Jaegers 4" f/15 Refractor

4.0 Jaegers 4"F15

Excellent images, no false color, great scope from yesteryear

This is a Big refractor and not easily portable

I am an avid fan of "Classical "telescopes owning a nice Cave 10"F6 Super Chromed deluxe which I restored. Recently I picked up an old Jaegers 4"F15 on a jaegers EQ head mounted on its long pier. It also came with a few older eyepieces, original diagonal, and an electric clock drive drive.

The scope was in pretty poor shape when I picked it up on consignment. The objective has some small chips around the edge. But luckily the retaining ring keeps them away from the clear aperture field of view. The OTA was dirty with many stains of rust, same with the pier. The clock drive was covered in rust. So even as physically bad looking as it was, I still was anxious to take a look through the scope.

To my horror using the original star diagonal, I noticed about 25% vignetting in a low power eyepiece. So I removed the diagonal, and looked through the tube to see what might be impeeding upon the light path. I was sure it was a loose baffle. But I checked them and they were fitted properly. I shinned a bright light through the OTA to see if anything could be amiss. Could not find a thing. Now I assumed it was the objective not properely seated in its cell. So I loosened the retaining ring, took the cell apart, looked for the optician alignment marks and aligned them, carefully cleaned off the accumulated dirt and film off the lense, replaced it back into the cell, and tightened the retaining ring till it just touched the objective, to keep the objective lense in alignment but still loose enough to not pinch the optic. I replaced everything and could not wait till night fall.

Horros, it was still showing that awful vignetting!! I tried my nice set of Ultima eyepieces thinking that maybe it was one of the old Jaegers eyepieces. No luck. Then it dawned on me, the diagonal, it must not be collimated to a 45 degree angle. I placed a high quailty 1.25" Celestron made in Japan diagonal and to my utter amazement, perfect images!!

The star test is now perfect, no vignetting in the FOV, Saturn was beautiful, no C.A. in this long focal length refractor. So now that I was satisfied the optics were good, I decided to check out the clock drive. After thoroughly cleaning and removing the rust, and lubricating it, the darn thing works like a charm and to my amazement is brass coated. I stll have not repainted the tube or the mount but I did clean it well (I purchased the white gloss paint for the tube and the gun metal gray for the pier), I will tackle that paint job this spring. But now I have a very functional, optically excellent long focal lenght refractor!! Bob Midiri