Telescope Cover?

[Johnmore]

I have a 4.5 reflector with a plastic cover over one end of the scope with another hole in it with a cover on it should I remove both of these when using to scope??

[speaker]

A little more information would help but I am assuming that the cover you are talking about is on the end opposite the primary mirror and points toward what you are looking at. The larger cover seals the scope and protects the internal mirrors from dust etc. The smaller cover fits on this cover and is an aperture mask to reduce light when looking at bright objects like the moon or planets. It also increases the focal ratio. These are usually found on larger aperture reflectors and refractors. On achromatic refractors they help reduce false color when looking at bright objects by increasing focal ratio. This is not an issue with reflectors.

[Johnmore]

You are correct. Should I take to bigger cover off when looking at nebula?

[Carlos_dfc]

Hi Johnmore.

You should take the whole of the bigger cover off for almost all viewing.

The smaller cap only serves one purpose - and that is to restrict the amount of light entering the telescope.
In the VAST majority of cases, you want all the light you can possibly get - also, larger aperture equates to better resolution (the ability to see small detail on the Moon, planets etc) - so always remove the WHOLE cover.

That small cap is mainly intended to be used when projecting the Sun onto a card, in order to see sunspots. (although you can also use it to dim the Moon at low powers)
If you used the whole of the telescope's aperture for solar projection, a 4.5" reflector would gather too much light (and heat) and there's a danger you might melt the eyepiece.
So if you project the Sun, leave the main cap on, and remove only the small cap.(This is called an 'aperture mask')

In all other cases, remove the whole of the cap.

**IMPORTANT NOTE**
Never look directly at the Sun through the telescope, even if you are using the aperture mask.
Also, never use an eyepiece SUN filter, they are dangerous, if you have one, chuck it in the bin.
The only SAFE Sun filters, are ones that cover the front of the scope, and filter the Sunlight BEFORE it enters the telescope.