The Svbony company provided me with a Svbony SV501P (70 mm) telescope for review. This is an entry-level budget lens telescope with a 70mm lens diameter and a 400mm focal length. The telescope is equipped with a photo tripod, an eyepiece, an erecting prism, a finder scope, and a good backpack for storage and transportation. Well, let’s get started!
Declared specifications
| Model | F9348A |
| Optical Design | Refractor |
| Aperture | 70 mm / 2.75″ |
| Focal Length | 400 mm |
| Focal Ratio | F5.7 |
| Optical Coatings | Multi-Coated |
| Objective lens | 2E/2G |
| Finder Scope | 5×24 Optical |
| Eyepieces | K 20 mm 1.25″ (20x) |
| Diagonal | Correct-Image Prism 45° 1.25″ |
| Tripod | SV101 Aluminum Alloy Tripod |
| Portable Backpack | YES |
| Weight | 2950g |
The telescope is delivered in a cardboard shipping box, inside of which there is another box with inscriptions and a photograph of the product. Inside there is a backpack in a protective film. Inside the backpack there is a telescope tube, a photo tripod in a separate bag, a 20 mm eyepiece in a plastic case, a 45 degree erecting prism, a finder with a foot, as well as instructions in several languages (including Russian).
The optical tube is wrapped in protective film, as well as a layer of paper. Tube length 380 mm. The lens hood is removable, diameter 100 mm, length 86 mm. The hood can be unfolded, then the tube will be even shorter – 330 mm, but it will not be possible to install a cover on the hood. The lid has a hole with a diameter of 42 mm. The tube is metallic, painted white, and has a metal dovetail fastening plate at the bottom. The telescope is very compact and lightweight.
The focuser is rack-and-pinion, partly plastic, partly metal. Focuser travel 63 mm. The outlet has a T2 thread (M42x0.75) for connecting additional accessories. Upon inspection of the tube, it was discovered that the focuser tube was noticeably distorted. This even led to partial cutting off of the aperture – in fact, the eyepiece is not located on the optical axis. At the top of the focuser there are adjusting hex screws that adjust the tilt and pressure of the plastic plate inside the focuser to the focusing tube.
The objective lens in the tube is achromatic, two-element, with an air gap. The coating is green, but the coating is partial and there are bright colorless highlights. Input aperture – 69.65 mm.
Finder 5×24, very simple. The measured aperture is 23 mm, but there is a diaphragm installed inside that reduces the aperture to 12 mm. The finder lens is a simple single lens, without coating. To prevent the finder tube from dangling on the leg, you need to install a flexible plastic strip inside (included in the kit). The finder eyepiece was screwed in crookedly (skewed) and was difficult to rotate – I had to completely unscrew it and carefully screw it back in. The image in the finder is upside down, this is normal. The image quality is poor, but this finder is suitable for pointing at the Moon, planet or bright star.
Erecting prism without coating. When used with a telescope and eyepiece, the image is completely straight (like through a spotting scope). The skirt and visual adapter are metal, the body is plastic. There is a metal ring inside the visual adapter to prevent the clamping screw from leaving marks on the eyepiece skirt.
There is one eyepiece included, with a focal length of 20 mm (Köllner system). Coating is partial.
The kit also includes a Svbony SV101 photo tripod, which acts as a simple alt-azimuth mount. The tripod legs are metal, the head is plastic. It can rotate left-right, up-down, and tilt 90 degrees. Tripod length when folded is 460 mm. The tripod head can also extend upward. The height of the installed tripod from floor level to the top is 462-650-900-1160-1390 mm. There is a bubble level at the base of the tripod.
Testing
It turned out that when installing a erecting prism and an eyepiece, the focuser tube additionally cuts off the useful aperture up to 60 mm – the focuser tube may need to be shortened.
With the included erecting prism, the image is completely straight, meaning the telescope can be used for ground-based observations as a telescope. However, I didn’t like the image quality – the image was too blurry and there were noticeable color halos. The Moon test was also disappointing – the image was spoiled by color halos (possibly due to the skew of the focusing tube), and it was not possible to obtain a sharp image.
With the included wrap-around prism, the image is completely straight, meaning the telescope can be used for ground-based observations as a telescope. However, I didn’t like the image quality – the image was too blurry and there were noticeable color halos. The Moon test was also disappointing – the image was spoiled by color halos (possibly due to the skew of the focusing tube), and it was not possible to obtain a sharp image.
Troubleshooting
First, I carefully adjusted the focuser using Allen keys and fixed the distortion of the focuser tube. After that, I carefully examined the lens. It turned out that the lens lenses are poorly held in the frame and even when pressed with a fixing ring they move under their own weight. It also turned out that if you place the tube vertically and lightly tap the lens barrel with your palm while rotating the tube, you can achieve some self-centering of the lenses. At the same time, you can hear the lenses making a sound when the tube shakes. By reinstalling the tube on the mount, I got an image without shifting the color channels. As a result, I unscrewed the fixing ring on the lens cell and inspected the cell. There is a significant gap between the lenses and the cell, so it is advisable to install some material (for example, a plastic strip) between the lenses and the cell. As a quick fix, I decided to simply take the lenses out of the frame, press them together and wrap them around the ends with electrical tape. The lenses are now more or less fixed relative to each other. After installing the lenses back into the lens barrel, I saw a noticeable improvement in image quality. At the same time, noticeable spherical aberration remains, making it difficult to obtain a clear image at high magnification. It may be necessary to experiment with the thickness of the spacers between the lenses, but I decided to leave everything as it is for now.
The telescope performed very well when photographing the Sun through the Herschel wedge with an aperture diaphragm of 42 mm, including in the calcium line.
The focal length of the telescope is the same as that of the Coronado PST H-alpha 40 mm chromospheric telescope, which greatly simplifies the alignment of color channels when obtaining multispectral images:
Red channel:
-Coronado PST H-alpha 40 mm telescope
-Sky-Watcher AZ-GTi mount
-Deepsky IR-cut filter
-QHY5III178m camera.
Stacking of 250 frames.
Green channel:
-Svbony SV501P 70mm telescope (with diaphragm 42 mm)
-Sky-Watcher AZ-GTi mount
-Lacerta Herschel prism
-Baader Solar Continuum filter
-ND3 filter
-QHY5III178m camera
Stacking of 100 frames.
Blue channel:
-Svbony SV501P 70mm telescope (with diaphragm 42 mm)
-Sky-Watcher AZ-GTi mount
-Lacerta Herschel prism
-Antlia CaK 3nm 393.3nm filter
-ND96-09 filter
-QHY5III178m camera
Stacking of 100 frames.
What about the photo tripod, in my opinion, it is still better to equip the telescope with a full-fledged azimuth mount. With a photo tripod, the telescope is suitable for terrestrial observations, as well as simple astronomical observations. At the same time, it is inconvenient to observe highly located objects (due to the 45-degree bend in the optical axis).
SUMMARY
Although Svbony positions the Svbony SV501P 70 mm as an entry-level telescope, I believe that even an inexpensive telescope should provide good image quality and not have critical defects such as focuser skew, “floating” lenses in the lens cell and hidden aperture cutoff. Perhaps I just received an defect item, but I hope that this review will be useful to both the Svbony company and the owners of this telescope.
You can purchase the Svbony SV501P 70 mm telescope in the official Svbony store on Aliexpress.
Реклама: ООО «АЛИБАБА.КOМ (РУ)» ИНН 7703380158