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03-30-2011, 04:19 PM   #1
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Catch in Focus Advise @ f1.4

Does anyone have experiense using the A50 f1.4 and Catch In Focus?
I'm using a K5

My first attempt was horrible and before I start trying to dial in the focus adjustment I wanted to know if I'm just chasing my tail @ f1.4

Is the a specific technique to getting the best results?

Does anyone know how fast you can focus and still get a sharp image?

Do I have to always come at focus from the same direction?

Is the area used for focus bigger, smaller or the actual size of the indicator in the viewfinder?

Thanks, Joe

03-30-2011, 07:01 PM   #2
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Do I have to always come at focus from the same direction?...Not that I know
Have you tried at other apertures / with tripod?
03-30-2011, 07:18 PM   #3
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If I stop down enough it's fine but I'm looking for an edge in shooting at f1.4
03-30-2011, 10:57 PM   #4
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If you stop down enough then DOF is taking affect. You are ALWAYS focusing Wide open regardless of lens and aperture unless you are using something like a M42 lens on the M setting (that has its own requirement for CIF).

Taken at f1.4 (M 50 f1.4 lens) using CIF on a K7..



http://farm5.static.flickr.com/4004/5134470237_a975c42233_o.jpg

CIF enabled - Check
AF-S set - Check
Center Point AF selected - Check (personal choice)

Practice a little and you'll get there.




Last edited by JeffJS; 03-31-2011 at 09:54 AM.
03-31-2011, 08:36 AM   #5
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Like any photography technique, catch in focus requires a little practice. Be aware that DOF is extremely narrow at f/1.4. The camera should fire regardless of which direction you are turning the focus ring as soon as focus is achieved. How fast? Practice. I have shot motorcycle racing on flat tracks and ice. For that, I let the action come to me. I pick my spot on a turn. Which one depends on the which way the wind is blowing. Then I just fire away with the bikes coming towards me. You can even use burst mode. I'm really not changing my focus much at all. I'll say it again. Practice. The nice thing about our digital cameras is that we can indulge ourselves and shoot a hundred pics to get the one we like.
04-02-2011, 06:54 PM   #6
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Modern focus screens don't show you the DOF of an image faster than f2.8. Either you trust the focus confirmation from the AF sensors, or you just do your best and burst while you sweep the focus through the range.

As for direction from which to focus. I believe it's better to focus from closer to farther. Even if you don't see a difference from one direction or the other, a bit of front focus is better than a bit of back focus, given the way how DOF works, you get more DOF behind the focus spot than in front.
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