Measuring Photo exposure without a meter

I have some bench marks I use like shorthand to jump to a certain exposure on my camera, where I don’t need to think about it too much. For the below photo I’ll take you through my thought process as I figured out the camera settings. For a more detailed look at the relationship between ISO, Shutter Speed and Aperture, click here.

Granda sitting in his favorite corner living room chair contemplating his next move.

Exposure Data for this photo
ISO	Shutter Speed	Aperture
200	1/60	1.8

SOFT Indoor light

In this photo I am shooting with a relatively diffused floor lamp as my only light, indoors… at night. I was shooting on relatively slow Kodak Gold 200 film. Slow in relation to film means the film needs more light to properly expose the photo. And this is a situation where there is not a ton of light to begin with. So 200 ISO is locked in.

ISO: 200

I know I need as much light as possible, so I open up the iris all the way to f/1.8 or perhaps f/2 (to sharpen up the image a bit).

f/1.8

That leaves the shutter speed. When I know I need more light I change to the slowest shutter speed at which I can keep images sharp, which is 1/125 of a second. Occasionally I will go to 1/60 if both me and the subject are going to stay still, like for a portrait. I shot this at 1/60 I am almost certain.

1/60 second

Additionally, in my scanning and digitization I probably was able to bring back a stop or two of light which adds the grain you may be seeing (along with digital noise from squarespace’s compression).

In summary

Shoot pretty wide open with soft indoor light if your ISO is 200 or less. Even at 400 or 800 I would rarely have my iris more stopped down than f/4 or f/5.6. It just isn’t worth taking a chance on underexposed photos. And in many cases I would speed up the shutter if I got to a brighter section of the room. Freezing motion will be better for sharpness and most of what I want to get.

Reasons you may want to use other settings in lower light indoor settings:

One might slow the shutter speed in order to capture motion in the frame. For instance if you wanted to see the hair on a woman dancing or the movement of hands in a portrait. For this however YOU will need to be incredibly still and would greatly benefit from a tripod for this kind of shooting. Additionally, you may close down the iris to have more depth of field, but this only works for captuing items that don’t move.

Grand Bayou Casino inside a gas station in Grosse Tete, LA. An example of “Sunny 16”

“SUNNY 16”

Sunny 16 is one of the most straightforward .

A more foolproof way to do this would be to use an exposure value chart to help you calculate your shutter speed. I will spare you by not sharing the full exposure value chart, which is eyewatering. Instead I will link to the Wikipedia article here where you can find it. I will below list the exposure value chart with some common light sources which roughly correlate with those values.

Exposure Values
Exposure Value	Type of Light
-6	Moonless overcast night sky
-5	Crescent Moon
-4	Bright Crescent Moon
-3	Quarter Moon
-2	Full Moon
-1	Bright Full Moon
0	Shadows of soft indoor light
1	Soft indoor light - not nearby
2	Nighttime-distant lights
3	Deep Twilight outdoors
4	Near Christmas Lights
5	Soft Incandesent
6	Typical Indoor Lighting
7	Night Street Scenes and Window Displays
8	Bright Street Scenes
9	Night Sporting Floodlights
10	Indoor Galleries/Metros
11	Next to a window on sunny day
12	Overcast/Shadows on sunny day
13	Cloudy with bright overcast skies
14	Typical Sunlight (Soft Shadows)
15	Sunny Sixteen (Full Sunlight)

If you use a chart like this and consult the chart you can see that if the scene you are shooting has about a 13 Exposure Value, then you can pretty reliably

The final question of why? Well because sometimes you don’t have time, in many cases if you understand the light you will know that what the meter says is actually for the sky behind your subject, not for their face and you can make adjustments accordingly.