Usability of Zone Focusing

Started Oct 22, 2020 | Questions thread
Gerry Winterbourne Forum Pro • Posts: 19,063
Re: Usability of Zone Focusing
13

Gurusathiy wrote:

A newbie here!! I'm an enthusiast landscape photographer and request inputs from members here on my confusion regarding manual focusing vs auto focus conundrum:-( I've read many articles on this but don't find a direct answer to my dilemma and hence posting this:

  1. I use Sony A6000 with a Zeiss auto-focus lens. I want to set focus once for all (either auto-focus lens/Manual focus only lens)

That will work as long as the subjects you want sharp are always the same distance from the camera. As soon as the distances change so must focus.

  1. and forget about focusing issues.

I'll talk about this later.

  1. I find auto-focus slow to my liking.

I don't understand this. AF takes at most a second or two - where is your landscape going to go in that time?

  1. When I shoot a landscape (typically mountains), I want sharp pics whether a subject comes in front of the camera or not without changing the focus ring.

This gets to the heart of the subject. A lens can focus at only one distance (I'll call this the focus plane); everything nearer or further is out of focus to some degree. The further from the focus plane the more things go out of focus.

Fortunately our eyes can accommodate a small amount of out-of-focus blur and still see things as sharp. There is a range of distances in front and behind the focus plane where things look sharp enough to be seen clearly. This range is called the depth of field (DOF).

For any given picture the DOF depends on a whole host of factors but the general principles of how it works can be seen in a site like this https://dofsimulator.net/en/. It's possible to calculate what DOF will be assuming certain standard conditions; there are plenty of online DOF calculators such as this one http://www.dofmaster.com/dofjs.html

  1. I know I need to focus on the subject to get it in focus but my primary necessity is to fix a focus and keep clicking whether there is a near subject or not.

What you are saying is that you need your DOF to be deep enough to include the near subjects. To do that you need to understand DOF, how to calculate it and how to set your camera to achieve it.

  1. I've read a lot about "Zone/Hyperfocal" techniques and they all talk about "acceptable" sharpness while I want pin sharp photos. how to achieve this?

When I said above "sharp enough to be seen clearly" that is the definition of "acceptable sharpness". "Pin sharp" is a colloquial term with no real meaning; and as I said above, a lens can focus at only one distance. It simply isn't possible to get the whole range of distances in perfect focus - optics just prevents it - so what you say you want isn't possible.

However, what you mean is that you want a range of distances to look so sharp that you can see things clearly. And that range is the DOF. What you are calling "pin sharp" is actually the range if "acceptable" sharpness.

  1. If I use a high quality manual focus lens with DOF scale printed, set it to 10' to Infinity

You can't set it to "10' to Infinity". You can set it to only one distance; you could pick 10' or infinity or any other distance but you can't put the focus index in two places sat once.

The quality of the lens is irrelevant; the rules apply to any and every lens that has a focus scale.

  1. and leave it there, will it help in achieving sharp photos without any need to recompose and focus again?

To repeat - this depends on the required DOF. Unless you know the distances and camera settings there is no one answer to this question.

  1. (please don't route me to point & shoot)

I don't understand this and I don't think you do either.

  1. Will the above trick help in snapping up moving subjects within that range as well?

There is no trick. What there is is understanding. If something is within the DOF it will be acceptably sharp whether it is moving or static (as long it doesn't suffer motion blur). Study DOF and the answers will become clear.

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Gerry
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I'm happy for anyone to edit any of my photos and display the results
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First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

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