As I'm accumulating information on this interesting subject, I realize I still lack some information, so this thread will hopefully collect more information and corrections. I have used the stale "inventory" spreadsheet from the Yahoo group, and have added to it with info from current Ebay listings, CN and AM ads, and historical AM and CN ads (still in progress at my leisure). I'm answering little questions like: "When did they switch from the threaded leg hole plugs to the flat caps?" Years are used for readability, and may be approximate. This will probably end up as a history of design changes, but for now I'll just go topic by topic. Feel free to comment on which changes you like, or speculate on the reasons.
- 1955 Mirror bracket change from a fragile cantilevered version to the box-like bridge we have today.
- 1956 "*Questar" logo replaces red and blue "Pepsi" badges.
- ??? Barrel and dew shield changed from original blue to purple.
- 1959 Star diagonal replaces Amici prism (choice may have been offered for a time). Moon map orientation reflects view through scope.
- 1961 Change in focal length and F-number from 1070mm, f12 to 1280mm, f14, with some production of 1156mm. (Source: Company 7)
- 1963 Logo changed from "*Questar" to "QUESTAR".
- 1964 "Wide field." Reduced restriction of the field of view for photography. Many changes, especially to center tube. Promoted as: "Twenty-one major changes in the control-box assembly permit a much wider photographic field of view…exposures are two f-numbers faster"
- ??? Axial port enlarged from the 0.95" size of the eyepiece holder threads (still unchanged all these years) to a much larger 1.2" port. Company 7 puts this at "late 1960s."
- ??? Axial port slightly enlarged (~0.010" larger).
- 1966 Duplex introduced (using modern Field Model introduced in 1964).
- 1967 Modern leather case replaces English leather.
- 1967 Broadband coating option introduced.
- 1967 Cervit option replaces Quartz.
- 1968 Finder filter introduced.
- 1972 Change from Konig/Erfle to Brandon.
- 1973-74 "Mushroom" Brandon eyepieces included.
- 1974-75 Skinny leg tips changed to fat on fixed legs.
- 1976-77 Skinny center leg tip chanced to fat.
- 1979-80 "Questar" eyepieces included.
- 1980 Zerodur option introduced.
- 1981 Push-in legs changed to screw-in.
- 1981 "QUESTAR" logo badges changed to "QUESTAR®"
- 1985 Vinyl case first offered.
- 1985-88 Threaded leg hole plug changed to flat. Need info on scopes between 8944 and 9597 to narrow this.
- 1990?? Powerguide I introduced.
- 1996 Powerguide II introduced.
- 2000-04?? Dew shield and barrel changed from shiny purple to matte "frosty" blue.
- 2000 50th Anniversary model introduced.
Unknowns:
- ??? Dew shield changed from bright/lighter purple to dark purple. 1970s? Or not a real change but simply variations in colors or gradual evolution - even some fading? Comparing a 1968 to 1983 of mine.
- ??? Star chart and moon map changed from etched and filled to painted. 1970s?
- ??? Logo badges changed from etched and filled to screen printed.
- ??? Logo badges changed from flat to domed.
- ??? Lens cap changed from synthetic insert in metal ring to all metal with bright trim.
- ??? Lens cap changed from bright trim to all black.
- ??? Axial cap chamfer mostly eliminated.
- ??? Control knobs changed from hollow (very early) to solid.
- ??? Focus knob changed from larger flanged to modern.
- ??? Control knob groove design changes.
- ??? Base plate changed from Synthane to aluminum.
- ??? Duplex mount added orientation spike adjacent to thumbscrew. (1980s)
This is a work in progress and contributions and data points are requested.
Edited by Optics Patent, 13 June 2017 - 10:01 AM.