MtnMan Loc: ID

Given the accuracy of the original post (e.g no vs. know) and lack of response to the topic my assumption is that the OP meant Depth of Field.

He was given links for that.

mcveed Loc: Kelowna, British Columbia (between trips)

Thus is the DOF calculator that I use when sitting at my desk.
http://www.dofmaster.com/dofjs.html

GreenReaper

After reading through some of the replies, sounds like some Hogs really like getting into the weeds on some topics. Simply put Depth of Field is a function of f/stop and focal length. Generally speaking it is considered to be 1/3 in front and 2/3 in back of your subject.
Have fun and keep smiling :)

boberic Loc: Quiet Corner, Connecticut. Ex long Islander

I don't know about any one else but I dont care about the difference between internal lens parts. I only care about how the thing performs and/or costs. The lens does not come with an instruction list which says part A goesinta part B. And the screws are in a sererate bag, allan wrench included. Unless, of course, you bought the lens at IKEA.

Apaflo Loc: Anchorage, Alaska

In fact, that is a semi-myth about the 1 to 2 front to back ratio of DOF. It does happen, but only over a relatively small range of focus distances.

The spread of DOF is 1:1 at very close focusing distances. It is 1:2 at a distance of 1/3rd the hyperfocal distance, and at longer focus distances becomes increasingly greater behind the point of focus until the focus distance reaches the hyperfocal distance (where the rear DOF reaches all the way to infinity). Hence there is only a small range where DOF is approximately 1/3 in front and 2/3 in back.

But also note that DOF is a function of aperture, focal length, focus distance and sensor size. All four are important.

These are important facts to know and use.

Apaflo Loc: Anchorage, Alaska

Right, but... neither Depth of Focus nor Depth of Field has anything to the with internal lens parts. And those would not be the topic of this thread.

amfoto1 Loc: San Jose, Calif. USA

Depth of Field is "in front of" the lens and is controllable by the photographer's choices of aperture, distance and focal length.

Depth of Focus occurs "behind" the lens, inside the camera at the film/image sensor plane, and is not subject to control by the photographer (in the types of cameras the vast majority of people are using today).

The term Depth of Focus is often mistakenly used to mean Depth of Field. That's almost certainly the case here, since the OP was asking about charts and help adjusting and working with DoF.

Depth of Field is effected by two things: lens aperture size and distance to the subject being focused upon (or distance to objects in the out of focus areas).

Lens focal length is another consideration, although it actually has almost no direct effect on DoF... If you stand close with a short focal length lens or far away with a longer focal length, DoF can be identical.

However, for practical purposes it seems like focal length has a lot of effect. Because of the way we use them.... the distances involved... high magnification lenses (i.e., telephoto/longer focal lengths) give the visual effect of shallower DoF than low magnification lenses (i.e., wide angle/short focal lengths).

Image size in-camera, as determined by the sensor size or film being used, also doesn't directly effect DoF. However, for reasons related to lens focal length it will be a consideration. Shorter focal lengths are used on smaller sensors, which give the effect of greater depth of field, while longer focal lengths are used on larger sensors or film formats to frame the subject the same way from the same distance. Another way of looking at it... the larger the image size on film or sensor, the longer the focal length you'll need to use to work from any given distance, so the "easier" it will seem to strongly blur down backgrounds.

For these reasons, DoF calculators ask you to provide data not only on distance to subject and aperture.... but also sensor/film format and lens focal length.

OP, there are a lot of places online where you can plug in data (camera sensor size, lens focal length, distance to subject and lens aperture) to calculate Depth of Field. I would recommend starting with this article and experimenting with the calculator they provide: http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

Hyperfocal distance is an important, closely related subject.... also discussed at the above website.

Thankfully, so far we haven't gotten into a "circle of confusion" discussion here. That would... well.... just confuse things even more!

CPR Loc: Nature Coast of Florida

We need a separate section for "I'm smarter than you and can write technical paragraphs longer than yours" posts.

SharpShooter Loc: NorCal

Yea, but then I would get kicked out and never get to post there!!!
SS

Apaflo Loc: Anchorage, Alaska

Depth of Focus changes with exactly the same things that change Depth of Field.

selmslie Loc: Fernandina Beach, FL, USA

Not exactly. Architect1776 had the right answer when he said, "Depth of Field is what the photographer is interested in; it is what is in acceptable focus in front of the lens. Depth of Focus is what only a technician is interested in ..."

Depth of field is an approximation based on subject distance, aperture and COC for a theoretical lens where the subject focal plane meets the image focal plane at the film/sensor. I say approximation because COC depends on the viewer's eyesight as well as the size of the final print, the print viewing distance and whether the image has been cropped.

Depth of focus is a completely different issue. It depends on the geometry of the image as it leaves the rear element of the lens. While it can be easily visualized for a symmetrical lens like one used in a view camera, the geometry is completely different for a telephoto or retro-focus lens, especially when the lens design used internal focus, i.e., the spacing between lens elements changes with focus distance. This is why you can't use extension tubes with some lenses like you can with others.

Depth of focus is important to the technician because it dictates how flat the film needs to be. The photographer can take it for granted that the camera and lens designers are working together.

Apaflo Loc: Anchorage, Alaska

Depth of Focus changes with exactly the same things that change Depth of Field.

You seem to have missed the significance of that statement. And also that it is essentially the same as what Architect1776 quoted from Wikipedia: "The same factors that determine depth of field also determine depth of focus, but these factors can have different effects than they have in depth of field."

Depth of Field and Depth of Focus are two different things, but the exact same factors affect each. That is because Depth of Focus is the sensor side conjugate of the scene side Depth of Field. The same effect on opposite sides of the lens.

The photographer need not be conscious of the effects of Depth of Focus in the same way as is necessary with Depth of Field, but everything the photographer does to manipulate Depth of Field also manipulates Depth of Focus.

Incidentally it has nothing to do with using or not using extension tubes.

selmslie Loc: Fernandina Beach, FL, USA

Duh! Who said they are not both affected by focal length, aperture and COC diameter?

But the two (depth of field and depth of focus) are not directly proportional to each other as you change subject distance, especially for asymmetrical or internal focus lenses that are not designed to be used with extension tubes or bellows.

If you don't understand the difference between a symmetrical lens and a telephoto or retro-focus lens, you clearly will not understand why. If you did, you would not be arguing the point.

Depth of focus tells us only how much error there can be in the flatness of the film without adversely affecting the sharpness of the image. Since sensors are "perfectly" flat and precisely perpendicular to the lens axis, depth of focus is not an issue for digital.

You are in over your head here.

Apaflo Loc: Anchorage, Alaska

Just like your claim about use of extension tubes, the above is not true either. Flat yes, but it is still an issue. Your insults are always projection. Go look it up.

selmslie Loc: Fernandina Beach, FL, USA

I will explain the difference. Suppose you have an infinitesimal point of light at a distance s from the camera with a lens to sensor distance of l.

The depth of field is how much you can move that point toward or away from the camera before the point blurs from a single pixel to the size of the COC.

Now suppose that you don't move the point but instead move the sensor. The depth of focus is how far you can move the sensor before the point covers more than a single pixel, up to the size of the COC.

But some lenses (such as IF) do not move the sensor relative to the lens so they keep the same depth of focus because l does not change, even when s changes. These lenses cannot use extension tubes effectively.

Simple lenses change both s and l simultaneously. These lenses can use extension tubes to focus more closely.

Telephoto and back-focus wide angle lenses behave differently and they may not be able to use extension tubes.

I don't have to look it up because I understand it. You can probably look it up until you are blue in the face and you may never understand it.