Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Apr 28, 2006, 5:50 PM   #11
Member
 
Join Date: Mar 2006
Posts: 38
Default

It is up to you to keep the settings within the physical limits of the camera. For your silky waterfalls, you will definitely need an ND filter. You can set the shutter speed as slow as you want. The camera will then try to set the aperture accordingly, but the lens has physical hardware limits on how big or small the aperture can be. If you set the shutter speed too slow, the lens cannot close down the aperture enough to prevent overexposure no matter what the exposure bias is. You must cut down on the amount of light entering the camera.

Similarly, in dim light, there is only a certain amount that the lens can open up. If you call for a too-fast shutter speed, the lens can open up only so far. You won't get enough light to the imager and your picture will be underexposed.

When in aperture priority mode, it is also possible in bright light to set the aperture so wide that the shutter speed can't be made fast enough to prevent overexposure.
scoundrel1728 is offline   Reply With Quote
Old Apr 28, 2006, 6:06 PM   #12
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

rey wrote:
Quote:
JimC

Thanks for your description. I think I understand what you said.

In my case, I want to capture the motion of waterfall. My first instinct would be use a tripod and use Shutter priority and decrease the shutter speed. Now, assuming the water, or other objects in the shot turns out too white, I would then use -EV to compensate until I get the desired result. I
It depends on why they're coming out too bright.

If they're coming out too bright regardless of your shutter speed (in Av Mode, Tv Mode, P Mode, etc.), then it's because the camera's meter things the scene needs to be exposed brighter than you want.

Then, you can use a -EV setting with Exposure Compensation so it exposes the scene differently, while still taking advantage of the Camera's meter (up to a point).

If they're coming out too bright because the shutter speed you selected won't allow the camera to choose an aperture small enough for the lighting (because the lens is limited to the smallest aperture you can set), then Exposure Compensation will have zero effect (because the lens would already be at it's smallest aperture setting).

In Tv Mode, you pick the shutter speed and the camera selects the appropriate aperture. Any number of Shutter Speed/Aperture Combinations will produce identical exposure. For example, any of these combinations would produce an image with the same brightness.

1/1000 second at f/2.8
1/500 second at f/4
1/250 second at f/5.6
1/125 second at f/8

When you pick a shutter speed, the camera is simply opening or closing the aperture so the scene is exposed the same in Tv Mode.

Let's take an example in lighting close to what you want to shoot in.

On a bright day, you may have light equal to an Exposure Value of around 15.

With your Nikon, you'll have a lowest ISO speed of ISO 200.

If you set your shutter speed to 1/250 second in Tv mode, the camera would choose an Aperture of around f/16 in that lighting to properly expose the scene.

If you use a -1.0 Setting with Exposure Compensation, it's going to try and use a one stop smaller aperture (f/22) to make the exposure one stop darker than it normally would expose it.

If you decide you need a slower shutter speed and set the camera to 1/125 second in the same lighting at ISO 200, the camera is going to try and set the aperture to around f/22. That will give you the same exposure as f/16 and 1/250 second.

If you wanted it one stop darker, when it's already at f/22 by using a -1.0 Setting with Exposure Compensation, if the lens wouldn't allow an aperture smaller than f/22, then your image would not change.

You'd probably get a flashing aperture in the viewfinder letting you know that your settings are exceeding the limitatons of the lens.

So, you would not be able to go any slower than 1/250 in that lighting, if a -1.0 EV setting was needed for proper exposure (because the camera couldn't set the aperture any smaller than f/22). Try to go slower and you'd get an overexposed image.

Some lenses go to f/22, some to f/32 and some may even go to f/48. The Nikkor 18-55mm kit lens has a smallest aperture of f/22 on the wide end, and f/32 on the long end.

If you don't need any exposure compensation for proper exposure, the slowest shutter speed you could use would be 1/125 second on the wide end of the lens on a typical bright day, since it's got a smallest available aperture of f/22. If it's overexposing at 1/125 second, too bad. Exposure Compensation won't help anything.

Also, you can expect softer images at the extreme aperture settings (larger or smaller).

I'd get an ND filter if you want a blurred effect in bright light.

Exposure Compensation is only designed to expose brighter or darker than the camera's meter thinks a scene should be exposed. It's not designed to overcome limitations of a camera's lens.

JimC is offline   Reply With Quote
Old Apr 28, 2006, 6:20 PM   #13
rey
Senior Member
 
rey's Avatar
 
Join Date: Oct 2005
Posts: 949
Default

Wow, that's a great explanation. Now I understand it perfectly. Thanks a lot!

rey is offline   Reply With Quote
Old Apr 28, 2006, 6:31 PM   #14
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

I'm not sure I didn't confuse more than I helped.

But, FWIW, I'm tired of looking at running water shot at slow shutter speeds. Some people seem to like the effect. I'm just not one of them. ;-)

JimC is offline   Reply With Quote
Old Apr 29, 2006, 6:23 AM   #15
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

A few more comments.

As already mentioned, Exposure Compensation is not designed to bypass limitations of a camera's lens.

As a result, the opposite also applies... If you try to set a shutter speed that is too fast for the lightng, ISO speed and largest available aperture for the lens (smallest available f/stop number), you'll get underexposed photos. If you want properly exposed images, the camera must leave the shutter open long enough.

Hardly a week goes by when someoine doesn't ask about why they're getting dark photos inside when they set their shuttter speeds too fast.

Just because you can set a shutter speed faster, doesn't mean that you'll get properly exposed images when you do it. You have to keep lens and ISO speed limitations in mind.

If your shutter speed in Tv Mode is too slow for the smallest available aperture of the lens for any given lighting and ISO speed, you'll get overexposed images.

If your shutter speed in Tv Mode is too fast for the largest available aperture of the lens for any given lighting and ISO speed, you'll get underexposed images. This is a common occurance when someone tries to use Tv Mode for low light sports and sets a shutter speed that's too fast for proper exposure.

So, in low light, I prefer to shoot using Av Mode (opening up the aperture so that shutter speeds are as fast as possible, without underexposing).

Someone that is familiar with shooting in the lighting may prefer Tv Mode, since they may use settings that insure they are not exceeding the lens aperture limitations, without the need to open the aperture up all the way.

You'll lose both Depth of Field and sharpness at wide open apertures, so if you can get fast enough shutter speeds without opening it up all the way, that technique is sometimes preferred by seasoned sports shooters.

With most DSLR models, the camera will give you a warning if your settings are exceeding the capabilities of the camera or lens, and will result in incorrect exposure based on what the camera's meter thinks is needed. This warning is often in the form of a blinking f/stop number or shutter speed in the viewfinder.

You also see similar limitations shooting in Av Mode. If you try to open up the aperture all the way in bright light, the camera may not have fast enough shutter speeds available for proper exposure. So, you'll get overexposed images if you don't heed the warning.

Bottom line... you have to keep camera and lens limitations in mind when using Av or Tv modes. If your settings exceed the capabilities of the camera (slowest or fastest available shutter speeds) or lens (smallest or largest available apertures), you'll have incorrectly exposed images.

JimC is offline   Reply With Quote
Old May 6, 2006, 11:40 AM   #16
Member
 
Join Date: Oct 2005
Posts: 48
Default

rey wrote:
Quote:



Unfortunately, we don't have any water fountain on any parks where I live, so I can't give this a try before going to a waterfall. But I'll look around on nearby cities to test this.

Make your own fountain, go outside with a hose pipe

Bob
inness is offline   Reply With Quote
Old May 8, 2006, 4:19 AM   #17
Member
 
Join Date: Oct 2004
Posts: 80
Default

inness, have you been using your hose pipe? (There's a ban in the UK)
jonathan1011 is offline   Reply With Quote
Old May 8, 2006, 10:53 AM   #18
Member
 
Join Date: Oct 2005
Posts: 48
Default

jonathan1011 wrote:
Quote:
inness, have you been using your hose pipe? (There's a ban in the UK)

sssshh its only a photograph :|( virtual reality ):GI'm in deepest dorset plenty of water in them there wells
inness is offline   Reply With Quote
Old May 29, 2006, 7:39 AM   #19
Junior Member
 
bmacs's Avatar
 
Join Date: May 2006
Posts: 6
Default



I am a newbie to photography and found ur comments very informative. I take photos of my son playing Australian Rules football every Sunday using a Sony DSC-H1. I have in most cases been using SP mode, but I will try AP mode next week. What I would likeare yourcomments on what focussing mode/technique to use. The H1 has 3 automatic modes and one manual mode. The automatic modes being Multi, Centre and Spot focus. I have been toggling between Centre and Spot with less than pleasing results. A large number of my photos at the full zoom are out of focus even though I ensured I had achieved focus lock (stable green dot and beep.) Why would they be out of focus eben though I got focus lock?

Your thoughts would be greatly appreciated.

Thanx :-)

Ashley


bmacs is offline   Reply With Quote
Old May 29, 2006, 10:24 AM   #20
rey
Senior Member
 
rey's Avatar
 
Join Date: Oct 2005
Posts: 949
Default

Quote:
Why would they be out of focus eben though I got focus lock?
It could be blur due to camera shake.

In full zoom, you have to hold the camera more steady, as little movements will cause blurriness. The rule is use a shutter speed of 1/focal length. So if you are shooting at 100mm, you have to use a shutter speed of more than 1/100 sec. If lighting is bad, you have to increase the ISO to compensate.

rey is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 5:11 AM.