Explore Scientific’s 3-inch Field Flattener/0.7x Focal Reducer is a multi-faceted accessory designed to enhance your astrophotography experiences. As a field flattener, this piece addresses the edge-of-field aberrations caused by curved focal planes to ensure your night at the eyepiece will result in crisp, true images.

As a focal reducer, this device will reduce your f-ratio by 0.7, which results in a wider field of view, brighter images and less exposure time. Recommended for our 127mm and 152mm refracting telescopes (excluding our doublet refractors), this field flattener/focal reducer boasts fully multi-coated optics.

This item comes with a threaded adapter that threads onto the Explore Scientific 2-inch rack-and-pinion focuser. Threaded attachment to a 2.5-hex focuser, which comes stock on our 127mm APO telescopes, requires purchase of an additional adapter. 

The field flattener/focal reducer offers 55 mm of back focus from the rear face of the device. The M42x0.75 adapter adds 3 mm, so the sensor needs to be 52 mm from the face of the adapter.

To connect to the 2.5 hex focuser, purchase item number 510366.

While technically this was designed for the f/8 system, through user experiences and our subsequent testing we have concluded that our 3-inch field flattener/reducer performs very well with our f/7.5 refractors.