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William Optics Flat61A Adjustable Field Flattener for ZenithStar 61


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Product Details

  • This Adjustable Flattener is made for use with the ZenithStar 61 telescope. It features a 45mm image circle for use with sensors as large as full frame, while also retaining your ZenithStar 61's native focal length! On the back, it features an M48 thread for attaching nearly any camera. If you're using a DSLR or Mirrorless camera, make sure you purchase an M48/wide t-ring for your camera's lens mount (sold separately).


    Adjustable Flat61 for Z61/ Picture Instructions:


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Product Reviews

Customer Reviews
4.8 Based on 11 Reviews
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Jason K.
United States United States

Great field flattener for the z61

Very easy to use this dial-in field flattener and easy to adjust for accessories. I added a field rotator and it was as simple as subtracting the thickness of the rotator from the flattener's adjustment ring. WO makes great quality products and OPT is a great distributor!!

United States United States

Exactly what I needed

It works exactly as expected. It was easy to dial in my back focus.

William C.
United States United States

Just perfect!

The wait was worth it. Covid has messed up the supply chain and I find myself waiting quite often, but OPT came through and I'm happy. Now I can get my Zenithstar 61II out (as soon as I get some decent sky!) and start shooting. I've been chomping at the bit here in SoCal and the skies have not been cooperating so having to wait a bit for the flattener didn't cause me much anguish. I am really impressed with Williams optics products, the attention to detail and build quality is amazing.

Ferenc S.
United States United States

Yet to achieve correct flat field

Using it with the z61 telescope and a canon 60D has been a rocky road using the recommended settings. Stars are still not flat at the corners so I had to go look up some forums to see other people’s recommendations who had hands on experience. It turns out I have to further reduce the distance on the adjusting part to get a better flat field . So far , it’s ok although I feel like the adjustable part of the flattener is a bit too loose once the locking ring disengaged and perhaps too much more play on the threads . This might contribute that I did have a mysterious light leak when I did some daytime testing and after the camera and the telescope was eliminated as the suspects , the light leak disappeared once o wrapped up the flattener part with black cloth and tape. The locking ring was tight on and plenty of space for adjustment so loose components or hanging on the last thread sort of issue with can’t be blamed. I will continue to field test it, hopefully I’ll find that darn sweet spot for the flat field and work out something not to have a light leak.

OPT Telescopes William Optics Flat61A Adjustable Field Flattener for ZenithStar 61 Review
United States United States

Outstanding quality.

You can't go wrong with William Optics. A must have for the W.O. Z61ii.

Andrew N.
United States United States

Well worth it!

Just what I needed to get a nice flat field with round stars to the edge. I am using it on my Astro-Tech AT60ED and works great. OPT shipped it super fast, and I had it within a couple of days.