The following information is a guide to many of the serial numbers and instrument types produced by Questar. There are quite a few spin-offs and variations involved in each sequence, and many similarities within each. This document should be helpful when trying to research or track down an item by serial number.

The following are the major groups of serial numbered items:

  • Standard and Duplex: XX-XX-_________-XX, starting # of 50 (1950) to current number of 13000
  • Field Model: F-__________-XX, starting at 50 (1957) to current number of 6000
  • 7 inch: XX-7-________-XX, starting at 51(1967) to current number of 999
  • MFL: _________-MFL, starting at 10001 (1982) to current number of 10455
  • QM100: QM100-________, starting at 100 (1990) to current number of 600
  • 50th Anniversary Unit: 50th-_______-SQTZ, starting at 20001 (2001) to current number of 20175
  • 700MM: _________-XX, starting at 10011 (1976) to current number of 10925
  • 12 INCH: XX-_______-XX-XX, starting at 4001 (1976) to current number 0f 4012
  • STAGES: 538xx______________, part number + date code
  • RMS SYSTEM: 67xxx_____________, part number + date code
  • The above list is a simplified version of a long list of possibilities.

    Useful items to remember with the 50 years of production at Questar
  • 1950

    In early years of production the Standard unit was called the Deluxe Model, not to be confused with the Duplex and there were no other units available. The Standard (Deluxe) model was produced in two mirror types, Pyrex and Quartz. All early units had Amici roof prisms and a narrow field maintube. The only optional coating was silver on the primary mirror. The standard coating was Aluminum. The optical system was an R1 type. The case was an English leather type. Optics were made by Cave Optical Co.

  • 1957

    Cumberland makes optics for Questar. The Questar Field Model is produced in addition to the Standard unit. Some early models had a cast rear unit different than the normal control box.

  • 1960

    The Amici roof prism is replaced with a 90 degree prism. The RA is changed to allow setting (#685).

  • 1961

    The finder system is changed to current design (#1117).

  • 1964

    The maintube is changed to the current Wide Field type.

  • 1966

    The Duplex (Dual Model) is produced #2597. Broad Band coatings are now an option.

  • 1967

    Cervit, a new mirror option, is available in addition to the Pyrex and Quartz. The Questar Seven is produced.

  • 1976

    The 700MM Telephoto Lens is produced. The Questar 12 inch is produced.

  • 1980

    The Questar 25th Anniversary Unit is produced.

  • 1980

    Questar QM introduced, early close focus microscope series.

  • 1981

    Questar DR dual range, Q-M1 close focus, and RF rapid focus are produced.

  • 1982

    The M-1 (QM-1), 700MM MKII and MFL are produced as a standard product. Original MFL units used the 700MM MKII round tube.

  • 1983

    The DR evolves into the DR-1 with a corrector spacer and the RII cell and optic as a standard product.

  • 1988

    The threaded legs become standard product for Questar 3.5 base.

  • 1990

    The QM100 is produced as a standard product. The 9 volt built-in Powerguide is introduced with the battery in the telescope base.

  • 1998

    The Questar Powerguide is replaced with the new Powerguide II, battery is in hand control.

  • 2001

    The Questar 50th Anniversary Unit is produced.

  • 2002

    Questar Classic 7 inch Titanium is produced.

  • The Standard and Duplex number system.

    Most units will have the following format with a one or two digit date first. This number sequence is generally only used for these two models. The year 2000 started the two digit code. Earlier years with single digit will only give you the year not the decade i.e. 1 could equal 51,61,71,81 or 91. Some early units did not have a date entry. You will need to see shipping papers to determine an actual year. There will be optical descriptions and options added to the serial number. If there are no optical or optional descriptions, the unit will have only standard Pyrex optics. Early units did not serialize Silver upgrade options. The following are some options and optical variations common to all serial number items.

    -Z- = Zerodur Mirror, replaced CV in 1979.
    -CV- = Cervit Mirror, stopped making CV in 1978.
    -Qtz- = Quartz mirror, be careful when seeing this option as it may also mean a corrector.
    -BB- = Broad Band coating, if no BB then unit should be standard AL reflector with MgF2 AR coating.
    -S- = Silver reflector coating with Mgf2 AR coating, or a special optical coating.
    -DP- = Duplex unit, if no DP then unit should be a Standard unit.
    -R- = Reworked/replaced/revised.
    -1/10- =1/10 wave system.
    -1/15- =1/15 wave system.
    -FF- = Fast Focus cam type, generally on FM unit, made in the 60's and 70's.
    -FFII- = Fast Focus rack and pinion type, made for a short time in the 80's.
    -RF- = Rapid Focus threaded rod, started in the 90's to date.

    Basic format samples:

    Date-Mirror Type-Unit Type-Serial Number-Coatings-Options

      02-________-BB = Standard Pyrex BB unit made in 2002.
      1-DP-________ = Duplex Pyrex unit made in 1971,1981,1991.
      9-CV-DP-________-BB = Duplex Cervit BB unit made in 1969,1979.
      8-QTZ-__________ = Standard Quartz unit made in 1958,1968.
      7-Z-DP-__________-1/10 = Duplex Zerodur with 1/10 wave optics unit made in 1977,1987,1997.
      # _________ = Standard Pyrex made in the 50's.
      R-9-________= Standard unit rebuilt.
      5-DP-Z-______-BB-FFII = Duplex Zerodur BB with FFII rack and pinion focus made in 1985.
    The above is only a reference. Items may change location within the serial number sequence.

    The Field Model number system

    This numbering system has many variations and model types that use the basic serial numbers. All have some identifier in the sequence which can help to determine which type unit it is. There are similar optical and optional variables also imbedded in the sequence see above Standard and Duplex listings. The base number was 50 and is now a 4 digit number at approx 6000.
    The Questar units which use this base numbers are: Field Model, Birder, QM-1 short and long mount, 3.5 Ruggedized all varities, Field Ranger and Field Ranger Light Weight.

    The Identifiers are:
      F= Field model
      M1= QM-1
      MQ, DR, DR-1= earlier version of a Microscope system
      FR= Field Ranger
      LW= Field Ranger Light Weight
      X = Birder 10X or Field Model with 10X Finder, Birder is a newer term used in the 90's
      XV = Birder 15X or Field Model with 15X Finder
      RF = Rapid Focus, The Birder model generally uses this type focus
      FF = A cam type external focus
      FFII = A rack and pinion focus
      CM = Cinema Model, A special Field Model with FF and large dial indicator
      AL=Aluminum Tube and Ruggedized unit or Long Mount
      SS = Stainless Steel Tube and Ruggedized unit
      IV = Invar Tube and Ruggedized unit
    Basic format samples:

    Unit Type -Mirror Type -Serial Number-Coatings-Options-Unit Type

    Field Model

      F-________ = Field Model Pyrex
      F-________-BB = Field Model Pyrex BB
      F-Z-_______-BB-RF = Field Model Zerodur BB with Rapid Focus
      F-_______-BB-FF = Field Model Pyrex BB with Cam Focus (FF)

    Birder or Field Model with 10X finder

      F-_______-X = Field Model Pyrex with 10x Finder
      F-_______-X-RF = Birder Pyrex with Rapid Focus
      F-Z-_______-BB-RF-X = Birder Zerodur BB Rapid Focus and 10X Finder
      F-______-BB-X-FFII = Field Model Pyrex BB with 10X finder and Rack/Pinion focus

    Ruggedized 3.5 inch.

    The serial number does not tell you which type tube: 10019,10020,10021 or other. You will have to see shipping papers for more information or describe the shape.

    Material -Mirror Type-Serial Number-Coatings-Options

    Materials are AL, SS, IV.

      AL-Z-_______ = Aluminum Ruggedized tube with Zerodur MgF2 optics.
      SS-Z-_______-QTZ = Stainless Steel Ruggedized tube Zerodur mirror and Quartz corrector.
      IV-Z-_______-FLTR = Invar Ruggedized tube with Zeodur mirror and special filter attachment.
      AL-_______ = Aluminum Ruggedized tube with Pyrex MgF2 optics.


    There are two variations to the tube. Short mount (Std. Field Model Mount) or Long Mount which is similar to a ruggedized mount on 10021 units. The Short mount will have the (F) at the front of the serial number. The Long Mount will have (AL) at the front of the serial number. All will have the M1 listed in the serial number.

      F-_____-M1 = QM-1 short mount with Pyrex optics
      F-_____-BB-M1 = QM-1 short mount with Pyrex BB optics
      F-_____-M1-QTZ = QM-1 short mount with Quartz corrector optics
      AL-______-M1 = QM-1 long mount with Pyrex optics
      AL-______-M1-QTZ = QM-1 long mount with Quartz corrector optics

    Field Ranger

    There are now two types. The standard Field Ranger with Field Model type mount and the new Light Weight (LW) with special low profile and weight mount. These units again use the FM serial number sequence and have the FR and LW identifiers in the serial number. Some early units may not have the identifiers. Some units may also have the RF (rapid focus) in the serial number. Other optical configurations are possible and will follow the format shown above.

      F-______-FR = Field Ranger with Pyrex optics
      F-______-LW = Field Ranger Light Weight with Pyrex optics

    MFL Number System

    The MFL number system was an add-on system to differentiate between a certain type of tube assembly and a multi-port attachment. It was related to the 3.5 inch size scope only and now has several different tube types involved with and without the multi-port housing. The orginal MFL units used the 700 MKII type rack and pinion focus housing and had a round 5-port attached. This same numbering system is now for any instrument which uses the MKIII fabricated tube assembly which includes all optic types smaller than 7". This would include the QM series of close focus optic and SZ microprocessor control series. As with all the number systems before, it will include similar optic and accessory functions. It is a five digit sequential series of numbers.

    Seven Inch Number System

    The serial number sequence used for the 7" size telescope includes all types, makes, and models which are 7" aperature. All variations will use the base number and the main identifier number "-7-" located in the serial number separately. The serial number will utilize the same formats as the 3.5" with optics and options. There is no date code in the serial number. The main identifier is the number 7. There are a few new identifiers which the 7" uses, not common to the FM and Standard/Duplex serial numbers. The Questar Seven was sold as a combination Tube and Mount as the Questar 7 Fully Mounted unit. This was similar to the 3.5" Duplex unit and would have a -DP- in the serial number. The barrel or tube and mount could be, and now is, purchased separately. Generally the 7" can be produced in all variations as with the Questar Field Model number sequence.

    No identifier should mean that the tube is only a Standard tube or Classic.

      -A- = Astro Barrel
      -WS- = Wide Sky, and early versions of the Astro Barrel from the mid seventies.
      -T- = New Lightweight Titanium Barrel.
      -DP- = Duplex or Fully Mounted. The Base unit will also have this number.
      -P- = Pyrex Mirror
      -Z- = Zerodur Mirror, 80's to date.
      -CV- = Cervit Mirror, 60's and 70's.
      -Qtz- = Quartz mirror or lens.
      -SZ- = Step Zoom
      -MFL- = Multi Focal Length, can also be round open MFL housing.
      -MMFL- = Motorized MFL, DC type. This unit was before the SZ took it's place.
      -W- = Weatherized MFL, LED MFL type.
      -FR- = Field Ranger
      -SPL- = Special with rack and pinion focus and manual round 5-port MFL housing.
      -FF- = Fast Focus, generally a rack and pinion which is part of the SPL.
      -SZII- = Step Zoom 182 unit.
    Unit Type - Mirror Type - Serial Number- Coatings - Options - Unit Type

      P-7-_______= 7' Barrel with Pyrex optics.
      P-7-_______-A = 7" Astro Barrel with Pyrex optics.
      Z-7-_______-BB = 7" Barrel with Zerodur BB optics.
      Z-7-_______-BB-A = 7" Astro Barrel with Zerodur BB optics.
      P-7-_______-DP = 7" Barrel with Pyrex optics and Fork Base i.e. Fully Mounted 7 with Pyrex.
      Z-7-_______-BB-DP = 7" Barrel with Zerodur BB optics and Fork Base i.e. Fully Mounted with Z-BB
      P-7-_______-FR = 7" Field Ranger with Pyrex optics.
      P-7-_______-MFL = 7" MFL Pyrex, may be round port or newer.
      P-7-_______-MFL-W = 7" MFL newer type LED with Pyrex optics.
      Z-7-_______-BB-SZ = 7" Step Zoom Zerodur with BB optics.
      P-7-_______-SZII or SZ2 = SZ182 type 7" Step Zoom.
      IV-Z-7-_______-QTZ = Ruggedized 7" with Quartz corrector and Zerodur Mirror.
      AL-7-_______ = Ruggedized 7" Aluminum barrel and Pyrex optics.
      P-7-_______-SPL = 7" MFL with round turret and rack and pinion focus, 70's and 80's.

      Variations may place the type unit in front of the P or Z or 7.

      SZ-P-7-_______ or MFL-7-_______ etc.

    All 7" size units will have the serial number sequence and a sequential number.