William Optics Flattener dedicated to the Zenithstar 61 optical tube ensures the maintenance of uniform image quality - flatness, because the flattener is a "flattener" - both in the center and on the edge of the frame, eliminating the negative influence of the refractor's optical system, which as you move away from the center of the frame, the sharpness of recorded objects gradually deteriorates. This flattener does not change the effective focal length (it has a multiple of 1x).
The Flattener works with systems (through the appropriate M48 ring):
• M4 / 3 • Sony A • Nikon • Pentax • Canon • Fuji
Technical parameters
• times: 1x • back focus: 67.7 mm (for M48) / 69.2 mm (for M54) • correction distance for SLR and mirrorless cameras: 1 mm • telescope mount: M54 thread • camera mount: M48 thread • possibility of mounting the filter: yes, thread M48 Product page on the manufacturer's website: https://williamoptics.com/new-adjustable-flat61-for-z61
Kit components
• flattener for Zenithstar 61 refractor with 1x multiplicity
Warranty
24 months
Important expert note
It should be remembered that this device is characterized by a constant backfocus value, that is the distance (distance) from (end, back) of the reducer / equalizer to eg the matrix of a digital camera. Generally speaking, both the reduction ratio for focal length reducers and its increase for Barlow lenses change with distance from the main focus, so you can easily choose the value you want. However, if we deal with flatteners or field correctors, then the focal length value must be strictly defined and it cannot be changed. This means that a sharp image can only be obtained when the user sets the correct backfocus (distance), which sometimes requires a precision of 0.1 mm. Most zoom accessories of this type have the backfocus length specified by the manufacturer. However, if you cannot find this information in the manual or on the website, make the general assumption that a typical backfocus value in astrophotography is 55 mm. If your camera is not rated to this value, or you use modified equipment, look for the products listed below that will solve your problem: teleskopy.pl/advanced_search_result.php?keywords=gso+m48
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