Double the Power, Not the Problems
The Tele Vue 2x BIG Barlow - 2" is an amplification lens engineered to double the magnification of your eyepieces without compromising the optical integrity of your telescope system. Designed for observers who use premium 2" and 1.25" eyepieces, this is not a simple two-element Barlow. It is a sophisticated four-element telecentric amplifier that delivers high-contrast, high-fidelity views for both visual observation and imaging.
Its primary purpose is to increase magnification while preserving the eye relief of your favorite long focal length eyepieces and maintaining a flat, well-corrected field. For the planetary observer or high-resolution deep-sky enthusiast, the Big Barlow transforms a low-power eyepiece into a high-power planetary instrument with a single motion, often with little to no refocusing required.
A Smarter Optical Path for High Magnification
At the heart of the Big Barlow is a four-element, telecentric optical design. Unlike a traditional Barlow that diverges the light cone, this system keeps the exiting light rays parallel to the optical axis. This subtle but critical difference is what allows it to be nearly "parfocal," meaning you will not have to substantially change focus when you insert it into the optical train.
This design also corrects for spherical aberration that can be introduced when using long focal-length eyepieces. The result is a sharper, higher-contrast image across the entire field of view. Stars remain tight pinpoints from the center to the edge, a performance characteristic that simpler Barlows often fail to achieve, especially in fast telescopes.
Maximum Light Throughput with Multi-Coatings
Every air-to-glass surface in the Big Barlow is multi-coated with Tele Vue's proprietary high-transmission coatings. This ensures that the maximum amount of light from your telescope's objective reaches your eye or camera sensor. The practical effect is a brighter, higher-contrast image with minimized ghosting and internal reflections.
When you are pushing your telescope to its magnification limits on a target like Jupiter, this increased contrast makes a real difference. Faint festoons in the cloud belts and subtle color variations in the zones become more perceptible because stray light has been effectively suppressed within the optical system.
Seamless Integration with Parfocal Performance
One of the most practical benefits of the Big Barlow's design is its parfocal nature. You can switch between observing with an eyepiece alone and with the Big Barlow in place and require only a minimal tweak of the focuser. This is a significant workflow advantage in the field, especially during nights of good seeing when you want to quickly increase power to catch fleeting planetary detail.
With a 32mm Plössl, you can frame the entire Double Cluster in Perseus. Insert the Big Barlow, and without a major focus change, you are now observing the core of one of the clusters at twice the power, resolving individual star colors. This seamless transition from low-power finding to high-power observing is what sets this amplifier apart.
Versatile Eyepiece Compatibility with the 1.25" Adapter
The Big Barlow is designed to be the only amplification lens you need. It includes a high-quality 2" to 1.25" adapter that features a non-marring brass clamp ring. This ensures your smaller, high-end eyepieces are held securely and perfectly centered in the optical path without scratching their barrels.
This versatility means you can use your entire eyepiece collection, from a massive 2" wide-field eyepiece for deep-sky vistas to a small 1.25" planetary eyepiece for lunar and planetary work. The robust build quality easily handles the weight and leverage of even the heaviest eyepieces in the Tele Vue lineup.
Direct Filter Integration for Enhanced Views
The 2" barrel of the Big Barlow is threaded to accept standard 48mm astronomical filters. This allows you to place a filter, such as a nebula filter or a planetary color filter, in the optical train before the eyepiece. This is particularly useful for enhancing contrast on specific targets.
For example, you can thread in a UHC or OIII filter and use the Big Barlow to increase the image scale on a target like the Orion Nebula (M42). The filter darkens the sky background, and the Barlow brings the fine details of the Trapezium region into clear view, all while using a comfortable, long eye relief eyepiece.
Built for Stability and Security
Weighing in at just over a pound, the Big Barlow is a substantial piece of equipment. Its all-metal construction is designed to prevent any flexure, even when holding heavy 2" eyepieces like a 31mm Nagler. This mechanical rigidity is essential for maintaining optical alignment at high magnifications.
The one genuine trade-off for this performance is its weight and size. It requires a robust 2" focuser and may necessitate re-balancing the telescope, particularly on smaller mounts. However, this is a necessary compromise to achieve a stable, flex-free optical train capable of supporting the best eyepieces available.
Is the Big Barlow the same as a Powermate?
No, while both use a 4-element design, the Big Barlow is optimized for visual use and being parfocal. The Powermate is a true telecentric amplifier designed for both visual and imaging, offering more flexibility for complex imaging trains and solar applications.
Will the 2x Big Barlow work with my fast f/4.5 Dobsonian?
Yes, the 4-element design provides excellent correction and maintains sharp star images even in fast optical systems. It is a much better choice for fast scopes than a standard 2-element Barlow, which can induce aberrations.
Do I need to rebalance my telescope when I use this?
At over one pound, it is very likely you will need to adjust your telescope's balance, especially when switching from a lightweight 1.25" eyepiece. It is best suited for telescopes with sturdy focusers and mounts that can handle the extra weight.
Can I thread a 2" filter onto the Big Barlow?
Yes, the 2" barrel is threaded for standard 48mm filters. This allows you to add a filter to the optical path before the eyepiece, which is useful for nebula or planetary observing.
Why is this better than a standard, cheaper 2" Barlow?
The Big Barlow's 4-element telecentric design offers superior aberration control, maintains the eye relief of your eyepiece, and is nearly parfocal. Cheaper 2-element designs often result in softer images, especially at the field edge, and require significant refocusing.
