Not only will the image contrast be higher in the other telescope

Not only will the image contrast be higher in the other telescope, the Barlow will also partially compensate for any coma. But even nicer is the fact that this telescope will probably have a much larger field of view than the one with the high power eyepiece!

As a rule, the shorter the focal length of the ocular, the shorter the eye relief. This fact is another good reason to use a medium power eyepiece with a Barlow lens to obtain a high power rather than to using a short focal length/high power eyepiece. The medium power ocular with the Barlow will retain its long eye relief and give you the higher magnification that you seek.

One further benefit of the Barlow lens is that it allows you to have at least twice the number of available magnifications with less accessories. You have one set of magnifications with the Barlow and one without it.

If you purchase a Barlow, be sure that the lens is achromatic and corrected for spherical aberration. Pay a little more to get these features if you have to.

Before we get off of the subject of oculars, I would like to point out that there is at least one relatively new optical design which allows short focal length eyepieces to have long comfortable eye relief distances. Several of the lens elements are made from the rare-earth element lanthanum to achieve this longer eye relief. The lanthanum elements also offer superior correction of most optical aberrations.

On telescopes where the observer must view from the rear of the tube, there is often need for an accessory called a diagonal eyepiece holder. It allows more comfortable viewing when the telescope is pointed near vertical. This feat is accomplished by use of a mirror or prism which redirects the image by 90 degrees. Newtonian reflectors don’t need such a device since the eyepiece is located on the side of the tube and toward the tube’s front end, but any other type of telescope should come with one.

Remember that I mentioned that 1¼ inch eyepieces are preferable to smaller eyepieces due to the wider field which they yield. Usually the longer the focal length of the eyepiece, the brighter the image and the wider the field. However, it is not advisable to use a 1¼ inch eyepiece with a focal length longer than about 35 mm, since it may cause some of the light from your objective to be lost and make your view dimmer. Some people get around this problem by installing a focuser on their telescope which accepts 2 inch eyepieces! Such a large eyepiece may have a focal length of up to 80 mm without sacrificing performance. A long focal length 2 inch eyepiece would be superb for initially locating objects or getting all of an extremely large object into your field of view. Since 2 inch focusers come with an adapter for 1¼ inch eyepieces, you can still use the smaller less pricy eyepieces for your higher powers. Even though they may be convenient, even deep sky observers won’t find 2 inch eyepieces to be truly necessary