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Decreasing shutter speed = Increasing Exposure Value?
Ok, probably it's a stupid question even in the beginner's forum. But I need a quick answer from you..

When I use my newly purchased DSLR to take nightshots, I found the camera tends to underexpose (using Aperture Priority shooting mode). In order to get everything brighter in the picture, should I:.

1. Use Manual to decrease the shutter speed?2. Use Exposure compensation to increase EV?.

Are they the same?.

And another question, what's the difference between large aperture (small f number) + shorter exposure time and small aperture + longer exposure time for nightshots?.

Any feedback is greatly appreciated!!! Thanks in advance!.

Cheers,Tony..

Comments (11)

The relationship between aperture and shutter speed remains the same. For example if proper exposure is f4 at 1/125 sec, then f5.6 at 1/60 would be the same exposure..

I'd leave EV alone unless you're alway compensating for something or want to shoot auto..

Personally, for night shots I like to use a smaller aperture than others might. It helps to control the bloom around light points like lamps and such. Since you're using a tripod (you are aren't you?) you can really use a slower shutter speed...

Comment #1

"f4 at 1/125 sec, then f5.6 at 1/60".

May I ask how you calculated them?.

When I use Aperture Priority mode, I don't have to worry about the shutter speed. But since I find the result kinda underexposed, what choice do I have?.

No I haven't a tripod yet. And my E-410 doesn't even have the Image Stabilization function so I have to shoot with a high ISO and large aperture to insure that pictures don't get blurred. I will soon purchase one and try using small aperture + long exposure time..

Thank you very much for your input!.

Btw, here's the link to some shots to which I was refering. They don't seem to feel alright .

Http://cheeziest.smugmug.com/gallery/4736282_w4Mjg#280530314_xhPhe..

Comment #2

Ulrichvonlich wrote:.

"f4 at 1/125 sec, then f5.6 at 1/60".

This was arbitrarily chosen as an exposure value, and doesn't necessarily reflect what you would have seen in any particular shooting condition. But the point was to show that an exposure at f/4 and 1/125s is the same as an exposure at f/5.6 at 1/60s (with respect to lighting). This means both exposures will be properly exposed at the same levels..

May I ask how you calculated them?.

When I use Aperture Priority mode, I don't have to worry about theshutter speed. But since I find the result kinda underexposed, whatchoice do I have?.

In A mode your best and easiest choice is to use the EV control. Increasing the exposure compensation (EV) is quick and easy to get the shot correct..

I had a look at your gallery and your shots don't necessarily seem underexposed. I find that on my E-3 the shots tend to be OVER-exposed and I typically dial in -0.7 to -1.0EV for night shooting..

Have a look here at some images I just posted a few days ago in OTF:http://forums.dpreview.com/...forums/read.asp?forum=1008&message=27621893.

There is no doubt in my mind that your E-410 can produce excellent night images - with a tripod of course. I have an E-410 as well, BTW..

No I haven't a tripod yet. And my E-410 doesn't even have the ImageStabilization function so I have to shoot with a high ISO and largeaperture to insure that pictures don't get blurred. I will soonpurchase one and try using small aperture + long exposure time..

Thank you very much for your input!.

Btw, here's the link to some shots to which I was refering. Theydon't seem to feel alright .

Tim'Be the change you wish to see in the world.' -Mahatma GandhiE3/E-1/E410/7-14/12-60/50-200/EC-14/C8080http://www.flickr.com/photos/timskis6/..

Comment #3

Ulrichvonlich wrote:.

Ok, probably it's a stupid question even in the beginner's forum. ButI need a quick answer from you..

When I use my newly purchased DSLR to take nightshots, I found thecamera tends to underexpose (using Aperture Priority shooting mode).In order to get everything brighter in the picture, should I:.

1. Use Manual to decrease the shutter speed?2. Use Exposure compensation to increase EV?.

Are they the same?.

And another question, what's the difference between large aperture(small f number) + shorter exposure time and small aperture + longerexposure time for nightshots?.

One of the reasons for choosing a small aperture might be to increase DOF (the sharpness from near to far in your images. A reason to choose a longer exposure might be to blur some movement in the photo for example water in a waterfall..

Any feedback is greatly appreciated!!! Thanks in advance!.

Cheers,Tony..

Comment #4

For starters.if you are shooting night scenes.skip the aperture priority and either shoot manually or in shutter priority!.

Auto exposure doesn't work all that well for night scenes and low light shooting..

Yes.decreasing the shutter speed is increasing the exposure value since you are letting more light in at the slower shutter speed..

J. D.Colorful Colorado.

Oly E-510:.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Remember.always keep your receipt, the box, and everything that came in it!..

Comment #5

Ulrichvonlich wrote:.

1. Use Manual to decrease the shutter speed?.

Yes.

2. Use Exposure compensation to increase EV?.

Same result..

Comment #6

Ulrichvonlich wrote:.

"f4 at 1/125 sec, then f5.6 at 1/60".

May I ask how you calculated them?.

Basically, those two exposures are exacty the same, even though the lens opening and shutter speeds are different..

In otherwords.they are both letting in the same amount of light..

Here is how that works:.

Assuming that I took a meter reading and calculated my exposure at f:4 at 1/125 sec, but wanted more depth of field and didn't want to take another meter reading once I adjusted the lens..

If I have my lens set at f:4 and shutter speed at 1/125 sec, then stop down (close) the lens one f:stop (letting in half as much light than at f:4) to f:5.6, then I need to compensate with the shutter speed by slowing it down one f:stop (to let in the same amount of light I blocked by closing down the lens) one shutter speed to 1/60 sec..

The difference between f:4 and f:5.6 is one stop of light..

The difference between 1/125 second and 1/60 second is one stop of light..

J. D.Colorful Colorado.

Remember.always keep your receipt, the box, and everything that came in it!..

Comment #7

Is playing around with the EV something that is mechanical or does the camera software brighten up the image?..

Comment #8

Qtfsniper wrote:.

Is playing around with the EV something that is mechanical or doesthe camera software brighten up the image?.

It's not a software effect*, the camera changes the aperture and/or shutter speed in order to get a brighter or darker shot. If you set the exposure compensation to +1, for example, you are saying to the camera "choose an exposure which is one stop brighter". Or, and I think this can sometimes be a better way to express it: "choose the exposure which you would have used if there was one stop less available light"..

The actual change that is made depends on the exposure mode. In Av mode for example, the camera must vary the shutter speed, just as it would if the lighting conditions changed. In Tv mode it must change the aperture. In full auto mode it can change either or both..

Exposure compensation is available on film cameras too, where software effects are not an option!.

*However there are digital cameras which have an auto ISO capability. In principle, exposure compensation could be implemented by changing the ISO speed, and that would of course be a software effect. I'm not aware of any that actually do this though...

Comment #9

Ulrichvonlich wrote:.

"f4 at 1/125 sec, then f5.6 at 1/60".

May I ask how you calculated them?.

Here is a series of f-numbers, in order of decreasing aperture size:.

F/2 - f/2.8 - f/4 - f/5.6 - f/8 - f/11 - f/16 - etc.

Your camera will almost certainly offer other values in between those, but the significance of the series above is that they are whole 'stops'. This means that each step represents half the *area* of aperture and therefore half the amount of light captured, all other things being equal..

The reason for the apparently strange numbers is that the f-number relates not to the area of the aperture but to it's diameter - or rather to the inverse of the diameter. If your maths is good you will immediately see that if the area is halved, the f-number is multiplied by the square root of 2 (i.e. approximately 1.4). If maths is not your thing, forget it and just use the series as above, the detail doesn't matter..

Here is another series, this time shutter speeds:.

1/2 -1/4 - 1/8 - 1/16 - 1/32 - 1/64 - 1/128 - 1/256 - etc.

It's slightly more obvious this time that each step represents half the time and therefore half the light captured. However for historical reasons, those are not the actual values you will see on your camera. In practice, the shutter speeds are rounded to:.

1/2 -1/4 - 1/8 - 1/15 - 1/30 - 1/60 - 1/125 - 1/250 - etc.

Once again your camera will offer intermediate values but we will stick to whole stops for this explanation..

Since the steps in both series, f-number and shutter speed, are the same, you can take an exposure such as your example of 1/125 at f/4, and maintain it by going up one series and down the other by the same amount. So going one step (i.e. one stop) to the right on the aperture scale we get f/5.6, and one step left on the shutter speed scale we get 1/60..

So 1/125 at f/4 = 1/60 at f/5.6...

Comment #10

Sigezar wrote:.

Ulrichvonlich wrote:.

1. Use Manual to decrease the shutter speed?.

Yes.

2. Use Exposure compensation to increase EV?.

Same result.

True..

But depending on the camera, Exposure Compensation may allow an adjustment by a limited amount: 2 or maybe 3 stops. If you need more than this, Manual exposure is the only choice...

Comment #11

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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