Svbony MK105

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

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.

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

SVBONY SV213 1.25″ 3x Barlow lens


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

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.


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



Svbony provided me with a Svbony SV705C color astronomical camera based on a Sony imx585 sensor for testing. This is a widescreen sensor with 4K resolution (3856 x 2180) and 1\1.2″ diagonal, introduced in 2021, which is an improved version of the similar Sony imx485 sensor.

The Svbony SV705C camera is of particular interest for shooting planets, the Moon, the Sun, including for creating videos in 4k resolution. Low read noise, high resolution, very large sensor, as well as the claimed absence of the sensor’s own glow (“amp glow”) make it also attractive for shooting comets and bright deep sky objects, including EAA (Electronically Assisted Astronomy). The camera does not have active cooling.

Specifications declared by the manufacturer

Model SV705C
Sensor IMX585
Total Pixels 8.3 Mega Pixels
Diagonal 12.85mm
Max Resolution 3856×2180
Pixel Size 2.9μm X 2.9μm
Chip Size 11.2mm×6.3mm
Frame Rate 45FPS
Shutter Rolling shutter
Exposure Range 32μs-2000s
Readout Noise 6.5e~0.7e
QE Peak ≈90%
Full Well 38k e
ADC 12 bit
BIN 1X1 2X2
Digital noise reduction​ HCG
Compatible OS Windows , Linux OS Raspberry Pi,Mac os, Chrome os
Caching 128M
Guiding Port ST4
Data Port USB3.0
Adapter 1.25″/2″/ M42X0.75/CS/C
Back Focal Length 6.5mm/12.5mm
Protective Window AR Coating
Working Humidity 30%-80%
Storage Humidity 20%-90%
Operating Temperature -10℃ to +50℃
Storage Temperature -20℃ to +60℃
Net Weight 575g
Product Size Ø58×38.3mm



I decided to write my impressions of the 685 nm IR-pass filter from Svbony. I bought it in January 2021. The main task is to shoot the Moon with a monochrome camera, since moving to the near infrared range allows you to slightly reduce turbulence when shooting. With a very stable atmosphere, you can set a green filter, while the resolution will be higher than in the red and IR ranges, however, such an atmosphere in combination with the visibility of the Moon is rare, and I get 99% of the shooting of the Moon in monochrome just with red or IR-pass filter. Yes, I also have an 850 nm IR-pass filter from ZWO, but with it the resolution drops noticeably, and the Sony imx178m sensor in my monochrome astronomical camera (QHY5III178m) is not very sensitive in the IR range.

The 685nm filter can be used quite successfully with high infrared sensitivity color sensors, especially Sony imx462 or imx464 sensors. Another possible application of IR-pass filters is flare suppression when shooting galaxies, since LEDs in IR shine much much weaker than in the visible range.

The 685 nm filter may be of interest for shooting Uranus and Neptune at large apertures (from 250-300 mm) due to the higher contrast of atmospheric details.

Of course, it makes no sense to use IR-pass filters for visual observations, since the eye sees very poorly in this range. Moreover, such filters are forbidden to be used when observing the Sun in order to avoid deterioration or loss of vision.

Note that mirror or mirror-lens telescopes are best suited for NIR imaging as they have little or no chromatism. The Barlow lens in the IR range can also add chromatism, which will negatively affect the sharpness of the image. In any case, my tests on mirror-lens telescopes, ED refractors and apochromats, as well as with a 2x Barlow lens, did not reveal a noticeable drop in sharpness due to uncorrected chromatism. For shooting with an achromatic refractor and a monochrome camera, you can try a red or green CCD filter – they do not pass the infrared range, as well as the blue region with chromatism.

The Svbony SV183 IR Pass 685 nm filter is made in 1.25 inch format, but there is also a 2 inch version on sale. From the outside, the surface of the filter seems to be a mirror-like feature of interference filters, but a bright light bulb looks dark red in the light. At the same time, absorbing IR-pass filters look black from the outside. However, interference filters have higher light transmission than absorption filters, and can also have a sharper cutoff of the spectral range.

The filter Svbony SV183 IR Pass 685 nm 1.25″ is supplied in a cardboard box with a plastic box inside. I have no complaints about the quality of making – the surfaces are clean, without cracks, scratches and scuffs.