Quote:
Originally Posted by Hans Tucker
"Roland then set out to make the ultimate astrograph. It was the first "EDF." It used the StarFire design, but with FPL-51 with an airspace. With a 4-inch field corrector and focuser, it took some of the most impressive widefield astrophotos ever taken. The 152mm f/7.5 EDF ($6400) was the first apochromatic telescope that I had ever seen that was completely color free -- even out of focus."
Thomas Back - A Brief History of Astro-Physics Lenses
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That's not quiiite right, I have an email, direct from Roland himself, confirming that my scope is an oil spaced triplet using FPL53 centre element. I have kept it for provinence
Here is an excerpt from the email exchange from over a decade ago, when I was asking Roland about my specific scope and how to remove the objective cell and other things:
Me:
Out of interest, do you remember what type of ED glass element was used in this lens set, which of the three elements it is and is it an oil spaced triplet?
Roland:
It is an oil spaced lens using FPL53 center element. Remove the three large head screws on the front and the lens cell can be lifted out. It is not necessary to mark the exact rotation of the cell because it was properly squared on during assembly by accurate positioning of the countercell (that's the white painted cell behind the lens cell, and it is held to the tube via the 6 side screws). Only if you remove the 6 side screws that the proper collimation is totally lost and you would have to start over again. So, simply remove only the three front screws, and you are in business. ( you would not believe how many people have sent me the countercell along with the lens cell, thinking that this is the only way the collimation is retained).
Roland
Mike