What Is a Barlow Lens and Camera Adaptor Used For?
By Australian Geographic | Published: 2026-11-04
Category: Guides pratiques
A Barlow lens doubles your telescope's magnification, and a camera adaptor lets you attach a DSLR. Here's how both work and when to use them.
Quick answer
A Barlow lens multiplies your telescope's magnification—typically 2x—so a 25mm eyepiece performs like a 12.5mm one. A camera adaptor on the same barrel lets you connect a DSLR for basic telescope photography.
Why a Barlow lens is more than just extra magnification
Doubling magnification sounds like a free upgrade, but it comes with trade-offs. The image gets dimmer because the same amount of light is spread over a larger area, and any wobble in your mount is twice as visible. That makes a Barlow best for bright targets like the Moon and planets, not faint galaxies.
A Barlow also lets you keep the eye relief of longer eyepieces. A 25mm eyepiece with a 2x Barlow gives you the magnification of a 12.5mm lens but with the comfortable viewing distance of the 25mm—useful if you wear glasses or find short eyepieces awkward.
When the camera adaptor makes sense—and when it doesn't
The camera adaptor turns the Barlow into a simple prime-focus connection for a DSLR body. It's a low-cost way to try telescope photography basics, but it isn't a complete astrophotography kit. You'll still need the correct T-ring for your camera brand, and the telescope must reach focus with the camera attached—something not every reflector or refractor does without an extension tube.
For deep-sky imaging, a Barlow is usually the wrong tool: it narrows the field of view and dims the subject. Use the adaptor for lunar craters, sunspots (with a proper solar filter) or planetary snapshots, and skip it for nebulae.
Barlow lens and camera adaptor FAQ
- Does a Barlow lens reduce image quality?
- A decent achromatic Barlow can soften the image slightly, especially at high power. The Sky-Watcher 2x uses multi-coated optics to keep light loss low, but avoid stacking multiple Barlows or using one with a very short focal-length eyepiece on a shaky mount. Test the Barlow on the Moon first—it's the most forgiving target for judging sharpness.
- Can I use the camera adaptor with any DSLR?
- You need a T-ring that matches your camera mount (Canon EF, Nikon F, etc.). The adaptor itself is a standard T-thread, so the T-ring is the only brand-specific part. Mirrorless cameras usually need a T-ring plus a short extension tube. Check that your telescope reaches focus with a camera before buying the T-ring.
- What eyepiece should I pair with a 2x Barlow?
- Start with a 25mm eyepiece—it gives a comfortable 12.5mm equivalent. Avoid pairing a 2x Barlow with an eyepiece shorter than about 10mm unless the seeing is excellent, because the resulting magnification will likely exceed what your aperture can support. A rough limit is 50x magnification per inch of aperture; stay below that for crisp views.
Product facts
- Sky-Watcher 2X Barlow/Camera Adaptor: The Sky-Watcher 2x 1.25” Achromatic Barlow Lens with Camera Adapter has multi-coated optics to improve light transmission. Better coating means brighter, clearer views when you push magnification, which matters most on dim targets.
Sky-Watcher 2X Barlow/Camera Adaptor
