Sloan Gen 1 Close-Out


These research filters were replaced in June, 2012 with our Generation 2 Sloan filters (click here). 

We are therefore offering our Gen 1 filters at close-out prices while quantities last. Only direct from Astrodon

The main differences are discussed  on the Gen 2 Sloan page.  Briefly,

  1. Different 50%T points for the i' and r' filters
  2. Introducing the z_s and Y near-infrared filters that together replace the z' cuton filter
  3. Retaining the z' filter for those preferring a cuton filter
  4. Significantly improving the out-of-band blocking to Tabs <= 0.03%T
  5. Edge-blackening each filter to reduce stray reflections


The incredibly high (>97%T) transmittance in the bandpass achieves the highest performance available.  The 100% coated construction using hard, sputtered coatings on 1/4-wave single fused silica substrates and no colored glass achieves long-term durability for consistent research over many years.

The following is a spectral compilation of actual scans of the Astrodon Photometrics Gen 1 Sloan filter set.

These filters are parfocal with all Astrodon LRGB and narrowband filters.


  • 50% transmission points provided above (+/- 3nm typical) (click here)
  • Peak transmission guaranteed > 95%  (>90% for u')
  • <0.1%Tave out-of-band 300 - 1100 nm
  • Striae-free, single fused silica substrates
  • 1/4-wave propagated wavefront prior to coating
  • <0.5 arcminute substrate parallelism
  • 3.000 +/-0.025 mm substrate thickness
  • 1.25" mounted
  • 49.7 mm dia. unmounted
  • 49.7 x 49.7 mm square unmounted
  • Proud supplier to Las Cumbres Observatory Global Telescopes, AAVSO and research organizations worldwide
  • Proudly made in the U.S.A.


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The Buy Now buttons direct you to PayPal for both PayPal and credit card purchases.  Credit cards, including international, are now accepted through PayPal without a PayPal account. UPS Ground for U.S. and UPS Expedited for International and Canada will be used for shipping.  ANY 1.25" filter can be mounted in a flat 31 mm insert for the same price. Please add a comment under instructions to vendor requesting 31 mm.


50mm sq. Gen 1
Unmounted u'


1.25" Gen 1
Mounted g'



1.25" Gen 1
Mounted r'



1.25" Gen 1
Mounted i'



50mm dia. Gen 1
Unmounted i'


50mm dia. Gen 1
Unmounted z'


50mm sq. Gen 1
Unmounted z'