This 1.25" 5x Antares high performance barlow # UB5S features a fully-multicoated achromatic design. This short barlow will work in diagonals or reflectors, has internal darkening and edge-blackened lenses, and is parfocal with most eyepieces. It features a clear aperture of 18mm. Suitable for high contrast, high power applications in any telescope. Made in Canada.
- Barrel size: 1.25" / 31.7mm
- Magnification factor: 5x
- Type: Achromatic
- Coatings: Fully multicoated
- Clear aperture = 0.71" / 18mm
- Weight: 4.3oz / 122g
- Total length: 3.17" / 80.4mm
- Length of lower chrome barrel: 1.48" / 37.5mm
- Length of upper black barrel: 1.69" / 42.9mm
- Filter threads: No
- End caps: Yes (2) but subject to change without notice
- Country: Made in Canada
Note that the use of any optical element like barlows and focal reducers changes the focus point of your telescope, requiring additional in-focus or out-focus travel. The exact amount of focus travel required will depend on the optics and mechanics of your specific set-up (telescope, diagonal (if used), barlow, and eyepiece). Hence, be aware that you may not be able to reach focus with all eyepieces or in all configurations with a given barlow.
Please note: This is a very high magnification barlow. It is not for everyone or for common viewing conditions. Before buying, please make sure that you are using realistic magnifications with your telescope. A good rule of thumb is that under very good conditions and with a very good telescope, the maximum power you will be able to use is about 50x of magnification per inch of telescope aperture. With average telescopes and/or average conditions, you should be able to use 30x of magnification per inch of telescope aperture. So for example, if you have a 6" telescope, under typical conditions you will be limited to 6x30 = 180x of magnification, and 6x50 = 300x of magnification at best.
Boosting the magnification beyond this recommended maximum for your telescope aperture is not realistic. This is bound to result in image break-down, causing fuzzy images, focusing difficulties, increased color around objects (caused by other optical elements in the telescope which are magnified by the barlow) and general disappointment, but this is not a fault of the barlow.