Do you use autofocus or focus manually?

I have a Canon Digital Rebel Xti. Sometimes I'm not able to get the sharpness I want with the autofocus even when I use a tripod. Is it my camera? Do some cameras have better autofocus than others? I've tried focusing manually, but I'm not very good at it. I would appreciate any suggestions or advice or thoughts on this subject.

Barb, I rely on autofocus most of the time. The main exceptions are when shooting macros or when I want to control the depth-of-field in a landscape. Troubleshooting unsharp images can be challenging. You may need to post more info about when you get sharp vs unsharp images. Is it all the time or particular conditions? You can get soft images from a tripod that's not steady enough or when the mirror flipping out of the way causes camera shake. The mirror impact is particularly a problem at shutter speeds between about 1/10 and 1 second. If it's the mirror, you can use mirror lock up to stop the shake. Softness on a tripod can also be you pressing the shutter. The solution to that is a remote shutter shutter release (can be cable or electronic)or use the self timer. Another possibility is that the images are focused, but not where you want them. That can happen when the part of the image that you want to be sharp is not what the autofocus is picking as a target. Check your images and see if everything is soft or just parts are soft.

Thank you for your advice, Mark. I have the most trouble with sharpness when I'm photographing trees and flowers. I always put the focus point on the part of the image that I want to be the sharpest and when I use a tripod it is steady and I use a cable release. When conditions are windy I use a faster shutter speed. But sometimes I still get images that are not sharp enough. I use Canon lenses, not L series, but I think they would be considered good quality.

Barb,
Mark is on point regarding several things to consider. Directly to your question, when shooting "flowers & trees", I use live-view on the camera and manually focus every shot. I don't know if your model has zoom capability on live view. I shoot a Canon 5DII & I can view then scene, then zoom in 10x directly to the area where I want to focus & really get the focus sharp. If I shoot while in live view mode, the mirror is already up inside the camera, so you also avoid the mirror slap that Mark references. I will pick the spot I think I should focus on. If I'm not sure whether that is the best hyperfocal spot, I'll shoot a few more using a spot closer, and one further away, just to be sure. Another trick is to review the photos just after taking them in the view finder. Zoom in on your focus spot to see if you got it sharp enough. Those view finders are not at great resolution, but after a while your eye will learn what "sharp" looks like in the view finder.

Barb, often when AF is not sharp it means the camera sensor vs the lens (distamce-wise) is out of adjustment. The Rebel series is notorious for this especially with a kit lens if you use that. The tolerance is wider for the lower-priced cameras, but no camera/lens combo is perfect. They added a micro adjustment to the 50D, 7D and 5D Mark II where you can dial in each lens (probablyh the high-end 1D series also), and that feature alone is worth the purchase price. However, all is not lost, because you can manual focus for the short term (which you always want to do when on a tripod anyhow, and make sure you turn off IS if your lens has it, IS can cause problems on a steady tripod). For the long-term, you can call Canon and send them both the camera body and the lens and they will tune the two together and drastically improve your results. That does raise an issue if you own several lenses however, because it could make a different lens worse. But if you have one lens, I highly recommend sending it to Canon for adjustment. If it's way out of adjustment, they may fix it free of charge, they've done that in the past. When asked which location of the three service centers to send it to, pick Irvine, CA. They seem to throw out the most freebie adjustments. In the meantime, you may want to save for that 7D, lol!

Wow, a lot of great advice Barb. I also will use AF at times but I am always aware where the lens is focusing. I have it set to center focus with one point so I can control it. That way I can put the point on the subject, focus, recompose the shot and shoot. I picked up a trick where I use the AE-L/AF-L button on the back of the camera to focus. This takes it off the shutter button so I can recompose and not have to hold the shutter button half way down. I shoot Nikon, but a guy with a Cannon showed me this. You can change it in the menu.

I also use the live view-zoom to manually focus on flowers, etc. when using a tripod with a remote trigger.

Thank you for the advice, Wick and Paul.

Wick, my camera doesn't have live view, but I will try your suggestion about looking at the picture in the camera right after I take it.

Paul, I use more than one lens so I need a camera that will work with all of my lenses. I might start saving for that 7D or some other camera!

Thank you for the advice, Walt. I also use the center focus with 1 point the way you do. I will try using the AE-L/AF-L Button as you suggested. That sounds better than holding the shutter button halfway down.

Using AF, focus on an object in a field and then see where the focus is falling. It will help with focus to know whether you have front or back focus. If you want to focus manually, make sure your diopter is adjusted correctly. For sharpness, use a good lens, a middle aperture, low ISO, and a high shutter speed.

I generally use autofocus unless I'm shooting from a fixed position with subjects that can occur at various points around the frame. I.e., when I want to place subjects somewhere other than directly under one of the AF sensors. I also quit using AF when the camera is having trouble sorting subject from background. Examples of the first might be runners at a finish line, and the second might be fireworks framed by nearby people or landmarks.

In practice I set up for the shoot with the AF, then turn off the AF (Nikon system) so there will be no shifting in the focus. If it's a critical shoot I'll even use gaffers tape to lock down the focus ring so there's no chance I'll inadvertently bump the focus ring in the heat of the action.

I have an XTi and a 50d. What I find is AF with Canon lenses to be good with both where my Tamron lens is not a good AF performer on either. With the 50d I generally use manual focus with live view when on a tripod. Makes a HUGE difference in sharpness. I now consider live view my favorite advancement of the digital era.

Thankyou, everyone, for the good advice. I'm starting to think about buying a camera with live view. I think that would be helpful to me. Until then I'm going to follow the advice you've given me about focusing.