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View Full Version : DoF too narrow for focus-recompose?

DigitalRelish
17-01-2009, 17:12
This is mainly aimed at the folks with the 85mm f/1.2 L lenses and the like.

When shooting wide open, what techniques do you use to (auto)focus? I read in another thread that focussing and recomposing was not a suitable technique for shooting at such large apertures. Presumably, this is because the recomposition might move the subject out of the area in focus?

Would this also be something to look out for in, say, a 50mm f/1.4 or a fast-ish zoom such as the 24-70L f/2.8?
puddleduck
17-01-2009, 17:15
Its certainly more hit and miss, and when you recompose you change the angle - and thus distance.

With my Sigma 50mm f/1.4 I tend to use outer AF points on my D700 much more than I would with an f/2.8 where I'd still focus and recompose.
malla1962
17-01-2009, 19:14
I never focus recompose for that very reason,I just use a off center FP.
admirable
17-01-2009, 19:18
I never focus recompose for that very reason,I just use a off center FP.

Same here, it's half the work!
photostar_1
17-01-2009, 19:18
This may be why I am struggling with getting sharp shots when wide open......Hmmmm. Perhaps I should try not using centre point all the time?
melevo
17-01-2009, 19:28
This may be why I am struggling with getting sharp shots when wide open......Hmmmm. Perhaps I should try not using centre point all the time?

im with this reply, i took some shots of my daughter at 1.4 and found them blurry, thats because the af took over and place it to the closest subject. (doh) not to thy self use manual selection!!!:bang:
DigitalRelish
17-01-2009, 19:31
I never focus recompose for that very reason,I just use a off center FP.

Can you explain how you go about this i.e. do you choose the relevant point before each composition?

I usually just use the centre point so that I know which point is in use and it caters for any composition whether I want the point of focus in one corner or against one side or dead centre etc.
HoppyUK
17-01-2009, 19:32
When shooting a portrait wide open, depth of field will be less than 1 inch. That's enough to throw it out when you AF focus and recompose.

I've heard that portrait photographers with this lens use manual focus, and usually on a full frame body which has a much brighter viewfinder than crop, and even less depth of field. Thinking back to my film camera days, I can imagine that this might be the best way.

Richard.
photostar_1
17-01-2009, 19:34
I know I probably should use manual focus, but at a gig (where I shoot wide open) with everyone leaping around the stage, and me and my varifocal specs, I find this almost impossible!
dazzajl
17-01-2009, 19:35
I find the quickest and often most accurate way to get the focus where you want it with very fast lenses is to do it manually.

By the time you've chosen the right focus point for the composition that you want, chances are that you've missed the shot anyway.
HoppyUK
17-01-2009, 19:57
...and me and my varifocal specs, I find this almost impossible!

Pathetic excuse! You'll be saying you're a girl next :D

Manual focusing is a skill we've all fogotten with such good AF systems, including me. But if you have big, bright viewfinder, ie full frame, and shallow depth of field so that the sharpness snaps in and out quickly, then with practise it's quite possible to follow a subject and keep it permanently in focus manually. It's quite liberating not to be staring at those damn red squares all the time, and just see the image on a clear screen.

Sports photographers with long lenses used to be really good at manual and choosing new lenses with focusing rings that always moved in the same direction was crucial. It was sometimes the one thing that kept Nikon and Canon users from switching - they focus in different directions :lol:

Richard.
DigitalRelish
17-01-2009, 20:09
Why did Canon drop eye-controlled auto-focus point selection? I thought it was a great idea and it seemed to work well on the EOS 5. It seems natural that you're going to be looking at the subject you want in focus at some point anyway so why not use the eye to choose the appropriate autofocus point?
malla1962
17-01-2009, 20:28
Can you explain how you go about this i.e. do you choose the relevant point before each composition?

I usually just use the centre point so that I know which point is in use and it caters for any composition whether I want the point of focus in one corner or against one side or dead centre etc.Just frame the shot then select the focus point.;)
pxl8
17-01-2009, 20:49
Selecting focus points is a bit quicker if the body has the thumbstick as you can use it to jump around the points very quickly :thumbs:
DigitalRelish
17-01-2009, 20:57
Maybe it's just me, but having to do that all the time would drive me nuts especially with subjects that aren't static. One of the reasons why I stick to using the centre point is that it's faster and less likely to result in a wrong button being pressed or the joystick being pushed in the wrong direction.
pxl8
17-01-2009, 21:00
Don't knock it till you've tried it.

Moving subjects you don't need to keep moving it, you just keep the point you selected over the subject - much easier than either framing with the subject centered all the time or trying to focus and recompose whilst the subject is moving :nuts:
DigitalRelish
17-01-2009, 21:10
I will try it!
HoppyUK
17-01-2009, 21:55
Why did Canon drop eye-controlled auto-focus point selection? I thought it was a great idea and it seemed to work well on the EOS 5. It seems natural that you're going to be looking at the subject you want in focus at some point anyway so why not use the eye to choose the appropriate autofocus point?

Good question. I never used it but can only assume it wasn't very reliable, which kind of figures, although you stae otherwise in the EOS 5. How did it cope with glasses wearers?

Richard.
DigitalRelish
17-01-2009, 22:42
Good question. I never used it but can only assume it wasn't very reliable, which kind of figures, although you stae otherwise in the EOS 5. How did it cope with glasses wearers?

The EOS 5 wasn't mine so I only got to play with it for a while, but it worked flawlessly for me, someone who didn't/doesn't wear glasses once it was trained to my eye. I recall it was supposed to work for people who wore glasses too.

Looking through the forum (http://www.talkphotography.co.uk/forums/showthread.php?t=63365&highlight=eye+controlled+focus), it seems people had very different individual experiences with the technology.