XSi autofocus issues

I was at a party last night for a friends birthday with my camera and was trying to take some pictures. The lighting was decent for a house at night time but nothing special.

I was changing back and forth between my 18-55 IS kit lens and my 50mm 1.8. Both were having issues focusing randomly. There did not appear to be any rhyme or reason to when it would falter but it frustrated me throughout the night.

Whenever this would happen, a circular green light would blink to the right side of my view finder. What does this mean? Does it explain why it wouldn't focus?

the green light blinking simply means it still isnt in focus

That makes sense. I am sitting here trying to take pictures of stuff in my room and it is still having issues. It also seems very slow to focus but I think that is a trait of the kit lens.

Try it in a brighter environment, see if the issue is still there.

How dark is the room? Does it focus properly if the room is brighter? It might just be too dark. Also, the AF works better if you focus on a point of high contrast.

Right now I am sitting in a light coloured, 12x12 room with 3 60 watt light bulbs. I would not think this to be dark to the point of causing problems. I will experiment tomorrow outside if it ever stops snowing.

Try just using the center focus point and point it toward a high contrast area and see what happens.

Are you in a mode that allows flash?

Do you have a Speedlite connected or are you using the camera flash?

Does it have these issues in daylight?

Does your battery need charging?

I always shoot in Manual mode but I tend to avoid the use of flash since all I have is the on camera and it washes people out horribly. The battery has a full charge and I haven't shot in daylight in quite a while. I will have to test it some more after class.

Sawbladz wrote in post #7107000
Right now I am sitting in a light coloured, 12x12 room with 3 60 watt light bulbs. I would not think this to be dark to the point of causing problems. I will experiment tomorrow outside if it ever stops snowing.

Weird. I'm in a similar-sized room lit by a single 26W CF bulb in a desk lamp aimed at the ceiling, and my kit lens focuses fine pretty much wherever I point it, unless it's directly at a featureless wall. But, the non-USM lenses tend to hunt for focus more in low light. There are times when my 50/1.8 II won't focus at all in low light.

Sawbladz wrote in post #7106458
That makes sense. I am sitting here trying to take pictures of stuff in my room and it is still having issues. It also seems very slow to focus but I think that is a trait of the kit lens.

It should focus pretty quickly, I have the same one.

Make sure you have adequate light! Sounds to me like there's not enough light. Pop open your flash and see if the AF assist starts strobing. I bet those shots will be in-focus!

Or better yet, just try to take some pictures outside in daylight before you assume that there's issues with the AF.