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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.
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 Telecentric System TZ-4 - 4x
Baader Telecentric System TZ-4 - 4x

Baader Telecentric System TZ-4 - 4x

by Baader Planetarium
SKU BAA-2459256
$469.00 - $469.00
$469.00
$469.00 - $469.00
$469.00
Price Match Policy!
  • 4x Telecentric Focal Extender
  • Engineered for Narrowband H-alpha Solar Filters
  • Creates a Parallel f/30 Light Path
  • Optimized Coatings for 656nm Wavelength
  • Provides 230mm of Back Focus for Accessories
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Telecentric System TZ-4 - 4x

    The Baader Telecentric System TZ-4 is an essential optical component designed specifically for high-resolution H-alpha solar imaging, delivering a 4x focal length amplification. It transforms a native f/7.5 telescope into the mandatory f/30 parallel light path required by sub-Angstrom etalon filters. With coatings optimized for the critical 656nm H-alpha wavelength and a generous 230mm of working distance, the TZ-4 ensures your entire optical train works in perfect harmony for maximum contrast and uniformity.

    True Telecentric Design: A Parallel Light Path for <1Å Etalons

    Unlike a standard Barlow lens that creates a diverging cone of light, a telecentric system produces a beam where the principal light rays remain parallel to the optical axis across the entire field of view. This is absolutely mandatory for narrowband solar filters with a bandpass below 1 Angstrom. A parallel beam ensures that light enters the etalon at the correct angle everywhere on the sensor, preventing bandpass shift that would otherwise degrade contrast and create uneven illumination.

    Optimized for H-alpha: f/30 Performance at 656nm

    The TZ-4 is engineered to convert an f/7.5 instrument into an f/30 system, the ideal focal ratio for most high-end solar etalons. All optical surfaces feature multi-layer coatings precisely matched to the glass types used, maximizing light transmission at the 656nm H-alpha line. If your telescope's native focal ratio deviates significantly, the aperture can be stopped down with an optional iris to achieve the target f/30 ratio, ensuring your filter performs at its theoretical best.

    Generous 230mm Back Focus: Room for Diagonals and Cameras

    A key practical advantage of the TZ-4 is the 230mm of back focus available, measured from the rear lens surface to the camera sensor. This substantial distance provides ample room to insert a Solar Spectrum filter housing, a 2" mirror diagonal for more comfortable viewing angles, and your imaging camera without running out of space. This flexibility allows for robust and stable imaging train configurations that are difficult to achieve with other focal extenders.

    TZ-4 vs. TZ-3: Understanding the Baader Telecentric Lineup

    The TZ-4 is a legacy component in Baader's telecentric lineup. For many applications, the newer Baader TZ-3 represents a more modern and optically superior calculation. It is often recommended to start with a TZ-3 and stop down the telescope's aperture to reach the target f/30, as this can yield higher contrast than using a TZ-4 on a poorly matched system. While a newly calculated, large-aperture TZ-4 is in development, the current model serves specific needs for achieving a 4x amplification factor where required.

  • Why can't I use a 4x Barlow with my Solar Spectrum filter instead of the Baader TZ-4?

    A Barlow lens creates a diverging light cone, meaning light rays at the edge of the field strike the filter at a different angle than those in the center. This causes a bandpass shift, degrading contrast and detail. The Baader TZ-4 creates a parallel light path, ensuring every ray of light enters the etalon at the correct angle, preserving the filter's specified performance across the entire solar disk.

    What telescope focal ratio works best with the Baader TZ-4 for solar imaging?

    The Baader TZ-4 is designed to work optimally with a telescope that has a native focal ratio of approximately f/7.5. This combination produces the target f/30 beam required by many narrowband H-alpha etalons. If your telescope is faster or slower, you may need to use an iris diaphragm to stop down the aperture to achieve this ideal f/30 ratio.

    How much space does the TZ-4 leave for my H-alpha etalon and camera?

    The Baader TZ-4 provides a generous working distance of 230mm from its rearmost lens to the focal plane. This is typically sufficient space to accommodate the etalon filter housing, a 2" diagonal, and your imaging camera without issue.

    My telescope isn't f/7.5. Can I still use the TZ-4 to get to f/30 for solar imaging?

    Yes. While the TZ-4 is optimized for a starting f/7.5 system, you can use it with other telescopes by adjusting the effective aperture. For a faster telescope (e.g., f/6), you would need to use an aperture stop or iris diaphragm in front of the objective lens to reduce the incoming light, effectively changing the focal ratio to the f/7.5 needed to achieve a final f/30 output.

    The documentation mentions the TZ-3 is a better design. Why would I buy the Baader TZ-4?

    The Baader TZ-4 is an older, established design that provides a specific 4x amplification factor. You would choose the TZ-4 if this exact magnification is required to bring your specific telescope to the necessary f/30 focal ratio. For new systems, Baader often recommends the newer TZ-3 due to its more advanced optical calculation, suggesting it may provide better contrast even if it requires stopping down the telescope's aperture.

    What does "telecentric" actually mean for my solar images from the TZ-4?

    For your images, "telecentric" means uniformity and maximum contrast. Because the light passing through your etalon is perfectly parallel everywhere, the filter's narrow bandpass is maintained across the entire sensor. This prevents bright or dark blotches (sweet-banding) and ensures that fine details like spicules and filaments are visible with the highest possible contrast from edge to edge.

  • Net weight (kg) 0.31
    Focal length extension 4-fach
    Outer Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2)
    Inner Connection (lens sided) M42 x 0.75 (T-2)
    Outer Connection (lens sided) ø 2" (50.8mm)
  • Baader Planetarium Warranty