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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-V Individual Filter

Baader Photometric UBVRI-V Individual Filter

by Baader Planetarium
SKU BAA-2961750V
$183.00 - $873.00
$183.00
$183.00 - $873.00
$183.00
Price Match Policy!
  • Bessel V-Band Standard: Precisely conforms to the internationally recognized Johnson-Cousins-Bessel V-band for consistent, scientific-grade magnitude measurements.
  • Photometric Grade Optics: Features a plane-parallel substrate with anti-reflection coatings to ensure maximum transmission and prevent ghosting, critical for accurate data collection.
  • Homofocal (Parfocal) Design: Engineered to be parfocal with other Baader UBVRI filters, eliminating the need to refocus when switching between filters in an automated sequence.
  • Multiple Formats Available: Offered in 8 formats including standard 1.25" and 2" mounted cells and various unmounted sizes up to 100x100mm for nearly any filter wheel or slider.
  • Sealed Coating Edges: The coating edges are sealed, preventing moisture intrusion and degradation over the life of the filter, ensuring long-term stability of the bandpass.
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Photometric UBVRI-V Individual Filter

    Available in 8 distinct formats from 1.25" mounted to 100x100mm unmounted, the Baader Photometric UBVRI-V Individual Filter is a scientific instrument designed for the precise measurement of stellar magnitudes. This filter is not a simple colored glass; it is an engineered component that strictly adheres to the Johnson-Cousins-Bessel V-band standard, making it an essential tool for variable star observation, exoplanet transit timing, and stellar classification.

    The Johnson-Cousins-Bessel V-Band for Scientific Measurement

    The Baader V-Filter isolates the "Visual" portion of the spectrum, centered around 550nm, to replicate the passband used by professional observatories worldwide. This standardization is the foundation of photometry, allowing your measurements to be directly compared with scientific databases and observations from other astronomers.

    Using this filter, you can create precise light curves of variable stars, measure the dimming of a star during an exoplanet transit, or determine the color index (B-V) of stars to classify their temperature and spectral type. It transforms your imaging setup from a picture-taking device into a scientific measurement tool.

    Homofocal Design for UBVRI Filter Sets

    Baader's photometric filters are designed to be homofocal, or parfocal. This means that when you switch between the V-filter and other Baader UBVRI filters in the same set, your telescope's focus point does not shift. Each filter is manufactured on a substrate of identical thickness, maintaining optical precision across the set.

    This is a critical feature for automated imaging sequences. It eliminates the need for time-consuming refocusing routines between each exposure, maximizing your data collection time on target and preventing focus drift from corrupting a photometric series.

    V-Band vs. Luminance Filters: The Standard for Repeatable Data

    While a standard Luminance (L) filter provides a brighter image for general deep-sky astrophotography, it is unsuitable for scientific photometry. L-filters have a very broad, often undefined bandpass that varies between manufacturers and can include significant near-IR transmission, contaminating the visual data.

    The Baader V-Filter's advantage is its precisely defined, repeatable bandpass. A V-magnitude measured with this filter is an objective data point that adheres to an international standard. For any scientific application where data must be consistent and comparable, the V-filter is the correct choice over a generic L-filter.

  • What is the primary use for the Baader Photometric V-Filter?

    The Baader V-Filter is designed for scientific photometry. Its main purpose is to accurately measure the brightness of celestial objects, such as variable stars, supernovae, and exoplanet transits, within the standardized Bessel V-band passband.

    Can I use the Baader V-Filter for imaging galaxies or nebulae?

    While you can, it's not the ideal choice. A standard Luminance (L) filter has a much broader bandpass and will collect more light, resulting in a brighter, higher signal-to-noise image in less time. The V-filter is a specialized tool for when measurement accuracy is more important than image brightness.

    Why is this V-filter different from a standard green CCD filter?

    A standard green filter is designed for creating RGB color images and its bandpass is not scientifically standardized. The Baader Photometric V-Filter is manufactured to precisely match the Johnson-Cousins-Bessel V-band specification, ensuring that measurements taken with it are consistent and comparable to data from professional observatories.

    Do I need to refocus when switching between this V-filter and my Baader B and R filters?

    No. Baader photometric filters are designed to be homofocal (parfocal). This means you can switch between any of the Baader UBVRI filters in your filter wheel without needing to adjust your focuser, which is essential for automated data acquisition.

    How would I use the Baader V-Filter to measure the light curve of an exoplanet transit like HD 189733b?

    For an exoplanet transit, you would take a continuous series of exposures of the host star (HD 189733) using the Baader V-Filter before, during, and after the predicted transit time. By measuring the star's brightness in each frame relative to nearby, non-variable comparison stars, you can plot a precise light curve showing the characteristic dip in brightness as the planet passes in front of it.

    If I'm observing a variable star like Algol (Beta Persei) with an 8" SCT, is the V-filter the right choice?

    Yes, absolutely. The V-filter is the standard filter for monitoring the brightness changes of eclipsing binaries like Algol (Beta Persei). An 8" SCT provides more than enough light-gathering power, and using the V-filter ensures your magnitude estimates can be submitted to and compared with data from organizations like the AAVSO (American Association of Variable Star Observers).

  • Filter Type Photometric Johnson-Cousins-Bessel V-Band
    Available Sizes & Formats 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
    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-V
    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 Planetarium Warranty