Posts Made By: Roland Christen

Broose! You should definitely stay out of Chevy dealerships. Too many goodies for your own good!!

Rolando

Generally these kind of eyepieces were made in large quantities by various subcontractors in Japan, Taiwan and China. When one subcontractor goes out of business, another takes his place, so then there will be variations in the optics and mechanics.

Even today generic Orthos, Plossls etc are marketed under a number of different trade names. The mechanical and optical designs are nothing special and in some cases depended on the parts that the specific subcontractor had in stock. It is easy enough, if you are an OEM, to order generic eyepieces and put your brand on them. They are available now by the millions if desired, from large optical corporations in China.

Lenses like the 6"F15 Jaegers are very insensitive to misalignment. Unless the cell is tilted by an obvious amount (several degrees), the lens really won't perform any better or worse.

Jaegers lenses, especially the 6"F15, had huge variations in accuracy of figure. Out of any 5 specimens, you could see a variation from some of the best to some of the absolute worst ever made by an optical shop.

I had a 6"F10 lens that had essentially perfect correction with no internal defects or striae in the glass. It produced a textbook perfect star image at high powers. One of my astronomy friends had a 6" F15 which produced nothing but a muddled fuzzy mess on any star. Either the glass was defective internally or the surfaces were so roughly polished that it was full of zonal defects. We could not put any kind of wavefront error on this lens, it was essentially all over the place.

The only way to know what you have is to put an eyepiece to the lens, aim it at a star, run the focus inside and outside and see what the extra-focal Fresnel disc looks like. get familiar with star testing and objective so you can recognize what defects might be present.

If you see that the lens might have huge spherical error, don't immediately despair. The previous owner may have taken it apart to clean it, and assembled the elements backwards.

There are 4 ways you can stack the two elements, but only one way is correct. That would be crown leading, with the shallower of the two convex crown surfaces toward the sky and the flint concave surface behind the steeper convex crown surface, also pointing toward the sky. There should be a small spacer of a few mm thickness between the two elements. Thickness of the spacer is not super critical, however it must be exactly the same thickness for the three.

Rolando

You da man!

Rolando

And here is the color image taken with the 175EDF. This scope really had to run with its little feet to keep up with the big TEC. Resolution of the star images was 1.7 arc sec FWHM for the 175 versus 1.4 arc sec for the 20". The seeing at the Hacienda was good by our standards here in the Midwest, but not sub-arc seconds that we experienced at the mountain top observatories at Tololo and Las Campanas.

Rolando

By adding 24 x 600 each OIII and SII narrowband images, here is a color image of the region in Hubble palette

Rolando

Thank you everyone for your kind comments.

Rolando

To show the jets, Dave inverted the luminance.

Rolando

Thank you all for your kind comments.

Rolando

Lots of people commented that the images was too garish. So I changed the mapping to H-a = red, SII = green and OIII = blue.

What do you all think?

Rolando