Focusing Issue

[denise_gaywood]

<p>Hi, I have a problem with the focusing on my 1100D.<br>

For xmas i was given the camera, and have now purchased to go with it a canon EF 50mm f1.8 lens. I was told this would be a good initial lens to help with portraits.<br>

My problem is when i focus on the subjects eyes, the red dots flash over the eye and 2 or 3 other points of the 9 points as well. BUT the eyes are slightly out of focus on the photo, and the middle of the forehead is actually much sharper than the eyes. </p>

<p>Please look at the attached image:</p>

<p><img src="https://dl.dropbox.com/u/13606141/IMG_7561.JPG" alt="" /></p>

<p>i cant for the life of me figure out why the point where i focus is blurry, but where im not focusing is sharp ?</p>

<p>Any help is much appreciated.</p>

[newmanuk]

Hi Denise .Welcome to Photonet, The lens you have is good for portrait work. Could I guess that this shot was taken with the lens wide open i.e at F 1.8 ? If so you have a very small depth of field to use As you observe the hair is pin sharp , try the same pose but use manual focus instead. Hope that helps ( joys of photography ...eh ! ) Regards miken

[newmanuk]

Try setting the AF point to single (center) In the manual it comes under selecting af point Hope that helps Miken

[mark_pierlot]

The AF array is picking up the nearest parts of your subject (tip of nose and closest part of hair). As Mike advises, diasable the outer focus points and use only the center point to focus directly on an eye (or whatever). Do this several times to rule out other factors. Also, unless you're using a tripod and your subject is very still, use a higher f/stop (aperture setting) to increase the depth of field. (The DOF at f/2.2 is pretty shallow, especially at close range.)

 

 

 

 

 

 

 

 

 

 

If the problem persists after this simple test, your lens is probably front focusing and needs to be calibrated.

[jamesgysen]

<p>Denise, I would tend to recommend Mikes second post and use the center AF point to lock focus on the near eye, then re-compose to your desired framing. Ensure your AF is also on Single Shot so the camera doesn't try to refocus as you re-compose. This camera and lens camera will do a very good job for you, just keep up the practice.</p>

<p>EXIF says f2.2 for those wondering.</p>

[chrisnielsen]

<p>If you move even slightly after locking focus you can have this issue too.</p>

[denise_gaywood]

<p>Hi all, many thanks for your replays. I have set the focus point to the centre point only and set the af to single shot, and now the aperture is set at 2.8. i have taken several shots in a row and can confirm that the forehead/eye brows are always sharper then the eyes.<br>

I am interested in the front focusing issue mentioned by <a href="/photodb/user?user_id=3882389">Mark Pierlot</a>, is there anyway i can prove this is happening, and how would i go about calibrating?<br>

Thanks again<br>

Denise <br>

</p>

[newmanuk]

On the main page try typing in focus testing .. by Bob Atkins Takes you thro the facts and figures Denise Miken

[JDMvW]

<p>Manual focus on the eyes, and have the camera on a tripod so's your body doesn't sway back and forth to change the plane of focus (which, as said) is quite shallow at f/1.8.</p>

<p>Autofocus is great, but it always has at least some cushion from depth of field in normal shooting. That's why MF is sometimes necessary.</p>

[neill_farmer2]

<p>At 2.2 the depth of field is very short. As seen the camera is getting it close. I think if Denise closes down a bit to f3.5, f4.5 then all would be in focus. There needs to be a bit of experimenting to see at what f number the subject is nicely in focus but the background remains blurred. The 1100D does not have AFMA, which I don't think is needed here. One of the difficulties with manual focus is that it is very difficult on crop cameras, and more so in lower light situations. I endorse going to centre point AF, at least then there is some control over what the camera focusses on.</p>

[peter_e]

<p>I agree with Neill. Even with a tripod, the subject may not hold still enough for focus and recompose with aperture wide open or MF. Close the aperture a bit and use center point AF.</p>

[JDMvW]

<p>Of course, it goes without saying that you also have to screw down the <em>subject</em> firmly to prevent their moving. :)<br>

My personal favorite portrait sitter is easier to handle.</p><div></div>

[beautox]

<p>It's all very well suggesting manual focus, but it's an EF 50 f/1.8...not very good for manual focus. The problem is not that the autofocus is not accurate, but that it's locking onto the wrong thing. The posters who have suggested using the center point are all correct imho. It would also be a good idea to stop down, if possible, to about f/4 to 5.6, to give a bit more depth of field, so the whole face is in focus</p>