Dust cap on dust cap?

[virtualpilot45]

I've just been messing around with my month old telescope (it's cloudy outside!) and I think I've found an extra dust cap on the dust cap, which is removable. The cap is on the top left of the big cap, and it goes into the hollow hole below it.

Is this a common feature on telescopes?

[virtualpilot45]

Meh, should have looked better.

http://stargazerslounge.com/equipment-help/86833-stupid-dust-cap-question.html

[John]

Yep, it turns your 150mm F/5 scope into a 50mm F/15 scope. Seems to be a Skywatcher / Celestron speciality - I've not seen it on other brands of scope (Skywatcher and Celestron are owned by the same company).

[ythanpythan]

Now that I didn't know. Thanks chaps.

[garethmob]

iv got one on my bresser voyager dob find it really nice on the moon if i forget my moon filter cuts the glare

[mikeknowle]

You mean it's not a cup holder. Opps.

[UrsaMajor]

I have the same on my scope. I was recently looking into filters and wondered if a solar filter could go over it? Or if i would need to take off the 8" dust cap and put one of these over?

Astro Engineering Sol-Vu safe solar observing filters for most telescopes