Daystar Flat Cap Diffuser for Solar Imaging

Daystar Flat Cap

The DayStar FlatCap is a precision Gaussian diffuser used to capture flat field reference images for solar imaging. It is temporarily installed over the front of the telescope and deliberately blurs the solar disk so that no solar surface detail remains. The resulting image contains only illumination gradients and optical defects from the imaging train, which can then be removed during software calibration.

How It Works

The FlatCap diffuses incoming sunlight into a controlled Gaussian intensity distribution. This strong diffusion suppresses solar structure while preserving dust shadows, vignetting, and uneven field illumination. These characteristics make it well suited for producing consistent and repeatable flat frames in solar imaging workflows.

Compatibility and Sizing

FlatCap models are sold by inside diameter. Measure the outside diameter of the frontmost component of your telescope or ERF, then round up to the next larger size. Included felt pads can be installed if needed to ensure a secure and centered fit.

Example: A telescope with a 160mm front diameter should use the FC170.

Important Safety Information

The DayStar FlatCap is not a solar filter and must never be used as one. It must be the first component to encounter light and must only be used in combination with a safe solar filter or a dedicated solar telescope. Improper use can result in eye injury or equipment damage.