Williams Optics RedCat 51 Review (NEW 10/6/19)

Redcat- everything you didn’t think to ask.

When Dave first talked to me about the Williams Optics “Redcat”, I had no idea what he was talking about, but I promised to look it up online.  I was impressed with the images I saw and the design of the telescope, or what I   considered to be a “lens” for my DSLR. I bought it immediately and I wasn’t disappointed.  Let’s look at the advantages and disadvantages of such a system.

OUT OF THE BOX

I can’t stress enough how well designed Williams Optics made the Redcat.  The entire unit is very compact measuring just under 9 inches in its foamed padded softcase.  The dew shield is reversed for storage and transportation, so this will easily fit into my camera bag.  (Figure 1)

SPECIFICATIONS

Objective size: 51 mm

Focal length 250 mm

F ratio: f/4.9

Lens Structure: Petzval 4 element

Field of View with ZWO ASI1600 MC camera:  4.3°

Weight: 4 lbs

Price: $728 + shipping and tax

FEATURES

Dew Shield

The dew shield is clever; whoever thought a dew shield could be clever? When you unpack the Redcat, slide the dew shield off the telescope.  The lens cap is on the opposite end.  Remove it, turn the dew shield around and screw it onto the telescope.  The end cap is actually two pieces. On its own it can be used it as an endcap for protecting the optics or for dark frames.  However you can also unscrew the end of the cap to reveal a bahtinov mask for focus applications.  (Figure 2)

Focus

Focus is obtained by turning the black center piece.  First however you need to loosen the retaining ring.  Once you have achieved focus, retighten the retaining ring.  It is a helical focus and is incredibly precise. There is no slop, and very fine movements are needed to make pinpoint stars.  I played around with the bahtinov mask, but found it wasn’t necessary or even a faster method then just slowly turning the black helical focus ring.  Of course the Redcat has focus reference numbers so you can write down a starting point for different filters or cameras. Figure 3

Filter Holder

You’ll be using 2” filters with the Redcat. Start with the allen wrench that comes along with the Redcat and loosen the three set screws in the back of the telescope.  Unscrew it by hand and inside is a threaded section that accepts 2” filters. BE CAREFUL not to touch the filter when screwing it into the system. You don’t need a special tool, just be aware. Once completed, screw the section back on the telescope and tighten the set screws again with the allen wrench.  Figure 4

Disadvantage

It is a real pain to try and change filters during an observing session.  Since everything screws into the system (which is good), everything has to be screwed off to change the filter which can result in cord tangle.  So cameras have to be cooled down and turned off with cords removed.  The Redcat does have a rotator but I find loosening that and trying to unscrew the camera seems counterproductive. Keep in mind if you have long enough cords and are careful you can unscrew the camera without shutting down.  Don’t untwist the cables once the camera is removed. You still need to rescrew the camera back on and the cables should untangle themselves in that process.  It can be done just be careful not to pull the cables.

Finder Scope

Do you need a finderscope with the Redcat? It is helpful.  They recommend a red dot sight, and I like a green laser. Either one is fine and will make setup easy when polar aligning. Figure 5

Base Mount

The base mount is unique and very well thought out.  One side is a Vixen style plate, and turn it over and you have an Arca Swiss plate.  It’s actually quite ingenious. CAUTION: When I first attached the Redcat to a side by side system (ADM products) I tightened down the Vixen plate, and as I removed my hand it slide right off into my hand.   I almost had a huge tragedy before first light!  I tried the Vixen base on the other side of the system (without the telescope) and had the same result.  When I tried it on the mount itself without the side by side it was fine; no problem and nice and tight.  All products were ADM.  I don’t know if you’ll have an issue or not, but please check it carefully. Putting friction tape on the sides of the adapter solved the problem.  Figure 6

Rotator

The Redcat comes with a rotator along with numbers to select the desired angle.  Just unscrew the rotator knob and turn the system.  It’s important that the set screws are in tight so you’re simply not unscrewing the entire unit like you would to change filters.  The rotator is especially convenient when setting up a DSLR camera.  You want to be certain any camera is tightened before using the rotator. Figure 7

Attaching Cameras

Any camera screws directly to the back of the Redcat to give a strong vibration and sag free fit. The ZWO cameras with their adapters screw on with no problem.  The DSLR cameras will not, and require a special 48mm T-mount adapter.  Save time and get it directly from Williams Optics.  I tried one from Orion first and it didn’t work.   The adapter screws directly on the threads of the Redcat and connects to the camera.  There are no spacers. Figure 8

OTHER OPTIONS

Williams Optics sells a visual back which I didn’t purchase which is actually an erecting prism so you can use it for terrestrial applications such as birding.  The mount they recommend is the Ioptron Sky Guider Pro which I also didn’t purchase as I’m using it on a CGEM mount at home.  I’ll be looking at this as a possible future purchase as I get ready to take this out on the road.

OBSERVING

I find a guide scope essential when using the Redcat.  I also find it hilarious that I’m using an Orion 60 mm Guide Scope for a 51mm telescope.  I like a side by side system, and have been using it successfully with ASIair software.

The field of view is so large on the Redcat (about 4½° with the ZWO camera) that I can do a two star alignment using the laser pointer, and plate solve to fine tune it later. 

For the following images I used an Optolong L-enhance filter which required anywhere from 10-15 minute exposures with the ZWO ASI 1600 MC under suburban skies.  Notice the size of the field of view with the Veil Nebula, and the wispy detail of the California and Heart nebulae.  Pay special attention to the edge of the images as stars are tack sharp to the corners. Figures 9-11

I haven’t done enough testing with the Redcat and the DSLR camera, but I’ll post some images at a future date.

CONCLUSION

My plan is to take the Redcat with me on a future trip to Australia.So check back for some updates on the portability of the system as I get ready for that trip down under.

For the price, this is an astrophotographers dream.Small and lightweight, it is well designed and made with incredible optics.  If you want a great system for wide field astrophotography at a low price look no further.