Opticstar Focal Reducer F 0.5 Focal Reducer for 1.25" Nosepieces
- F 0.5 focal reducer
- Fits standard 1.25" focusers
- Two lens system for better correction
- Improved green multicoating
- Metal and glass construction
When attached to a telescope the f0.5 focal reducer will typically reduce exposure times to near a quarter when imaging extended objects like galaxies, nebulae and the Moon.
Telescopes with low focal ratios require shorter exposures when imaging extended objects (for example an f/8 system will require four times the exposure of an f/4 system). This does not apply to non extended objects (point sources) like stars where aperture dictates what can be seen/captured.