SVBONY SV555 54mm f/4.5 Petzval APO Astrograph Lens
- 54mm Aperture / 243mm Focal Length (f/4.5)
- 5-Element Petzval APO Optical Design
- 44mm Full-Frame Image Circle
- Variable f/4.5 to f/22 Aperture Ring
- Includes EAF Mounting Kit and 360° Rotator
The Svbony SV555 combines a 5-element Petzval optical system with the functionality of a professional telephoto lens, delivering a flat 44mm image circle for full-frame sensors. Its 54mm aperture and 243mm focal length produce a fast f/4.5 focal ratio, while a unique variable aperture control allows you to stop down to f/22 for enhanced control over star shapes and depth of field. This astrograph arrives ready for automation, including a mounting kit for popular electronic focusers right out of the box.
The SV555's core is a 5-element, 3-group Petzval objective that acts as its own field flattener, ensuring sharp, point-like stars across a full-frame 44mm image circle. This apochromatic (APO) design virtually eliminates chromatic aberration, rendering vivid, high-contrast images without color fringing. At a 243mm focal length, you can capture vast swaths of the Milky Way or frame large targets like the Andromeda Galaxy (M31) and the North American Nebula (NGC 7000) in a single shot.
Unlike fixed-aperture astrographs, the SV555 features a manual aperture ring, adjustable from a wide-open f/4.5 to a narrow f/22. Shooting at the native f/4.5 maximizes light gathering for faint deep-sky objects. Stopping down slightly can tighten star performance at the extreme edges of the field or increase contrast for lunar imaging, giving you a level of optical control typically reserved for camera lenses.
The SV555 is engineered for a seamless imaging experience. It includes a dedicated mounting kit for popular EAF systems, a lockable 360° camera angle adjuster for precise framing, and a helical focuser for fine adjustments. A built-in 2" filter holder sits within the optical train, allowing easy integration of light pollution or narrowband filters without altering your back focus. The 184mm Vixen-style dovetail plate provides a secure connection to your mount.
The primary competitor in this category is the William Optics RedCat 51, a highly regarded Petzval astrograph. While both deliver a flat, full-frame field, the SV555 presents key differences.
The 5-element Petzval design incorporates corrective optics directly into the main lens assembly. This means the Svbony SV555 produces a flat, corrected image field across its entire 44mm image circle without requiring a separate, external field flattener, simplifying your imaging train.
The variable aperture gives you enhanced optical control. While the native f/4.5 setting is best for capturing faint deep-sky objects, stopping down to f/5.6 or f/8 can slightly improve star shapes at the very edge of the frame or increase contrast on bright objects like the Moon. It also provides flexibility for terrestrial and daytime photography.
Yes. The Svbony SV555 is designed with a 44mm image circle, which fully illuminates the sensors of full-frame DSLR and mirrorless cameras. The back of the lens features a standard M48x0.75 male thread, allowing you to connect your camera with a brand-specific M48 T-ring.
Nothing extra. The Svbony SV555 includes an EAF mounting kit in the box. This kit is designed to attach popular ZWO EAF models directly to the helical focuser, allowing you to achieve automated, precise focusing right away.
The SV555's 243mm focal length provides a very wide field of view, making it ideal for large celestial targets. Paired with a full-frame camera, you can easily fit the entirety of the Andromeda Galaxy (M31) or the expansive nebulosity of the North American Nebula (NGC 7000) and the Pelican Nebula (IC 5070) within a single frame.
The Svbony SV555 has two filter mounting options. It features a built-in 2" filter holder located inside the optical tube for standard 2-inch threaded filters. Additionally, the front of the lens has an M72 thread for attaching larger front-mounted filters.
| Brand | SVBONY |
| Objective Design | Petzval (5 Elements in 3 Groups) |
| Aperture | 54mm |
| Focal Length | 243mm |
| Focal Ratio | f/4.5 - f/22 |
| Image Circle | Φ 44mm (Full Frame) |
| Optical Coatings | Fully Multi-Coated (FMC) |
| Focuser | Helical |
| Camera Connection | M48x0.75 Male Thread |
| Camera Rotator | Lockable 360º |
| Filter Threads | M72 (Front), Internal 2" Holder |
| Mount Type | Vixen-style Dovetail Plate |
| Dovetail Length | 184mm |
| Net Weight | 2450g (excluding accessories) |
SV555 54mm f/4.5 OTA
× 1
EAF Mount Kit
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Handle with Vixen Finder Saddle
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Dovetail Plate with M6 Holes
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Camera Angle Adjuster
× 1
2" Filter Holder (Assembled)
× 1
Plastic Lens Cover
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Soft Padded Case
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