Hi, the following information seems close to fully cover the facts regarding your camera. Since the it's only a 3:1 zoom, the viewfinder is aerial view, so clear focusing is not really possible, easily that is. Use the distance scale on the lens. To set up the viewfinder for your eyesight, zoom all the way in, and aim the camera at an object like a telephone pole which is more than 500ft away, and set the lens to Infinity, then rotate the viewfinder diopter adjustment until the image is sharp.
If the builtin light meter is working, you should be able to use the Vision 50 film, Tri-X B&W, Vision 200T, Agfa 200 Daylight, and a few others. It's a basic camera, but does have that nifty slower 9fps setting, which will really allow some shooting in low light, albeit the slow frame rate and thus sped up motion of anything moving (which could be adjusted later in software upon digitizing). Some of these early 1970s camera also require a small button battery of 1.35volts(or two) to power the light meter, so make sure your light meter works off the Double A batteries BEFORE you try using any film. There's also the MANUAL EXPOSURE knob, which if it works okay, you can set the aperature to any setting and use a separate hand held light meter. Using this, you can use ANY Super 8mm film in a silent cartridge in this camera. It has some other nice features such as single frame and the viewfinder information to what aperture you're using etc. IF it needs the button battery, the battery check lamp won't light unless those are in there as well. Anyhow, still a nice small compact camera to take anywhere and have fun with. Good luck!
Best regards, Martin Baumgarten
Argus/Cosina 755 XL [big brother to the XL735]
marketed in fall of 1973
Silent Super 8 cartridge
lens: Cosinon f: 1.2 \ F: 9-27 mm
zooming ratio: 3x [3:1 ratio]
focusing: manual, 4 ft to infinity
zooming: auto and manual
filter size: ?(possibly 49mm or 52mm)
viewfinder: single-lens reflex with adjustable eyepiece
viewfinder information: aperture scale, under-exposure warning signal, film-end light
exposure: auto and manual exposure control; TTL EE, CdS photocell
film speed: ASA 25 with daylight filter (ASA 40 without), ASA 100 with daylight filter(ASA 160 without)
ASA notching: default tungsten ratings of ASA 40 and ASA 160
backlight control button: yes
CCA filter: built-in 85A filter; coupled with movie light socket
filming speed: 9, 18 fps, single frame
shutter opening angle: >180 degrees, eXisting Light filming
remote control socket: yes
cable release socket: single frame
movie light socket: screw type
synchro flash socket: ?
accessory shoe: yes
film counter: 1-15 m
handle: detachable pistol grip
film drive motor: DC micromotor
battery check button: yes
power source: 4 x AAA batteries only
weight: 2 lb., 2 ounce
dimensions: 2" x 3" 3/4 x 5" 1/4
tripod socket: 1/4"