Distance Setting mark?

[wsbII]

Hello,
New guy here :} Learning as fast as I can thanks to all of you...

So I am reading Peterson's book (Understanding Exposure) and trying to figure out how to properly shoot depth of field. In the book one thing he confuses me on is a comment in figuring out how to focus when shooting at small aperatures (f16-f22 for example). He talks about " aligning the distance above your distance setting mark on the lens. Your focal length will determine the distance you will choose." I know I'm new, but I've read this section multiple times, consulted my lens manual, and consulted my camera manual. I can find the distance index and mark to align, but how do I know what distance is appropriate for the focal length? Is there a reference out there to indicate which distance to focus at for each focal length or am I missing something. Any help would be greatly appreciated...
Thanks!
Bill

[OsmosisStudios]

What he's referring to is a focus distance scale. Some lenses have it, some dont. On Nikon lenses it usually appears as a small window with focus distances on it: it indicates at what distance the lens is focused.

You can see it here on the front end (left) of the lens barrel. All makes and models are a bit different, but thats what to look for,

[teaking]

Heres a link to a recent tutorial on DOF for landscape photography I read and found it quite interesting maybe it will help you

http://photo.tutsplus.com/tutorials/...e-photography/

[FoG]

Originally Posted by teaking

Heres a link to a recent tutorial on DOF for landscape photography I read and found it quite interesting maybe it will help you

http://photo.tutsplus.com/tutorials/...e-photography/

very interesting link

[wsbII]

Thanks for the tips. I think I am understanding and can take some shots now. I do wonder, in the Peterson book he made it seem so easy. Like just set the distance to the indicated focal length on the lens. He didn't indicate any calculations etc. I don't know if he is just that experienced that he just knows the focal distance for his lens and focal lengths. I can do the math, but still wonder if there isn't some easier way...

[inkista]

I use a DoF calculator on my iPodTouch and old manual focus prime lenses.

This is one of the few instances where Peterson's going off experience in the film days with manual focus lenses, rather than dealing with the current lenses a new dSLR user faces. The 18-55 kit lenses, for example, have no distance scales at all.

For me, I think everywhere Peterson uses f/22 in UE ought to be replaced with f/16, because of our ability to see the diffraction effect, now that we're working at higher resolutions than we did with film, but he's never gonna change that setting; he loves f/22.

The thing is, back in the (older) film days, we were working not only with manually focused lenses, but also all primes, and we were all using the same image size (35mm film). So the lenses could look like this:



On the bottom: the aperture setting ring.
On the top: the focus ring with the distance scale, marked off in both feet (yellow) and meters (white).
In the middle: the DoF scale.

To set this lens to hyperfocal distance (on a full-frame body), all I have to do is put the ∞ symbol on the distance scale opposite the aperture I'm using on the right hand side of the DoF scale. Then I'm set to hyperfocal, and where my aperture on the left is on the distance scale is my near focus distance. (Ain't sliderule technology grand?)

Of course, this doesn't work on a crop body camera (sigh). Hence my need for a DoF calculator/chart in the field.

Remember that hyperfocal depends on three things: Your aperture, your sensor size, and your focal length. With a prime lens and film, two of those values are fixed, so you could have a DoF scale like that. With zooms, it's kind of impossible.

Distance scales are far less useful these days, because everything's optimized for autofocus, which means shorter distance "throws" (I.e., the full focus range on the lens above is about 270° or so (I.e., the ring twists 3/4 of the way around the barrel going from the smallest focus distance to infinity)--I can manually focus with great precision. On my 18-55, the full focus throw is maybe 30°. That's why modern distance scales on autofocus lenses are kinda/sorta useless--too tiny to mark off or use with any precision. But it helps make the autofocus faster and easier on the mechanics.

[wsbII]

Thanks Inkista. Your insight helps. It also creates a few more questions. Is there a diffrence between hyperfocal and just making sure you are focused right for DOF shots? I wasn't specifically looking for hyperfocal, but rather just want to make sure that I can have the camera focused from front of shot (or close to it) to back of shot. The two objectives may be the same thing, but I don't know the difference. What I am hearing is that in order to shoot DOF from front to back in focus I need to do the calculation (or carry a chart) and focus on an item that distance away, recompose, and shoot. Doesn't sound liek there is an easy way around this until I build up some experience with the technique. Thank everyone for the info- it helps me know what I need to do.
Bill

[Chip]

Bill -

As a very rough general rule, the DOF is divided into thirds: 1/3 of the DOF is made up of the distance from the subject towards the camera, and the other 2/3 of the DOF is made up of the distance from the subject away from the camera. This is a helpful little rule for deciding if you want mostly foreground or mostly background to be in focus.

So, using inkista's lens as an example, on a full frame camera, if you were shooting at f/16 and if your subject was1.2 meters away, them everything from about 0.8 meters to about 2.3 meters would be in the DOF. If you were at f/4, then everything from just 1.1 meters to about 1.3 meters would be in the DOF.

Hope this helps.

[inkista]

Originally Posted by wsbII

Is there a diffrence between hyperfocal and just making sure you are focused right for DOF shots?

Yup. Hyperfocal is specifically if you want to get the deepest DoF possible for that sensor/aperture/focal length combination. Generally, if you can find the hyperfocal distance, everything from half the hyperfocal distance to infinity will be in focus. This is generally something useful only for landscape photographers.

What I am hearing is that in order to shoot DOF from front to back in focus I need to do the calculation (or carry a chart) and focus on an item that distance away, recompose, and shoot.

No, you don't need to do this just to get something in focus. The definition of DoF is the distance range away from the camera that will be acceptably sharp (i.e., in focus). The charts/calculator are to figure out how much DoF you have and where it lies with precision. But you can also just take the shot and chimp, focus bracket (manually if your camera doesn't have a mode to do so), or (if you have one) use the DoF button to preview.

The main thing to understand is that when you're composing your lens is actually wide open at its maximum aperture, so what you're seeing through the viewfinder isn't an accurate representation of the DoF you'll get in the shot. It'll be accurate if you're shooting wide open, but if you're using any other aperture setting, you're getting a narrower DoF. Some cameras have a DoF preview button that lets you stop down the lens while you're composing. The viewfinder gets dimmer, but you will have accurate DoF feedback.

Nikon entry level bodies (below a D80/D90), however, do not have a DoF preview button, so you may just have to chimp and adjust.

[Blaze Jaffe]

That was a great link, good reading!!!