SVBONY Telescope Filter 2" UHC Filter for Observations of Deep Sky Objects Ultra High Contrast Filter Reduce Light Pollution

I used the SVBONY 2-inch UHC filter for visual observation, and this is my first UHC filter. I was able to see the M94 galaxy, which I had never seen before against the bright sky background, with my 8-inch SCT. This filter makes the sky appear much darker while keeping most nebulae visible. I noticed significantly better contrast with the M17 Omega Nebula, though I feel that some fine details might have been filtered out and lost. I would not recommend it for visual observation of globular clusters like M3 and M5. The image was only slightly less sharp, and I thought I saw some reflections. The craftsmanship is excellent; the glass appears to be top quality and very clean. In my video, you can see that this filter gives an image with a slight violet tint. I can't compare it to a high-end UHC filter because I don't have one, but for its price, I think this filter is excellent. It will most definitely help you see faint deep-sky objects that you might have wondered if they were even there.

The virtue of high contrast filter (or city light filter) is to coat some relevant materials on very flat glass, selectively transmitting wavelength that suits the filter's purpose. So ideally speaking if you live in Bortle class 1 area, you don't need it. But there are only a few places you will find near your city even in the western side of the US. Therefore this filter can do the right job for you, for most cases. Indeed, non-flat glass and uneven coating will mar your filter and in the end, it mars the quality of an optical image projected on your eyepiece or the camera sensor. For that, perhaps very high-end quality astrophotography might want something more expensive filters. As an amateur, this filter is just perfect. You may lose some lights as filters wouldn't have 100% transmittance for necessary wavelengths. Despite such light loss, transmitting only the necessary wavelengths is important as your camera sensor doesn't want to be saturated by unnecessary wavelengths hitting your sensor. One of the best representative unnecessary wavelength shall be city light. Longer you expose through one shot of the picture, more importance of the filter you fill find. Attached is Trifid nebula,stacked many images taken 30 seconds for each.

Glass had strange oily marks resembling spaghetti noodles on both sides. Was this some kind of disgruntled employee at the factory? Was this a previously returned item? I'll never know. I tried my best to clean it, but several spots remain. Replacing immediately. Edit: amazon exchanged it for another and this one is perfect.

I’ve only had a couple of sessions worth of imaging with this filter, but the results so far are great. I’m close to downtown in a major city and to a street light and I definitely notice a difference in picture quality with this filter. It’s great for nebulae and really brings out the reds. It’s not so good for galaxies and star clusters as far as I can tell. Just starting to really dabble in filters and this one was worth the buy.

Orion nebula looks stunning compared to not using a filter. Highly recommend!