William Optics FluoroStar 91

Worth knowing before you buy

How does the William Optics FluoroStar 91 perform optically compared to other premium refractors?

The FluoroStar 91 is not directly discussed in these forums. However, the broader discussion shows William Optics scopes are well-regarded for build quality and color options, with the FLT 120 praised for being a mid-range option between the FLT 91 and FLT 132 that balances performance and cost.

What are common mechanical issues with early production units?

Early FLT 120 units had issues with the velvet tape friction grip in the rings being too thin, causing the OTA to slide back and forth. William Optics confirmed this issue and provided additional velvet tape to add thickness to the inner rings as a solution.

How do I determine the correct back focus distance for flatteners?

William Optics provides back focus distances for flatteners on their product pages, though new models sometimes lack complete information initially. For the FLT 120 with FLAT68III the distance is 10.

Is the FLT 120 a good upgrade from smaller William Optics refractors like the FLT 91?

The FLT 120 is positioned as a logical step up for those who want more aperture without the weight and cost of the FLT 132. Users considering it should note it requires proper back focus calculations for flatteners and may benefit from the slightly improved mechanical design compared to early FLT 91 units.

What's the overall build quality of William Optics telescopes?

William Optics scopes are noted for robust tube construction and well-machined rings, with users praising the quality of materials and finishing. However, anodization can fade with sun exposure over time, a known issue across William Optics' product line that users should expect with outdoor use.