Built for full-frame, not just APS-C. The QB0.73x is Takahashi's modernized answer to today's small-pixel, full-format sensors, giving the FSQ-85EDX astrograph the field correction those chips actually demand.
Faster and wider in one step. Screwing in the QB0.73x cuts your focal length by almost a quarter, down to 330 mm at F/3.9, so you gather more light and frame wider without swapping telescopes.
New glass, tighter stars. Four lenses in two groups of new, highly refractive, low-dispersion ED glass cut chromatic aberration further, halve the RMS spot size at the edge of the field, and shrink star sizes by a third compared to the previous reducer.
Numbers that back it up. Spot radius comes in at 1.6 microns RMS at center, 1.9 microns at the APS-C periphery, and 3.9 microns at the full-frame edge, keeping stars tight corner to corner.
Straightforward mounting, with the right adapter. The QB0.73x screws directly onto the CAA (Camera Angle Adjuster); pair it with the CA-35 photo adapter (SKY-90, TATKA35201) to recover the 56.2 mm needed for a wide-field T-ring, standard camera, or ZWO camera.
ZWO friendly with one extra piece. Running ZWO gear through the CA-35? The OU073 conversion ring from Optique Unterlinden picks up the M48 or M42 threads your accessory train needs.
Compact enough to always keep in the case. At 78 mm x 63 mm and 520 g, the reducer adds virtually no bulk to your imaging kit.
Specifications
Item Number: TKA37580
Optical Design: 4 lenses (2 groups)
Corrected Image Circle: 44 mm
Input Mechanical Interface: M72x1 thread, male
Output Mechanical Interface: M56x0.75 thread, male
Metal Back Distance: 72.2 mm
Size: 78 mm x 63 mm
Weight: 520 g
Compatibility: Takahashi FSQ-85EDX refractor
What's in the Box?
QB0.73x Focal Reducer x1
Note: The CA-35 photo adapter (SKY-90, TATKA35201) and, for ZWO cameras, the OU073 conversion ring are required for full camera mounting and are sold separately.
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