The Moon, May 29, 2023, 18:31
Equipment:
-Svbony MK105 telescope
-Sky-Watcher AZ-GTi mount
-ZWO IR-cut filter
-ZWO ASI 183MC camera
Processing: Autostakkert (100 frames from 1000), AstroSurface, panorama from 2 with Microsoft ICE.
svbony
Svbony MK105
At the end of October 2022, Svbony announced the release of a mirror-lens telescope of the Maksutov-Cassegrain system with an aperture of 105 mm. This was quite unexpected, since before that among Svbony telescopes there were only lens telescopes (refractors). And so, Svbony kindly provided me with a MK105 telescope for testing.
Svbony MK105
The meniscus optical system was invented by the Soviet scientist and optician Dmitry Dmitrievich Maksutov in 1941. In the Maksutov-Cassegrain system, the primary mirror is a spherical high-aperture mirror. Spherical aberration of the primary and secondary mirrors is compensated for with a full aperture lens corrector (meniscus) at the front of the tube. In this case, a convex spherical secondary mirror can be deposited directly on the meniscus, but then the relative aperture of the telescope should be in the range of 1:12–1:15 to eliminate spherical aberration as much as possible. For the first time I looked into the meniscus telescope around 2007 and since then I have fallen in love with the “poppies” for their compactness, the complete absence of chromatism, the absence of rays in the image and unpretentious maintenance. However, despite the apparent simplicity (all optical surfaces can be spherical!), increased requirements are imposed on the mechanics, mirrors, and especially the meniscus, otherwise the telescope will not be able to provide alignment stability and diffraction image quality.
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I tested a 3x Barlow SVBONY SV213 lens with a 1.25″ barrel. The manufacturer claims a three-element optical design and blackening of the lens edges. Thanks to the three-lens design, the image quality across the field should be better than that of simple two-lens Barlows. At the same time, the SVBONY SV213 is not telecentric:
– magnification can be increased using an additional extender tube
– increases the eyepiece eye relief
– works worse with eyepieces (especially with wide-angle ) than a telecentric lens like Svbony SV216 2x.
SVBONY SV213 1.25″ 3x Barlow lens
SPECS
| Brand | SVBONY |
| Model | SV213 |
| Barrel Size | 1.25 inch |
| Magnification Factor | 3X |
| Number of Lens Elements | 3- Elements |
| Lens Coatings | Fully multicoated |
| Outside Length of Upper Body | 2.30inch / 58.5mm |
| Insertion Depth | 1.02inch /26mm |
| Max Diameter Excluding Thumbscrew | 1.57inch / 40mm |
| Net Weight | 3.14oz / 93g |
| Filter Threads | M28.5×0.6 |
| Barrel Material | Aluminum Alloy |
| Number of Thumbscrew | 2PCS |
| Thumbscrew Thread Specification | M4x8 |
| Compression Band/Ring in Eyepiece Holder | Yes |
I received for test Barlow lens Svbony SV216. The Barlow lens is an optical accessory that allows you to increase the focal length of the telescope several times. It can be used both for visual observations and for astrophotography. The manufacturer claims consistent 2x magnification, fully multi-coated 4-element construction, blackened lens ends, a flat field of view, and a 1.25″ fit with M28.5 x 0.6 filter threads.
SVBONY SV216 1.25″ 2x Barlow lens
However, constant magnification implies another important property – telecentricity, that is, this Barlow lens does not change the slope of the rays coming from the lens. The telecentric Barlow lens cannot be “overclocked” by an additional sleeve, does not increase eyepiece eye relief, introduces less distortion and works better with wide-angle eyepieces.
Specs
| Brand | SVBONY |
| Model | SV216 |
| Barrel Size | 1.25 inch |
| Magnification Factor | 2x |
| Number of Lens Elements | 4- Elements |
| Lens Coatings | Fully multicoated |
| Outside Length of Upper Body | 2.34inch / 59.5mm |
| Insertion Depth | 1.55inch /39.5mm |
| Max Diameter Excluding Thumbscrew | 1.73inch / 44mm |
| Net Weight | 7.72oz / 219g |
| Filter Threads | M28.5×0.6 |
| Barrel Type | Straight Barrel |
| Barrel Material | Stainless Steel |
| Number of Thumbscrew | 3PCS |
| Thumbscrew Thread Specification | M3x10 |
| Compression Band/Ring in Eyepiece Holder | Yes |
Colorful Moon, March 7, 2023, 22:30-22:50
Equipment:
-Svbony MK105 telescope
-Sky-Watcher AZ-GTi mount
-ZWO IR-cut filter
-Svbony SV705C camera
Processing: panorama from 4 frames, Autostakkert (100 frames from 2700), AstroSurface. Scale 50%.