3X Explore Scientific Focal Extender; 1.25-inch Barrel; 4 Elements

I have seen mix reviews on this focal extender and honestly some of the negative ones makes me wonder if some of the end users fully understand how it is suppose to work. I bought this to double the focal length of my Explorer Scientific AR127 Telescope and when I use it with the eyepieces that I have, it worked PERFECTLY. When I go to use this extender in concert with my DSLR, at first I had focusing issues and quickly realise that I had to reposition this extender about 1 inch out from fully mounting it on the telescope to get my DSLR in focus. but still was able to make sure that the extender was secured solidly. Also just like a teleconverter used on a telephoto lense, the focal length will double and the F stop will also drop in half thus the amount of light will deminish. In my case, my telescope has an F stop apiture of f-7.5. With this extender, it is now an f-15 so I have to increase the ISO and slow down my shutter speed on my DSLR to compensate for the light loss. I however was still able to get an amazing TACK SHARP photos of the moon and other objects I photographed through my telescope. If you are looking for a way to double your focal length of your telescope, this extender is a great piece of glass that will do the job well.

Great quality extender. Very high quality construction, and great optical quality. It's heavy, but it's a lot of glass.Note that this is an extender, not a barlow. The difference is an additional optical element that the light rays of an extender are parallel, so it maintains the same 2x magnification regardless of distance. A standard barlow has a cone-shaped light path, meaning the magnification varies based on how far away the barlow is from the eyepiece or camera. For astrophotography, I wanted the same 2x no matter where I placed the extender in my imaging setup; thus, this worked perfectly.

Build quality is unreal - beautiful machining, good coatings. The 1.25 to 2" adapter itself is fairly impressive, with a nice brass compression ring, and undercuts to try to avoid the sick feeling of dropping an eyepiece. It does what it is designed to do very well, but I'm going to focus on a few caveats.-This thing is HEAVY. You may need additional counterweights to get a dobsonian to balance. If your focuser is particularly sloppy, it may need additional tension to hold focus with this and a 2" eyepiece.-You may need additional out or in-focus travel. Test with your set up immediately to return or get extension tubes as needed.

keep in mind-you need to have steady to good seeing in your sky for this to make a difference. otherwise stretching the dang f/ratio is going to tease the limit of your scope. if you know from experience that this will be an issue then hold off on buying it. use either 1.5X, 2X, or 3X. But if this is something you like to have in your collection then get one.

Solid construction and nice optics (I'm no expert, but I can see the Cassini division clearly enough). This Barlow lens does everything and more than i expected of it. It has been a great addition for planetary viewing, particularly for Saturn and Jupiter. I use it mostly with my 25mm Plossl (on an Orion 130ST EQ) which gives me good eye relief and magnfication equl to my 10mm plossl with the 2x Barlow. If I want to get even closer, I stack the 2x Barlow and 5x Barlow with the 25mm Plossl giving me about 260x magnificaiton. Nice crisp view of the moon's craters and deep star clusters too. Well worth the price. I'd buy from this company again.

I'm donating all my other Barlows this is the best I ever had when I use high magnefication light transmission is excellent and doesn't lose any eye relief.

This Focal Extender works great for my use.

a definite improvement over conventional 3 element barlows- less chromatic distortion and less coma at the periphery- excellent value as well.