Question on Shutter Speed, Aperture, ISO Settings

BJPhotography · Mar 2, 2011

I took a picture of the dog on the bed in low light. My iso setting was at Lo80. My camera was set to 125 F5.6. I used a flash. Why was the photo so bright? When I took the photo with the ISO setting higher, the picture was darker. So what is it that makes the picture brighter and darker? The fact that the ISO setting was so low or the other settings. Please explain. Im trying to learn.

mwcfarms · Mar 2, 2011

Iso is the sensitivity to light. your fstop or aperture is the opening of the lens which either is closed down allowing less light (imagine your pupil.) the larger the Fstop number the less light that gets in. Which requires slower shutter speeds. They all work together. If it was too bright with flash how was it with no flash? If you change one sometimes you have to change the other. Higher fstops require slower shutter speeds and lower fstops which allow the most light in require fast shutters or you get too much light. If you could post the photo it might help too. When you raised your iso was it better.

MissCream · Mar 2, 2011

BJPhotography said:
I took a picture of the dog on the bed in low light. My iso setting was at Lo80. My camera was set to 125 F5.6. I used a flash. Why was the photo so bright? When I took the photo with the ISO setting higher, the picture was darker. So what is it that makes the picture brighter and darker? The fact that the ISO setting was so low or the other settings. Please explain. Im trying to learn.

This makes no sense.
Can you post the two pictures?

mwcfarms · Mar 2, 2011

Im wondering if she meant Iso high instead of lo.

peppies · Mar 2, 2011

What makes the picture lighter or brighter? It's a combination of the following THREE factors (the exposure triangle):

1. ISO
2. Aperture
3. Shutter Speed

All three affect your exposure. So the fact that your ISO was higher in the second shot does not necessarily mean your image must be lighter because if you had your camera in auto mode, changes to the Aperture and/or shutter speed could affect the exposure as well. All three work together to control your exposure. And because the amount of light in a real world varies greatly, different combinations are needed to achieve what you want. Each of the three factors control the exposure in a different way and as such have a different effect and "trade-offs" on your photos. For instance increased ISO will give you more noise, changes in Aperture will affect your depth of field, variations in Shutter Speed can make your subject blurry due to the movement or camera shake or completely freeze the motion at high speeds.

BJPhotography · Mar 2, 2011

This is the first one I took. The ISO setting was high, 1600. My camera is not on Auto. Its on Manual. Im trying to remember what the other settings were at for this photo.

This is the second one I took with the ISO Setting set to LO80 (thats the setting on my camera). The other settings were at F5.6 125. Why is this one brighter and the other one so dark?

MissCream · Mar 2, 2011

You didn't fire the flash on the first one.............

BJPhotography · Mar 2, 2011

I forgot to mention too that I used a flash on both.

dxqcanada · Mar 2, 2011

First image ... flash did not fire.
Exposure settings not enough to get brighter image.

Second image ... flash fired.

The EXIF data embedded in the image states no flash in image 1

willis_927 · Mar 2, 2011

yep ^

dxqcanada · Mar 2, 2011

Camera Maker: SONY
Camera Model: DSLR-A100
Image Date: 2011-03-02 19:09:01 (no TZ)
Focal Length: 50.0mm (35mm equivalent: 75mm)
Aperture: f/9.0
Exposure Time: 0.020 s (1/50)
ISO equiv: 1600
Exposure Bias: none
Metering Mode: Center Weight
Exposure: Manual
Exposure Mode: Manual
White Balance: Auto
Flash Fired: No (enforced)
Orientation: Normal
Color Space: sRGB
GPS Coordinate: undefined, undefined
Caption: SONY DSC

BJPhotography · Mar 2, 2011

Hmmm. Thats odd. I had the flash on for both. Interesting. Makes me look stupid now but Im sure I had the flash on for both. That was the whole reason I was confused.