Help with photo lingo translation

[tag03urit]

I just finished reading Bryan Peterson's Understanding Exposure and there is a phrase that he uses in a lot of his captions under the photos he has in the book. The phrase is (he is describing what he did to take the photo), "I used an aperture of BLANK and preset the focus via the distance setting on the front of the lens" That last part is what I'm having trouble understanding. What is the distance setting? and how/why do you preset the focus? Any help would be appreciated! TIA!

[gonzogolf]

manual focus lenses have a printed scale on them so that if you wanted to focus on something 10ft away you just dialed in the 10ft setting on the scale. Obsolete on autofocus lenses. No need to worry about it

[tzalman]

Understanding Exposure was written many years ago and some things in it are not applicable to some modern cameras. This is one of them.

[Digital_zen]

There are actually still times when presetting your focus can help a lot, but you can still autofocus to do it. I often prefocus to a spot on the ground toward which any moving object (usually my son or daughter) i nearing, then there is (hopefully) time to recompose while keeping my focus locked, then shoot when the subject comes into focus.
Also when shooting at night I use my cell phone to create a lighted "focus assist device" use the autofocus, on the lighted screen of the phone, then switch the lens over to manual focus, remove the phone from my shot and shoot away.
Many ideas that seem antiquated are still quite useful in digital photography.

[Brikwall]

A number of current lenses still have the distance scales on them but the information they display is rather limited. In general, they show only the focus index (the distance at which the lens is actually focused) and the depth-of-field scale for just one aperture setting (usually f/22). Both still have their uses - albeit the DOF scale more than the focus index - and it's unfortunate the lens manufacturers have, for the most part, deemed them obsolete. However, there are other means of accomplishing the same tasks, as noted by Digital_Zen.

[neilwood32]

Presetting focus is still a very useful procedure especially for landscape photographers.

They can use it to maximise the DOF by the use of hyper focal distances. Unfortunately it is something lens manufacturers have decided to omit so we now have to use DOF calculators

[Wilt]

Apart from the issue that the Distance scale has so few distances marked on them, sp as to make DOF scales useless on modern AF lenses, the other reason the DOF scale is useless in the context of digital SLRs with fixed FL lenses is the fact that they apply only to FF cameras, but not to APS-C cameras!

[KCMO Al]

AF has changed the way we used to work in many ways. Most AF lenses have very short throws, meaning that they focus faster. Back in the old days, precisions focus lenses often took more than one turn of the barrel to focus. I remember the Alpa 50 macro was like 3 turns from infinity to macro range. Some of the less expensive lenses in the Canon line don't even have a distance scale.

[tag03urit]

I understand now, thank you!