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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-R Individual Filter

Baader Photometric UBVRI-R Individual Filter

by Baader Planetarium
SKU BAA-2961750R
$183.00 - $873.00
$183.00
$183.00 - $873.00
$183.00
Price Match Policy!
  • Conforms to the Johnson-Cousins-Bessel R-Band Photometric Standard
  • Engineered for Scientific Photometry and Data Collection
  • Plane-Parallel Substrate for Sharp Stars Across the Field
  • Available in 8 Formats for Any Telescope System
  • Offered in Mounted (1.25", 2") and Unmounted (31mm, 36mm, 50mm, 50x50mm, 65x65mm, 100x100mm) versions
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Photometric UBVRI-R Individual Filter

    The Baader Photometric UBVRI-R Individual Filter provides a standardized red passband for scientific photometry, available in 8 distinct formats from 1.25" round mounted to 100x100mm square unmounted to precisely replicate the Johnson-Cousins-Bessel 'R' band. This ensures your measurements are comparable with professional datasets worldwide, with options including 1.25" and 2" mounted versions, and 31mm, 36mm, and 50mm round or 50x50mm, 65x65mm, and 100x100mm square unmounted formats for maximum system compatibility.

    The Bessel R-Band Standard: 1 Filter for Consistent Data

    This filter is not designed for aesthetic imaging; it is a scientific instrument. Its transmission profile is engineered to match the Johnson-Cousins-Bessel R-band, the global standard for astronomical photometry. This adherence means the brightness measurements you take of variable stars, exoplanet transits, or supernovae are directly comparable to data from other observatories, forming a crucial part of collaborative pro-am research.

    Plane-Parallel Substrate: 0 Internal Reflections for Accurate Photometry

    In photometry, any artifact can corrupt the data. Baader manufactures these filters from fine-optically polished, plane-parallel glass to eliminate halos or ghost images that could alter stellar magnitude measurements. The goal is 0 internal reflections affecting the focal plane, ensuring that the light measured is purely from the target star. Advanced, non-ageing coatings and blackened filter edges further suppress stray light for the highest possible contrast and data accuracy.

    8 Formats for Universal Integration: From 1.25" to 100x100mm

    Baader produces this photometric filter in 8 formats to accommodate nearly any imaging system. Whether you use a standard 1.25" filter wheel on a small refractor or a large format camera on a research-grade reflector, there is a size that fits your optical train.

    • 1.25" and 2" Mounted: Ready to thread into standard filter wheels and accessories for immediate use.
    • 31mm and 36mm Unmounted: Common sizes for dedicated astronomy filter wheels, offering a larger clear aperture than their 1.25" counterparts.
    • 50mm Round, 50x50mm, 65x65mm, and 100x100mm Square: Unmounted formats for large-format CCDs and professional filter sliders, ensuring the sensor is fully illuminated without vignetting.

    Baader Photometric R vs. LRGB Red: 1 Standard for Science

    A standard LRGB red filter is designed to gather maximum signal for creating visually pleasing images, often with a broad passband and gentle cutoffs. A photometric filter has a different priority: strict adherence to 1 scientific standard. The Baader Photometric R filter features the sharp, precise bandpass required by the Bessel system. This may result in slightly lower overall light transmission compared to a deep-sky filter, which is the necessary trade-off for producing scientifically valid, repeatable, and comparable data.

  • Why do I need a Baader Photometric R filter instead of my regular LRGB red filter?

    Your LRGB red filter is designed for beautiful astrophotos by capturing a broad swath of red light. The Baader Photometric R filter is a scientific tool designed to isolate a very specific, standardized slice of the red spectrum defined by the Johnson-Cousins-Bessel system. This precision allows you to take brightness measurements (photometry) that can be compared with data from other astronomers and professional observatories worldwide.

    What kind of data can I collect on a variable star like Algol (Beta Persei) with the Baader Photometric R filter?

    Using the Baader Photometric R filter, you can create a light curve for Algol. By taking a series of timed exposures, you can precisely measure its change in magnitude as its companion star eclipses it. Because the filter conforms to the R-band standard, your data can be submitted to organizations like the AAVSO (American Association of Variable Star Observers) and contribute to the long-term scientific study of the star.

    Is the Baader Photometric R filter parfocal with other Baader filters?

    Baader Planetarium engineers their filter sets to be as close to parfocal as possible, meaning minimal refocusing is needed when switching between them. However, for precise scientific work like photometry, it is always best practice to briefly check and adjust focus after changing any filter, including the Baader Photometric R filter, to ensure the sharpest possible data.

    Which size of the Baader Photometric R filter do I need for my 8" SCT with a standard filter wheel?

    For an 8" SCT using a common 1.25" filter wheel (like those from ZWO or QHY), the 1.25" Round Mounted Baader Photometric R filter is the correct choice. If you are using a larger 2" filter wheel or an off-axis guider that requires more back focus, the 2" mounted version would be appropriate. For unmounted filter wheels, check your carousel's documentation for the correct diameter (e.g., 31mm or 36mm).

    Can I use the Baader Photometric R filter for visual observing?

    While you can look through the Baader Photometric R filter, it is not designed for visual use. Its narrow, specific bandpass is optimized for digital sensors (CCDs and CMOS cameras). For visual observation, a standard red planetary or deep-sky filter will provide a brighter and more useful view.

    How do I clean my Baader Photometric R filter without damaging the coatings?

    Use a gentle, multi-step process. First, use a blower bulb to remove loose dust. If smudges remain, apply a small amount of pure, lab-grade isopropyl alcohol or a dedicated optical cleaning solution to a clean microfiber cloth or optical wipe. Gently wipe the surface in a circular motion from the center outwards. Never apply fluid directly to the filter surface.

  • Available Options 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-R
    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-R Individual Filter

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