Either it's slow shutter as mentioned above, or you accidently moved the switch (ON THE LENS) that turns it to manual focus. If you post up a photo we could probably tell you which it is.
If using a semi-auto setting like Av the camera will use long shutter speeds if needed to get proper exposure. If you're trying to take shots indoors, then this is probably what's happening.
There are a few reasons you can end up with a blurry image:
1) Improper camera settings based on the type of image you were taking (mostly due to the shutter speed being too slow to be a hand-held shot, or the subject was moving too fast for the shutter speed you set.) If the subject isn't moving and also if the camera isn't moving, then the shutter can be open as long as necessary to get a great exposure with no blur -- which means you'd want to use a tripod (or other device that prevent the camera from moving.)
This is usually the most likely reason for the issue you describe. If you're new to photography with a DSLR camera, a highly recommended book is "Understanding Exposure" by Bryan Peterson. It's written for beginners so he's careful to explain concepts using terms that everyone would understand. The Scott Kelby Digital Photography series is also popular (I think that's up to four books now.)
2) The camera didn't focus on your intended subject. There can be a lot of reasons why this happens. It's possible there wasn't enough light to allow the auto-focus system to get a lock. It's possible there was a distracting element in the frame which was closer than your intended subject. It's possible the camera AF mode was set to AI Servo and you didn't wait for the camera to finish focusing before fully pressing the shutter button. It's possible the AF/MF switch on the lens was set to the MF position so the camera didn't even try to focus. The list goes on.
If this is the issue, then there's a series of videos by Canon's Rudy Winston did at B&H Photo. These are all posted to YouTube and free. It's in three parts and is well worth the investment of time -- once you watch it, you'll understand WHY the camera behaves the way it does when it comes to focus and everything will finally make sense.
3) Lastly... it's possible that a camera or lens could be damaged and incapable of focusing. This is usually the least likely reason but it's possible.
If you can post an image showing an example of what you mean and, VERY important... please DO leave the EXIF data in the image. The EXIF data is hidden information in your image that the camera records. It tells us information about the camera model, lens model, exposure information, and other settings. That info is very useful as we can usually quickly tell if your exposure settings were adequate.
That depends how they are positioned. Are they side by side or one in front of the other?
All lenses have a given DOF (depth of field). So not just the "eye" is going to be in focus in most situations. Also as the aperture gets smaller (a larger number f2--->f8) will have more of the subject(s) in focus.
When i take a picture indoors the picture looks good. But when i zoom it in to look at it it is blurry.
I have the camera set on full auto.
It is the Cannon EOS Rebel XTI.
I am new to this and don't understand a lot about the Camera.
I also got a 75-300mm Tramron lens and it will only shoot to 200mm.
Anything above that the camera shows ERROR.
Is it something i am doing wrong.
Please E-Mail me as i won't find this page again
My E-Mail is [MOD NOTE: Email address removed per FORUM GUIDELINES] all lower case
Thank You So Much
Jan Allen Sr
"I also got a 75-300mm Tramron lens and it will only shoot to 200mm."
The Tamron is probably not compatible with your Rebel. That is the chance you take when you buy third party lenses and gear.
"But when i zoom it in to look at it it is blurry."
I would bet they are blurry even when you don't zoom in. You just don't notice it as much. The biggest cause of blurry indoor photos is not enough light which slows the SS down too much. More light or a real flash are two remedies if a higher ISO doesn't help.