Multiplying a Barlow?

[RogerTheDodger]

From a few other posts people have said about using a Barlow Tube with the lens removed to increase the magnification of another Barlow (unless I mis-understood...), so in what order would they be used?

focusser->empty barlow->normal barlow->EP?

Just thinking of buyin a 3-4x barlow and wondering what combinations may be available.

[Space Cowboy]

focusser->->normal barlow-empty barlow>EP

[RogerTheDodger]

Thanks.

Just wish I still had access to a mech workshop... I could knock up an empty tube on a lathe in a few mins... or I can now pay £20 for an extension tube

[brianb]

You're almost certainly trying to get far too much magnification!

Best results usually obtained visually with no barlow - the short focus long eye relief eyepieces you might need to get a high mag on a short focal length instrument have a barlow integrated into the eyepiece.

Don't go over 30x per inch of aperture / 1.2x per mm of aperture - you won't see any more, it will be more difficult to find and track objects and the apparent contrast drop with excess magnification reduces the visibility of fine planetary detail.