[Larne]

Hi,

First post (although I have been a reader for a little while) so hello all.

I have done some searching on my problem and didn't find anything specific but obviously I apologise in advance in case this is something that someone has already covered.

Okay, on with it. I have had a 400D for a while now, great camera and I like it a lot, but since I started playing with my images in Photoshop I have become aware that they are a bit soft. No major problem with that, I have been using the stock 18-55mm that comes with the kit I am happy consider that what I am running into are the limitations of the lens.

Digging through some of my gear the other day I found an EF 50mm f/1.8 lens that I must have had around 10 years so I thought I would give that a try and see how I got on. After returning from a day out with the family I was horrified to discover that every image I had shot was out of focus.

The light was poor so I had left the lens wide open at f/1.8 and for most all shots I was using spot focusing on the target's face then, holding the focus lock, recomposing and taking the picture. What was more noticeable was that not only was the face always blurred but that there would be some part of the picture that was closer to the camera that was always in very sharp focus.

This looked a lot like the camera was focusing just short of the actual selected target so I ran some experiments. Using some sections of tree trunk in the back garden I experimented with the 50mm and discovered that the focal plane (if that is the right term) appears to be just in front of the point where I am focusing. This is very apparent at f/1.8 but becomes much less apparent as the aperture gets smaller (as you would expect).

What I am not sure about is whether this is a problem with the 50mm (which is pretty old) or something more fundamental with the camera. With a max aperture of f/3.5 at 18mm on the 18-55mm it is hard to tell whether it is missing the focusing point, although my experiments make me suspect that it is.

I have had many Canon film cameras before and have never had cause to question the autofocus which has always been brilliant. Perhaps I am merely doing something wrong but if so I don't know what as I am doing the same as I always have in terms of focusing and composing shots.

Does anyone have any thoughts or suggestions? Is it just the lenses? I have a EF 28-135mm IS USM on the way so will be repeating the experiments with that when it arrives to see if I get any different results.

Thanks in advance for any comments.

Niall

[P-E]

I can only advise that if you google for the 'D70 focus chart' which you can print off and test your lenses.

I'm sure someone else will be along to help further

[Chris H]

Have a read of this thread


Canon EOS 400D

[Dabhand16]

Also this might be of interest too.

[Larne]

Hello again.

Thanks for the prompt and informative responses.

The D70 focus chart is an excellent idea. Using that the line where I get sharpest focus on my 50mm is the one marked 10mm in front of the focus point. I tried it on f/1.8 and f/2.8 and I get the same result in both cases. So it looks to me rather like the lens is past it - it is old (it was second hand when I bought it a decade ago) and today I actually had it lock up at f/2.0 and cause the camera to shut down with an Er99 so I am guessing I need look no further.

Results on the EF-S 17-55mm are much more encouraging. At 17mm f/3.5 the target is perfectly sharp with the depth of field extending approx 1/3 in front of the point and 2/3 behind (as I understand it should be). At 55mm f/5.6 it is perfectly in focus, to the extent that I can actually see the texture on the paper. Sure it is soft but a quick run through the Unsharp Mask filter on Photoshop elements turns it nice and crisp.

Thanks again for the help. At least now I know the problem is the 50mm lens and I will be disposing it once I work out the best way of recycling it. I will run the same tests on the EF 28-135 when it arrives and hopefully they will be positive.

Cheers,

Niall

[Markulous]

You could always use that 50mm as a manual focus lens (as per the older M42 lenses) - oh, and to Pixalo