It finally clicked!


TPF Noob!
Jan 13, 2012
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Ok, so I was looking at results from yesterday's early morning shoot (separate thread), and realized (I'm sometimes very thick-skulled) that if noise is from ISO, probably lower ISO would be lower noise, and that's ok because I know I can increase shutter speed, and use a tripod with remote release.

So this morning I did a test, and with the blinds closed in the living room so only minimal light was coming in, put the camera on the tripod. Started with ISO 6400, aperture 4, relatively fast shutter speed for proper exposure. Shot at every ISO setting all the way down to 100, decreasing shutter speed as I went. Once I got to 100 ISO, I then decreased the aperture (increased the setting number).

I immediately took the 20 or so photos I ended up with and look at them one by one.

Now I see for myself the difference that a slow shutter with low ISO can make for high noise. Won't work in wind or with moving subjects, of course. But for what I needed to learn, this was a perfect experiment.

I suppose that sometimes I just have to experiment for these things to "click" rather than be all book-read.

Next weekend I'm going back to the same location to do another photo shoot in the sunrise, and see what I can get when I'm not too lazy to use the tripod and proper settings. Probably five billion percent increase in satisfaction with the photos I get for the little effort it takes to haul around the tripod.

Thanks for listening,


(pun intended in post title, btw)...
It's always most satisfying to figure this stuff out on your own eh? Nothing like seeing results.

See if your camera has "Long exposure noise reduction" or something similar. It will help you considerably with your slow shutter, low ISO noise issues.
Thats an excellent way to learn how it all works and also what I ended up doing too. Once you have a basic idea of what each setting produces it really all falls into place.
Nice when it "clicks", isn't it? :)
Once I got to 100 ISO, I then decreased the aperture (increased the setting number).
It is helpful to understand that as the aperture gets smaller so does the f-number. Because they are fractions f/2 is a larger number than f/8 is.
The f represents the lens focal length - be it 18 mm, 50 mm, 100 mm, 85 mm, or whatever.

At a focal length of 50 mm and f/2, the lens aperture diameter is 1/2 as wide as the focal length of the lens - 25 mm - 50 mm/2 = 25mm
At a focal length of 50 mm and f/4, the lens aperture diameter is 1/4 as wide as the focal length of the lens - 12.5 mm - 50 mm/4 = 12.5 mm
At a focal length of 50 mm and f/8, the lens aperture diameter is 1/8 as wide as the focal length of the lens - 6.25 mm - 50 mm /8 = 6.25 mm
:thumbup:! Now here's another test you can try - get a grey card and shoot it at the native ISO at the exposure the meter recommends, then do +1, +2, +3, +4, +5 (additional stops of exposure), and the same way going the other way - Then you'll see when the pixels all line up at the right or left - and that's your dynamic range. Do the same at a high ISO - and you will see much less dynamic range. How much less? depends on the camera. But it is worth trying it out to see what happens when your ISO goes high.

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