focus issues? (see photo)

mwphotography · Jan 31, 2014

Attaching a photo I made with my Canon 5D (mark I), 50mm 1.2L lens. Shot in manual at ISO400, f1.2, 320/sec. Auto-focus mode. Was using a center focus point with back button AF; I focused on the roses in tea strainer and then recomposed. Have noticed focus issues for a while, and would like some advice... Is this a depth-of-field problem? Or maybe it's just me... Incidentally, I love this lens. Just wish I could make better pictures with it.

Edited to add: maybe it doesn't look so bad after all... I just wanted the roses in the strainer to look crisp. Maybe this is a noise issue...? Any and all comments welcome. Thanks so much.

Bossy · Jan 31, 2014

1.2 has an incredibly small focal plane. Stop it down a couple.

Derrel · Jan 31, 2014

Multiple factors might be involved. A few factors: focus micro-adjust for that lens at close range; slight difference between focus-and recompose distance and the use of a specific AF point located exactly over the subject's physical location within the final composition; slight movement of the camera between the focusing stage and the moment of exposure;VERY shallow DOF at such close range means almost zero margin for ANY factors.

SHooting at f/1.2 from very close-range demands that almost everything be perfectly done. Focus and recompose's error in distance could,and probably does, exceed the actual depth of field at that close distance.

What makes focusing by EYE difficult is that the 5D-II's viewfinder screen shows the apparent depth of field of a lens of about f/4.8; the grind on the viewfinder screen does NOT show the true, shallow DOF of the f/1.2 max aperture, so when you try to focus BY human hand and eye, the feedback the screen gives is NOT all that helpful!

In situations like this, one of the oldest methods is the best: focus bracketing, and picking the DESIRED best result from multiple frames...

robbins.photo · Jan 31, 2014

mwphotography said:
Attaching a photo I made with my Canon 5D (mark I), 50mm 1.2L lens. Shot in manual at ISO400, f1.2, 320/sec. Auto-focus mode. Was using a center focus point with back button AF; I focused on the roses in tea strainer and then recomposed. Have noticed focus issues for a while, and would like some advice... Is this a depth-of-field problem? Or maybe it's just me... Incidentally, I love this lens. Just wish I could make better pictures with it.

Edited to add: maybe it doesn't look so bad after all... I just wanted the roses in the strainer to look crisp. Maybe this is a noise issue...? Any and all comments welcome. Thanks so much.

Well if you look you'll see that part of the image is in sharp focus, the problem appears to be your DOF or Depth of Field. By shooting wide open at 1.2 and being so close to the subject this gives you a very narrow DOF, so only those items that are on the same horizontal plane as your focus point are going to be sharp, the further you move away from that horizontal plane the blurrier things will get.

Try stopping down the lens. You can do this by increasing the aperture number, which decreases the amount of light coming into the lens. That might seem backwards but the reason for that is that apertures are actually expressed in fractions, so the higher the number the more it closes the lens and the less light it allows to pass through.

By stopping down the lens you'll increase your depth of field, which will make other portions of the image sharper as you move further away from the horizontal plane on which whatever point you've focusedon resides.

Braineack · Jan 31, 2014

recomposing at f/1.2 while shooting something close?

KmH · Jan 31, 2014

F/1.2 and a close point of focus (PoF) distance delivers an incredibly shallow depth-of-field (DoF).

Many new to photography do not consider how the PoF distance also affects the DoF. Online Depth of Field Calculator
Using f/1.2 but increasing the PoF distance makes the DoF deeper.

But if you need to use a close focus distance, using a smaller lens aperture (bigger f/number) is the way to make the DoF deeper.
Understanding Depth of Field in Photography

mwphotography · Jan 31, 2014

Thanks for the replies! I really appreciate it.

Derrel, you've given me something to think about. It's probably that I'm focusing and then recomposing, which is silly especially at such a shallow depth of field...

Is that what you mean, Braineack? To clarify "recompose" here's what I did: I used the center focus point, pressed the AF button on the back of the camera body, shifted the camera ever-so-slightly to get both items in the frame, and then snapped. That slight shift ruined my focus didn't it...

Come to think of it, I should have simply toggled through the focus points and selected the one that was directly over my subject. Correct?

I tend to overthink.

To provide a little background: I've been a wedding photography second-shooter on-and-off for five years. Considering starting my own business... You're probably thinking I should have figured this out by now! Ha!

Don't get me wrong, I fully understand DOF. I think I've just underestimated how shallow 1.2 really is. I've come to this forum hoping to expand my technical knowledge. I really need it. So any and all help is welcomed and wonderful.

Thanks!

Edited to add: I'm shooting with an original 5D... Any thoughts on clarity or noise with this body? I don't know how many actuations it has ...purchased used in excellent condition.

Also: besides focusing on a single eyelash, for example, and creating creamy blur, tell me: what else is 1.2 good for? I researched before purchasing this lens and sometimes wish I'd saved money and bought the 1.4...

robbins.photo · Jan 31, 2014

mwphotography said:
Thanks for the replies! I really appreciate it.

Derrel, you've given me something to think about. It's probably that I'm focusing and then recomposing, which is silly especially at such a shallow depth of field...

Is that what you mean Braineack? To clarify "recompose" here's what I did: I selected the center focus point, pressed the back button AF button, shifted the camera ever-so-slightly to get both items in the frame, and then snap. That slight shift ruined my focus didn't it...

To provide a little background: I'm just starting my own business after second-shooting for five years. You're probably thinking I should have figured this out by now! Ha! I do understand DOF. Makes perfect sense. (But still appreciate the feedback, however.) I think I've underestimated how shallow 1.2 really is. I've come to this forum hoping to expand my technical knowledge. So any and all help is welcomed and wonderful.

Thanks!