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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader Photometric SLOAN/SDSS g' Individual Filter
Baader Photometric SLOAN/SDSS g' Individual Filter

Baader Photometric SLOAN/SDSS g' Individual Filter

by Baader Planetarium
SKU BAA-2961700G
$192.00 - $883.00
$192.00
$192.00 - $883.00
$192.00
Price Match Policy!
  • SLOAN/SDSS g' Bandpass: Conforms to the modern standard for astronomical photometry.
  • Photometric Grade: Produces scientifically valid data for research, including light curves and color indices.
  • Multiple Sizes: Available in 8 formats for compatibility with all standard filter wheels and sliders.
  • Precision Manufacturing: Advanced coatings and a fine-optically polished substrate prevent image degradation.
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Photometric SLOAN/SDSS g' Individual Filter

    The Baader Photometric SLOAN/SDSS g' Individual Filter enables professional-grade data acquisition by precisely isolating the standardized g' (green) bandpass—available in 8 distinct formats from 1.25" mounted cells to 100x100mm unmounted squares—allowing astronomers to generate light curves and color indices for variable stars and exoplanets with data directly comparable to major sky surveys.

    The SLOAN/SDSS g' Standard for Scientific Data

    This filter is not for creating aesthetically pleasing color images; it is a scientific instrument designed for photometry. It strictly adheres to the bandpass defined by the Sloan Digital Sky Survey (SDSS), the most extensive astronomical survey to date. This standardization is critical, as it ensures that measurements you take in your backyard can be accurately compared, transformed, and combined with data from professional observatories worldwide.

    By isolating the g' band, you can accurately measure stellar magnitudes and color indices, which are fundamental for classifying stars, studying stellar evolution, and detecting the subtle dimming caused by an exoplanet transit. For serious amateur astronomers contributing to organizations like the AAVSO or conducting pro-am collaborations, using a standardized filter like this is non-negotiable.

    8 Filter Sizes for Universal Integration

    Baader offers the SLOAN/SDSS g' filter in a comprehensive range of sizes to fit virtually any imaging setup. This ensures that whether you are using a small personal telescope or a large observatory-class instrument, you can integrate this photometric filter into your system without compromise.

    • Mounted Options: The 1.25" and 2" round mounted filters are ready to thread into standard filter wheels and eyepiece barrels.
    • Unmounted Round Options: For custom mounting in modern filter carousels, 31mm and 36mm unmounted filters provide a perfect fit.
    • Large Format Options: For imagers with large full-frame or medium-format sensors, Baader provides 50mm round, 50x50mm, 65x65mm, and 100x100mm square filters to prevent vignetting and ensure even illumination across the entire field.

    SLOAN/SDSS g' vs. Johnson-Cousins V: The Modern Standard

    While the Johnson-Cousins UBVRI system was the standard for decades, it was designed for photomultiplier tubes. The SLOAN/SDSS u'g'r'i'z' system was developed specifically for the response of modern CCD and CMOS sensors. The Baader g' filter offers a squarer, more defined transmission curve than the older Johnson V filter, with minimal overlap with adjacent bands.

    This clean separation between bands is crucial for accurate color-color diagrams and photometric transformations. While the g' band is centered in the green part of the spectrum like the V band, it is not a direct replacement. For modern scientific work, the SLOAN/SDSS system is the current professional standard, and this filter is your entry point to that system.

  • What is the Baader SLOAN/SDSS g' filter primarily used for?

    The Baader SLOAN/SDSS g' filter is a scientific tool for photometry—the precise measurement of the brightness of celestial objects. Its primary uses include creating light curves for variable stars, detecting exoplanet transits, and determining the color index of stars, asteroids, and supernovae.

    Can I use the Baader SLOAN/SDSS g' filter for visual observing or LRGB imaging?

    No, this filter is not recommended for general visual use or as a substitute for a standard green (G) filter in an LRGB set. Its specific, narrow bandpass is designed for measurement, not for creating natural-color views or images. Visually, it would produce a strong monochromatic green image, and in LRGB imaging, it would result in an incorrect color balance.

    How does the Baader SLOAN/SDSS g' filter's bandpass differ from a Johnson V filter?

    The SLOAN g' band is centered in the green region of the spectrum, similar to the Johnson V (Visual) band. However, the g' band is wider and has a "squarer" transmission profile designed for modern digital sensors. The two systems are not directly interchangeable, and photometric measurements taken with a g' filter must be transformed mathematically if they are to be compared to older V-band data.

    I have a Johnson-Cousins filter set. Should I upgrade to the Baader SLOAN/SDSS g' filter?

    If you are conducting scientific photometry and want your data to be compatible with modern professional surveys and databases, upgrading to the SLOAN/SDSS system is highly recommended. The Johnson-Cousins system is still valid, but the SLOAN system is the current standard for digital detectors and is preferred for most pro-am research projects.

    How would I use the Baader SLOAN/SDSS g' filter to measure the light curve of an exoplanet transit in Cygnus?

    You would pair the Baader SLOAN/SDSS g' filter with a monochrome camera on your telescope and take a continuous series of exposures of the target star before, during, and after the predicted transit time. Using photometry software, you would measure the brightness of the target star relative to several nearby, non-variable comparison stars in each frame. The g' filter ensures these measurements are consistent and standardized, allowing you to plot a precise light curve showing the characteristic dip in brightness as the planet passes in front of its star.

    If I'm imaging the Sombrero Galaxy (M104) with a 10" Newtonian and the Baader SLOAN/SDSS g' filter, what data do I get?

    Imaging M104 with the Baader SLOAN/SDSS g' filter will produce a high-contrast monochrome image showing the galaxy's structure in the green part of the spectrum. Scientifically, this data represents the galaxy's brightness in the g' band. If you also imaged it with r' and i' filters, you could combine the data to measure the color indices of different regions, helping to distinguish between older, yellower stars in the central bulge and younger, bluer star-forming regions in the disk.

  • Filter Type Photometric SLOAN/SDSS g' Band
    Available Sizes & Mounts 1.25" Round Mounted, 2" Round Mounted, 31mm Round Unmounted, 36mm Round Unmounted, 50mm Round Unmounted, 50x50mm Square, 65x65mm Square, 100x100mm Square
    Net weight (kg) 0.01 (1.25" Round Mounted, 2" Round Mounted, 50mm Round Unmounted)
    0.02 (50x50mm Square Filter)
    0.03 (65x65mm Square Filter)
    0.08 (100x100mm Square Filter)
    Filter size 1.25 inch (1.25" Round Mounted)
    2 inch (2" Round Mounted)
    36 mm (36mm Round Unmounted)
    50.4 mm (50mm Round Unmounted)
    50 x 50 mm (50x50mm Square Filter)
    65 x 65 mm (65x65mm Square Filter)
    100 x 100 mm (100x100mm Square Filter)
    Filter shape round (1.25" Round Mounted, 2" Round Mounted, 36mm Round Unmounted, 50mm Round Unmounted)
    square (50x50mm Square Filter, 65x65mm Square Filter, 100x100mm Square Filter)
    Single or Set? Single Filter
    Filter mounted Mounted (LPFC 6mm) (1.25" Round Mounted, 2" Round Mounted)
    Unmounted (36mm Round Unmounted, 50mm Round Unmounted, 50x50mm Square Filter, 65x65mm Square Filter, 100x100mm Square Filter)
    Filter Usage SLOAN, CMOS, CCD
    Special Features Life-Coat™ Warranty
    Filter Thickness (without cell) 2 mm (1.25" Round Mounted, 2" Round Mounted, 36mm Round Unmounted)
    3 mm (50mm Round Unmounted, 50x50mm Square Filter, 65x65mm Square Filter, 100x100mm Square Filter)
    CWL (Central Wavelength) SLOAN-g'
    Transmission Range Transmission according to SLOAN-Specification
    AR-Coating Reflex-Blocker™ hard coated, planeoptically polished
    Suitable for f/ratio f/15 to f/1.8

    • Baader Photometric SLOAN/SDSS g' Individual Filter (in selected size)

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  • Baader Planetarium Warranty