Explore Scientific 2X Barlow for 1.25" eyepieces


Availability: In stock

This new four-element 1.25" 2x Explore Scientific focal extender (Barlow lens) has an exceptionally flat field and essentially no color fringing with all telescope types and focal ratios . . .
Our Product #: ESB1X2
Explore Scientific Product #: FE02-125

Product Description

The 1.25" 2x Explore Scientific premium Barlow (described by Explore Scientific as a focal extender, rather than a Barlow) uses an advanced four-element optical design to deliver a flatter field of view with sharper field edges than even the best three-element apochromatic Barlows.

This Explore Scientific focal extender doubles the power of any 1.25"eyepieces used with it, providing high powers while maintaining thecomfortable eye relief of longer focal length eyepieces. This makes aBarlow/long focal length eyepiece combination ideal for those who must wear eyeglasses while observing due to astigmatism.

All air-to-glass surfaces are fully coated with multiple layers of individually tuned ion-deposited anti-reflection materials for maximum light transmission and contrast. The lens edges and all internal metal surfaces are blackened to maximize the image contrast. Your eyepieces are held in place by a non-marring clamp ring that won't scratch your eyepieces as a conventional metal thumbscrew can.

While not specifically claimed to be apochromatic in performance, color fringing in this Explore Scientific focal extender is essentially eliminated with all telescope types and focal ratios.

This Explore Scientific focal extender is protected by a one year warranty that can be extended to a transferable limited product lifetime warranty at no cost by simply sending in the warranty card. With the extended product lifetime warranty, this Explore Scientific focal extender is protected for as long as it continues to be manufactured, plus an additional five years.

Tech Details

Barrel Size 1.25""
Power 2x
Warranty 1 year, extendable to lifetime


Review by:
First I bought the 3x version of this focal extender to supplement a conventional 2x Barlow. I liked it so much I decided to get this focal extender as well. A Barlow has three elements while a focal extender has four and that makes a big difference. (Posted on 10/4/2019)
Review by:
Explore Scientific really hits the sweet spot for value. This is a very enjoyable and usable barlow. Really great for quickly doubling the power and going back down. (Posted on 9/16/2019)
Review by:
I already owned and ES 2" 2x extender which I am very happy with. Mostly used for astrophotography, but with a flip mirror and filter wheel, I exceeded the focal range on my C14. Solution is to put a focal extender inside my Crayford focuser. Optics work fine, but the black housing is unnecessarily fat. I have to replace it. Minus a star for the housing. (Posted on 9/10/2019)
Review by:
This has proven to be an invaluable addition. It's been terrific with my AT72EDII to get a bit more reach both visually and with my Sony A6300 aps-c camera. It's seemingly perfect. I can't say they all are as good as mine, but this is utterly transparent - adds no coloration and has a flat field. It's amazing how I can push the little 72 with this and an old Nagler 4.8 for 180x. Splits Alpha Centauri beautifully! Old timers here in South Africa are incredulous. Lunar views, too, are spectacular with almost no CA whatsoever. (Posted on 8/1/2019)
Review by:
I bought this focal extender since ES markets it as a "free lunch" - double your eyepiece collection without additional optical aberrations or changes in eye relief. And while it's certainly not bad, I do notice a difference than without it in the optical chain. I did a little side by side test using an 8mm Paradigm Dual ED eyepiece and an 18mm Paradigm Dual ED eyepiece in this Barlow (for an effective 9mm eyepiece). I noticed stars didn't resolve as sharply or evenly in this focal extender than as without. And the whole reason I did that test in the first place is that I noticed I wasn't getting as nice views using this focal extender.

So while it does the job of a Barlow well, I personally prefer to not use it, and I'm planning on eventually buying some individual eyepieces for the magnification ranges I thought I could cover by using this focal extender. I will be keeping it around to use for Barlowed laser collimation, but any cheapo Barlow would do that job equally. (Posted on 12/28/2018)
Review by:
The 1.25" 2x Explore Scientific barlow is a 4-element design that performs like a telecentric barlow. The construction of this barlow is outstanding and I was very pleased with the large set-screw for locking eyepieces with the compression ring as it makes it easy to lock the eyepiece with gloves on. Optically the performance of this barlow is outstanding. I've used it with a 20mm XW, Silvertop plossls, Sterling plossls, and AT Paradigm eyepieces. In all of these eyepieces the 2x ES barlow has outstanding performance. Edge performance is cleaned up and the field is very flat with this barlow. I have found it performs extremely well for both deep sky and lunar observations and have not tried it for planetary observations yet. As with any telecentric barlow the 2x ES barlow maintains the eye relief and exit pupil characteristics of the eyepiece so it does not introduce problems with blackouts and I have not seen any vignetting when using it either. (Posted on 8/4/2017)
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