First Light William Optics Cat 91

Michael Jarvis:
Thanks for this post.  I have the Redcat 51 and it's been a great travel scope.  I really like what I have seen for the Cat 91.  Do you think it would work well using both OSC and mono APC cameras?  I live in light polluted Chicago and always use filters with my OSC imaging.  What made you choose the Cat91 over other similar refractors?  Your image looks great!!  Many Thanks.

Hi Michael,

I think that it makes no difference if you image mono or osc with that scope.

I have a TS Optics CF APO 90mm as my main refractor for some time but I have always struggled with tilt caused by the focuser. That was the main reason to try out the Cat. Its WIFD focuser moves the lens, not the imaging train so it won't tilt. The images I have taken so far are visibly better (flatter, sharper) than those from the CF. 
Besides that, the spot diagrams, the Petzval design, the attention to detail, and the premium build quality are a plus, so I'm very happy with the Cat. 

The only downside might be the dimensions and the weight. The CF 90mm is much smaller and lighter. I can take it as hand luggage on a plane as it can be retracted shorter than 50cm. The Cat has a fixed length.

CS,

Stefan

Looks nice. I've got an Esprit 100 ED and this post has got me looking at the Redcat 91 to see which I will recommend to people in the future, as they're similar in price when the Esprit is on its (very common) sale.

For those perhaps considering the same options, here's some of the major differences that I see:

• The Esprit comes with accessories for visual astronomy (finderscope, 90 degree mirror, etc)
• The Redcat comes with a soft case, whereas the Esprit is a hard case w/ foam cutouts. The redcat case is quite a bit smaller than the Esprit case because the Esprit case fits the visual accessories.
• Dear god the rotator on the Esprit sucks. Like actually this is maybe the biggest downside it has against the redcat.
• The Redcat OTA is a smidge lighter than the Esprit OTA (note that the Redcat OTA weight is often listed w/o including the weight of the rings... so when you include those, it's pretty close to equal. But the Esprit is heavier by a few hundred grams).
• The Esprit, being a triplet, allows you to interchange flatteners/reducers. Whereas the Redcat does not.
• Esprit has a slightly longer focal length, but is f/5.5 versus f/4.9.
• The Esprit comes with an annoyingly short losmandy dovetail

Well- I just posted this that might help you decide one way or the other……
https://www.astrobin.com/bczxui/?nc=collection&nce=47657

Chase Davidson:
I'm kinda obsessed with the Cat 91 right now. It's been in my cart for the last month. I love my Redcat 51 and I have large triplet that I've had fun with the last two years but I'm ready for something smaller and sharper. I've debated the ASKAR 600 with a reducer, the Esprit that Noah mentions above, the Pladies 111 and even a Tak 102 but nothing seems to match the spot diagram, price range and ease of use as this Cat 91. I'm a hair trigger away from buying this scope. Someone please talk me off the edge.

Just to add fuel to the fire, here's my first light with the Cat91
https://www.astrobin.com/1lbhs7/

Jonathan:

Chase Davidson:
I'm kinda obsessed with the Cat 91 right now. It's been in my cart for the last month. I love my Redcat 51 and I have large triplet that I've had fun with the last two years but I'm ready for something smaller and sharper. I've debated the ASKAR 600 with a reducer, the Esprit that Noah mentions above, the Pladies 111 and even a Tak 102 but nothing seems to match the spot diagram, price range and ease of use as this Cat 91. I'm a hair trigger away from buying this scope. Someone please talk me off the edge.

Just to add fuel to the fire, here's my first light with the Cat91
https://www.astrobin.com/1lbhs7/

Hey Jonathan, I've been following your progress with that cat91 (because I'm that obsessed at the moment). Side question: How are you liking your Player One camera? If I was going to drop more money on a 6200mm I was also debating looking at the Player One version of it. Does it connect with the AsiAir? Any mentionable differences in Player One over ZWO?

Chase Davidson:

Jonathan:

Chase Davidson:
I'm kinda obsessed with the Cat 91 right now. It's been in my cart for the last month. I love my Redcat 51 and I have large triplet that I've had fun with the last two years but I'm ready for something smaller and sharper. I've debated the ASKAR 600 with a reducer, the Esprit that Noah mentions above, the Pladies 111 and even a Tak 102 but nothing seems to match the spot diagram, price range and ease of use as this Cat 91. I'm a hair trigger away from buying this scope. Someone please talk me off the edge.

Just to add fuel to the fire, here's my first light with the Cat91
https://www.astrobin.com/1lbhs7/

Hey Jonathan, I've been following your progress with that cat91 (because I'm that obsessed at the moment). Side question: How are you liking your Player One camera? If I was going to drop more money on a 6200mm I was also debating looking at the Player One version of it. Does it connect with the AsiAir? Any mentionable differences in Player One over ZWO?

Any cooled astro camera that is not ZWO will not be compatible with the ASIair. I have both the ZWO 6200mm and the PlayerOne Zeus -m. The Player one is better in every way from build quality to the tilt plate that actually has four point adjustment that is accessible while installed, to the additional options and aquisition modes. They also advertise that they use industrial grade sensors which is typically present in far more expensive variants from Moravian. 

The only downside I found in the Player One is the fact that it only has one USB out port as opposed to two on the ZWO. I solved that by connecting a USB-C hub to that port and sticking it on the side of the camera. Also it will not work with ASIair, but honestly I have already transitioned away from that ecosystem and now my new remote setup is completely ZWO free except for the guide camera. Really enjoying my NINA experience so far, which personally I think is a must for remote imaging, although there are ways to run ASIair remotely too.