How to focus on eyes (Continued......)

bomberman

bomberman

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Following on from the thread that got a little bit out of control...

http://www.talkphotography.co.uk/forums/showthread.php?t=203575

I have a few more questions about eye focus:

I was out with my softbox and a model and a 50mm 1.8 the other day, and i'd decided i like the bokeh of this lens best at f/1.8 so that's what i wanted to use (the nifty fifty 1.8 only has 5 aperture blades so bokeh ain't the best stopped-down). So i used the "focus re-compose" method using the nearest AF point to get the eyes in focus. My camera is just a 400d, it dosen't have fifty-odd focus points or any fancy focus-tracking mechanism, just 9 af points.

Looking back through my pics it seems to have worked in about 70-80% of them. and i took a couple of hundred. some are obviously blurred due to the model pulling faces at me (!), some are slightly back-focused, some are borderline being very sharp and come up well in PP, and a handful of them are PIN sharp.

So i think i did well, BUT a couple of things are bothering me. When i got up close for a full face and she had her head turned at about 30-45 degrees to the lens i was finding that i got one eye in and one eye out of focus. Is this because i'm shooting at 1.8 and there isn't enough DOF? In all cases the eye furthest away was the brightest, so that's the one i used to lock onto with AF. Would it help if i focused on the nearest eye? where does DOF start?

secondly, i was having problems in low light. this is a trait of the AF with this lens if there's not enough contrast on the eye then it hunts for focus. At one point she asked me "why is it making that funny noise??" :lol:

What do you do to get around this? In the really dark shots we took at night i had to resort to getting her to shine a torch light in her face while i got a focus lock-on :lol: I got a lot of errors this way, probably because by the time she'd brought her hand down again she had moved her head. Fair play to her though she was cooperative :thumbs:

Here's a sample of an OOF one so you can see what im talking about
http://i186.photobucket.com/albums/x294/mrlovelady/IMG_0095.jpg?t=1266667433

Staff Edit : Image(s) removed. (Link(s) left in place). Pictures must not exceed current forum limits as per the rules. Please feel free to replace this with a fresh/resized image and remove this text :)
 
Not sure there's a way round the hunting apart from upgrading your lens. I found the 50 hunted like crazy in low-light. 85 seems much better.

If the subject's eyes are different distances from the camera then there's nothing you can do about getting them both in focus, apart from stopping the aperture down a bit.
 
Try manual focusing? I've always been wary of manual focusing, but it's about learning to trust your own judgment. As time has gone on, I'm finding that I'm getting really good results.

Also, have you got a decent flash unit? Try using the focus range finder thing with whatever AF point you want to use, but with the flash itself obviously turned off.
 
It is the narrow DOF.
Using the brighter eye was quite a good idea, but if you are using such a narrow DOF it usually looks best with the closest eye in sharp focus :thumbs:
 
Always focus on the eye nearest to the camera - it looks wrong otherwise...
 
bomberman said:
Following on from the thread that got a little bit out of control...


What do you do to get around this? In the really dark shots we took at night i had to resort to getting her to shine a torch light in her face while i got a focus lock-on :lol: I got a lot of errors this way, probably because by the time she'd brought her hand down again she had moved her head. Fair play to her though she was cooperative :thumbs:
]
Click to expand...

You hold the torch not the model, but don't use a very bright LED one like I did once :nono: A model throwing a hissy fit is never very nice to witness :naughty:
 
I found the 50 hunted like crazy in low-light. 85 seems much better
Click to expand...

85mm 1.8 is deffo on my wish-list.

Try manual focusing?
Click to expand...
Also, have you got a decent flash unit? Try using the focus range finder thing with whatever AF point you want to use, but with the flash itself obviously turned off
Click to expand...

I might give it a try, but i don't think my YongNuo flash units allow me to use the AF assist with the flash disabled. that did cross my mind though. it's a shame the AF assist won't work off camera.

it usually looks best with the closest eye in sharp focus :thumbs:
Click to expand...
Always focus on the eye nearest to the camera - it looks wrong otherwise...
Click to expand...

Thanks i'll give it a try. Does the DOF begin from the point of focus then?
 
DOF is roughly a third in front of the focus point and two thirds behind. As long as you don't have any front/back focus issues then the maximum sharpness is bang on the focus point.
 
just make sure you don't take any pics at ISO 2000. I hear that makes the eyes out of focus. :D
 
there are times when manual focus has its good points..usually when auto isnt doing the job properly
 
How do people use manual focus? When focussing on someones eye thats 3 meters away from me I can barely see their eye through the viewfinder, let along see if it is in focus, am I missing something?
 
joescrivens said:
How do people use manual focus? When focussing on someones eye thats 3 meters away from me I can barely see their eye through the viewfinder, let along see if it is in focus, am I missing something?
Click to expand...

at 3 metres you may be using a long lens
doesnt your camera have a split image finder or microprism
mine doesnt but i dont get the eyes sharp all the time and rely on autofocus
 
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