William Optics Flattener 4 - 0.8X Reducer

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William Optics Flattener 4 - 0.8X Reducer
Item # WO-P-FLAT4
  • This William Optics AFR-IV Flattener is made for refractors with a focal length of 500mm - 1000mm.
  • The AFR-IV, also called the Flattener 4, fits into 2" focusers and has a built-in rotating T-ring adapter which accepts any standard camera T-ring.
  • The lens-to-sensor distance range on the William Optics AFR-IV Flattener is 66-86mm, and the clear aperture is 54mm.
  • The William Optics Flattener 4 is made with Ohara glass and is Super Transmission Coated.


William Optics Flattener 4 - AFR-IV

The revolutionary William Optics AFR-IV Adjustable Flattener and (0.75x-0.8x) reducer is made for 500-1000mm refractors, including the William Optics FLT98, FLT110, FLT132, and others. This 2-element, 2" is black-anodized for durability and beauty. All internal surfaces are blackened to eliminate reflections.

The WO AFR-IV Flattener has a rotating t-ring thread that will accept any standard t-ring for your camera. The included T-ring adapter comes with a locking screw and extra retaining screws. This field flattener inserts directly into a 2" focuser. It is easy to set the optimum back focus distance...just twist.

William Optics AFR-IV Flattener Highlights...

  • The lens is designed to cover full size DSLR cameras with a clear lens aperture of 54 mm
  • The WO Flattener 4 has an excellent air-spaced doublet design with STM coatings, and is made with the best Ohara optical glass.
  • Superb William Optics anodized finish.
  • All internal surfaces are threaded and blackened.
  • Rotating T-ring thread for any 35mm camera. The T-ring adapter is provided with a lock screw and extra lock retaining screws.
  • Will accept any standard T-ring for your camera.
  • Inserts directly into 2" focuser.
  • Lens-to-chip distance : 66-86mm
  • 0.75x-0.8x Reducer
  • Rotating T-ring adapter
  • Clear Aperture : 54mm
  • L 84mm : W 95mm : H 144mm
  • Weight : 595 g
Additional Information

Additional Information

Manufacturer William Optics
Barrel Size 2"
Warranty 2 Year Warranty

Customer Reviews 1 item(s)

The Quality Standard of Service
The FLAT-4 focal reducer did not work on my ES102 apo. However, Chris Hendren, the OPT imaging specialist, gave me a thorough clinic on how reducers work with just enough technical information so that I could understand. He had suggestions which I tried but ultimately it was just an equipment mismatch. I had worked with the product for more than 30 days so knew my right to a refund was forfeit. OPT gave me an RMA for store merchandise minus a 10% restocking charge . When I sent it back, though, the full purchase price showed up as a refund on my credit card. This is a great company that will go to those lengths for their customers. I would recommend OPT without reservation, and look forward to more purchases in the future.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by exmedia / (Posted on 9/5/2014)
Included Items

Included Items

  • William Optics Flattener 4 - AFR-IV
  • Rotating T-Ring Adapter
Questions & Answers

Product Questions

Will this work with Orion EON 120mm (900mm focal length with 7.5 focal ratio) and QSI583 WSG CCD?
Do you know if this will work on an Astro-Physics 130 GT with a focal length of 819mm?
I am imaging with a Canon 60Da DSLR.

I have a William Optics FLT 110, wich flattener is better for it? This one or the WO flattener 68II? Another question, the thread for the T-ring is m42 or m48 in the flattener 4? Thank you.
I have a TS120 mm 900mm f7.5 telescope and a Televue TV-76 I use with an Atik infinity camera. My question is how does one calculate the adjustable focus distance the flattener 4 should be adjusted to? Is there a formula to use? I think the Atik Infinity has a 13mm distance from chip sensor to coupling ring.
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