C9.25 dew shield lenght

I'm planning to build a new dew shield for my C9.25 OTA. What is the
recommended lenght to avoid vignetting?

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\\__ Falco Stellare -
Togli il TAPPO per avere l'indirizzo giusto

Falco Stellare wrote in message .. .
I'm planning to build a new dew shield for my C9.25 OTA. What is the
recommended lenght to avoid vignetting?

As the previous person indicated, you can make it very long, so treat
this as a free variable.

What else would anyone want a dew shield to do?

Stray light control: If the tube extension opening is at the center of
curvature of the primary, then you will block all stray light. So you
have a week reason to make it the same length as the original tube.

Weight Balance: If the tube is made out of the correct weight stuff,
you can achieve perfect balance and observe with both clutches dis-
engaged and still track the sky!

So the trick is to use the shield to attack all three problems at
the same time. I did this on my C11!

Mitch