Collimating Cap.

[banjaxed]

I have had my 200P Dob for a few months now and have not checked the collimating yet. All the instructions recommend using a collimating cap but they don’t seem to be readily available. Are they really necessary or will my Cheshire be enough ?

[Rob Sellent]

I have a homemade cap but never found it of much use. If you want to make a cap, you can either follow this type of description, or just get yourself an empty 35mm film canister, cut the bottom off, then drill a hole in the center of the cap (where the dimple is).

However, Moonshane's tip-top-tip milk carton washer thing and collimation guide is the business . And not a mention - if I recall correctly - of caps. Suffice to say, the Cheshire should be fine for collimating a Dob.

Edited September 26, 2019 by Rob Sellent

[banjaxed]

Thanks for the link Rob, looks like the best explanation I have seen yet. I can forget about the cap. 

[JG777]

You can buy the caps.

https://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html

[wookie1965]

I just used Cheshire sight tube really easy.