I chose the Televue 3x Barlow largely because of their reputation on various Astronomy forums and that I already have a 2x barlow and was interested to see what benefit the 3x barlow gave. Also, it is a two element barlow as compared to an apochromatic barlow, which has three elements and therefore reflects a couple percent more light away.
I've not noticed any visual distortions when using the barlow, not even at the edge of the field of view. Overall, images were crisp, and there isn't any degradation in image quality compared to my standard 2x no brand Barlow considering the 3x barlow is pushing my f10 SCT to effectively f30. I had noticed that it was sometimes difficult to achieve sharp focus when using an eyepiece greater than 17mm but that appeared to be more of an issue with the standard focuser built in to my 8 inch SCT. I have now purchased a precision focuser which has given me a lot more control during sharp focus.
I am very impressed with the sturdy construction of the Televue 3x barlow. The tube is solid and quite heavy which gives it a good professional feel and backs up the extra cost paid for such a quality Barlow lens. It fits nicely inside the diagonal and stays put thanks to the very perfect fit and locking screw which keeps the barlow rigid without leaving marks on the tube.
Overall a great product at a reasonable price considering the increase in quality this barlow gives to the viewing and astro photographic experience as a whole.
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