Explore Scientific 3X Barlow for 1.25" eyepieces


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This new four-element 1.25" 3x Explore Scientific focal extender (Barlow lens) triples the power of any eyepiece used with it, with flat-field and essentially apochromatic performance . . .
Our Product #: ESB1X3
Explore Scientific Product #: FE03-125

Product Description

The 1.25" 3x Explore Scientific premium focal extender (Barlow lens) 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 triples the power of any 1.25" eyepieces used with it, providing high powers while maintaining the comfortable eye relief of longer focal length eyepieces. This makes a Barlow/long focal length eyepiece combination such as this 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 3x 1.25" 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"
Number of optical elements 4
Power 3x
Warranty 1 year, extendable to lifetime


Review by:
I bought this focal extender to supplement my 2x conventional Barlow. What I found was my 3x view was as sharp maybe sharper than the 2x view from what I thought was a good Barlow. So happy with it I bought the 2x focal extender in this series to supplement this. (Posted on 10/4/2019)
Review by:
I mostly used for planetary astrophotography. I appreciate having an extender which gives approx the same magnification factor, regardless of back focus. (Posted on 9/10/2019)
Review by:
Comes in a really cool flippy box. Does the job with alacrity and without adding aberrations. Looks and feels awesome.
One thing worth noting however, the top does not unscrew to allow screwing into filter threads to prevent sag in a long light train. (Posted on 7/22/2019)
Review by:
I purchased this mainly for planetary photography, and it has done an excellent job. It is well built and produces crisp images. I will consider E.S. focal extenders in the future if I decide to add to my collection. (Posted on 1/8/2019)
Review by:
Although I have not used this much as most of my astrophotography is focused on deep sky objects, the Explore Scientific 3x Barlow works great and I highly recommend it. I had obtained and image of Jupiter using this with my modest 80mm refractor and it rivals images with much larger aperture scopes. (Posted on 10/18/2018)
Review by:
The focal extenders by E.S. are excellent, both visually and for imaging. They're very well machined, high quality, nicely packaged and optically are excellent. I use them for imaging to control imaging scale. I use the E.S. focal extender instead of the popular Powermate because it essentially does the same thing for much less cost. (Posted on 10/8/2018)
Review by:
I've got one of these 3x focal extenders and it's great. I bought it to augment my 2x Barlow and it outperforms that to the point that I'm going to replace my good 2X Barlow with a 2X focal extender from this series. They are that good. (Posted on 10/6/2018)
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Supplied Accessories

Dust caps