iso question

bb40

bb40

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will
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i was watching a video online yesterday by gavin hoey and he was doing an indoor shoot of dropping a slice of lemon into a glass of water against a white background. he did a couple of test shots to get his background white one by increasing his flash power and the other by increasing his iso from 200 to 400. he didn't want to increase his flash anymore so he could freeze the water motion but what i would like to know is how increasing his iso does make his background whiter ( which it did ). i can't get my head around, so i'm hoping one of you guys can explain.:help:

thanks in advance
 
I assume he was shooting manual so double the ISO without altering aperture or shutter speed is effectively doubling the exposure of the ambient scene.
 
Thanks for reply stu. He was shooting manual. Just couldn't get my head around. Cheers
 
It didn't strictly make it whiter it just appeared whiter as he had a better exposure previously he was under exposing the background which will make it appear dark.
 
a1ex2001 said:
It didn't strictly make it whiter it just appeared whiter as he had a better exposure previously he was under exposing the background which will make it appear dark.
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That's what was puzzling me. I couldn't figure out that by him not changing the shutter speed or aperture it was making it whiter.
 
bb40 said:
i was watching a video online yesterday by gavin hoey and he was doing an indoor shoot of dropping a slice of lemon into a glass of water against a white background. he did a couple of test shots to get his background white one by increasing his flash power and the other by increasing his iso from 200 to 400. he didn't want to increase his flash anymore so he could freeze the water motion but what i would like to know is how increasing his iso does make his background whiter ( which it did ). i can't get my head around, so i'm hoping one of you guys can explain.:help:

thanks in advance
Click to expand...

Could you post a link to the video please? I like Gavin Hoey's tutorials but not seen that lemon one.
 
All the iso setting does really is make the sensor more sensitive so it can collect more light.. it works independantly of shutter and aperture and comes in very useful... I use it sometimes for long exposure photos where I need a set aperture for depth of field and a certain shutter speed for a particular blurry water effect.. the iso allows me to achieve these and get the best exposure too
 
CaveDweller said:
Could you post a link to the video please? I like Gavin Hoey's tutorials but not seen that lemon one.
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Sorry I don't know how to post links to it. If you search YouTube for him it should be on there or on adorama.
 
bb40 said:
Sorry I don't know how to post links to it. If you search YouTube for him it should be on there or on adorama.
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Try this, don't know it will work.

https://BANNED/gavin_hoey/status/431791720196362240
 
simonkit said:
All the iso setting does really is make the sensor more sensitive so it can collect more light.. it works independantly of shutter and aperture and comes in very useful... I use it sometimes for long exposure photos where I need a set aperture for depth of field and a certain shutter speed for a particular blurry water effect.. the iso allows me to achieve these and get the best exposure too
Click to expand...

I knew it increased the sensitivity of the sensor but I always thought it was used so you could get increased shutter speed still loads to learn I see
 
Raising the ISO increases the brightness of the whole image - both flash and ambient light (if there is any). Using a lower f/number has the same effect, but also changes depth-of-field.

It's only shutter speed that has no effect on flash brightness, but changes ambient light exposure.
 
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