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A question of focal sharpness


jim_ford

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With my cameral securely mounted to a tripod, I plan to photograph a certain forest path which my wife and walk nearly every evening. The plan is to shoot this path from one vantage point during each the four seasons, then mount four exposures under one piece of glass.

The vantage point is important. There is a subject of interest approx. 12 feet in front of the camera and then the path recedes about 150 yds into the distance.

Composition dictates the lense will be 50'cron. My questions is what F stop will give the most acceptable focus. I've read that 5.6 to 8 is the 'sweet spot' but then stopping down to 11/16 will give sharper depth of field. I certainly will experiment but was wondering if anyone had an opinion.

As always, thank you.

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Jim:

 

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The 50 f2.0 does loose a tad of sharpness at f16 compared to f5.6 or

f8, but that may not be as important as the extra depth of field

you'll get depending on what you are after. Take several shots at

different apertures and also maybe focus bracket. You should be able

to get everything in focus from 12 feet to infinity without much

trouble.

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The markings on my Summicron 50mm lens indicate that f/11 will cover from 12 feet to infinity. Is this lens similar to the "50'cron" you mention? Depth-of-field tables probably give more exact numbers. I would be disappointed with any Leica lens if I had to worry whether it would give a good enough inmage at f/11 or f/16 as compared with f/5.6 or f/8. Thaat is to say, why lay out the money for Leica gear if this is going to be a serious consideration with it?
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I have read that some landscape photographers, when using hyperfocal

settings, under estimate the marking's ability to render the maximum

amount of sharpness. Since in real life, focus is actually on a

plane... and the degree of "unsharpness" is dependant on

magnification and the f-stop. The degree of "acceptable" softness is

what the depth of field settings indicate. if very critical

sharpness is required, many photographers use the depth of field

markings for one f-stop less than what is actually set for the

exposure. If the exposure is using f11, then set the infinity mark

to the f8 DOF marking.

 

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Each composition has a portion that HAS to be sharp and parts that

can go slightly soft without effecting the overall pictorial effect.

If you must choose, I'd put the focus on the foreground object at the

expense of infinity sharpness. foliage will blend together in the

background, but a larger foreground object would jump off of the

print if it is soft. I often bracket my DOF, just like some folks

bracket exposure... then I pick the one that works best.

 

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Since you are going to work on this for a year, it would be worth a

roll of test film now to establish your process. Write down all of

the parameters for the test... distance, f-stop, framing, etc... and

upon reviewing the test shot, pick the ones that work for you. When

it is time for the real ones... just set everything the same, and

there you go.

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