Help shooting low light with my Nikon D40? Can't make it work

I have a Nikon D40-with a Nikon Dx 55-200mm lense. I'm shooting a wedding this weekend and I was just informed that it will be in a very low light setting. I have tried and tried to adjust my ISO on all settings to shoot these pics but when I adjust it-I can't make the shot-it just won't shoot. I push the button and nothing happens-what am I doing wrong? I'm a novice but am trying to learn-this is just a friends wedding, very informal and small but I want to do my best. ANY help would be appreciated!

Basically, you must first take the camera of Auto to set ISO manually.

You can find excellent directions on adjusting the ISO settings here:
http://www.ehow.com/...n-d40.html

I recommend setting the Nikon D40 in AE or Aperture Priority mode when manually adjusting ISO settings. This allows you to control the aperture while the camera automatically chooses the right shutter speed. Ideally ISO 400 to 800 are the best compromise for low noise images. Are you using the VR 55-200mm lens or the one without VR (Vibration Reduction)? You will be more likely to have blurred images without VR. Frankly that lens may simply be too slow to get many sharp photos unless you push the ISO settings up to 1600. You will see noise at that setting quite clearly if you plan to enlarge your images. Using a noise reduction software may help with that.

http://petersonlive.com

One reason might be that by default your camera won't trigger until it's focused, all cameras have difficulty finding an edge in dim lighting with small aperture lenses, the lens just 'hunts'. Result it doesn't trigger.

You need a lens with a wider aperture.

As far as I know the D40 doesn't have any way of emitting light to help with this issue. Other DSLR cameras pop up the flash and put some light into the subject in low light, others have an Infra Red lamp that can help.

You may be trying to focus closer than the minimum focus distance of the lens, anything that causes the camera not to focus will stop the shutter from firing.

Aperture priority is usually the best Mode to be in, set the aperture and half press the shutter and the camera will tell you the shutter speed it needs with the ISO you have set. To avoid blur aim for 1/focal length, so for a 50mm lens 1/50th of a second should be your minimum shutter speed, for a 200mm aim for 1/200th of a second.

Your camera won't fire unless it is locked on focus and in low light that is difficult. Lower end lenses have an even harder time.
More than that, you won't be able to get an image that is useable in low light conditions with the limits that camera and lens have together. For a non-flash image you will need to have an ISO much higher than your camera is capable of AND an f/ of 2.8.

Now you haveyour Ava moment, why in helleould you go to a friends weddin, pretendingto be a phtopgraper… Using a toys!

Things that may help…

Use manual focus
Bring a tripod
Bring a flash
Do some test shots at the locations, before the wedding
Is that lens your fastest lens?
Rent a faster lens

Make sure you know the photo guidelines for the church

This is why we keep telling people:

A- don't shoot a wedding just cause you have a fancy camera.

B- you need the right gear to shoot a wedding.
1 main camera
1 backup camera
24-70 f2.8
70-200 f2.8
Two TTL shoe mount flashes…

My suggestion is go rent a proper lens. You can rent a 24-70 f2.8 L (canon but they have a nikon equivalent) for about 30$ and a 70-200 f2.8 for about 35$. Flashes can be rented for about 8$.

With my 24-70, I can focus in very dark conditions and then I use a flash bounced on the ceiling (or wall or people or… ) to illuminate the scene.

Example: (I think that's the right link… Flikr is blocked at work and I'm on my lunch).