Why ...

[Probablynot]

... has the black plastic cover that covers the open end of my SW150P got two holes in it, each of which has its own special little black plastic cover?

[spaceboy]

For stopping down the aperture while observing the moon. Take the cap of the one and place it on the other (holder)

[LukeSkywatcher]

The BIG one is the full aperture of the scope. Take it off. The smaller one was originally to observe the sun (with a filter). It cuts down the aperture of the scope.

[JamesF]

You lot, you're such teases.

Ignore them, Brian. They're actually cupholders for your tea/coffee/hot chocolate on those long freezing cold winter observing sessions.

James

[Probablynot]

Ah. Your replies all make sense. Sort of.

[barkis]

I think when the large cover is left on the scope, and the two small ones are removed, it aids focusing. When you come to focus on a star for example, you will initially see two images, true focus is acheved when the two stars merge into one in your eyepiece.

Ron.

[kenmyers]

The small hole is to reduce aperture. Litterally to make your scope 'smaller'.

[ollypenrice]

Don't use the one for the sun with a rear filter of any kind. They are very dangerous. Only ever use a high grade FRONT solar filter and/or use the projection method.

Olly

[scuffer]

Another thing learnt , I wondered why they were there but never thought to question why ?

[Mike73]

You lot, you're such teases.

Ignore them, Brian. They're actually cupholders for your tea/coffee/hot chocolate on those long freezing cold winter observing sessions.

James

I use mine to hold a 1 million candle power torch, its great, no more tripping over things in the dark but haven't seen any stars in ages!

[Pappy Nick]

Consider yourself lucky !!!

My Heritage 130p only came with the one big cap. I was most put out !!!

[JamesF]

That's because with the Heritage 130P it's best used stood on a table, so you've already got somewhere to put one of your coffees.

James

[Probablynot]

When you come to focus on a star for example, you will initially see two images, true focus is acheved when the two stars merge into one in your eyepiece.

Ron.

Cool! All very Quantum!

[knobby]

If you take one of the caps off it lets you hang the cover on the carry handle of a Skywatcher dob ...

[Frank the Troll]

The small hole is probably an arperture stop used for visual equalision for viewing planets, and best used with a 32mm EP, or possibly a 25mm