Sharpstar reducers and flatteners are custom designed and built to work with Sharpstar imaging telescopes. Here is a rundown of the available products.
Sharpstar 140PH reducer 0.74x Reducer and Flattener
Designed to work with the Sharpstar 140PH apochromatic triplet refractor, the Sharpstar 0.74x Reducer and Flattener produces a flat field and razor-sharp images across a full-frame image circle.
The three-element design takes the 140PH from f/6.5 to f/4.8. The camera end of the flattener has M48x0.75 threads, while the telescope side has M88x1 threads to connect directly to the 140PH focuser. This flattener transforms the Sharpstar 140PH into a powerful and highly capable imaging tool.
Sharpstar 140PH specifications include:
- Works with: Sharpstar 140PH apochromatic triplet refractor
- Focal ratio: f/4.8
- Imaging circle: 44mm
- Lens number: Triplet
- Max outer diameter: 88mm
- Back focus: 55mm
- Overall length: 106mm
- Surface coating: Full multi-layer coating
- Weight: 0.9kg
Sharpstar 61EDPH Focal Reducer 0.8x Reducer and Flattener
The Sharpstar 61EDPH F/4.5 is a dedicated full-frame focal reducer designed to work with the Sharpstar 61EDPH and 61EDPHII f/5.5 apochromatic refractors. The 0.8x reducer and flattener supports the efforts of astrophotographers who use cameras with up to full-frame sensors for wide-field deep-sky imaging.
This focal reducer features a triplet air-spaced structure and large optics that achieve excellent field flatness and illumination over a 44mm image circle. The 2.3″ reducer’s drawtube has a female M63×1 thread that attaches to the telescope’s focuser while the other end includes an external male M48×0.75 thread for a camera to ensure the 55mm back focus requirement is satisfied.
The back focus can be extended to 99mm by unthreading the back adapter of the reducer which gives access to another M63x1 thread to attach additional accessories such as a filter wheel. The reducer also includes a female M48x0.75 thread for attaching a filter and a mechanism to rotate the attached camera by 360 degrees to achieve the best image framing.
The Sharpstar 61EDPH specifications include:
- Use for telescope model: Sharpstar 61EDPH/61EDPHII
- Reducing Focal Ratio: F/4.5
- Fully Illuminated Image Circle: 44mm
- Number of Lens: Three-piece
- Main Outer Diameter: 66mm
- Focal Plane: 55mm (can expand to 99mm by removing the end interface)
- Total Length: 95mm (including M48 Thread)
- Surface Coating: Full-Surface Multi-Layer Coating
- Weight: 0.45kg
Sharpstar 76EDPH Focal Reducer 0.8x Reducer and Flattener
The Sharpstar 76EDPH F/4.5 is the latest development in dedicated full-frame focal reducers. Designed to work with the Sharpstar 76EDPH apochromatic refractor, this 0.8x focal reducer features a triplet air-spaced structure and large optics that achieve excellent field flatness and illumination over a 44mm image circle.
One end of the reducer features a M74×1 thread that connects to the pinion focuser. The other end uses a M48×0.75 thread to attach to the camera or a 48mm T-ring for a DSLR. The focal plane is 55mm from the end interface.
The reducer features a 360-degree rotator that allows you to easily rotate the camera for image framing. A M48x0.75 female thread allows the use of standard 2″ filters.
The Sharpstar 76EDPH specifications include:
Reducing focal ratio: f/4.5 (0.8x)
Image circle: 44mm
The lens type: Triplet
The largest diameter: 88mm
Back focus: 55mm
Total length: 77mm (including M48 thread)
Surface coating: Full surface Multi-Coated
You can learn more here.
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