Askar SQA70 f/4.8 Quintuplet Petzval Refractor Telescope
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Askar SQA70
The Askar SQA70 is a premium quality quintuplet air-spaced ED glass Petzval Astrograph.
Excellent star point performance
70mm aperture, 336mm focal length, f/4.8 focal ratio.
The 70mm aperture f/4.8 quintuplet air-spaced lens design offers a focal length of 336mm. The objective lens includes two elements of ED glass. The central star point has an RMS radius of less than 1.84 μm, and the star point at the corner is less than 2.4 μm. It also has excellent full-field illumination and MTF data.
Petzval Structure
The integrated self-flattening Petzval design supports a 44mm full-frame image circle so there is no need for additional flatteners and no need to calculate back focus.
Integrated Tube Ring
Integrated with the OTA is pair of tube ring sets with a hollow design in the middle to reduce overall weight. Enlarged hand screws allow users to open and close the tube ring without additional tools.
There are 4x M4 and M6 threaded holes on both sides of the tube ring. This is convenient for installing a base or dovetail plate to connect different accessories. You can even set up another smaller OTA;s for imaging or guiding.
The handle on the top of the tube ring is slotted with a multifunctional finder base, which can be used to install additional astronomical accessories.
Finder Bases
On both sides of the focuser, there are two finder bases. This not only eliminates the need for disassembling when changing the position of the finder scope but also provides additional mounting positions for other accessories.
Diversified Photography Scene Applications
In addition to connecting an astronomical camera for astrophotography, the SQA70 can also be connected to a mirrorless camera or DSLR camera for additional imaging possibilities.
360° Rotator
The rear of the focuser is equipped with a 360° high-precision rotator with a scale to allow the user to adjust and save the angle of rotation. It is also equipped with an enlarged locking screw for easy locking even under high tension loads.
Dual-Speed Focuser
The included 2.5" rigid dual-speed rack-and-pinion focuser is compatible with most motorized focusers on the market. The focusing travel is 32 mm and the focuser tube is engraved with high-precision measurement scales. The entire focuser barrel is CNC machined with an anti-reflective matte paint, providing extra protection to eliminate stray light.
High Quality Machining
The entire SQA70 tube is crafted using high-quality CNC machining with anondized and surface paint treatments. The top of the handle and the focuser are all designed with exclusive nameplates.
Read End Adapters
The back end of the SQA70 is equipped with a variety of adapters, all of which are toothed and ribbed, making it easy to rotate manually without slipping. The adapters are available in sizes M54, M48 and M42 and can be used to attach various accessories, such as cooled cameras.
All Metallic Handle (optional)
85mm all-metallic handle can be purchased separately for easy use.
Riser Blocks (optional)
20mm all-metal riser blocks can be purchased separately and are available to further minimize the risk of telescope and mount collision when used during equatorial mount operation. These adapters also create more space at the bottom of the OTA to accommodate different connecting devices or power cords.
MTF Chart
The modulation transfer function (MTF) is a quantitative description of the clarity of the image (including resolution and contrast) of an optical lens. The vertical axis is the MTF value, and the horizontal axis is the distance from the center of the frame to the edge.
In the two sets of curves corresponding to low and high frequencies, even at the edge of the 55mm image circle the sagittal lines and sagittal lines distance of the SQA70 lens remain very small, and at the low frequency of 10LP/mm, it is higher than 0.9 overall, showing the high resolution and sharpness of the SQA70.
Relative illumination
Relative Illumination (RI) represents the combined effect of light loss and attenuation at the corners of the lens, and the RI curve illustrates the change in illuminance (%) across the imaging range on the sensor. Illumination variations can adversely affect the image. The vertical axis means different percentages of example illumination intensities, and the horizontal axis is the distance from the center of the frame to the edge.
The SQA70 guarantees a high illumination of above 90% at the 44mm image circle, minimizing vignetting.
Spot Diagram
The imaging quality of the optical system can be evaluated by analyzing the distribution of the spots on the spot diagram.
The SQA70 has a central star point with an RMS radius of less than 1.84μm, and the star point at the corner is less than 2.4μm, showing very small stellar points.
Longitudinal chromatic abberation curve
This curve is a representation of the deviation of different wavelengths of light at the focal point. The different curves in the diagram correspond to different wavelengths of light.
Longitudinal chromatic abberation (LCA) occurs when different wavelengths (colors) of light fail to converge at the same focal point along the optical axis of a lens or the image, usually manifesting as blurred edges or color halos. The longitudinal chromatic curves of SQA70 lenses show very small spacing and even coincide. The curve's curvature is very low, indicating the chromatic aberration is well controlled. The sign of an very good lens.
Specifications
- Aperture size: 70mm
- Focal length: 336mm
- Focal ratio: f/4.8
- Objective lens: Quintuplet petzval APO (including two pieces of ED glass）
- Total length:
- 332mm (when the dew shield is contracted)
- 372mm (when the dew shield is stretched)
- Format specifications: Full-frame (44mm)
- OTA weight: 3.68kg (8.1lbs)
- Gross weight (including tube ring and dovetail plate): 9.9lbs
- Rear-end thread type: M42/M48/M54 adapters (M48 adapter is threaded for 2" filters)
- Rear-end connection distance: Supports 37-68mm range (recommended connection distance is 55mm)
- Soft sided case, external dimensions: 42x20x23cm (16.5x7.9x9.1in)
| Product Banner Type | new |
|---|---|
| Free Shipping Graphic | Free US Shipping |
| Telescope Focal Length | 301 - 400mm |
| Hide Found a better Shipped Price on Frontend? | Yes |
- 1x SQA70 OTA
- 1x Oxford cloth case
Askar SQA70
The Askar SQA70 is a premium quality quintuplet air-spaced ED glass Petzval Astrograph.
Excellent star point performance
70mm aperture, 336mm focal length, f/4.8 focal ratio.
The 70mm aperture f/4.8 quintuplet air-spaced lens design offers a focal length of 336mm. The objective lens includes two elements of ED glass. The central star point has an RMS radius of less than 1.84 μm, and the star point at the corner is less than 2.4 μm. It also has excellent full-field illumination and MTF data.
Petzval Structure
The integrated self-flattening Petzval design supports a 44mm full-frame image circle so there is no need for additional flatteners and no need to calculate back focus.
Integrated Tube Ring
Integrated with the OTA is pair of tube ring sets with a hollow design in the middle to reduce overall weight. Enlarged hand screws allow users to open and close the tube ring without additional tools.
There are 4x M4 and M6 threaded holes on both sides of the tube ring. This is convenient for installing a base or dovetail plate to connect different accessories. You can even set up another smaller OTA;s for imaging or guiding.
The handle on the top of the tube ring is slotted with a multifunctional finder base, which can be used to install additional astronomical accessories.
Finder Bases
On both sides of the focuser, there are two finder bases. This not only eliminates the need for disassembling when changing the position of the finder scope but also provides additional mounting positions for other accessories.
Diversified Photography Scene Applications
In addition to connecting an astronomical camera for astrophotography, the SQA70 can also be connected to a mirrorless camera or DSLR camera for additional imaging possibilities.
360° Rotator
The rear of the focuser is equipped with a 360° high-precision rotator with a scale to allow the user to adjust and save the angle of rotation. It is also equipped with an enlarged locking screw for easy locking even under high tension loads.
Dual-Speed Focuser
The included 2.5" rigid dual-speed rack-and-pinion focuser is compatible with most motorized focusers on the market. The focusing travel is 32 mm and the focuser tube is engraved with high-precision measurement scales. The entire focuser barrel is CNC machined with an anti-reflective matte paint, providing extra protection to eliminate stray light.
High Quality Machining
The entire SQA70 tube is crafted using high-quality CNC machining with anondized and surface paint treatments. The top of the handle and the focuser are all designed with exclusive nameplates.
Read End Adapters
The back end of the SQA70 is equipped with a variety of adapters, all of which are toothed and ribbed, making it easy to rotate manually without slipping. The adapters are available in sizes M54, M48 and M42 and can be used to attach various accessories, such as cooled cameras.
All Metallic Handle (optional)
85mm all-metallic handle can be purchased separately for easy use.
Riser Blocks (optional)
20mm all-metal riser blocks can be purchased separately and are available to further minimize the risk of telescope and mount collision when used during equatorial mount operation. These adapters also create more space at the bottom of the OTA to accommodate different connecting devices or power cords.
MTF Chart
The modulation transfer function (MTF) is a quantitative description of the clarity of the image (including resolution and contrast) of an optical lens. The vertical axis is the MTF value, and the horizontal axis is the distance from the center of the frame to the edge.
In the two sets of curves corresponding to low and high frequencies, even at the edge of the 55mm image circle the sagittal lines and sagittal lines distance of the SQA70 lens remain very small, and at the low frequency of 10LP/mm, it is higher than 0.9 overall, showing the high resolution and sharpness of the SQA70.
Relative illumination
Relative Illumination (RI) represents the combined effect of light loss and attenuation at the corners of the lens, and the RI curve illustrates the change in illuminance (%) across the imaging range on the sensor. Illumination variations can adversely affect the image. The vertical axis means different percentages of example illumination intensities, and the horizontal axis is the distance from the center of the frame to the edge.
The SQA70 guarantees a high illumination of above 90% at the 44mm image circle, minimizing vignetting.
Spot Diagram
The imaging quality of the optical system can be evaluated by analyzing the distribution of the spots on the spot diagram.
The SQA70 has a central star point with an RMS radius of less than 1.84μm, and the star point at the corner is less than 2.4μm, showing very small stellar points.
Longitudinal chromatic abberation curve
This curve is a representation of the deviation of different wavelengths of light at the focal point. The different curves in the diagram correspond to different wavelengths of light.
Longitudinal chromatic abberation (LCA) occurs when different wavelengths (colors) of light fail to converge at the same focal point along the optical axis of a lens or the image, usually manifesting as blurred edges or color halos. The longitudinal chromatic curves of SQA70 lenses show very small spacing and even coincide. The curve's curvature is very low, indicating the chromatic aberration is well controlled. The sign of an very good lens.
Specifications
- Aperture size: 70mm
- Focal length: 336mm
- Focal ratio: f/4.8
- Objective lens: Quintuplet petzval APO (including two pieces of ED glass）
- Total length:
- 332mm (when the dew shield is contracted)
- 372mm (when the dew shield is stretched)
- Format specifications: Full-frame (44mm)
- OTA weight: 3.68kg (8.1lbs)
- Gross weight (including tube ring and dovetail plate): 9.9lbs
- Rear-end thread type: M42/M48/M54 adapters (M48 adapter is threaded for 2" filters)
- Rear-end connection distance: Supports 37-68mm range (recommended connection distance is 55mm)
- Soft sided case, external dimensions: 42x20x23cm (16.5x7.9x9.1in)
| Product Banner Type | new |
|---|---|
| Free Shipping Graphic | Free US Shipping |
| Telescope Focal Length | 301 - 400mm |
| Hide Found a better Shipped Price on Frontend? | Yes |
- 1x SQA70 OTA
- 1x Oxford cloth case
Askar SQA70 f/4.8 Quintuplet Petzval Refractor Telescope # SQA70