Review: William Optics Redcat 71 My new favorite lens

Welcome to the William Optics Redcat 71 review. After more than three years of engaging in this hobby, I finally chose to upgrade my equipment to enhance my imaging skills. A colleague at Microsoft recently bought a new setup and offered to sell me his current hardware at a substantial discount. I acquired the new telescope, a William Optics Redcat 71, as part of a package deal and certainly paid less than the $1800 USD retail price.

👉 Links to certain products on this page will result in me receiving a commission for the sale. All proceeds are put back into the purchase of equipment and supplies for astrophotography.

This is my Redcat 71!

First, let's address a common question I'm asked.

Redcat review: how does it compare with the Svbony SV503 70ED?

The SV503 was my first refractor and is a very capable scope, especially when coupled with the field reducer/flattener. Let's take a look at the head-to-head comparisons I made:

Feature	SV503 70ED	Redcat 71	Notes
Aperture	70mm	71mm
Focal length	420mm	348mm	The field of view is very similar.
F/ratio	f/6	f/5	The Redcat is only slightly faster.
Retail (2023 vs 2025)	$400 / $260	$1700 / $1600	The Redcat may be 4x the cost but I receive about 10x the benefit
Length	12.52"	16.81"	The Redcat definitely takes up more space and is less portable.
Weight	4.9 lbs.	7.1 lbs.	Yeah, a lot more weight to haul.
Design	S-FPL-51 2-element achromatic doublet	FPL-53 4-element Petzval apochromatic doublet	The Redcat 71 uses superior glass and provides a much cleaner, clearer image without chromatic aberration.
Dew shield	Built-in	Built-in
Focus	Dual-speed toothed focuser	Helical or WFID	Both focusers provide fine controls with locking mechanisms. It was easier for me to install an electronic auto-focuser on the Redcat due to the design.
Stars	Stretched at edges of frame with halos	Round to the edge and no halos	The superior optics of the Redcat really shine when it comes to stars. The SV503 requires a field flattener/reducer to provide pinpoint stars to the edge.
Backfocus	Difficult	Easy	The SV503 requires precise backfocus or stars will get distorted. The Redcat, on the other hand, only requires you to find focus. If you are able to space your sensor so you are able to focus it, the stars will be round throughout the field of view.
Chromatic aberration	Significant	Minimal	My consistent issue with the SV503 is blue/purple halos around stars that I don’t get with the Redcat.
Closing thoughts	This is a fantastic scope and probably the best option I am aware of at its price point. With the addition of a flat field will produce remarkable images.	The fact this telescope was designed for astrophotography is evident in the quality of the images it produces. The ease of backfocus, star shape and lack of halos or significant chromatic aberration make this worth every dollar of investment.	If your budget can afford it, I recommend the Redcat. The SV503, on the other hand, is far less expensive, more portable and easier to use on traditional tripods and portable mounts.

OK, now that I’ve shared the comparisons, let’s dig into the details.

Specifications

The Redcat 71 comes with a nice, wide field of view at 348mm focal length. The 71mm aperture makes it f/5, a decent speed for deep sky photography. The design does not require a reducer or flattener, and with my 2.5x TeleVue PowerMate increases to 870mm.

Here is what the field of view using a ZWO ASI294MC Pro and a Sony A7R IV camera with the Redcat 71 pointed at M42: the Great Orion Nebula.

Fields of View based on Camera

The Redcat with a 2.5x Barlow-style lens has the perfect field of view for photographing the moon.

800mm - 1000mm is a great range for moon photography

In fact, don't take my word for it. Here's an image I took with the "moon configuration."

A certified genuine 100% Newport cloudy moon.

The Redcat is a Petzval refractor, which includes additional lenses between the objective lens and the focuser. This design results in a significantly flatter field, reduces the requirement for precise backfocus spacing, and produces images that are free of star halos and have minimal chromatic aberrations. This apochromatic doublet refractor utilizes exceptionally high-quality FPL-53 glass for superior correction of spherical and chromatic aberrations compared to achromatic lenses.

Field of view images courtesy of Astronomy tools.

Let’s check out what comes in the box!

What’s in the box

Although I purchased my Redcat 71 secondhand, the owner did a great job of retaining all of the parts and manuals. The standard package includes:

• The 348mm focal length telescope (of course)

• A threaded dust cap made of sturdy metal that fits M48 threads

• A tilt adapter to correct for issues in your imaging train

• A built-in field rotator so you can rotate your camera angle to frame your target

• A saddle handlebar with M4 thumb screws you can use to add a guide scope

• The helical focuser (standard version) or proprietary WIFD focuser

• A focuser tension ring to lock in focus when you achieve it

• A focuser gear ring you can use with a belt to attach an auto-focuser

• Arca Swiss/Vixen Plate to easily attach to most mounts

• Mounting Rings

• A built-in dew shield to reduce condensation on the lens

• A Bahtinov mask to assist with achieving focus

• A carrying bag to transport the unit

• No need for a field flattener because of the design

It’s a very solid offering and I found I had all the elements I needed to integrate it with my own system.

What’s not in the box

Honestly, nothing. The box had everything I needed.

Things I wish I knew

I really wasn’t surprised by much with this scope, other than just how great the quality is. It is heavier and bulkier than the Svbony, but still very portable. I’ve taken it with me on several occasions to the beach to zoom in on waves, ships, and whales.

The pudding (proof is in it)

I’ve had the opportunity to shoot a variety of targets with the Redcat so far. Here are some examples. First, let’s take a look at star quality. This is a single raw, uncropped and unedited (except for stretching the brightness levels to make it visible) 5-minute exposure.

This is the upper left corner, zoomed in so you can see the quality of the stars at the edge.

An example image captured with this scope

Perfectly round stars at the edge

Here is a nebula, star cluster, and the moon.

Pros and Cons

The pros:

• No pulling out hair in frustration trying to achieve perfect backfocus distance

• Beautiful stars

• Minimal chromatic aberration

• Superior image quality

• Sturdy design

• Easy to mount and accessorize

• Built-in field rotator

• Built-in dew shield

• Built-in focus tension ring

• Great for both lunar and deep sky observations

  
  

The cons:

• At over $1,000 it's a commitment/investment

• Too heavy for basic tripods and mounts

• I wanted to have at last three cons, but can’t think of a third

  
  

I’d love to hear your thoughts in the comments!

Conclusion

My only regret with my purchase of the Redcat 71 is that I didn’t buy one sooner. That is a compliment to SvBony for the SV503 for its performance at a ~$400 price point. The Redcat optics combined with a high resolution camera and narrowband filters is opening new doors and possibilities for my imaging sessions. I’m creating my favorite images in over three years of practicing this hobby. A month ago, I would have declared this as my main scope for all full-disk lunar and deep sky observations in 2024.

However, there is a twist: I just received my HyperStar for my Celestron EdgeHD 9.25” SCT and have not yet had the opportunity to test how that will impact my imaging plans in the coming year.