Understanding Exposure pg 38,39

[RebelTasha]

I don't understand what it is trying to say.
I don't understand the "simple" solution to the common dilemma..

I also don't understand the "Note" box in yellow and how it relates to my Canon XT...

To me my camera still needs to focus on something if the lens is set to AF until I hear the little beep, otherwise it will not be focused and the whole picture may or may not come out...

To me I am getting from those pages I don't need to focus but need to do something else but I don't understand what it is I am supposed to be doing..
Help I've read it over and over... I think it's too simple for me to understand.. lol...

 

[Rachelsne]

i havent read the book, I sometime over complicate things too lol, I am going to buy the book sometime soon, then maybe I too will wonder what it all means.

 

[spiffybeth]

i dont have the book in front of me because im at work. can you tell us what it says?

 

[lockwood81]

I just read that section and since I don't have a Canon, I really didn't pay attention when I first read it awhile back. To me it should be something covered in your user manual, he is just giving a general overview, and it may not be something available on all Canons, maybe just the pro models.

 

[RebelTasha]

Ok well he is talking about "Storytelling Apertures"
"The solution to this common dilemma is simple: you don't focus the lens at all, but rather preset the focus via the distance scale"

The yellow box talks about an auto depth of field scale where you can autofocus the foreground and then the background and the camera will only beep if you're range of dof is greater than the aperture choice can offer and how great an invention that is...

I think it is saying that there is some way I can focus on something close then something far away and then it will decide which is best by beeping but I'm totally lost to be honest..

I KNOW how DOF works I know how to get a shallow depth of field and how to have everything in focus..
But where to focus when using an F22 I would be interested in.. but well...
Maybe someone could read it and explain it hopefully someone with a Rebel XT...

 

[Sarah23]

That confused me too...Im glad you posted about it! I have no idea what he was talking about either.

 

[spiffybeth]

is the section about film cameras?
i know on all my film lenses there is a distance scale so if i wanted to shoot something 12 meters or 5 feet or however far away, i could set my lens to that focal distance and not have to change anything. because my slrs are old school, there is nothing to beep at me, but if i had to guess, id say that's what he's talking about.

in the second shot here, you can clearly see what im talking about.
http://thephotoforum.com/forum/showthread.php?t=119139

someone feel free to correct me if im wrong.

 

[rubbertree]

I was stuck at the same spot you were when I read that book until I realized that this is a feature on certain lenses, mine does not have the auto depth of field scale!

 

[RebelTasha]

I have read on and everything is pretty much what I already knew about but it has really helped confirm everything so that I can confidently use it and know I am headed in the right direction..
But I continuously go back to these two pages to see if I can make sense of it..

I really appreciate that I am not the only one because when he used the word 'simple' I was excited to read on but then it completely lost me. The way it was worded in the yellow box it made me feel like it was a new thing and since the book I have was revised I assumed I should know this..

Spiffy I don't have any of those numbers on my lens too bad because it sounds like a neat concept.

So where would be a good place to focus if say using F22 to do storytelling aperture?
On the far tree or the middle of the dandelion field or closer still?

 

[ksm]

I also do not have the book in front of me but here goes:

DOF Scale ... Not all lenses have those especially the kit lenses. Highe r end lenses usually have those and they are pretty useful.

That auto DOF focus near and far and the camera will tell you if you have the necessary DOF. That is a Canon specific utility that some have and some don't (maybe it is even dependent on lenses) never used it, I don't have a Canon.

So where does that leave you as far as where to focus? Well you can really be technical and look up the hyperfocal distances of the lens you are looking from the manufacturer webpage or you can use the following rule of thumb which I'm pretty sure is also mentioned in that book,

Rule of thumb:

Look at your scene figure out what you want in focus, pick a small aperture and then focus a third of the distance between the closest thing you want in focus and the furthest thing you want in focus

 

[christopher walrath]

At a small aperture like f22 or smaller everything from seven feet to Duluth will probably be in reasonable focus. The thing to due would be to evaluate your subject. What is MOST important to the feeling you want to transfer through your photograph? I would get real close to the focus on your emphasis, your most important part of the image and then perhaps budge the focus a smidge closer to the middle to include as much as you can. But never sacrifice your subject to be all-inclusive.

Here's an online DOF calculator for those who want it. I'm gonna check it out now.

http://javascript.internet.com/math-related/field-depth.html

 

[caspertodd]

I have the A. DEP setting on my Canon. In the manual it basically says to move the AF point over the subject, and all subjects covered by the AF points will be in focus. The aperature value will blink if the correct DOF cannot be obtained. It does not say anything about beeping though.

 

[Dutchboy]

I've found the wikipedia article on depth-of-field very illuminating. It also explains about the DOF scales you find on many lenses, and more. Excellent article!

http://en.wikipedia.org/wiki/Depth_of_field

:thumbup: