TS Universal 2-Inch Field Flattener for Refractors from f/5 to f/8
|TS 2" Field Flattener - Universal Field Flattening Lens|
This revolutionary new field flattening system is the first one to our knowledge that offers a superior quality compared with conventional systems:
-- larger possible illuminated field through elimination of the "T2 keyhole". The flattener has 45mm clear aperture compared with 37mm for typical T2 adaptations.
-- excellent performance on a broad range of very different refractor telescopes from f/5 to f/8.
-- very large Back Focus distance of 109mm (exceptions: see belo). This allows you to attach extra accessories between the camera and the flattener, like off-axis guiders, filter quick changers, ...
-- a multitude of different adaptations is possible. The flattener uses the standard 2" filter thread
-- visual use is also possible with the 2" filter thread adaptation - just screw the flattener into the 2" barrel of the star diagonal mirror - this will improve image sharpness towards the edge even for photographic use.
The left image shows a typical setup of the field flattener with f/6 to f/7.5 refractors and a digital SLR camera.
-- The flattener is on the far left. It disappears completely inside the focuser.
-- Next to the flattener is an M48 extension tube to get the proper distance. The extension tube is available in several different lengths.
-- In this case the camera adaptation is through the conventional T2 thread via a T2 bayonet ring. For Canon EOS a separate adaptation is also available with a larger clear aperture.
-- For convenience a 2" stopping ring is used to have a clearly defined focal position of the entire setup.
-- We are happy to assemble a kit specifically suited for your telescope, camera and accessories!
-- field flattener with blackened lens edges. Multi-coated.
-- no focal reducer function!
-- thread on the camera side: M48 (2" filter thread) male
-- thread on the telescope side: M48 (2" filter thread) female
-- clear aperture 45mm (much larger than with conventional T2 systems)
-- the flattener disappears completely inside the focuser. It does not inherently require any extra back focus.
Recommended distances between the M48 thread of the flattener and the sensor of the camera:
The recommended distances from the M48x0.75 thread of the corrector to the sensor of the camera
In principle this rule applies: the shorter the refractor´s focal length, the longer the working distance to the sensor has to be.
♦ focal length < 450 mm: 128 mm
♦ focal length 450-490 mm: 123 mm
♦ focal length 500-550 mm: 118 mm
♦ focal length 560-590 mm: 116 mm
♦ focal length 600-690 mm: 113 mm
♦ focal length 700-800 mm: 111 mm
♦ focal length ab 800 mm: 108 mm
An underrun or an overrun of the distance of up to 5% has no visible effect on the sharpness in the field of sensors with formats up to APS-C. With larger sensors, the tolerance is reduced to 1-2%.
Available accessories for the field flattener -- 2" on T2 adapter with 39mm length
-- 2" barrel extensions 15mm, 20mm or 30mm length
-- Variable T2 extension 10 to 12mm
-- T2 Extension tubes 7.5mm, 15mm and 40mm
These various adapters allow you to use the flattener with any telescope with any individual accessories, such as off axis guiders, filter wheels, filter quick changers, ... You will be able to maintain the correct distance between the field flattener and the camera.