SVBONY Telescope Barlow Lens 5X, 1.25 Inch Telescope Accessory, Fully Multi Coated Broadband Green Film Barlow Lens 5X for Astronomy & Astrophotography

My telescope is 5'' f/5 newtonian reflector.Its usable maximum magnification is about 260X.But, bundled high power eyepiece gives only 65X.Whenever watching moon surface, I wanted more magnification.In theory, 4X barlow lense should be ideal, utilizing maximum potential, but not more.In reality, even 3X barlens was out of reach with its prohibitive price.(Considering the price of telescope itself.)With the help of amazon's powerful sorting by price (from low to high), I met this lense.The price is good and seller's specification says it is APO design, which is typically high quality.But, there was a very negative review from other user.Anyway, I wanted utilize all the potential of my telescope,and I bit the bullet and tried it myself.Fortunately, the result was rewarding.It is a little long and heavy, but it gives high magnification power and clear image quality only for $25.Considering its wonderful price tag, I give it 5 stars.ConThis lens is a little long and heavy that it easily breaks the weight balance of telescopes.(So, negative review from other user who mentioned focal length has its own value.)With weight balance broken, the telescope get unstable and pointing get a little tricky.High magnification power of this barlow lens, make the problem worse.Even the slightest movement from unstabilization also get magnified,And the target gets out of the field of view easily.There are 2 common ways to recover the balance.1. Re-balancing- Loosen the bolt holding the dovetail and adjust the positon and tightening the bolt.- Check if balanced, and if not repeat it again.- No additional monetary cost but irritating.(You should go through this procedure whenever attaching this barlow lens.)2. Attaching some magnet to the rear part of the telescope, fuctioning as a counter-weight.- Purchasing some magnet means additional monetary cost, but remember?, this lens is such a bargain.- Attaching some magnet is much more convenient than loosening & re-tightening a bolt,and if the OTA does not have dovetail plate, this is the only way.- In theory, about the same weight (as that of this lens) of magnet will be needed.If not sure about the proper size of magnet,purchasing multiple small magnets and adjusting the number of magnet attached, is a safe choice.(Small magnets easily get sticked to each other as a bundle,so handling a large number of small magnets is manageable.)There is also a problem with too high magnification.With 5X, it is so easy to go over the maximum capability of the telescope optics.(Maximum usable manification is usually 2 * aperture in mm.)And after the maximum, image get blurred.In my case, this barlow lens and bundled high power eyepiece together gave about 120% of the maximum, and image quality get degraded a little.ProAt such a bargain price, it gives 5X magnification power with good enough image quality.With low power bundled eyepiece attached to this lens, image quality is quite good.With high power bundled eyepiece and this lens gives 120% of the maximum magnification,and image get blurred a little, but I am happy to utilize all the potential of the optics.Detailed view of the Moon surface is very satisfying.It is good to keep portability with low focal length, and get high magnification, too, with this lens.CautionYou need stable mount and well-aligned finderscope (or red dot finder).It feels like the telescope got 5X more sensitive with this lens attached.Unstability of the mount and misalignment of finderscope get also magnified.That's why weight re-balancing is important.Conclusion.A little long and heavy. Easily breaks the weight-balance.But after recovering the balance, it gives 5X magnification with good image quality.It is a perfect fit for short focal lengh telescopes, which typically lacks magnification power.If you need higher magnification, but worried about additional expenditure, I definitely recommend this lens.

I bought a 2x to 3 x adjustable Barlow from Orion for 3 times what this cost, and this Barlow is FAR SUPERIOR! I am recording video on the surface of the moon at a CLEAN magnification of 600 X (see note below) - "ZEKE!!! - THAR BE ALIENS IN THEM THAR HILLS!" (or maybe not) but I can sure see things I have NEVER SEEN BEFORE up there! I am recording it with a $20 bare Sony Effio-E 1000 line resolution CCD Image array crudely (but carefully) mounted to the end of my best 10mm eyepiece and it looks pretty darned good! (eyepieces seem like a crap-shoot to me - getting a good one at a decent price is a gamble, at best) . The video is slightly wavy (as always) from the atmosphere (I need to head for the mountains), but it is still VERY MUCH USABLE! I did increase my chances of this working by collimating the telescope and cleaning a few mirrors and and lenses (it helps).NOTE: Magnification = Barlow Mag. Power TIMES (Telescope focal length in mm ÷ Eyepiece focal length in mm). For my 8" Orion Dobsonian Reflector, that is 600 = 5 TIMES (1200 / 10). I am not sure what the lens material is, but it is WELL ABOVE AVERAGE for quality (for the cost). No, it is not a finely crafted Japanese or German lens, but by golly, whoever is making these things is pretty darned good at LENS WORK, and the machining on the housing is decent quality, as well. I am VERY HAPPY with this Barlow! WAY MORE THAN I EXPECTED. I will add one of my videos in the near future (I need to edit to cut clips out since they are all about 1 Gigabyte - which is a wee bit more than Amazon allows)This Barlow is HIGHLY RECOMMENDED. I'm tickled!

Ok, for the amount of money spent on this Barlow, it’s a great deal. There is some discoloration...chromatic aberration....where the edges of viewable object gets a fewExtra colors that are not supposed to be thereIt was stronger than my 2x Orion Barlow...so it really made a nice addition to extending the lenses I already haveAgain, it’s a great deal for the money.

Good value and Good quality Product.

It works well , took me a lil while to focus , but it worked well with 17 10 6 mm lenses..brought in more detail and magnified it very well... I realized my telescope had great potential , you need patience , take your time..you will be amazed with this lense.