RedCat 71 WIFD vs Ultra-Cat 76 — which one’s really better?

ScottF · Nov 7, 2025 at 09:28 PM

Having a standard focuser makes adding an electronic focuser easier and avoiding belts and such

The 71 is a WIFD - no belts needed.

The 76 appears to be the better scope though - 5-element Petzval (vs 4 “Petzval-like”), better glass, larger image circle, slightly faster/longer for essentially the same price.

If you look at the spot diagrams for both, the Ultracat 76 should have far tighter stars from the center and especially the corners.

Hey there, I have been imaging with the newer RedCat 71 WIFD with a ASI2400MC pro for ~one year. The scope has had zero issues, the removal of back focus has been a real boon. The images are excellent with tight stars right to the edges,. My only issue, if I was to have one, would be the screw that hold the rotation of the focuser barrel. It has a tendency to loosen which results in the inadvertent rotation of my camera and the ZWO filter wheel. My solution, (very high Teck) was to attach a wire to the filter wheel to fixed location on my scope to prevent any rotation.

Ultra Cat 76 Arrived today! paired with 2600MC pro, 120mm guide, on AM3 mount. Got it assembled, went out just to polar align, check focus. Took some test shots stars look good. Will try and do a short run tomorrow night. Moons gonna be a bit bright though. Had been running a redcat 51 for a while. Took the guiding a while to settle down. It did but I am a little concerned it was the weight, I had my top end all on the scale, I was under 15 lbs .

im very excited to hear u guys opinion about the ultra-cat 76 im thinking of buying one after new years, i would really appreciate your opinions and concerns about the scope.

Thank you

CS

Deniz Üzel · Nov 7, 2025, 03:50 PM

Hey everyone,

I’m setting up a deep-sky rig and can’t decide between these two William Optics bundles:

🔹 RedCat 71 WIFD + ZWO AM3 Full Package

🔹 Ultra-Cat 76 + ZWO AM3 Full Package

Both are almost the same price, so I’d love to know:

– Which setup would you go for, and why?

– What are the real differences between the RedCat 71 WIFD and Ultra-Cat 76 (optics, image circle, sharpness, speed, etc)?

– Is the 76 worth it, or are they basically the same in real-world performance?

Any insights from people who’ve used either (or both) would be awesome.

Thanks in advance — clear skies!

– DÜ

I have the UltraCat 108 with an ASI6200MM Pro. The HFR I have been getting using HocusFocus from all of my filters ranges from 1.54 to 1.67. That is far better than any other scope I own. I love the scope, but I was never able to master the STX (tilt adjuster). The push plate is sort of floating as it has no ‘nut to butt’ position (zero tilt coming from the tilt adjuster) where the push plate is flat against the pull plate. Instead it is riding on auto tension screws. I replaced the OTA tube extender, the STX and the rotator with an adapter I had made in Germany. Coated the inside with air brushed Musuo Black. For any tilt, I put an OGMA Z’Tilter on the camera and with 5 adjustments, I was as flat as you can get it. In short, the optics are outstanding. I would expect the same out of the UltraCat 76. Beware of the STX, but I’ve read where some people love it. I own 3 WO scopes, RedCat51 WIFD, FLT91 and the UC108. But in fact, it’s always something with William Optics. The FLT91 came with dust all in the tube and don’t get me started on the focuser sag of the 91. The UC108 came with a huge spec in between the front lens group, so I sent it back and got another. Also, I discovered a huge light leak in the UC108 and it turns out eight screws had not been inserted and a gasket had not been placed inside the tube. They sent the screws and gasket out to all of us that had ordered in the first batch. It seems to be a crap shoot when it comes to WO.

EDIT: And I forgot to mention that I now have a permanent black cloth covering the ruler window of the WIFD focuser of the RedCat 51 as it has a light leak. Not too bad, but enough that I can see it in the BIAS and DARK subs if I shoot in a lighted room, or outside in daylight. Even more so in the histogram of those subs.