Every 6 months or so, on a nice sunny day, like today in Canberra, I take my beloved AstroPhysics 152EDF F7.5 Starfire (Oil spaced FPL53 triplet...with 4" field flattener ) out of storage and give it several hours of indirect sunlight, just to prevent mould. It is stored in a dry environment in our light filled warm city apartment, but I like to make sure. I remove all caps from the OTA and finder scope, lay it on the bed pointing out the window but not so the sun could shine in directly of course. So far, after several years of using this approach, the objective looks excellent and clean There are some tiny chips around the dust cap edge of the (removable) dew/dust shield, just from putting the cap on and off and because it is stored standing with the objective end down, otherwise it is is pristine condition.
What a scope, haven't used it for a few years now, so can't wait to eventually get it setup under the pristine dark skies up at Eagleview
For a 90's scope the optics look pristine. I thought these scopes came with the 2.7" focuser .. one with a 4" focuser must be a rare beast.
Now you have made me feel guilty ... I need. to pull out the APOMAX
Rare indeed, Roland only made two of these astrographs, with 4" focuser and 4" FF and a 90mm corrected image circle. He then changed the glass supplier and produced its successor, the 155EDF. So it is indeed a real collectors item
Needless to say, visual views through it are exquisite. I recall clearly seeing the Red Spot Jnr back in 2005 (?) and detail within the Great red spot, easily split a 1" double and 6 stars visible in the Trapezium at 50X magnification.
"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
"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
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
Last edited by strongmanmike; 15-04-2022 at 07:13 PM.
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).
Mike, Apologies I didn't mean to be rude by questioning the information in your original post. I am really intrigued with your scope (I am interested in the technical aspects of the top high end APO refractors by Takahashi, TMB, Astro-Physics, Zeiss) and I was trying to place your scope in a build time line but outside the Astro-Physics catalogues the only time line I could find was what was in Thomas Backs Essay. When you mentioned FLP-53 it threw out my estimation on when your scope was manufactured. I gather the reason it didn't rate a mention in Thomas's essay was possible because only two were made so it wasn't by definition a commercially available product but a possible prototype to the 155EDF.
My own classic APO Story
Years ago I purchased a APOMAX 130 f12 so called Super APO but it had a decal on the OTA saying Fluorite APO. I was concerned that the optics in my newly acquired purchase were not original even though it had the unique APOMAX lens cell. I actual wrote to Fred Mrozek who's name appears in Thomas Backs essay as a former friend of Roland whom assisted Roland in the early days before he founded Astro-Physics. Surprisingly Fred replied and gave me some insight to the build of the APOMAX although he wouldn't tell me the material the objective was made out of, I later found out it was FLP-52. I subsequently came across the Astro-Physics article by Thomas Back which I found a fascinating read. I still don't know why the previous owner or the owner before them put the decal on the OTA .. the only material that I knew was confused with or incorrectly termed fluorite was FLP-53. Ok .. Rant over. Sorry for hijacking your thread.
I was aware of the essay by Thomas Back and I also think your suggested feelings for the confusion are probably correct as they were also mine . I decided to ask Roland directly to settle my curiosity and in our exchange I explained the exact model, date of acquisition and the original purchaser, so I guess we have to take Roland's word on it. If the maker himself tells me that, then that's good enough for me He only made two units and I am the very lucky owner of one of them
) out of storage and give it several hours of indirect sunlight, just to prevent mould. It is stored in a dry environment in our light filled warm city apartment, but I like to make sure. I remove all caps from the OTA and finder scope, lay it on the bed pointing out the window but not so the sun could shine in directly of course. So far, after several years of using this approach, the objective looks excellent and clean 
There are some tiny chips around the dust cap edge of the (removable) dew/dust shield, just from putting the cap on and off and because it is stored standing with the objective end down, otherwise it is is pristine condition.
