Night shots: relation between apeture and shutter speed.


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Sep 15, 2003
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#1
Hi all,

May i know what are the differences when taking night shots with the following settings

1) shooting at large aperture and slightly shorter exposure time
eg. f2 , 2s

2) shooting at small apeture and longer exposure time
eg. f 8.0 , 15s


I tried this little experiment and found that the pics do not differ much except for the lights. In, 1) the light sources seems to be concentrated
2) produced star shapes..

What are the recommended settings for taking night shots?
 

Sep 15, 2003
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#2
here are some of the pics i took yesterday at esplanade.


f3.2, 2s


f8, 7s

notice that the 1st pic seems more "orange" than the 2nd one. any explantion?
 

Zerstorer

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Jul 8, 2002
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#3
sound-of-rev said:
Hi all,

May i know what are the differences when taking night shots with the following settings

1) shooting at large aperture and slightly shorter exposure time
eg. f2 , 2s

2) shooting at small apeture and longer exposure time
eg. f 8.0 , 15s


I tried this little experiment and found that the pics do not differ much except for the lights. In, 1) the light sources seems to be concentrated
2) produced star shapes..

What are the recommended settings for taking night shots?
For digital cameras, larger apertures with shorter exposure times will allow lower noise images. The tradeoff would be shallower and possibly CA like artifacts for some consumer digital cameras.

Smaller aperture and longer exposure time is preferred if the noise levels do not increase noticeably. Some may also like the diffractive effects that give the lights a star dispersion.

The difference between the 2 shots is due to a problem of white balance. Either the white balance was altered between the 2 shots or that because the composition was changed, the camera's WB sensor was getting a different WB reading. If you want consistency between images, it would be best to set a predefined colour temp or a custom white balance so that it won't vary.
 

Sep 15, 2003
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#4
Zerstorer said:
For digital cameras, larger apertures with shorter exposure times will allow lower noise images. The tradeoff would be shallower and possibly CA like artifacts for some consumer digital cameras.

Smaller aperture and longer exposure time is preferred if the noise levels do not increase noticeably. Some may also like the diffractive effects that give the lights a star dispersion.

The difference between the 2 shots is due to a problem of white balance. Either the white balance was altered between the 2 shots or that because the composition was changed, the camera's WB sensor was getting a different WB reading. If you want consistency between images, it would be best to set a predefined colour temp or a custom white balance so that it won't vary.
Thanks for your reply :)

Actually i set the same white balance settings for both of the pics. I don't quite understand "composition was changed... " How is this composition changed with respect to the aperture and exposure timing? In these 2 pics, i merely changed the aperture value and exposure timing only.

How to predefined a colour temp or custom WB? I'm using F717
 

Zerstorer

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Jul 8, 2002
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#5
Composition means your framing for the shot, obviously you took them at a different angle and position.

What WB setting were you at? The ambient light at your position and that of the subject may both contribute to confuse your WB sensor. Also, note that light sources based on gas emitters(sodium, fluorescent) do not emit the same wavelength of light at a given time, instead their colour changes rapidly manytimes a second but they are averaged out and viewed as single colour by our human eye. A digicam however will capture the colour at the particular instant.

I'm not familiar with your F717, try reading the manual and search for the Custom WB procedure. You could also experiment with the predefined WB settings in camera to see which gives an acceptable result.
 

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#6
sound-of-rev said:
Actually i set the same white balance settings for both of the pics.
Are you using "Auto WB"? Is you are using other preset white balances like "Tungsten", then you white balance should not change between the two shots.
 

TME

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#7
Might it have to do with his distance from the lights of the hotel? The shot with the orange cast seems to be taken further away..... red shift? But I also notice that the second shot seems to be taken flat on to the hotel whereas the first seems to have a slight downward perspective.... this way the light entering the camera may change a little to give different effects..... actually u should try the exact same shot and vary the aperture and/or shutter speed, then u will know the difference mah...... like that different perspective not a very fair comparison...... my 2 cents......
 

Ah Pao

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#8
Apparently, the auto WB for some digicams are not very consistent. I once tried taking multiple exposures of the same scene--the camera was mounted on a tripod, exposures triggered using self-timer. The only thing changing in the scene was my position in the shots.

The shots that came out was...argh...I had hard time trying to make everything the same colour cast...

So, the moral is, if you want to have consistent results, best not to totally depend on the auto WB but set according to your scene.
 

Sep 15, 2003
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#9
TME said:
Might it have to do with his distance from the lights of the hotel? The shot with the orange cast seems to be taken further away..... red shift? But I also notice that the second shot seems to be taken flat on to the hotel whereas the first seems to have a slight downward perspective.... this way the light entering the camera may change a little to give different effects..... actually u should try the exact same shot and vary the aperture and/or shutter speed, then u will know the difference mah...... like that different perspective not a very fair comparison...... my 2 cents......
Yah, i took these 2 pics at difference places. The 1st one on the rooftop on esplanade and the latter on the bridge itself. I didn't know that the difference in distance will produce "different" kind of lights,
anyway my WB is both set to "flourescent" (sp?)

Thanks for all the replies anyway, learn alot more from here
:)
 

showtime

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#12
sound-of-rev said:
Hi all,

May i know what are the differences when taking night shots with the following settings

1) shooting at large aperture and slightly shorter exposure time
eg. f2 , 2s

2) shooting at small apeture and longer exposure time
eg. f 8.0 , 15s


I tried this little experiment and found that the pics do not differ much except for the lights. In, 1) the light sources seems to be concentrated
2) produced star shapes..

What are the recommended settings for taking night shots?
if you were wondering, the star shapes is due to the apperture blades not being fully circular with you stop down... the number of star sides is a relation to the no of apperture blades...
 

TME

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#13
showtime said:
if you were wondering, the star shapes is due to the apperture blades not being fully circular with you stop down... the number of star sides is a relation to the no of apperture blades...

I think the aperture size is also important right? I think when stopped down to around f/11 and smaller, the less than circular shape produced by the aperture blades is more proounced compared when the lens s wide open at f/2.8. So apart from the number of blades I think the aperture size will alter the star shape that u see.....
 

TME

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#14

showtime

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#15
TME said:
I think the aperture size is also important right? I think when stopped down to around f/11 and smaller, the less than circular shape produced by the aperture blades is more proounced compared when the lens s wide open at f/2.8. So apart from the number of blades I think the aperture size will alter the star shape that u see.....
yes certainly... perhaps i did not include it in the post... thanks for the addition infor mation
 

TME

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#16
Ah Pao said:
Apparently, the auto WB for some digicams are not very consistent. I once tried taking multiple exposures of the same scene--the camera was mounted on a tripod, exposures triggered using self-timer. The only thing changing in the scene was my position in the shots.

The shots that came out was...argh...I had hard time trying to make everything the same colour cast...

So, the moral is, if you want to have consistent results, best not to totally depend on the auto WB but set according to your scene.

I dun know but to my mind, standing in different positions can cause the light reflected from the flash to the camera to differ also..... a more controlled test is to shoot scenery at night where the light reflected is more or less a constant (like lighted buildings) and change the aperture and shutter values...... I think u can see the difference in the settings more easily....... comment?
 

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