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Antlia Photometrics Sloan griz (4pcs) Filter Set - 50mm Unmounted
The Antlia Photometrics Sloan griz Filter Set follows the Sloan Digital Sky Survey (SDSS) photometric system, the most common filter set used by observatories today. Its four filters cover 400nm to the sensitivity limit of silicon CCD cameras near 1100nm. Peak transmission is 98% (95% for g') with blocking of OD5 or greater. The filters have a 1/4-wave propagated wavefront prior to coating and a 3mm thickness identical to existing standards, and the set is suitable from f/15 to f/1.8.
Professional g'r'i'z' Bandpasses from 400nm to >812nm
This set is built around the Sloan Digital Sky Survey (SDSS) photometric system, the most common filter set used by observatories today. The four included filters define specific spectral windows: the g' filter covers 400-550nm, the r' filter 555-705nm, the i' filter 688-850nm, and the z' filter captures wavelengths longer than 812nm. Antlia states that these wider transmission windows allow fainter objects to be measured in a shorter time, which suits photometry work such as variable star and exoplanet transit measurements.
1/4-Wave Substrates with OD5 Blocking
Antlia builds these filters on double-sided polished substrates with a 1/4-wave propagated wavefront prior to coating. Each filter is coated individually, not cut out of a larger coating plate, using Ion Gun Assisted Deposition, which Antlia states makes them consistent, durable and accurate. Blocking is OD5 or greater, and Antlia states this minimizes the already small leakage and creates superior contrast.
Suitable from f/15 to f/1.8, with 3mm Thickness
Antlia states that the Sloan griz' filter set is suitable from f/15 to f/1.8. The filters are 3mm +/-0.05mm thick, identical to existing standards, made with utmost care for parfocality.
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What is the primary application for the Antlia Photometric Sloan griz filter set?
This filter set is designed for scientific photometry, the precise measurement of the brightness of celestial objects. It is used for research applications such as monitoring variable stars, measuring the light curves of supernovae and exoplanet transits, and determining the color indices of stars and galaxies, following the standards of the Sloan Digital Sky Survey (SDSS).
Why is the u' filter not included in this Antlia Sloan set?
Antlia does not produce the u' (ultraviolet, 300-400nm) filter because of the mediocre quantum efficiency of cameras in the ultraviolet range.
How does OD5 blocking on the Antlia Sloan filters improve my data?
OD5 blocking means the filter attenuates out-of-band light by a factor of 100,000 (10^5). Antlia states that this blocking minimizes the already small leakage and creates superior contrast.
Can I use the Antlia Sloan griz set with fast optics?
Yes. Antlia states that the set is suitable from f/15 to f/1.8.
Are the Antlia Sloan filters made for parfocality?
The Antlia Sloan filters are 3mm +/-0.05mm thick. Antlia states the thickness is identical to existing standards, with utmost care for parfocality.
What kind of astronomical targets are best suited for the Antlia Sloan griz set?
This set is ideal for any target where you need to measure brightness changes or color information. Examples include:
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Variable Stars: Tracking the pulsation periods of stars like Cepheids or RR Lyrae.
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Supernovae: Measuring the brightening and fading of exploding stars in distant galaxies.
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Exoplanets: Detecting the slight dip in a star's brightness as a planet passes in front of it.
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Asteroids: Determining rotation periods from brightness variations.
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| Filter Type |
Photometric Sloan (SDSS) filter set, 4 filters |
| Available Sizes |
50mm Round Unmounted |
| g' Filter Bandpass |
400-550nm |
| g' Filter Peak Transmission |
95% |
| r' Filter Bandpass |
555-705nm |
| r' Filter Peak Transmission |
98% |
| i' Filter Bandpass |
688-850nm |
| i' Filter Peak Transmission |
98% |
| z' Filter Bandpass |
>812nm |
| z' Filter Peak Transmission |
98% |
| Out-of-Band Blocking |
>=OD5 |
| Filter Thickness (50mm) |
3mm +/-0.05mm |
| Substrate Wavefront |
1/4-wave propagated wavefront prior to coating |
| Coating Method |
Ion Gun Assisted Deposition, individually coated |
| Recommended f-ratio |
f/15 to f/1.8 |
| Parfocality |
Yes, identical thickness to existing standards |
| Excluded Filter |
u' (300-400nm) filter not produced |
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g' Sloan Filter (50mm Unmounted)
× 1
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r' Sloan Filter (50mm Unmounted)
× 1
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i' Sloan Filter (50mm Unmounted)
× 1
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z' Sloan Filter (50mm Unmounted)
× 1
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