SVBONY Telescope Focal Reducer 1.25” 0.25X Focal Reducer with C-Mount | Adapter to CCD Camera, for Telescope Eyepiece Photography, Internal Threaded Design, Broadband Green Coated Lens

I bought this to try to widen the star field on my f/4 guidescope. Three things I learned 1) focal reducers work at f/7 or higher. 2) The back focus for 0.5 is around 32-37mm. 3) This works nicely when screwed onto an eyepiece.

It's not amazing, but it's definitely a great upgrade for the price. I'm happy to use it and find it a pretty good value. It almost replaces my 25mm plossl. I have no issues with the image quality, and the build is solid. Used with a150mm SCT.

It works ... but not what I was shopping for. Nor is very adaptable. I misread the product info and thought I was purchasing a T to C thread 0.5x focal reducer. Not an eye-piece filter thread reducer.

Used Their Products Before....Never a Problem....

I got this lens to expand the field of view on my telescope. The first picture attached to this review is prime focus through the telescope, and as you can see it's not quite large enough to get the entire moon. The second picture is the same camera, same settings, and same weather conditions, taken through this lens. The most obvious problem is the massive glowing halo around the moon. That was present in every shot I took with the lens. Less obvious, but more problematic, is that it can't actually get things in clear focus, making it impossible to resolve fine detail. The only reason I gave this lens 2 stars instead of 1 is because it does what it is supposed to do in that it expands the field of view to allow you to see larger objects.

Off-axis stars and planets are distorted by coma, not surprising at this price. But it does work.

Really not worth even the low price asked. Anything imaged through this reducer is surrounded by a significant halo, I assume due to a poor curve of the lens.

Works well for terrestrial viewing, I will try it on the moon soon...

Performs as required

Foggy image, no matter what I do. Using 8" Newtonean, reducer attached to svbony 305 pro camera, the reducer is 5.5 cm from the sensor.