Astronomy Specialist




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The DayStar FlatCap is a Gaussian diffuser that is temporarily installed over the front of your telescope when taking flat field reference images. By strongly blurring the Sun, the only details you will see in the reference image are from defects in your imaging train that can be removed in software.

The FlatCap is sold by inside diameter of the mounting cap. Measure the outside diameter of the frontmost component of your telescope or ERF, and then round up to the next larger size. For example, a telescope with a 160mm front should use model FC170, and then optionally install the included felt pads for a secure fit.

 DayStar solar filters Imaging FlatCap flat field filter

Warning: The Daystar Flat Cap is NOT a solar filter.

Not for use in a concentrated beam, FlatCap must be the first component to encounter light. This is a not a solar filter, eye or equipment damage will result unless used in combination with a safe solar filter or solar telescope.


Spun Aluminium mounting ring with polymer diffuser
Intensity distribution
Divergence angle
4 degrees FWHM
Exposure time adjustment factor
100 x longer
Maximum FOV
1 degree with Sun backlight
Wavelength transmission range
350 - 800 nm
Operating temperature
-10 to 100 °C


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