William Optics v2-U RedCat 51 APO f/4.9
William Optics v2-U RedCat 51 APO f/4.9William Optics v2-U RedCat 51 APO f/4.9William Optics v2-U RedCat 51 APO f/4.9
William Optics v2-U RedCat 51 APO f/4.9William Optics v2-U RedCat 51 APO f/4.9William Optics v2-U RedCat 51 APO f/4.9

William Optics v2-U RedCat 51 APO f/4.9

  (21 Reviews)
✓ 2 year warranty


12x in stock shipped 1-2 working days

About this product

Model:  wo_redcat_51lx
Part Number:  L-RC51II-U

NEW updated RedCat v2-U  51 / 250mm f/4.9 APO. 

This latest v2-U version of the popular RedCat 51 has an improved helical focuser and updated tension adjustment.

Please download the following PDF to see the differences between the Redcat 51II and Redcat 51II-U

The William Optics RedCat 51 APO is a 51mm f/4.9 Petzval refractor with synthetic fluoride (FPL53 and FPL51) glass elements for a full-frame, flat field image.

Provides high-resolution images when used for astrophotography or wildlife photography.

Its fast f/4.9 focal ratio and compact size make it ideal for convenient wide-field astrophotography or piggybacking. 

It incorporates a smooth helical focuser, a field rotator graduated by degree, a slot for 48mm filters and a reversible dovetail for either Vixen-style or Arca-Swiss mounting. 

Sky and Telescope Review of Redcat 51

Supplied in soft carry/storage case. 

Telescope Field of View Simulator


What's in the box

  • RedCat 51 f/4.9 scope
  • Soft Carry Case
  • Patented Bahtinov Mask


Focal RatioF/4.9
Focal Length250 mm
Objective TypePetzval (4 elements in 3 groups) and Ohara FPL 53 ED element. 
Image CircleΦ 44mm (Full Frame)
Dimensions225mm x 80mm x 80mm
Tube Weight1.47kg

Customer reviews

Average Rating (21 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
11 June 2023  | 

What more can I say. Its a lovely small scope.

Rating (max 5):  
Excellent telescope!
23 February 2023  | 

This has been and is my first proper telescope and I have loved using it through my first full Astrophotography year. I have waited until now to post my review so that I could go into a bit of detail on my experience with it so far. I have found it a joy to work with and have been able to really get my footing and learn the ropes of the do's and don'ts relatively well. It is a very well put together piece of kit and you can feel the quality. The images I have been able to produce have been crisp and when linked with my guide camera and goto mount it's been so much fun hunting down targets. From someone wanting to learn Astrophotography to a seasoned professional I would say this is a beautiful piece of kit and is worthy to be in anyone's collection. Even now when I am starting to look to a longer focal length I plan to keep this to work on other projects in the future. When going through the process of purchasing my RedCat51 I contacted Alex of FLO many times, he was incredibly helpful and was able to give me great feedback and answers on everything I could come up with. I totally recommend this telescope to anyone starting out seriously in Astrophotography and I also completely recommend First Light Optics as a supplier. Before I used to jump between company's, but from the moment I started using them they have been flawless and I always put them forward as thee go to company for Astrophotography.

Rating (max 5):  
Beautiful piece of kit
09 November 2022  | 

I've not had a chance to use this site to the current UK weather, but it seems very well made. I already have the matching WO spotter scope, just looking to get to use it out in the wild....

Rating (max 5):  
An excellent wide field scope
15 August 2022  | 

As it is already know to everyone, this is an excellent astrograph, optic quality is really nice and the price is fair, you get even a little bit more than you are paying for. I have used it only a few times because of the weather but the ease of use and quality are evident. Without a doubt a telescope that will make anyone happy!
Cómo es sabido por todos, este es un astrografo excelente, la calidad óptica es realmente buena y el precio justo, recibes un poco más de lo que estás pagando. Lo he usado una pocas veces debido al clima pero la facilidad de uso y la calidad son evidentes. Sin duda, ¡un telescopio que hará feliz a cualquiera!

Rating (max 5):  
Just Get It
15 August 2022  | 

Easy to use, no complaints, worth the money. Just get it

Rating (max 5):  
Very happy with scope
16 May 2022  | 

The scope looks great, and the build quality is good. So far I haven't been able to test it as the clouds just won't go away. Taking some general test shots, the images look fine and focus is smooth and easy. Can't wait to use it in anger. Service from FLO was top notch as usual!!!

Rating (max 5):  
Awesome Piece of Kit
30 January 2022  | 

Absolutely excellent piece of kit. Build quality is fantastic and the built in bahtinov mask is amazing, very quick and easy to achieve perfect focus.
Literally the biggest complaint I can find is fine threads made of aluminium on the lens cap/bahtinov mask make squeaky sounds.
Granted, I'm using it on a crop sensor Canon but absolutely no vignetting to speak of and sharp, crisp stars across the whole field.
The usual stellar service from FLO is also nice, 15-20 working days delivery quoted at order, so naturally it was delivered in 14 working days

Rating (max 5):  
Totally newbie thrilled with red cat
05 January 2022  | 

I’m really new to astrophotography and not had much luck so far mostly due to clouds and focusing. With a clear night last night I set this beautiful scope up and had a go not expecting much but omg it was fabulous and I got lots of photos of Orion Nebula that I only hoped to get and the detail was much more than I ever expected. Can’t wait to get out tonight to try another target

Rating (max 5):  
A little star.
03 December 2021  | 

There is a serious reason why this tiny scope is so popular amongst astrophotographers.
It's truly a gem. Optically excellent, build quality is also excellent. If you're on the market for small astrograph - well you've found one

Rating (max 5):  
Delighted with my RedCat.
12 May 2021  | 

I could not be more pleased with my RedCat purchase. This is an outstanding little scope which I have used alongside my Samyang 135mm for wide field imaging of larger nebula targets. I can find nothing to fault with the RedCat. The finish is superb and the optical performance with my ASI1600 meets all my expectations. I am delighted I don't need to purchase a dedicated reducer/flattener and that my parafocal filters are really parafocal after all - not the case when used with my Samyang. As noted by others I cannot see me ever selling the RedCat - it is definitely a keeper. As ever the service from FLO was second to none.

Read all 21 customer reviews...


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