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maxlyons
Joined: 20 Jun 2003
Posts: 3345
Location: USA
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 Posted: Tue Feb 19, 2008 8:30 pm Post subject: Re: TuFuse: Focus and Exposure blending software |
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| rjacobs wrote: |
How do you determine the number of focus increments for a scene? This one for example. Thanks.
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Educated guesswork.
In theory, if one had a DOF calculator, a ruler or measuring device, and a camera that allowed adjustment of focus in extremely accurate increments, one could calculate the precise distances at which to focus the camera so that the entire scene was captured within the DOF of at least one frame. In practice, I don't have either the equipment or patience to use this approach!
Max |
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Terrywoodenpic
Joined: 06 Mar 2006
Posts: 350
Location: Saddleworth England
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| Posted: Wed Feb 20, 2008 5:19 am Post subject: Re: TuFuse: Focus and Exposure blending software |
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| maxlyons wrote: |
Educated guesswork.
Max |
many beginners do not appreciate how much of photographic practice depends on prior learning and experience. much of it condensed into quite subconscious rules of thumb.
How much we consider to be in focus is mostly subjective, as a lens can only have one plane of best focus at a time (which may be curved).... everything closer or further away from that plane is to one degree or another out of focus.
One could construct a table of distances at which to focus for a particular lens, and aperture, that would cover distances from inches to infinity with reasonable sharpness.
But why bother as the result would be based on a chosen circle of confusion, which itself is based not only on maths but on viewing conditions, and subjective criteria. None of which take into account of the quality of the sample lens and its capabilities.
As Max says, Educated Guesswork is what works.
For the photograph in question... I expect the close focus was some where around the Leaf... the second was around the rock in the close middle distance and the last near infinity. Only Max would know for sure.
You need to remember depth of field is dependent on distance.
close distance conspire to less depth of field.
You can get some Idea of the distances to set if you consider old cameras with Zone focussing... they had marks for close ups, groups and distant mountains. for most people this worked very well, they of course had no Idea of the math behind it.
_________________
Terry
After 60 + years in photography, Now Down sized to Canon G6 Digital and Olympus OM1n film cameras, and accessories. Now up sized/added a Canon 40D and minolta G600 |
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rjacobs
Joined: 04 May 2007
Posts: 81
Location: Virginia
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| Posted: Wed Feb 20, 2008 11:32 am Post subject: Focus increments |
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Max, Terry,
Thanks for the reply.
Richard |
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