Professional product title: "High-Quality 1.25" FMC Zoom Telescope Eyepiece with Adjustable Focal Length (7-21mm/8-24mm/10-30mm) - Ideal Accessory for Astronomic Telescopes"
▶7-21mm Zoom eyepiece
Feature:
1.Fully multi-coated Premium eyepiece zooms to any focal length between 7 mm and 21mm
2.Zoom from low to high power in an instant with this versatile eyepiece
3.Compatible with any telescope that accepts 1.25” eyepieces
4.6 -Element 4-Group premium optical design
5.Comfortable 18mm - 16.3mm eye relief more comfortable, especially for eyeglass wearers
Technical parameters:
1.Brand: SVBONY
2.Model: SV135
3.Focal length: 7-21mm
4.Zoon Type: Linear
5.Lens structure: 6PCS / 4group
6.Eye Relief: 18mm - 16.3mm
7.Interpupillary Dist.:15mm
8.Barrel Size: 1.25"
9.Field of view: 57~40°
10.Coatings: Fully Multi-Coated-Green
11.Rubber Eye Guard: Yes
12.Meterial: Metal
13.Color: Black
14.Thread Size: M28.5*0.6
15.Overall length: 93mm
Net Weight: 133g / 4.67oz
Package Include:
1XSVBONY SV135 7-21mm 1.25 inch Eyepiece
1XLens Covers (Objective and Eyepiece)
1XLens Cleaning Cloth
▶8mm-24mm zoom eyepiece
Features:
1.SVBONY Super-wide Angle 1.25" 8mm-24mm zoom eyepiece.
2.The zoom eyepiece allows you to change magnification power without swapping out eyepieces.
3.7-Elements / 4-groups made of high index glass deliver sharp, high contrast vistas.
4.A simple twist of the zoom eyepiece housing changes the focal length from 24mm to 8mm, providing a variety of viewing magnification powers.
5.Exceptionally long 18mm-19.5mm eye relief range allows eyeglass wearers to enjoy the entire field of view without needing to remove their glasses.
6.Sleek black barrel with safety undercut to reduce the possibility of the eyepiece slipping out of the focuser or diagonal.
7.Blackened lens edges, anti-reflection threads for maximum contrast.
Specification:
1.Brand: SVBONY
2.Model: SV171
3.Focal Length: 8-24mm
4.Eye Relief: 18-19.5mm
5.Apparent Field of View: 38°-56°
6.Barrel Size: 1.25inch
7.Lens Structure: 7-Elements/4-Groups
8.Filter Threads Standard: 1.25" Filter Thread (M28.5 x 0.6)
9.Coatings: Fully Multi-Coated
10.Blackened Lens Edges: Yes
11.Barrel Safety Recess: Yes
12.Eyecups: Twist-Up
13.Eyecups Material: Metal
Net Weight: 300g / 10.58oz / 0.66lb
Package Includes:
1XSV171 Black 1.25in 8-24mm Zoom Eyepiece
1XTwo Rubber Dust Cover
1XMirror Cloth
SVBONY SV171 Zoom Eyepiece 8mm-24mm review
https://star-hunter.ru/en/svbony-sv171-zoom-eyepiece-8mm-24mm-review/
▶10mm-30mm zoom eyepiece
Features:
1.SVBONY super-wide angle 1.25" 10mm-30mm zoom eyepiece.
2.The zoom eyepiece allows you to change magnification power without swapping out eyepieces.
3.5-Elements / 3-groups made of high index glass deliver sharp, high contrast vistas.
3.5 elementos / 3 grupos hechos de vidrio de alto índice brindan vistas nítidas y de alto contraste.
4.Exceptionally long 17mm-18.5mm eye relief range allows eyeglass wearers to enjoy the entire field of view without needing to remove their glasses.
5.Sleek black barrel with safety undercut to reduce the possibility of the eyepiece slipping out of the focuser or diagonal.
6.Blackened lens edges, anti-reflection threads for maximum contrast.
Specification:
1.Brand: SVBONY
2.Model: SV170
3.Focal Length: 10-30mm
4.Eye Relief: 17-18.5mm
5.Apparent Field of View: 33°-51°
6.Barrel Size: 1.25inch
7.Lens Structure: 5 -Elements/-3Groups
8.Filter Threads Standard: 1.25" Filter Thread (M28.5 x 0.6)
9.Coatings: Fully Multi-Coated
10.Blackened Lens Edges: Yes
11.Barrel Safety Recess: Yes
12.Eyecups: Twist-Up
13.Eyecups Material: Metal
14.Net Weight: 198g / 6.98oz / 0.44lb
Package Includes:
1XSV170 Black 1.25in 10-30mm zoom eyepiece
1XTwo Rubber Dust cover
1XMirror Cloth
▶7 - 21mm 8-24mm 10-30mm ZOOM Eyepiece
For Use:
Note:
A plastic sheet with adjustable distance is arranged inside,
There will be shaking,
Is a normal phenomenon,
Do not open it!
Telescope Zoom Eyepieces – What Are They & Should You Use One? What Is A Zoom Eyepiece?
Zoom eyepieces are a single eyepiece that you can adjust to alter its focal length which changes magnification. Put the eyepiece into your telescope and by simply turning the barrel of the zoom eyepiece you’ll zoom into or out from whatever you’re looking at.
Advantages Of Zoom Eyepieces
There are a number of advantages to owning an eyepiece that you can alter the magnification of. Some are more obvious than others but what follows is our comprehensive list.
●One Eyepiece Doing The Job Of Many
The two common focal length ranges covered by zoom EPs are 7mm to 21mm,8mm to 24mm, and 10mm to 30mm. You can select any focal length between these minima and maxima, which gives a lot of variety of magnification.
In a regular collection of fixed eyepieces, we might find 10mm, 15mm, 20mm,25mm, and30mm. In this example, a zoom eyepiece can replace five stand-alone eyepieces and offers magnification in between each of those sizes which you wouldn’t have without it.
This is the most obvious advantage to owning an adjustable eyepiece: you have one eyepiece doing the job of five.
Coupled with a Barlow lens this number is doubled, so now you have two eyepieces doing the job of six individual ones (five standard and a Barlow).
●Cheaper Than Owning Separate Eyepieces
Hand in hand with our first advantage goes one of price. It is almost always going to be the case that one zoom eyepiece cost less than four individual fixed focal length eyepieces.
While it certainly isn’t the best zoom eyepiece available, you can see how it will be cheaper to buy this than five Equal quality separate eyepieces.
●No Changing Of Eyepieces
With a zoom eyepiece, there is no swapping between eyepieces to change the magnification. Let’s say you have a planet in view at low magnification. Normally, to increase magnification, you would have to switch out for another eyepiece.
Not with a zoom though! With a zoom eyepiece, there is no need to break away from your observing to change the focal length. Instead, simply rotating the collar will increase magnification, letting you see more detail on the planet’s surface.
Depending on the model you have, you may still need to adjust your telescope’s focus, but if you go for a parfocal model, like this one from Orion, you won’t have to.
The internal lenses of a parfocal zoom eyepiece move inside the barrel as the focal length is adjusted to keep focus. Ranges of fixed eyepieces can also be parfocal, like the F9152X range from Svbony.
●Match Magnification To Seeing Conditions
Having the flexibility of focal length means you can make small adjustments to reflect the current seeing conditions. Rather than having to swap between your standard eyepieces, small adjustments of the barrel on your zoom may be all that is needed to present a decent image.
●Put You More In Touch With Space
This last advantage comes through a combination of others we’ve already looked at.
Being able to seamlessly move from one magnification to another, without breaking off to change eyepieces, and being able to make the most of poor seeing conditions means longer spells of time at the eyepiece.
Not having to break away from your view gives you the feeling that your telescope is no longer there and, instead, you are looking out into space through a window.
As you move from low to high magnification, for example, you can see double stars split in real-time, planetary surface features ping into existence that you couldn’t see a moment ago, and you’ll tease out new details that might be missed when swapping from one eyepiece to another.
In summary, you can always find the best magnification for the job you’re doing and you can always find the sweet spot for the conditions. Your astronomy could be much more rewarding with a zoom eyepiece than it is with individual eyepieces.