Can someone explain the D40 3-area AF and the D80's 11 area AF

koejarlisch said:

The D40 has 3 focusing areas, on the left of the viewfinder, in the
middle and on the right. the D80 has 11 areas. so, with the D80 you
can focus on different places without moving your camera position.
that's pretty much it..
--
joe.

Click to expand...

methinks it's a little more than that... among other things, I'm
sure the d80 can track a lot better than the d40

The main thing you need for maual focus is a good screen and a birght viewfinder. These things seem to be misisng on modern cameras, its a shame really.

As I'm getting old and grey my eyes aren't that brilliant anymore either, and they're probably more important than the focusiing screen anyway

I can though use one central focus point which has the greatest sensitivity and use that one to manage the rest of the scene very easily.

So I still don;t know why you need more than one.

I have just been reading the thread on dynamic autofocus and the fatc it isn;t that good anymore with multiple focus points.

On my Pentax Z1 which had excellent dynamic focus tracking. I managed to focus on the object and then shoot with it always in focus. The Z1 also was able to keep the same image size ie a sthe object got closer the zoom changed so the object remaind the same size. Now that was good if you wanted to focus on an athletes face as he/she ran past.

Of course you can't track a moving object across the scene with only one focus point. I think you probaly need more than 5 for that though.

--
Bluenose

I have learned much from these posts, The lesson on recomposing, especially as it affects shallow DOF, was an eye-opener! This explained a good portion of the blurry D40 photos. I reshot the same photos by increasing DOF, thus eliminating the blur. Though, at times I think this method betrayed the shot, which is where the AF points came in handy. I toyed with the 3 AF points on close ups (a floral arrangement and a toy arrangement) and was able to distinguish which area was active. This caused me to wonder if I'd use and prefer the D80s 11 AF points.

Why is Bluenose happy with one central point and I am not? Perhaps our eyes and brains see the world in different ways and express that through how we interface with the camera. Or maybe his technique is simply straightforward and I'm missing the point. I will try to think it through. Enlightenment welcome.

Another snag I unraveled was the realization I had expected P&S (DOF) results from a DSLR that behaves more like film. Once I shifted gears, the road was smoother. Still, a DSLR is not film, is not a P&S, is kinda both, is not either. Smile.

Everyone's information and perspective helped me work the D40 before returning it, and has deepened my view of DSLRs.

Having more focusing areas would have no effect at all on depth of field.

jimr said:

jimr wrote:
Having more focusing areas would have no effect at all on depth of
field.

Click to expand...

It has an effect in that focusing and recomposing a shot with shallow DOF can cause focusing errors...

Having more focusing points helps you focus without having to recompose so you do not have these focusing errors when using shallow DOF...

Bob

--

People are more violently opposed to fur than leather because it's safer to pick on rich women than biker gangs.

http://www.pbase.com/mofongo

Mofongo said:

Mofongo said:

jimr wrote:
Having more focusing areas would have no effect at all on depth of
field.

Click to expand...

It has an effect in that focusing and recomposing a shot with
shallow DOF can cause focusing errors...

Having more focusing points helps you focus without having to
recompose so you do not have these focusing errors when using
shallow DOF...

Click to expand...

Not necessarily so. Many use the center only focus to take tighter control over where the actual focus point is. There can ONLY be one point of actual focus with DOF taking care/or not of the distances beyond and before that actual point of focus.

Mofongo said:

Bob

--
People are more violently opposed to fur than leather because it's
safer to pick on rich women than biker gangs.

http://www.pbase.com/mofongo

Click to expand...

jimr said:

jimr wrote:
Not necessarily so. Many use the center only focus to take tighter
control over where the actual focus point is. There can ONLY be one
point of actual focus with DOF taking care/or not of the distances
beyond and before that actual point of focus.

Click to expand...

Jim, actually it is true. See this article to understand what I am refering to:
http://visual-vacations.com/Photography/focus-recompose_sucks.htm

You are correct that there can only be one point of actual focus but when you select the focus point manualy in shallow DOF photos rather than using the center and recomposing you will not have focusing errors, especially in closeups. (recomposing moves the camera further or closer to the subject)...

That is the reason more advanced cameras have multiple focus points, so you don't have to recompose, especially when on a tripod)...

Bob

--

People are more violently opposed to fur than leather because it's safer to pick on rich women than biker gangs.

http://www.pbase.com/mofongo

jimr said:

Mofongo said:

jimr said:

jimr wrote:
Having more focusing areas would have no effect at all on depth of
field.

Click to expand...

It has an effect in that focusing and recomposing a shot with
shallow DOF can cause focusing errors...

Having more focusing points helps you focus without having to
recompose so you do not have these focusing errors when using
shallow DOF...

Click to expand...

Not necessarily so. Many use the center only focus to take tighter
control over where the actual focus point is. There can ONLY be one
point of actual focus with DOF taking care/or not of the distances
beyond and before that actual point of focus.

jimr said:

Bob

Click to expand...

Click to expand...

jimr, did you actually read the link posted earlier in the thread:
http://visual-vacations.com/Photography/focus-recompose_sucks.htm

Not sure how you can claim that focussing and recomposing a shot enables a photographer to "take tighter control over where the actual focus point is"

Ant.