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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 UBVRI-B Individual Filter

Baader Photometric UBVRI-B Individual Filter

by Baader Planetarium
SKU BAA-2961750B
$183.00 - $873.00
$183.00
$183.00 - $873.00
$183.00
Price Match Policy!
  • Conforms to the standardized Johnson-Cousins/Bessel B-band passband
  • Designed for research-grade scientific photometry
  • Advanced anti-reflection and dielectric coatings for maximum transmission
  • Precision plano-parallel substrate prevents image degradation
  • Available in 8 formats from 1.25" mounted to 100x100mm unmounted
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Photometric UBVRI-B Individual Filter

    Available in 8 formats from 1.25" mounted to 100x100mm unmounted, the Baader Photometric UBVRI-B Individual Filter is a scientific instrument that precisely isolates the standardized blue (B) band of the Johnson-Cousins/Bessel system for research-grade data acquisition. This is not an aesthetic filter for color imaging; it is a tool for collecting accurate stellar magnitude data that can be transformed and compared with results from professional observatories worldwide.

    The Bessel B-Band Standard for Scientific Photometry

    The core function of this filter is to adhere strictly to the Bessel B-band transmission curve. This standardization is critical for scientific applications like monitoring variable stars for the AAVSO, measuring exoplanet transits, or tracking supernova light curves. By ensuring a consistent passband, your instrumental magnitudes become scientifically valid and directly comparable to a global body of research.

    Baader Optical Quality: Precision Manufacturing for Reliable Data

    Accurate photometry demands more than just a specific transmission curve. Baader manufactures these filters with non-compromising optical and mechanical quality to ensure your data is not corrupted by the instrument itself. The optically polished, plano-parallel substrate guarantees that the filter will not introduce aberrations or distort the star's point spread function, which is critical for precise magnitude extraction from your images.

    • Advanced Coatings: Multi-layer dielectric coatings produce a hard, scratch-resistant surface with sharp bandpass cutoffs and high transmission, while anti-reflection coatings minimize halos and internal reflections.
    • Substrate Homogeneity: Each filter is made from a carefully selected glass substrate, free of internal stresses and imperfections, ensuring uniform performance across the entire field.

    Photometric B-Filter vs. RGB-B Filter: Data vs. Aesthetics

    It's crucial to understand the distinction between a photometric filter and a standard astrophotography RGB filter. An RGB blue filter is designed to produce pleasing, natural colors in combination with red and green filters. Its passband may be wider or shaped differently to achieve better color balance or block light pollution.

    The Baader Photometric B-Filter has a singular purpose: to replicate the Bessel B-band. Its transmission profile is not optimized for color aesthetics but for scientific accuracy. Choosing this filter means prioritizing data integrity over visual appeal, a trade-off that is essential for any serious photometric research.

  • What is the main difference between the Baader Photometric B-filter and a standard RGB blue filter?

    A standard RGB blue filter is designed for aesthetic tricolor imaging, with a passband shaped to create good color balance with other filters. The Baader Photometric B-filter is a scientific instrument with a passband that strictly adheres to the standardized Johnson-Cousins/Bessel system, ensuring measurements are comparable to professional data.

    Can I use the Baader Photometric B-filter for visual observing?

    No, this filter is not intended for visual use. It is designed for CCD and CMOS cameras and has a relatively narrow, specific passband that would result in a very dim and strongly colored image visually. Its purpose is measurement, not direct observation.

    Do I need the other U, V, R, and I filters to do useful science with the Baader B-filter?

    Not necessarily. While a full UBVRI set allows for comprehensive analysis of a star's color and temperature, a significant amount of valuable research is done using a single band. Time-series photometry, such as monitoring a known variable star or an exoplanet transit, can be effectively performed using only the B-filter.

    How would I use the Baader Photometric B-filter to measure the light curve of an exoplanet transit?

    You would mount the Baader Photometric B-filter in your filter wheel and take a continuous series of images of the target star system before, during, and after the predicted transit time. Using photometry software, you measure the brightness of the host star relative to several nearby, non-variable comparison stars in each frame. Plotting this relative brightness over time reveals the characteristic dip in the light curve as the planet passes in front of its star.

    Why are there so many sizes of the Baader Photometric B-filter available?

    The wide range of sizes, from 1.25" mounted to 100x100mm unmounted, ensures compatibility with nearly any imaging setup. Smaller mounted filters are used in standard amateur filter wheels, while larger unmounted filters are required for cameras with large format sensors found in advanced amateur and professional observatory systems.

    I want to contribute to the AAVSO database for a Cepheid variable like Delta Cephei. Is this Baader B-filter the right tool?

    Yes, this is precisely the correct tool for that task. The American Association of Variable Star Observers (AAVSO) requires data to be submitted in, or be transformable to, the standard UBVRI system. Using a filter like the Baader Photometric B-filter, which is designed to conform to the Bessel B-band, is the critical first step in collecting high-quality, standardized data that can be accepted into their international database.

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

    • Baader Photometric UBVRI-B Filter (Selected Size)

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  • Baader Planetarium Warranty