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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 Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter
Baader Clear Focusing Filter

Baader Clear Focusing Filter

by Baader Planetarium
SKU BAA-2458415
$55.00 - $155.00
$55.00
$55.00 - $155.00
$55.00
Price Match Policy!
  • Enables precise focusing for dim narrowband filters
  • Perfectly parfocal with other Baader Planetarium filters
  • Optically polished to ensure no image degradation
  • Available in multiple formats from 1.25" mounted to 65x65mm square
  • LPFC (Low Profile Filter Cell) on mounted versions for maximum compatibility
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Clear Focusing Filter

    The Baader Clear Focusing Filter, available in multiple formats including 1.25" and 2" mounted cells and unmounted sizes up to 65x65mm, solves the most critical challenge of narrowband imaging: achieving perfect focus on a dim target. It is designed to be perfectly parfocal with Baader's line of imaging filters, allowing you to use a bright, full-spectrum star to achieve sharp focus before swapping to a restrictive line filter without any change in the focal point.

    The Parfocal Solution for Dim Narrowband Filters

    Narrowband filters transmit such a tiny fraction of the visual spectrum that focusing can be an exercise in frustration. Stars become too faint for autofocus routines or to produce clear spikes on a Bahtinov mask. The Baader Clear Focusing Filter eliminates this problem by providing a bright, full-spectrum view for focusing.

    Because this clear filter is manufactured to the exact same optical thickness as Baader's narrowband, LRGB, and other imaging filters, the focal plane does not shift when you switch between them. You can achieve critical focus once with the clear filter and be confident that every subsequent narrowband exposure is perfectly sharp, saving valuable time and eliminating wasted sub-exposures.

    Optically Polished Glass for Pinpoint Focus Accuracy

    This is not simply a blank piece of glass; it is a high-quality optical window. Each Baader Clear Focusing Filter is optically polished to maintain the integrity of your light path, ensuring that the focus you achieve is true and not compromised by optical imperfections. This prevents any degradation of your final image resolution.

    The 1.25" and 2" mounted versions feature Baader's Low Profile Filter Cell (LPFC), designed to prevent vignetting and fit easily into any standard filter wheel or drawer. For users with specific needs, the filter is also available in a wide range of unmounted sizes, from 31mm round to 65x65mm square, to accommodate nearly any imaging setup.

  • Why do I need a Baader Clear Focusing Filter for narrowband imaging?

    Narrowband filters, like H-alpha or OIII, block almost all light, making stars extremely dim and difficult to focus on. The Baader Clear Focusing Filter is parfocal (maintains the same focus point) with these filters. This allows you to focus on a bright star with a full-spectrum view, then swap to your narrowband filter without needing to refocus, ensuring perfect sharpness.

    Is the Baader Clear Focusing Filter just an empty filter cell or blank glass?

    No. It is a high-quality optical window that has been optically polished to a high standard. This ensures it does not introduce any distortion or aberrations into your optical train. Using a non-polished piece of glass would compromise the critical focus you are trying to achieve.

    Will the Baader Clear Focusing Filter be parfocal with filters from other brands?

    Not necessarily. Parfocality depends on the precise mechanical thickness of the filter substrate. The Baader Clear Focusing Filter is specifically designed to match the thickness of other Baader Planetarium filters. While it may be close with other brands, perfect parfocality is only guaranteed within the Baader system.

    If I'm imaging the Pelican Nebula (IC 5070) in SII, how does the Baader Clear Focusing Filter help?

    Imaging the faint sulfur emissions of the Pelican Nebula requires long exposures through a very dim filter. Instead of struggling to focus on a faint star through the SII filter, you would use the Baader Clear Focusing Filter to focus on a nearby bright star like Deneb. Once your focus is locked, you can swap to the SII filter in your filter wheel, slew to the nebula, and begin imaging, confident that your focus is perfect.

    I use a filter drawer with a fast f/4 Newtonian. Is the Baader Clear Focusing Filter still effective?

    Yes, it is especially effective with fast systems. Fast optics have a very critical focus zone, making precise focus even more important. The Baader Clear Focusing Filter allows you to use all available light to nail that critical focus point, which is extremely difficult to do with a dim narrowband filter at f/4. The parfocal design ensures that focus is maintained when you insert your imaging filter.

    Which size of the Baader Clear Focusing Filter do I need?

    The correct size depends on your filter wheel, filter drawer, or camera setup. The Baader Clear Focusing Filter is available in several standard sizes:

    • 1.25" and 2" Mounted: For standard filter wheels and focusers that accept threaded filters.
    • 31mm and 36mm Round Unmounted: Common sizes for 1.25" filter wheels.
    • 50.4mm Round, 50x50mm Square, and 65x65mm Square Unmounted: For larger filter wheels designed for full-frame and medium-format sensors.
  • Type Clear Focusing Filter
    Optical Quality Optically Polished
    Primary Use Achieving parfocal focus with narrowband and LRGB filters
    Available Formats 1.25" Round Mounted, 2" Round Mounted, 31mm Round Unmounted, 36mm Round Unmounted, 50.4mm Round Unmounted, 50x50mm Square, 65x65mm Square
    Mounted Filter Cell Low Profile Filter Cell (LPFC) on 1.25" and 2" versions
    Net weight (kg) 0.01 (1.25" Round Mounted, 2" Round Mounted, 50.4mm Round Unmounted Filter)
    0.02 (50x50mm Square Filter)
    0.03 (65x65mm Square Filter)
    Filter shape round (1.25" Round Mounted, 2" Round Mounted, 31mm Round Unmounted Filter, 36mm Round Unmounted Filter, 50.4mm Round Unmounted Filter)
    square (50x50mm Square Filter, 65x65mm Square Filter)
    Single or Set? Single Filter
    Filter Usage Focusing/dust protection
    Filter Thickness (without cell) 2 mm (1.25" Round Mounted, 2" Round Mounted, 31mm Round Unmounted Filter, 36mm Round Unmounted Filter)
    3 mm (50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter)
    Transmission Range full Spectrum
    AR-Coating dielectrically coated, planeoptically polished
    Type of Filter Clearglass (31mm Round Unmounted Filter)

    • Baader Clear Focusing Filter (select size)

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  • Baader Planetarium Warranty