Manual focus question

Started 2 months ago | Questions thread
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DavidWright2010 Senior Member • Posts: 1,081
Manual focus question

So I wandered around the garden this afternoon, using the (manual focus) Rokinon 135 mm f/2 lens. I shot at f2.2 to stress the focus accuracy. The auto-focus area mode was set to 'spot'.

Shooting hand-held, I adjusted focus until the focus system beeped, and snapped the picture. In some cases the focus was perfect on the spot I had focused on:

I focused on the stamen in the lower left

I focused on the stem of the orange

Other cases showed front-focus

I focused on the large background leaf

Or back-focus

I focused on the bud, but the background leaf is sharp

Or no focus at all

I got a focus beep on the right-most crabapple

So I thought to test my technique. Here is a 45 degree angle test - focused on the pencil - comparing (left) focus from infinity down to a focus beep (center) focus from near to far until a focus beep, and (right) focus using live view.

There is a slight tendency to give a focus indication early (look how the focus from near to beep - in the center- has way more focus in front of the pencil. But in all cases the pencil looks good.

So then I thought that perhaps the area considered for focus test is bigger than the square one sees in the viewfinder. There is a description on p. 64 of the manual on how to change the size of the focus area, but it does nothing in viewfinder focus mode.

Sorry for that long description. My question is, at f/2.2 should I expect a keeper rate of only 50-60%, hand-held and viewfinder focus confimation?

Or is there something wrong with my technique?


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