Sharpness

[mrs920]

I have a Canon Rebel and have been shooting with a 50mm/1.8 lens. When I first got it, my pictures turned out really sharp in the areas that I wanted in focus. I have lately been having a hard time getting the focus point to be sharp... I have used various f/stops, increased the shutter speed to avoid shake, changed ISO... tried in manual mode and AV/TV mode... shot inside and outside. I even had a photographer friend help me and said that the focus point was not terribly sharp. I find that the pictures may look OK in the view finder, but once they are on the computer, they are just blurry/not sharp. My friend thought maybe something was wrong with the lens? I am finding that my camera doesn't feel dependable and that drives me crazy. Anyone have any thoughts?

[Elmo]

I lean more to what did you change, like picture styles or changing from jpeg to raw?

[RecurrentNerve]

Also, this may seem like a stupid question, but have you accidentally changed the focus of your viewfinder?

Also does the problem persist if you focus manually? i.e. is it perhaps an autofocus issue?

[dcclark]

Originally Posted by RecurrentNerve

Also, this may seem like a stupid question, but have you accidentally changed the focus of your viewfinder?

To be more specific, there's a diopter adjustment next to your viewfinder. Changing that can really mess with your viewfinder. Try moving that little slider around. I've accidentally nudged mine a few times.

[mrs920]

Thanks, this was helpful and interesting to check out! It really effected the sharpness of the viewfinder... does it have any effect on the actual image on the disc that you upload? I find that the imagine may look OK on the viewfinder but looks blurry when I upload it. Also, now my viewfinder (when all photo info is displayed) is showing a "+1" (assuming this is for the adjusted focus?)... is there a "neutral" position for sharpness with the diopter knob? Why wouldn't you want it extremely sharp all the time? I don't recall changing the diopter but very well could have a while ago...

Is it worth taking the lens in to see if a piece of glass is loose?

[Elmo]

What field is that +1 displayed in? If that is exposure Comp. You will be over exposing giving a false impression of soft focus. Show us a picture and include exif data.

[inkista]

Are you sure you're using the right AF points? Turning off the grid and using only the center focus point and then doing a half-press and recompose may be the technique you need to learn here. The 50/1.8 is notorious for inaccurate AF--particularly in low light. And if you're using the old 300D, it only has the old primitive 7-point AF grid.

I'd also suggest looking at one of your unsharp photos in ImageBrowser, and having it show you which AF point was used. It may be that the AF system chose to focus on something else, and that there really is something else in focus in the photo, it just wasn't focused on what you thought it was.

There could be something wrong with the lens, but technique is most likely the culprit if this is your first fast prime. To test the lens, I'd suggest putting it on a tripod (to eliminate camera shake as a possibility), shooting in bright daytime light at something flat with text (like a calendar) on a wall that you're certain the camera is perpendicular to (i.e., it's all at the same distance from the camera, so DoF won't be an issue). At f/4 (which is the sharpest aperture for this lens). Then manually focus with liveview and 10x magnification to take the AF system out of the equation. If the lens still exhibits softness, and especially if it's softer on one side than on the other, then sending it in for service may be required.

Don't do the slanted ruler test thing unless you have a LensAlign, because there's no way to tell if you actually aimed the AF accurately at a specific distance.

But as I said, technique is the most likely culprit 9 times out of 10.