Back Focussing 50mm 1.8?

Guitarman0 · 27 Jan 2012 at 21:35

I received my canon 50mm f1.8 in the post today and have got a bad feeling it is back focussing

Here are some sample shots I took with the number 11 set right inside the center focus point. RMA time?

f1.8

100% crop

f2.8

100% crop

Invertigo · 27 Jan 2012 at 21:38

Try this chart

The camera should always focus on the black line, because it won't pick up the light grey, whereas a ruler could cause slight error.

theheyes · 27 Jan 2012 at 22:01

It's front focusing slightly, but it doesn't actually look that bad to me although it's hard to tell without using the lens. What made you think there was a problem? Were you getting soft shots or did you test it out of the box? Another thing I found with my 50 1.4 that front focused (by 4-5cm) was that it did miles better outside. In my experience indoor lights, especially fluorescent, can be really iffy.

Demon · 27 Jan 2012 at 22:35

You really want to do as someone mentioned, print a proper Focus check chart out, which will have a single focal point, that would be more conclusive proof..

But it wouldn't surprise me if it gave similar results..

Didn't someone say the other day that microadjust in-camera wasn't a handy feature? It sure saves going through RMA etc

Guitarman0 · 27 Jan 2012 at 22:36

theheyes said:
It's front focusing slightly, but it doesn't actually look that bad to me although it's hard to tell without using the lens. What made you think there was a problem? Were you getting soft shots or did you test it out of the box? Another thing I found with my 50 1.4 that front focused (by 4-5cm) was that it did miles better outside. In my experience indoor lights, especially fluorescent, can be really iffy.

I took a few photos of my mum and although I thought I had focus bang on her eyes it came out with focus more on her forehead however she was a moving subject and I have never used a lens above aperture 3.5 so it may have been my fault. Just finishing off photos of that chart and will post here when done. Thanks for the help so far.

Guitarman0 · 27 Jan 2012 at 22:48

Well here are the pictures from the chart and I am starting to wonder if there is a problem after all. Looking at the shot at 1.8 I still think it is fron focussed slightly but is this worth RMAing for? Or is the lens just fine?

1.8

100%

2.8

100%

4

100%

5.6

100%

Guitarman0 · 27 Jan 2012 at 23:02

After doing some more playing around I have tried autofocussing on a point and trying to correct it with manual zoomed in 10x in live view and I can't seem to get it any sharper. I think my problem is I was expecting it to be sharper at f1.8 than it is. Will test it more tomorrow.

Demon · 27 Jan 2012 at 23:02

That looks bang on to me, you can expect very minor errors as, it may picked the rear or the front of the target line as a worse case.

To me that looks not too bad at all..

mithrandir · 27 Jan 2012 at 23:13

Looks like a good lens to me.

dannyjo22 · 27 Jan 2012 at 23:14

Spot on to me, pixel peeping is bad for your health and sanity!
I had a 17-55 that was out I tried for a year to get to grips with it, in the end I sent it away for calibration and it was out.

The 1.8 is particularly poor at 1.8 but yours on a tripod looks about as good as you will ever get.

Guitarman0 · 27 Jan 2012 at 23:48

O.k. thanks guys. I guess it was just that initial worry that something might be wrong

(I have had more than my fair share of faulty goods bought from online!).

Cheers

joxang · 27 Jan 2012 at 23:50

Looks completely spot on dude

.

Purgatory · 28 Jan 2012 at 00:57

Looks fine to me that lens after you used the focus charts. I wouldn't worry about it being faulty, it looks in perfect health and working in the margins it was designed for.

=XDC=FluphyBunny · 28 Jan 2012 at 09:47

I doubt an L series lens would be any better than that

Have fun its a great little lens, love mine