Explore Scientific 2" Field Flattener for f/5 - f/7 Refractors - ES-FF2F5/F7

Explore Scientific f/5 - f/7 Field Flattener with 2" Barrel

• Explore Scientific 2" field flattener for refractors with a focal ratio of f/5 to f/7
• This field flattener will not change (reduce) the telescope's focal length
• Fully multi-coated optics
• Easily attaches to a a DSLR camera with user-supplied t-ring
• 38 mm of clear aperture
• Requires 55mm of back focus/spacing between the device and the camera sensor
• The body sports a premium high glossy anodizing finish

If you are doing astrophotography with a fast refractor, field curvature may appear in the corners of your images, making the stars smear perpendicular to the axis of the image. This is called coma -- coma is Latin for comet, because the stars look like comets. The faster the refractor, the more obvious the field curvature becomes, and as curvature increases, the closer to the center the coma appears. The larger the sensor, the worse the coma.

Astrophotographers can easily correct for coma by using a field flattener – an optical device that goes between the telescope and the camera. Field fatteners are not interchangeable, because these devices are designed to work with a small range of focal ratios.

The Explore Scientific field flattener is designed to work with telescopes with focal ratios between f/5 and f/7.  Please note that this flattener does not reduce your telescope's effective focal length.  Like most field flatteners, it requires 55 mm (+/-2 mm) of spacing between the back of the device and the camera sensor.  

According to Explore Scientific, this field flattener works with the following Explore telescopes:

DAR1020765-01
DAR127065-02
DAR152065-01
ES-ED0806-02
ES-ED10207-02
FCD100-0806-01
FCD100-10207-02