Astrodon 65mm Square Sloan r' Filter
Astrodon's newest generation of Sloan Digital Sky Survey filters are of the highest quality, as usual- improving beyond previous models notably, and even introducing two entirely new filters! This is the r', or red filter. The dielectric coatings used on this filter ensure steep cut-on and cut-offs and peak transmissions in excess of 95%.
It is of note that the Sloan Digital Sky Survey- SDSS- photometric system is the most commonly used filter set today, even being used in the Hubble Space Telescope. Much of photometry up to magnitude 23 will be done in this system with meter-class telescopes.
The r' filter in particular has had it's 50% transmission point increased by a slight but noticeable margin. Increasing from the former 555/695 to the new generation's 562/695, it's a margin worthy of note despite not looking major. After all, a slight alteration can make a world of difference! The r' filter is a red filter, as noted above.
Astrodon r'_65mm Square Sloan r' Filter: Specifications
- 50% Transmission point of 562/695
- Peak transmission guaranteed > 95%
- <=0.03%Tabs out-of-band 300 - 1100 nm
- Single striae-free fused silica substrates
- 1/4-wave propagated wavefront prior to coating
- <0.5 arcminute substrate parallelism
- 3.000 +/-0.025 mm substrate thickness prior to coating
- USA Made