Description
Vixen's standard "photo-visual" SD apochromatic refractor with a focal length of 625mm.
Vixen SD apochromatic refractors feature "Super extra-low Dispersion" optical glass in their objective lens. With the use of an SD reducer HD kit or an SD Flattener HD kit, an image circle of 44 mm in diameter is obtained to be used for photography with DSLR cameras with a full-frame imaging sensor.
Vixen Telescope SD81SII Optical Tube Assembly Description
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The SD lens suppresses residual chromatic aberration far below the threshold of visibility.
A lens of refracting telescopes has chromatic aberration, which is caused by different wavelengths of visible light (colors) focusing at different distances. The Vixen SD lenses, made of FPL53 super extra-low dispersion glass, allow for correcting the chromatic aberration over a wide spectrum of light. The SD lenses focus visible rays of light from the Cray(red), d-ray(yellow), e-ray(green), F-ray(blue), to g-ray(violet) at nearly the same position. As shown in the diagrams of spherical aberration, it verifies that the chromatic aberration is highly corrected over a wide spectrum of light with the SD lenses. Especially the g-ray, which affects image contrast, is suppressed excellently. The SD81S delivers outstanding sharp images with high contrast for both visual and photographic applications. Brighter F7.7 images will satisfy the most demanding visual astronomer or astrophotographer.
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Optical tube of a moderate length for visual observation and astrophotography.
The optical tubes of the SD81S, SD103S, and SD115S are designed to be shortened to their length. It is convenient to carry and set up, and balancing the optical tube is easier.
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Quick change of viewing orientation with a flip mirror
The provided filip mirror allows you to change the light pass for a comfortable observing posture. With two eyepieces of different focal lengths attached to the flip mirror, you can switch magnifications quickly.
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Versatile accessories for visual observation and astrophotography.
The focuser drawtube has 60mm threads in diameter for attaching a variety of optional eyepieces and accessories for visual and photographic purposes.
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Optional accessories to expand your pleasure of astrophotography.
This kit consists of components for prime focus astrophotography with the SD81S, SD103S, or SD115S optical tube. This reducer is made to be used in combination with an accessory such as a wide photo adapter 60DX, sold separately.
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Specifications
SD81S Optical Tube Assembly
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Objective lens, effective aperture81mm SD apochromatic, multicoated
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Focal length625mm
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Focal ratioF7.7
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Resolving power1.43 arc seconds
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Limiting magnitude11.3
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Light gathering power134×unaided eye
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Focusing mechanismRack-and-pinion, with lock knob
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Finder scopeXY Red dot finder II (1×aimimg device)
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Adapter thread / Visual back60mm and 42mm for T-ring / 50.8mm and 31.7mm push fit with flip mirror diagonal
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AccessoriesTube rings, Dovetail tube plate, Metal carry handle
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PhotographyUsable with Prime focus, Eyepiece projection, and Afocal imaging
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Solar observationAvailable with Sun projection screen set B
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Dimensions/weight90mm dia. and 585mm long / 3.6kg (Net 2.3kg)
Accessories
- Flip Mirror Daigonal
- Dovetail Tube Plate
- 7×50mm with dark-field illuminated reticle
- 50mm XY Finder Bracket II
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