OVL Field Flattener

OVL Field Flattener

  (26 Reviews)
✓ 2 year warranty


2x in stock shipped 1-2 working days

About this product

Model:  skywatcher_field_flattener
Part Number:  20225

A high-quality, non-focal-reducing Field Flattener optimised for DSLR imaging on refractor telescopes with focal ratios around f/5.5 to f6.0. 

Will also provide much improved results on refractors with focal lengths narrowly outside this optimised f/range.

Integral T-Ring adaptor thread. High quality CNC machined body with gloss black anodised finish.

Features standard 2" push-fit barrel for use with 2" focusers.  Threaded for 2" filters.

Customer reviews

Average Rating (26 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
Optics works fine, but not the thread size
28 March 2024  | 

I think optics works well with my SW 72ED, but if you guys are seeking the adapter for camera side threads of M48, pls DO NOT buy the standard M54 female to M48 male adaptor on the market. As I measure the thread, its dimension is 54.7mm, a bit larger than 54mm. So I bought StellaMira flattener M48 adaptor in FLO, that works with this OVL. So I guess OVL and StellaMira flattener are built from same taiwan manufacturer. Really sucks for this Taiwan manufacture who is not complying with the standard and play these tricks.


There has clearly been a misunderstanding because OVL and StellaMira Flatteners (they are indeed made in the same factory) do not have an M54 thread under the camera-side adaptor. And they have never had an M54 thread.
The thread they do have is designed to work with StellaMira thread adapters.
There are no tricks :-)

Rating (max 5):  
Great flattener for 72ED
07 May 2023  | 

I got this in Nov 2022 and Iíve been using it since then several time a week on my Skywatcher 72ED and Iím very satisfied with pinpoint stars up to the edges paired with the ASI585MC and Sony A6400 and Nikon D5600. Works great with the scope and all 3 cameras combination and need to add spacers to get in focus. I highly recommend it.

Rating (max 5):  
18 March 2023  | 

Muy bien con el 72 ed gracias.

Rating (max 5):  
Brilliant Accessory
13 June 2022  | 

I purchased this flattener a few months ago and due to bad weather could only test in the past few weeks. I was pleasantly surprised by the excellent quality and look of this flattener, the glass looks superb. Tested on some single shots using a Skywatcher 72ED, adjusted back focus slightly on my ZWO 294MC PRO and the did a 2 pane mosaic of the Carina nebula. perfectly focused stars up to the edges, no noticeable aberrations. Definitely a good purchase for the price!

Rating (max 5):  
Great advice from FLO staff
19 May 2022  | 

Acquired a SW 72ed refractor & needed parts to attach my camera. A quick email response from Alex meant that I could quickly order the flattener, T ring & adapter which meant I had a solid imaging train & the correct backspacing for my camera. Just need a clear night to try it all out. I continue to be impressed by the service from FLO & it has become my one stop shop for all my astrophotography needs. Great stuff

Rating (max 5):  
More information
30 April 2022  | 

I bought this field flattener for my skywatcher Evostar 72 ed and I didn't even try it because my sky is cloudy since 2 weeks, and it's going ti be so for other 2 weeks. In my order there were 3 products: the flattener, an adapter ring and clouds. Can I give back clouds as written in the return terms? Sorry for my bed english.

Rating (max 5):  
not really a good FF for my refractor
25 March 2022  | 

I bought this FF last summer. I have a skywatcher 72ED with an astro camera Altair 269c (aps-c). I didn't succeed to get the right back focus (55 mm or 56 mm or something else). Thus the FF gives me some halos around bright stars.
I do not recommend to buy this equipment. I don't use it anymore and i lost 80 pounds for nothing.


Sorry to hear the flattener wasn't a good match for your 72ED and Altair camera (we don't stock Altair cameras so are unable to advise) but your purchase was covered by our 30-day return policy, so you were able to return it for refund :-)

Rating (max 5):  
OVL Field Flattener
24 March 2022  | 

A realy good product. Works great with SW Evostar 72ED. Front thread for filter installation. Overall good build quality. When attached to the scope fit well and doesnt move at all. A good alternative to the reducer/flattener from SW.

Rating (max 5):  
OVL flattener
06 January 2022  | 

Brilliant service from FLO and the flattener does everything it should do on my Skywatcher ED72. Plenty of focus tube travel, lovely flat field as compared to when not using the flattener. It is also well machined and feels quality, but also pretty light and takes 2 inch filters in the nosepiece. The nose piece holds firmly with the upgraded FLO ED72 two inch compression adapter Superb.

Rating (max 5):  
Great product
13 April 2021  | 

I tested the product on my Skywatcher 72ED and was very satisfied with pinpoint stars up to the edges paired with the ASI294MC. Highly recommended.

Read all 26 customer reviews...


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Q1. Can I change the thread on the camera side of the OVL Flattener from M42/T to something else, as I've seen the M42 thread is removable?

Whilst you can remove the M42/T thread on the OVL Flattener, underneath it has a non-standard thread that might not fit other adaptors available at FLO.

Instead, if you need more flexibility in your camera threads, we suggest looking at our StellaMira M42 or M48 flatteners or reducers, which have directly compatible and swappable M42/T and M48 thread adaptors:


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