• 1. Introduction
• 2. Filter Specifications and Test Setup
• 3. Filter Comparisons
• 4. Retail price in US: Price comparison of 36mm unmounted set of LRGB filters
• 5. Conclusion

1. Introduction

I was recently contacted by Optolong, a filter manufacturer in China, who asked me to test their filters. They sent me a set of 36mm unmounted LRGB and a set of 36mm Narrowband Filters (H-Alpha 7nm, OIII and SII 12nm). I was impressed when they arrived; nice packaging and presentation in a similar plastic case to the Baader.

I limited my comparison for LRGB only which was carried out on the 15th and 16th August with similar average seeing conditions. The narrow band filters are not the final version that will be used for comparison. At the time they were only manufacturing them in 12nm pass band. The Baader equivalent is 7nm, which is more the industry standard. Subsequently,