Telephotography of restricted areas

How to get that magnification

Does a 4x teleconverter exist? Yes, but to be more generic, what we need to achieve is an increase in the effective focal length by a factor of 4. A teleconverter is just one way to achieve this. The first thing that comes to mind is the Televue Powermate series. There is a 4x powermate in the series and the current generation product can be set up with T-threads. [More about this later.]  There are other T-barlows as well, though the Televue is a good bang for the buck product. The other way to get more magnification is with eyepiece projection.  

Eyepiece projection requires hardware that can hold the eyepiece in the light path. Most of these devices are wobbly. The only exception I found is the Takahashi eyepiece projection hardware (TCA-4).It is designed to hold 1.25 inch eyepieces, and can accommodate 0.965inch eyepieces with a reducer.  The only drawback to the device is that it is threaded for Takahashi telescopes. The Televue Powermate is more universal, but it is held in place with set-screws. One side is T-threaded, but the other side is designed to fit into a 2 inch eyepiece holder.

To do eyepiece projection, you (DOH!) need an eyepiece. This is generally done with an orthoscopic eyepiece, though Takahashi makes two eyepieces designed for eyepiece projection.