Does standing further back & zooming in increase the acceptable focus zone?

[WayneF]

It's all gone a bit advanced for me, lol

In short, if I've understood you all correctly:

If using the same camera, lens & aperture, the depth of field (focusing sweet area) remains roughly the same if you do these 2 things:
1) take a photo of point A from point B
2) then stand a lot further back and zooming in to point A to get the same frame as 1)

In conclusion, there's no focusing advantage to be had by standing further back and zooming in (your depth of field remains roughly the same).

If saying depth of field remains roughly the same, it seems important to specify "to get the same frame", which you did specify. The rule of thumb (with same aperture) is "same subject size is the same depth of field". And it is roughly true, generally, within limits.

Here is a more indepth look at it:
Depth of Field When Image Size is Constant


But it might help understanding to note that what it is actually largely about is the degree of magnification, about how well we can actually see the blur in the image.

Generally, to be usable knowledge, it seems enough to know that DOF increases with these basics, which we should all know:

Stopped down aperture (actually affects Circle of Confusion, sharpness)
Shorter focal length (is just less magnification of CoC)
Greater focus distance (is just less magnification of CoC)
and if switching cameras, with a smaller sensor or film size (because it necessarily uses a shorter focal length, and affects enlargement)


CoC is an easy obvious concept, once we've seen it.
http://en.wikipedia.org/wiki/Circle_of_confusion

A DOF calculator takes all these things into account, but another thing we should know is that while DOF can easily be computed out to many decimal places, but in real life, the numbers are pretty vague, because it also depends on a judgement about typical eyes, in a specific viewing situation (estimated to be what can be seen from 35mm film enlarged to an 8x10 inch print viewed at 10 inches). It is about enlargement, but our own viewing situation/enlargement is rarely ever the same. What we can see (DOF) also depends on enlargement of the result. It is more a concept than exact numbers. We should treat the numbers as ball park numbers, perhaps more or less appropriate to our own case. But we should know how to increase or decrease it, and to position it to where we need it to be.

This is Nikonites. Don't confuse opinion and speculation by offering up facts, and for godsake never point out speculation when you see it - there are folks here that have torches and pitchforks at the ready.

It's just human nature to try to help, even if maybe we don't really know. I'm guilty too, I think we all are. We like to explain how we think it ought to be, when maybe how it actually is may be different. I see a post asking about some standard feature on maybe an Acme X4000 camera, and I think I know and want to help, but I have to realize I've never seen an Acme.

 

[paul_b]

I think this whole thing has gotten way more complicated than it needs to. @paul_b I bet you weren't expecting quite this response to your question. For practical purposes the simple answer is that the depth of field will be very close to the same, but you will change the perspective of your shot, and so the composition will be significantly different.

That's what I needed to know, Ty.

Ps guys, We all knew nothing in the beginning. Sometimes the cleverest form of intelligence is working out what someone else doesn't know. Its not just about what you know. Sharing that information is human kindness, so Ty