Sharpstar 3" 0.85x Reducer and Coma Corrector for Newtonian Telescopes for Full Frame Sensors This large coma corrector that also serves as an optical reducer, has been designed for commercially available Newtonian telescopes with an aim to improve their performance for imaging. Its 3" size offers a 44mm diameter corrected field suitable for imaging with an up to FULL FRAME sized sensor. It is compatible with most Newtonian telescopes that you can buy in a telescope shop with f/4 to f/6 focal ratio and between 150mm and 600mm aperture. It will reduce the required exposure time by changing an f/4 system into f/3.4, f/5 into f/4.25 and f/6 into f/5.1. It will also improve the image quality of the periferial stars. SPECIFICATIONS Model：150mm-600mm, paraboloid reflectorFocal ratio：F4-F6Magnification: 0.85xImage Circle: larger than 44mm, the optimal Image of 44 mm.Camera side connection: female M68, female M54, male M48Telescope side connection: male M82Number of lenses: TBCOuter diameter: 3"Back focus: 55mm (from end face of M54 thread, but please note, this might slightly vary depending on the optical system. Sharpstar boss, Michael offered to calculate the precise back focus on request...We would need to know the aperture and focal length of your Newtonian telescope...)Overall Length: 119mm (without the length of the M54 thread)Optical Coatings: Fully multi-coatedWeight: 0.87kg EXAMPLE OF USE: In the case of a Sharpstar 20032PNT, the focal plane is 55 mm from the M54X0.75 thread at the end of the focuser (from the end of the coma corrector, to be more precise...), and 52mm from the M48x0.75 thread. This "standard" back focal distance provides ample space for any visual or photographic equipment, being it a dSLR or a CCD / CMOS camera. CLICK ON THE BELOW IMAGES FOR LARGER RESOLUTION!
