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Old 12-05-2021, 12:13 PM
ubique (Hugh)
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ubique is offline
Join Date: Aug 2008
Location: Brisbane
Posts: 174


#17406 - NextGen WideField NGW 0.50X Telecompressor Lens

This Telecompressor (reducer/flattener) is a hard to find, high quality Optec 0.5 reducer, it was designed for Celestron and Meade SCT telescopes, f10 becomes f5.

It also corrects spherical chromatism and optical curvature in these scopes. PLEASE NOTE: It doesn't work as well in HD or ACF scopes.

Lenses are in excellent unmarked condition, no scratches or fungus.

Ideal for the ZWO183 series or similar cameras, this reducer comes with the correct adapter to fit a ZWO camera. CCD to reducer distance is 60.5mm
This 1/2 times reduction in focal length allows for 4 times greater field area and 1/4 reduction in exposure time for extended surface objects such as bright nebulae.

That means a 12.5 minute exposure at f10 is reduced to 3.1 minutes at f5
or a 5 minute exposure at f10 is reduced to 1 minute and 15 seconds at f5.

Focal Ratio.......... Equal Exposure Times
f/10 .......................12.5 minutes
f/6.3 ........................5.0 minutes
f/5 ...........................3.1 minutes

Read about it on the Optec web page-

Excerpt below-
The NGW WideField 0.5X has been specifically designed to speed up the focal ratios of the popular f/10 Schmidt-Cassegrain telescopes distributed by Celestron and Meade. It will bring the focal ratio down to a solid f/5, perfect for imaging objects like bright nebulae that require long exposure times. Because the WideField is optimized for the Schmidt-Cassegrain design, it is also excellent at correcting the optical problems like spherical chromatism and optical curvature that are common in these telescopes.
CCD camera users should note that the NGW reduces the image plane field size to at most 17.5 mm, so this optic will work best with cameras of this chip size or smaller.
The optical design of the NextGEN 0.50X was done with Zemax and optimized for four field points using wavelengths of 450, 550 and 650 nm. The goal was for the smallest blur diameters for the four field points. The system was modelled using the actual optical prescription for a SCT with the inherent aberrations of this telescope. The resulting lens curvatures of this designed were made without adjusting the radii to the optical lab's tool list. Custom tools were made for all surfaces.

$450 Posted

PM me if you are interested
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Last edited by ubique; 12-05-2021 at 08:30 PM.


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