mm
Focal length	190mm
Focal ratio	f/3.8
Objective lens	Quadruplet petzval APO
Total length	147mm(when the dew shield is contracted)         182mm(when the dew shield is stretched)
Format specifications	Supporting APS-C format and optimized for 1-inch sensors
Gross weight	1.4kg

Askar has yet to announce the price for the 50P telescope. We expect the price to be around $700, given its optics. The telescope is currently listed as back-ordered on Askar’s official website.

An addition to the small astrograph segment

The small-aperture astrograph category has expanded rapidly in recent years. Manufacturers increasingly emphasize fast focal ratios and integrated correction. Within this context, the 50P occupies a defined position.

Its most distinctive specification is the f/3.8 focal ratio. Many competing small refractors operate between f/5 and f/6. By pushing the focal ratio lower, Askar prioritizes photon efficiency for extended objects. This does not increase aperture-limited resolution, but it does improve surface brightness capture per unit time.

The telescope’s 50 mm aperture keeps the system compact and lightweight. This design choice favors portability over raw light-gathering power. Users who already own longer focal length refractors may view the 50P as a complementary wide-field instrument.

The optimization around 1-inch sensors also shows current camera trends. Square sensors have become popular for mosaics and balanced framing. Importantly, the telescope does not attempt to serve visual observers. Its optical configuration and backfocus requirements prioritize imaging. This focus allows Askar to refine the design around a specific use case rather than compromise for dual-purpose operation.

Clear skies!

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