Explore Scientific 2" Field Flattener

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Accessories Added


  • 2-Inch Accessory
  • Use with ED Refractors 
  • Corrects Natural Field Curvatures
  • Edge-to-Edge Crisp, Sharp Images 
  • 45 mm Back Focus




Explore Scientific 2" Field Flattener

The 2-Inch Field Flattener for ED APO Refractors by Explore Scientific: 

One of the truths of refractor optical design is a curved focal plane. While the center of the view remains crisp and clear the edges of that view become increasingly out of focus. Even the most precision ground optics will exhibit curvature but while this is typically not an issue for the observing astronomer (whose target is typically in the center of the field of view) blurry edges can be a huge issue for the astrophotographer. With the addition of this field flattener, aberrations that are caused by this curvature are corrected! Your images will be tack sharp from edge to edge. Created using fully multi-coated optical glass to maintain optical integrity, the Explore Scientific will slide securely into the 2-inch opening of your telescope.

  • The Explore Scientific 2-Inch field flattener was designed to be compatible with any ED refractor that will accept 2-inch accessories.
  • Corrects the natural field curvature exhibited by refractor optical designs.
  • Crisp, sharp images from edge to edge - a must have accessory for the astrophotographer.
  • 45 mm back focus

DSLR USERS, PLEASE NOTE this field flattener will NOT work with your DSLR and standard T-Ring, as the back focus is 45mm. If you use a Canon or Nikon DSLR, please use one of the options below:

Field Flattener for Nikon users: ES-FFEDAPO-NI

Field Flattener for Canon users: ES-FFEDAPO-CA


OPT Product Number: ES-FFEDAPO-00


Accessory TypeFlattener
Barrel Size2"
Free ShippingYes
ManufacturerExplore Scientific
WarrantyLifetime Warranty


Ask a Question
  • is the telescope tube end internally threaded to accept 2" filters?

    This flattener will accept 2" threaded filters.

  • Can the 4k object database be upgraded via software download?

    Unfortunately, there is no way to expand the number of objects in the hand controller, but you can connect the scope to a computer or smartphone with optional cables and/or wifi adapters, and then the software or app you use will have many more than 4000

  • I would like to know if this flattener will be really good to astrophotography use with my Explore Scientific 80 mm F6 apo.

    This field-flattener will offer as good or better a fit/match for Explore Scientific's refractors than any other similarly priced optic available. It is compatible with your 80mm f/6, along with any of the other 2" focuser equipped refractors from Explor

  • Can you describe the markings or defects that make this 'very good' condition? Are there any optical defects?

    Optically speaking, the mirrors are in great condition, There are few cosmetic scratches on the carbon fiber tube which will not do anything with regards to the image quality.

  • How many lens elements does this unit have?

    Hello Rick, Thank you for your question. I checked with Explore Scientific & it has 2 lens elements.

  • Most field flatteners are designed for a specific scope or a certain range of focal lengths. It looks really short and that would be a big plus. Will it work with my 130mm f/7 ? and how about my faster f/6 and f/5 scopes ?

    As best as Explore Scientific can tell me, the flattener is designed to work at f/6 and f/7 with a back focus of 55mm. It should work reasonably well at faster focal ratios, but you would need to experiment with the spacing - typically increasing the dist

  • Is the male thread on the "Explore Scientific 2" Field Flattener For ED APO Refractors" M42 or M48 ?

    This field flattener has male M42x0.75 (T2) threads on the camera side.