Use your light meter or install a smartphone app.
You can download Pocket Light Meter on iOS devices or LightMeter on Android devices.
Aperture: Set the aperture to f/8
ISO: Choose ISO100 or ISO600 depending on the film you are using.
Time: Get the shutter speed reading and select the desired speed on Time Machine.
Some light meters might show ISO640 instead of ISO600. That will work also.
Photos by Kim Smith Miller, an experienced SLR670m user, click to see more side-by-side comparisons by her.
Since the light meter have different settings: full stop, half stop and third stop, you should set the shutter stop to "full stop". Then it will be the same numbers as Time Machine.
SLR670 Family - The basic introduction
The SLR670 family has written a bold new page in instant photography. If you want to find a Polaroid that can shoot in almost every lighting condition, here's the one. SLR670-S is the most powerful in the family, you can use both SX-70(ISO100) and 600 film without extra accessories. In this video, you will know the basics of the camera, by which mode you can shoot under strong sunlight, have light painting or even shoot at night. The more you know, the more fun it is!