Experience with our dew cap for the Celestron C8 3D printing

Dear Mr. Kloss,

I am happy to respond to your request for feedback. I've had two nights of clear skies now and can already say a few things about the dew cap:

The construction is great, and the dew cap fits perfectly on my Skywatcher 8" Quattro. It's nice that there's a stop, meaning that if the dew cap sits flush everywhere, it's perfectly centered and not tilted. Nevertheless, I use the locking screws for security, and they fit perfectly. The dew cap is very stable, but I'm still concerned about whether it's a good idea to leave it on the telescope in the observatory during midsummer when temperatures exceed 30°C, as the cap could potentially deform. How it performs in frost and whether the material becomes brittle remains to be seen.

Regarding the side openings for dew drainage, I have to say that I initially wanted to seal them because I was worried that it would affect the way I create flats/darkflats, where you leave the cap on. However, it seems to have no or no visible effect unless you shine the light directly into one of the holes. The dew cap is super blackened all the way to the edge. The weight is also very light. All in all, I like it very much.

There was considerable dew formation both nights, and the dew cap did its job well, also counteracting any stray light that otherwise tends to hit the focuser directly. So, all in all, it's good, but this design with the groove for catching water and the side outlets doesn't work so well for me. During observation, it's certainly fine and prevents water from getting into the tube. But I park the telescope horizontally in the observatory, of course, so that the telescope can be as high as possible and I can just barely close the roof. In this parking position, the water should drain away. But even if one of the holes is at the bottom, the water drains only very poorly. In the normal parking position, it's certainly a bit better, but even then, ultimately, everything will only drain through one hole. You should also avoid wiping the inside of the dew cap dry. It seems as if some of the black paint might come off. Perhaps it's just a few traces of paint, and so far, it hasn't been much, but I'd rather not dry-wipe it, although that would also cause limescale stains.

Perhaps the holes could be made a little deeper so the water drains away more quickly? Or ensure that the water drains outwards and doesn't collect in the first place? It's difficult... Lined with velour, the water would probably stay in the film for a while and then quickly form ice crystals in the winter, creating additional reflections. Anyway, it's not that trivial.

The bottom line is, this is complaining at the highest level, and I really have no reason to find fault with the dew cap. So, I'm really very happy with it and thank you very much for this great product.

Best regards,

Jürgen T

Link to dew cap for the Celestron C8:

https://www.teleskop-spezialisten.de/shop/3D-Druck-Entwicklungen/Tauschutzkappen/Tauschutzkappe-Celestron-C8-EdgeHd-800-SC-Taukappe::5690.html