Nakoh 92GX f/6.5 Quintuplet Petzval Flat‑Field Astrograph
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- 92mm f/6.5 quintuplet astrograph with a 598mm focal length and fast f/6.5
- Japan-made SD glass + ED glass for color correction and reduced chromatic aberration
- Flat-field Petzval design delivers sharp, round stars without an additional field flattener
- Large 55mm image circle supports full-frame and larger imaging sensors
- 3.2" dual-speed rack-and-pinion focuser with 43mm of travel and EAF compatibility
- 360° precision camera rotator with engraved scales and secure locking
- M48 and M54 imaging connections with an integrated 2" filter thread
- Flexible mounting system with both 300mm Vixen-style and Losmandy-style dovetail plates
Nakoh 92GX: Five Elements. One Exceptionally Flat Field.
The Nakoh 92GX is a 92mm aperture quintuplet Petzval astrograph designed to deliver sharp, high-contrast images for demanding astrophotography applications. Its five-element optical system incorporates one Japan-made SD glass element and one ED glass element, taking advantage of their low-dispersion characteristics to significantly reduce chromatic aberration, including unwanted purple and green fringing. Multi-layer lens coatings further suppress stray light, improve light transmission, and minimize reflection loss for brighter, cleaner images with excellent color correction and fine detail.
Building on the classic four-element Petzval design, the 92GX uses an air-spaced triplet front group and air-spaced doublet rear group configuration. This arrangement provides enhanced correction of spherical aberration and coma while producing a naturally flat imaging field, eliminating the need for an additional field flattener. The result is consistently round, sharp stars from the center to the edge of its large 55mm medium-format image circle, making the 92GX well suited for large-sensor astrophotography.
Why the 92GX is a Standout!
Flexible Connections
Includes a four-piece camera adapter set for flexible DSLR and astronomy camera setups, with M48 and M54 connections plus an integrated 2" filter thread. Matte inner surfaces help suppress stray light and reflections for cleaner images.
360° Rotator
The 92GX features a high-precision 360° rotator with engraved degree markings for accurate camera and image orientation. A knurled locking screw securely holds the selected rotation angle in place for a stable imaging setup.
EAF-Ready Focuser
Features a 3.2" dual-speed R&P focuser with precision scales and a stable anti-friction inner tube. Compatible with popular electronic focusers, it also includes an M4 accessory mounting point and protective fine-focus knob cap.
The 92GX in Action!
Needle Galaxy - NGC 4565 by Dan Conover
Leo Triplet - Arp 317 by Dan Conover
Advanced SD & ED Glass Design
By fully utilizing the anomalous dispersion properties of premium SD and ED glass, the 92GX significantly minimizes refractive index variation across different wavelengths. This suppresses chromatic aberration—especially purple and green fringing—resulting in sharper, cleaner star images with excellent color accuracy!
Expansive 55mm Image Circle
The 92GX delivers a generous 55mm image circle, providing full coverage for full-frame sensors with additional room to support larger imaging formats. Its advanced Petzval optical design maintains a flat field with sharp, round stars from the center to the edges, making it well suited for wide-field astrophotography with large-format cameras.
Versatile Tube Ring & Accessory Mounting
The 92GX features a tilted tube ring design for secure support, paired with an enlarged thumb locking screw for quick, tool-free adjustments. A lightweight hollow base provides additional mount clearance, while multiple M4 and M6 threaded holes on the tube ring and removable metal handle provide flexible mounting points for guide scopes, finder bases, and other astronomy accessories.
Dual Dovetail Mounting Options
A 300mm Vixen-style dovetail plate provides broad compatibility with popular equatorial and alt-azimuth mounts, with multiple mounting positions for easier balancing. The 92GX also includes a 300mm Losmandy-style dovetail plate, giving users the flexibility to configure the telescope for a wider range of mounts and imaging setups.
92GX Spot Diagram
The imaging quality of the optical system can be evaluated by analyzing the distribution of star points in the image.The horizontal axis represents the distance of the star point from the image center, while the vertical axis represents the RMS radius of the star point. The RMS radius of the central star point for the 92GX is less than 1.2 micrometers, the star point radius at the edge of the 44mm frame is less than 2 micrometers, and at the edge of the 55mm image circle it is less than 2.7 micrometers. The stars are sharp and rounded, demonstrating excellent performance across the medium format (55mm).
Relative Illumination
The relative illumination uses the field radius as the horizontal axis and relative brightness percentage as the vertical axis to illustrate the attenuation of light from the center to the edge of the field of view. The 92GX delivers excellent relative illumination across the full frame, with a smoothly declining curve from the center to the edge of the 55mm image circle. Even at the edge of the 55mm image circle, relative illumination remains close to 100%, effectively minimizing vignetting
Specifications:
- Aperture: 92 mm (3.6 in)
- Focal length: 598 mm
- Focal ratio: f/6.5
- Lens design: Quintuplet Petzval APO
- Glass design:
- 1x SD glass [made in Japan]
- 1x ED glass
- Image circle: 55 mm
- Resolving power: 1.26 arc seconds
- Limiting magnitude: 11.57
- Light Gathering Power: 172x
- Tube Length:
- Hood Retracted: 502 mm (19.8 in)
- Hood Extended: 588 mm (23.1 in)
- Focusing Range:
-
Visual: 73mm-116mm (2.87–4.57")
-
Imaging: 37mm-80mm (1.46–3.15")
-
- Weight:
- OTA: 5.24 kg (11.5 lb)
- Total: 6.88 kg (15.2 lb)
- Rear-end Interface:
- 1.25"
- 2"
- M48 (with built-in 2" filter thread)
- M54 imaging adapter
Nakoh 92GX Dimensions
Imaging Train Flow Chart
Visual Observation Flow Chart
Other Information
- Country of Manufacture: China
Nakoh 92GX: Five Elements. One Exceptionally Flat Field.
The Nakoh 92GX is a 92mm aperture quintuplet Petzval astrograph designed to deliver sharp, high-contrast images for demanding astrophotography applications. Its five-element optical system incorporates one Japan-made SD glass element and one ED glass element, taking advantage of their low-dispersion characteristics to significantly reduce chromatic aberration, including unwanted purple and green fringing. Multi-layer lens coatings further suppress stray light, improve light transmission, and minimize reflection loss for brighter, cleaner images with excellent color correction and fine detail.
Building on the classic four-element Petzval design, the 92GX uses an air-spaced triplet front group and air-spaced doublet rear group configuration. This arrangement provides enhanced correction of spherical aberration and coma while producing a naturally flat imaging field, eliminating the need for an additional field flattener. The result is consistently round, sharp stars from the center to the edge of its large 55mm medium-format image circle, making the 92GX well suited for large-sensor astrophotography.
Why the 92GX is a Standout!
Flexible Connections
Includes a four-piece camera adapter set for flexible DSLR and astronomy camera setups, with M48 and M54 connections plus an integrated 2" filter thread. Matte inner surfaces help suppress stray light and reflections for cleaner images.
360° Rotator
The 92GX features a high-precision 360° rotator with engraved degree markings for accurate camera and image orientation. A knurled locking screw securely holds the selected rotation angle in place for a stable imaging setup.
EAF-Ready Focuser
Features a 3.2" dual-speed R&P focuser with precision scales and a stable anti-friction inner tube. Compatible with popular electronic focusers, it also includes an M4 accessory mounting point and protective fine-focus knob cap.
The 92GX in Action!
Needle Galaxy - NGC 4565 by Dan Conover
Leo Triplet - Arp 317 by Dan Conover
Advanced SD & ED Glass Design
By fully utilizing the anomalous dispersion properties of premium SD and ED glass, the 92GX significantly minimizes refractive index variation across different wavelengths. This suppresses chromatic aberration—especially purple and green fringing—resulting in sharper, cleaner star images with excellent color accuracy!
Expansive 55mm Image Circle
The 92GX delivers a generous 55mm image circle, providing full coverage for full-frame sensors with additional room to support larger imaging formats. Its advanced Petzval optical design maintains a flat field with sharp, round stars from the center to the edges, making it well suited for wide-field astrophotography with large-format cameras.
Versatile Tube Ring & Accessory Mounting
The 92GX features a tilted tube ring design for secure support, paired with an enlarged thumb locking screw for quick, tool-free adjustments. A lightweight hollow base provides additional mount clearance, while multiple M4 and M6 threaded holes on the tube ring and removable metal handle provide flexible mounting points for guide scopes, finder bases, and other astronomy accessories.
Dual Dovetail Mounting Options
A 300mm Vixen-style dovetail plate provides broad compatibility with popular equatorial and alt-azimuth mounts, with multiple mounting positions for easier balancing. The 92GX also includes a 300mm Losmandy-style dovetail plate, giving users the flexibility to configure the telescope for a wider range of mounts and imaging setups.
92GX Spot Diagram
The imaging quality of the optical system can be evaluated by analyzing the distribution of star points in the image.The horizontal axis represents the distance of the star point from the image center, while the vertical axis represents the RMS radius of the star point. The RMS radius of the central star point for the 92GX is less than 1.2 micrometers, the star point radius at the edge of the 44mm frame is less than 2 micrometers, and at the edge of the 55mm image circle it is less than 2.7 micrometers. The stars are sharp and rounded, demonstrating excellent performance across the medium format (55mm).
Relative Illumination
The relative illumination uses the field radius as the horizontal axis and relative brightness percentage as the vertical axis to illustrate the attenuation of light from the center to the edge of the field of view. The 92GX delivers excellent relative illumination across the full frame, with a smoothly declining curve from the center to the edge of the 55mm image circle. Even at the edge of the 55mm image circle, relative illumination remains close to 100%, effectively minimizing vignetting
Specifications:
- Aperture: 92 mm (3.6 in)
- Focal length: 598 mm
- Focal ratio: f/6.5
- Lens design: Quintuplet Petzval APO
- Glass design:
- 1x SD glass [made in Japan]
- 1x ED glass
- Image circle: 55 mm
- Resolving power: 1.26 arc seconds
- Limiting magnitude: 11.57
- Light Gathering Power: 172x
- Tube Length:
- Hood Retracted: 502 mm (19.8 in)
- Hood Extended: 588 mm (23.1 in)
- Focusing Range:
-
Visual: 73mm-116mm (2.87–4.57")
-
Imaging: 37mm-80mm (1.46–3.15")
-
- Weight:
- OTA: 5.24 kg (11.5 lb)
- Total: 6.88 kg (15.2 lb)
- Rear-end Interface:
- 1.25"
- 2"
- M48 (with built-in 2" filter thread)
- M54 imaging adapter
Nakoh 92GX Dimensions
Imaging Train Flow Chart
Visual Observation Flow Chart
- 1x 92GX OTA
- 1x Carrying handle
- 1x Telescope tube
- 1x Mounting plate set (Vixen & Losmandy-style)
- 1x 1.25-inch Eyepiece Adapter
- 1x 2-inch Eyepiece Adapter
- 1x Imaging Adapter
- 1x Product manual
- 1x Warranty card
- 92mm f/6.5 quintuplet astrograph with a 598mm focal length and fast f/6.5
- Japan-made SD glass + ED glass for color correction and reduced chromatic aberration
- Flat-field Petzval design delivers sharp, round stars without an additional field flattener
- Large 55mm image circle supports full-frame and larger imaging sensors
- 3.2" dual-speed rack-and-pinion focuser with 43mm of travel and EAF compatibility
- 360° precision camera rotator with engraved scales and secure locking
- M48 and M54 imaging connections with an integrated 2" filter thread
- Flexible mounting system with both 300mm Vixen-style and Losmandy-style dovetail plates
Nakoh 92GX: Five Elements. One Exceptionally Flat Field.
The Nakoh 92GX is a 92mm aperture quintuplet Petzval astrograph designed to deliver sharp, high-contrast images for demanding astrophotography applications. Its five-element optical system incorporates one Japan-made SD glass element and one ED glass element, taking advantage of their low-dispersion characteristics to significantly reduce chromatic aberration, including unwanted purple and green fringing. Multi-layer lens coatings further suppress stray light, improve light transmission, and minimize reflection loss for brighter, cleaner images with excellent color correction and fine detail.
Building on the classic four-element Petzval design, the 92GX uses an air-spaced triplet front group and air-spaced doublet rear group configuration. This arrangement provides enhanced correction of spherical aberration and coma while producing a naturally flat imaging field, eliminating the need for an additional field flattener. The result is consistently round, sharp stars from the center to the edge of its large 55mm medium-format image circle, making the 92GX well suited for large-sensor astrophotography.
Why the 92GX is a Standout!
Flexible Connections
Includes a four-piece camera adapter set for flexible DSLR and astronomy camera setups, with M48 and M54 connections plus an integrated 2" filter thread. Matte inner surfaces help suppress stray light and reflections for cleaner images.
360° Rotator
The 92GX features a high-precision 360° rotator with engraved degree markings for accurate camera and image orientation. A knurled locking screw securely holds the selected rotation angle in place for a stable imaging setup.
EAF-Ready Focuser
Features a 3.2" dual-speed R&P focuser with precision scales and a stable anti-friction inner tube. Compatible with popular electronic focusers, it also includes an M4 accessory mounting point and protective fine-focus knob cap.
The 92GX in Action!
Needle Galaxy - NGC 4565 by Dan Conover
Leo Triplet - Arp 317 by Dan Conover
Advanced SD & ED Glass Design
By fully utilizing the anomalous dispersion properties of premium SD and ED glass, the 92GX significantly minimizes refractive index variation across different wavelengths. This suppresses chromatic aberration—especially purple and green fringing—resulting in sharper, cleaner star images with excellent color accuracy!
Expansive 55mm Image Circle
The 92GX delivers a generous 55mm image circle, providing full coverage for full-frame sensors with additional room to support larger imaging formats. Its advanced Petzval optical design maintains a flat field with sharp, round stars from the center to the edges, making it well suited for wide-field astrophotography with large-format cameras.
Versatile Tube Ring & Accessory Mounting
The 92GX features a tilted tube ring design for secure support, paired with an enlarged thumb locking screw for quick, tool-free adjustments. A lightweight hollow base provides additional mount clearance, while multiple M4 and M6 threaded holes on the tube ring and removable metal handle provide flexible mounting points for guide scopes, finder bases, and other astronomy accessories.
Dual Dovetail Mounting Options
A 300mm Vixen-style dovetail plate provides broad compatibility with popular equatorial and alt-azimuth mounts, with multiple mounting positions for easier balancing. The 92GX also includes a 300mm Losmandy-style dovetail plate, giving users the flexibility to configure the telescope for a wider range of mounts and imaging setups.
92GX Spot Diagram
The imaging quality of the optical system can be evaluated by analyzing the distribution of star points in the image.The horizontal axis represents the distance of the star point from the image center, while the vertical axis represents the RMS radius of the star point. The RMS radius of the central star point for the 92GX is less than 1.2 micrometers, the star point radius at the edge of the 44mm frame is less than 2 micrometers, and at the edge of the 55mm image circle it is less than 2.7 micrometers. The stars are sharp and rounded, demonstrating excellent performance across the medium format (55mm).
Relative Illumination
The relative illumination uses the field radius as the horizontal axis and relative brightness percentage as the vertical axis to illustrate the attenuation of light from the center to the edge of the field of view. The 92GX delivers excellent relative illumination across the full frame, with a smoothly declining curve from the center to the edge of the 55mm image circle. Even at the edge of the 55mm image circle, relative illumination remains close to 100%, effectively minimizing vignetting
Specifications:
- Aperture: 92 mm (3.6 in)
- Focal length: 598 mm
- Focal ratio: f/6.5
- Lens design: Quintuplet Petzval APO
- Glass design:
- 1x SD glass [made in Japan]
- 1x ED glass
- Image circle: 55 mm
- Resolving power: 1.26 arc seconds
- Limiting magnitude: 11.57
- Light Gathering Power: 172x
- Tube Length:
- Hood Retracted: 502 mm (19.8 in)
- Hood Extended: 588 mm (23.1 in)
- Focusing Range:
-
Visual: 73mm-116mm (2.87–4.57")
-
Imaging: 37mm-80mm (1.46–3.15")
-
- Weight:
- OTA: 5.24 kg (11.5 lb)
- Total: 6.88 kg (15.2 lb)
- Rear-end Interface:
- 1.25"
- 2"
- M48 (with built-in 2" filter thread)
- M54 imaging adapter
Nakoh 92GX Dimensions
Imaging Train Flow Chart
Visual Observation Flow Chart
Other Information
- Country of Manufacture: China
| Telescope Focal Length | 501 - 600mm |
|---|
- 1x 92GX OTA
- 1x Carrying handle
- 1x Telescope tube
- 1x Mounting plate set (Vixen & Losmandy-style)
- 1x 1.25-inch Eyepiece Adapter
- 1x 2-inch Eyepiece Adapter
- 1x Imaging Adapter
- 1x Product manual
- 1x Warranty card
Nakoh 92GX f/6.5 Quintuplet Petzval Flat‑Field Astrograph