Canon 50mm f/1.8 not focusing properly

thisdoesfine

I'm having a problem with focus on my T3i and the 50mm f/1.8 lens.

I'm still new to dslr's as we just got ours in April 2014 and this 50mm lens less than a month ago.

I'm mainly taking photos of my 1 year old daughter. I keep the shutter speed high because she's obviously not posing. I know using f/1.8 isn't great so I usually put it at f/4-5.6.

Still, the AF doesn't seem to grab what I'm focusing on. I use the AF setting with the center red dot. I put it on her eyes and take the shot and it usually ends up focusing on her shirt, nose or hand. It's more noticeable the smaller the f number with f/1.8 obviously very noticeable.

I use the highest shutter speed possible and even when I don't care about the white balance and just flash the crap out of it, the focus still doesn't seem to be on point.

I keep ISO at 100 as well and try to shoot mainly in Manual or Aperture modes. Portrait seems to always want to use f/1.8

Any suggestions or things I can try?

ohyeahar

First thing I would do is make sure your autofocus is working correctly. Just line up a couple of items at different distances from you. Photograph each one and see if your focus misses the mark.

Once you've established that your AF is working fine, I have the following suggestions for you:

You mentioned you like to keep your shutter speed as high as possible. With a 1-year-old, I feel like 1/125 is more than adequate unless she's really thrashing about. In those instances, 1/250 is definitely fast enough. The point is to slow down your shutter. It's not necessary to use something like 1/500 or faster. Sports photography are done at those speeds. I'm sure your child is not THAT fast yet. =)

You mentioned you stop down your aperture to f/4 or smaller. That's fine. It's up to you, but it's still ok to shoot wide open. I often photograph my own kids wide open at between f/1.8 and f/4. If I need more depth if field I just step back a bit. As long as you’re not at your minimal focus distance, then you have a pretty good depth of field even at f/1.8.

ISO 100 is great obviously because that gives you the best image quality. By being hesitant to bump up the ISO, you're are limiting yourself needlessly. It's pretty hard to tell without pixel peeping the difference between ISO 100 and 800. Most cameras give sufficiently clean shots at ISO 1600. If you’re going to make prints at 4x6, ISO 3200 still looks pretty clean.

thisdoesfine

I've still been trying to figure this out and I've done a few test shots on a tripod. I think I may have a lens with front focus (just learned that term). Here's a link to a test shot I did on a tripod with aperture priority.

The focus is on the black line text in the middle of the page. If you look to the sides you can see the focus seems to be closer to the camera.

Has anyone had this issue with a new lens and had Canon replace it? I'm about 60 days out from purchase so I don't think the store would take it back.

Are there still things I could do to fix this? Am I off in my thinking of where the focus is?

Thanks for any feedback y'all!

http://taleof3.byethost8.com/images/frontfocus.jpg

Exif data:
f 1.8
1/100
50mm (obviously as this is a nifty fifty)
Flash

thisdoesfine

I forgot to mention that although I didn't upload the pictures, the same thing continues as I move the f stop number bigger.

ohyeahar

It does look like there’s front focus going on, but that picture isn’t very conclusive.

Could you try another shot?
-Mount cam on tripod.
-Use Av mode, set aperture to f/1.8 and ISO to 100.
- Use timer or remote release.
- Angle that sheet of paper up a bit more, perhaps at around 45 degrees.

Then upload the full resolution shot and share it with Dropbox, Google Drive, Flickr, etc. Any service that allows full res upload and download is fine. The shot you uploaded was compressed so heavily that it’s unclear what’s compression artifacts and what’s softness.

thisdoesfine

I haven't got around to setting up the test shot again. I did, however, take some shots outside at my local disc golf course and I've uploaded the photos to a google drive to share. I did not use a tripod but I don't think it would have helped. My focal point was manual and on the basket. All of my shots that day came out this way where the focal point on the actual picture is not where it should be. I half pressed my shutter and didn't move the camera around after doing so. Here's the link. I'll be doing a test shot scenario again soon and will also upload those. I'm getting frustrated with this lens (or me) though. :(

https://drive.google.com/folderview?id=0B1CnT_VStbvWTmhNZFlRQlg5LVE&usp=sharing

thisdoesfine

I updated the contents of the shared folder I reference above. It now has new test shots done on a tripod with the same chart in the initial post. I made the paper as close to 45 degrees as I could and then I also did some test shots with batteries lined up in an angle. The focal point is always on the black line on the paper and the 5th battery from the left or the 1st from the left (obvious which). Some shots were done in live view (no apparent front focus) and others were done via the viewfinder (front focus apparent in my opinion).

Thanks for any help anyone can provide.

I'm really wondering if the front focus I notice is within the normal accepted range or if I should buy another or send this in for repair.

I realize it's only a $125 lens, but I don't just have $125 laying around at the moment.

:)

Moose

@thisdoesfine - I took a quick look at the photos on my iPhone and I agree with @ohyeahar, I don't think the front focusing issue is conclusive. I'm wondering if you're just experiencing the effects of a shallow depth of field.

At f/1.8 the depth of field is so shallow that even the slightest movement (you or the subject) will throw the intended subject outside of the field of focus. At f/4 to f/5.6, the depth of field is much wider, but if you're close the the subject you can still run into issues where some movement by you or the subject will take them outside the optimum focus area.

With regards to landscape shots, you shouldn't shoot any lower than f/8 to really maximize the depth of field and put more of the scene in focus. Professional landscape photographers will many times shoot at f/11 and take a series of shots focusing on the foreground, middle and background and then combine the images into a single landscape shot where everything is in sharp focus.

Anyways, you might try taking a few shots where you fully press the shutter with the focus point on your subjects eyes. For the test, try to find an adult who can remain still through the shot so you can determine if you really do have a technical issue with the lens. Happy shooting!

thisdoesfine

Thanks for the replies everyone. I actually ended up going and buying a new 50mm f/1.8 at the local electronics store. I told them my intentions were to troubleshoot and asked if I could return the lens if I got the same results indicating either camera or user issues and not the lens. They said no problem and the new lens is much better. The lens I used in the shots above is still under warranty (3 months old), but I think I'm just going to sell it on ebay instead of sending it for repair, note my perceived issues with it and hope I get the majority of my money back.

As for using the f/1.8 on the landscape shots, I wasn't really looking for a nice photo. I just wanted to see where the focus ended up. Thank you for the ideas of multiple focal points though, I'm gradually learning post processing and that would come in handy if I did want a nice shot of a scene totally in focus! :)

Have a blast shooting!

Moose

Glad you got it sorted out @thisdoesfine. Focusing issues can be a real pain in the neck. Please don't be a stranger. If you come across any interesting tips or tricks for the T3i, please do share them with the forum. You're insights and experiences are welcome here anytime!

flylooper

I agree. At such low f-stops the focal plane is so thin that hand holding the camera becomes a real liability. Even breathing while holding the camera could interfere with the focus. Best to raise the f-number (f/8?) and the problem will go away (it should at least).

BTW, why sell the defective lens on eBay? You're just handing off your problems with the lens on some other fellow who probably wants to do what you wanted to do with it. Get it fixed or trash it, or at least explain your problems with it in the description.