Depth of Field, Black and White, Aperature, and Landscape Questions

Everyone,

I would appreciate your help with a few questions I'm trying to get answers to

in order to improve my photography skills. If you can help with one or more of

them, I would really appreciate it! Please check my portfolio on this site if

you would like--it may give you an idea of what I shoot and also, what level of

success I've had with my current knowledge/skill.

1) Depth of Field--I've been experimenting with different lenses, aperatures,

distances, etc. and was wondering if someone can put the concept concisely into

words for me. What creates the "blur" in the foreground and/or background of

your focal point? What makes it more or less out of focus? I know the answer

has to do with aperatures, focal lengths, and the distance between subjects but

if someone could put it in words I'd appreciate it! Sometimes it works for me

but there are times when I think a background object will be completely out of

focus and it is sharp as a knife so I get confused.

2) This may be a stupid question--if I'm shooting landscape shots I always use

a tripod and shut my camera down to its smallest aperature to get great depth

of field. If I'm going this, does it matter where my focal point is? In other

words, is everything really in focus or if you focus on the most distant part

of the foreground potentially out of focus?

3) I know this is really rookie-esque but when I shoot, I basically do 2

aperature photography--I shut it all the way down if I want everything in focus

or open it all the way up if I want to focus on something and blur the rest. I

guess this is like playing 2 or 3 club golf--you drive until you reach the

green and then you putt! But, I'd like to improve--let's say you are shooting a

landscape shot, when would you not shut it all the way down to the smallest

aperature? Is the only answer to that "if you want some things in sharper focus

than others?" I know that with the widest aperature you get a shorter depth of

field (right? This relates to #1) and the narrowest gives the most things in

focus so obviously the middle aperatures are somewhere in between. Is that an

accurate statement and am I missing anything? So, would the middle aperatures

just for getting most things in focus without have everything in focus? Any

need in using them for a landscape shot or just shut it all the way day like I

have been doing?

4) I just started doing black and white shots and have some mixed results. To

be honest, I generally shoot black and white when the sun is high and colors

stink. Does having direct sunlight give less pleasing black and whites just

like it does with color? I know when the sun is high it will wash out your

colors--is the same true for black and white? To this point, I've been using

B&W when I can't shoot color. I guess another way to ask my question is, do the

same lighting conditions make for good black and white and color photographs or

do you look for different lighting? (or, can B&W tolerate direct light/washed

out colors better than color and still get a pleasing shot) So, to sum up, in

regards to lighting conditions, when do you shoot black and white?

Thanks for helping me with these very basic questions. I think I know part of

the answers for most of them but do not completely understand things and would

like to. Any help you can offer is greatly appreciated. Like I said, please

feel free to look at my portfolio is it will help you help me--I have a feeling

that while my pictures are not "great," they are probably more advanced than my

questions! THANKS!

Answer to Q1:

See http://www.dofmaster.com

Stopping down the lens to the max aperture may not be the best thing either as diffraction will effect the picture and will effectively reduce sharpness.

Answer to Q2:

See answer to Q1

Answer to Q3:

See answer to Q1

Answer to Q4:

Sounds like your colour shots are over-exposed. Use better meter technique and/or "Sunny 16" for better exposures. Regarding B&W film, it generally has more dynamic range and allows for more over/under exposure.

There is only one point in true focus, the rest of the image is not, but because of what's called the "circle of confusion" we get "depth of focus". DOF is primarily dependent on aperture and subject distance. The blur and variation there of depends on the "circle of confusion" which you may want to look up as it's difficult to describe, at least for me!

Often, you do not want to use the smallest aperture because of a loss of image quality due to diffration. Use the aperture necessary to give to the amount of DOF that you need for an image. If the nearest object in the image is 100' away there is no need to use the smallest f/stop. Doing so increases your exposure time which has it's own disadvantages. Look up "hyperfocal distance". Using the appropriate aperture and the hyperfocal distance, you can keep everything in focus from the closest object in the frame to infinity.

There's a lot of information about aperture here and elsewhere, but you have to spell it correctly to search for it.

In nontechnical language, lenses fundamentally need to direct light from a single object hitting them at their center and at their edge at the same point on the film. They are only capable of doing this for an object at one distance at a time (and even that is optimistic, but we're assuming a theoretical perfect lens). If the object is not at the distance the lens is focused on, the light hitting the edge will be directed at a different point on the film from light hitting the center. The distance between these points is greater the further the edge of the lens is from the center, which is why wider apertures have less depth of field and more background blur.

1. DOF is a bit complicated to explain fully in forum posts. The first thing to grasp, is that there is a single plane, somewhere in the subject space (what you're taking a photo of) that is accurately focused on the film. Everything -- <I>EVERYTHING</I> -- that is nearer or farther than that plane, will be less focused as it gets farther from the plane of focus. However, since the human eye is subject to the same optical rules and limitations as anything else, a certain amount of defocus will still appear to be focused; that's your depth of field. There's a ton of excellent tutorial stuff on the net, I commend you to google until you get it.<P>

2. Hyperfocal focusing. For a given focal length, f/stop, and format, there is a certain distance called the hyperfocal distance. This takes into account the DOF of that f/stop, and by setting your focus to that point you will have everything from 1/2 of the hyperfocal distance out to infinity acceptably focused. Depending on your tolerance for defocus, your hyperfocal distance may not be the same as someone else's recommendation, although the standard values given are usually pretty good. There is some difference of opinion about using hyperfocal focusing; a minority prefer to focus at infinity for landscape scenes.<P>

Stopping down to very small apertures, while it gives more depth of field, usually gives poorer resolution due to diffraction. Diffraction is dependent solely on the numerical value of the f/stop, and as a result it is more of a problem as the format becomes smaller. Small formats (35mm and most digital) can't tolerate very small stops, while large formats such as 8x10 make it almost a non-issue. Also, lenses don't perform equally well at all f/stops. Most lenses are best at 2 or 3 stops down from wide open, beyond that they just aren't as sharp. <P>

3. By doing 2 aperture photography, you're sacrificing creative control. Your choice, of course.<P>

4. Color vs. B&W is a creative choice. Good light is good light, and bad light is bad light regardless of film choice. IMO, B&W photography is LESS tolerant of bad light. With no color variation, B&W is totally about texture and shadow, neither of which are improved with bad light.<P>

BTW, I like a lot of the stuff in your portfolio. <P>

(P.S.: there's only one "a" in aperture. Sorry to nitpick.)

1. Building on what Ocean Physics said, it may be helpful to picture one of the cones light passing through the lens forms. If you are focused on the subject, the tip of the cone is right at the film plane. If the lens is set at f/2, the cone is broad with a big base; if the lens is set at f/22 the cone is skinny with a small base. If you picture the circular cross-sections of these cones at the same distance from the tip, the f/2 circle will always be larger than the f/22 circle. In other words, the image-forming light from each out-of-focus object will be spread across a larger "circle of confusion" at f/2 than at f/22.

3. Diffraction is the unavoidable scattering of light that occurs in certain circumstances, including when it passes an edge. When light scatters, it doesn't fall where it "should" on the film and resolution suffers. The edge involved here is the edge of the iris diaphragm. The smaller the aperture, the higher the percentage of image-forming light that is subject to diffraction. You can easily see this from the formulae for the perimeter (pi * diameter) and the area of a circle (pi * radius squared). As diameter increases, the circumference increases linearly and the area increases geometrically.

Tyler,

do yourself a favor and google Harold Merklinger. Go to the first one that comes up at the trenholm website and download "The Ins and Outs of Focus".

Then read this a few times and learn to ALWAYS (for landscapes) focus on the farthest object you want to depict. This may be the mountain range a few miles off, and NEVER focus at what is called hyperfocal distance, if you want maximal sharpness in your pics. Close the lens so that a useful amount of foreground is in focus, but never go to f/22, except with super long lenses. As the lens opening should be around 5mm, f/11 is mostly good enough and avoids diffraction unsharpness.

I shoot landscapes often with 20mm lenses at f/5.6 for stunning results front to back because my lenses are very good and are sharpest in that range.

Go out and do a few pics the Merklinger way: focus on the most remote object, adjust aperture to get some DOF.

And for comparison, do the same pic with hyperfocal distance focusing. Just to "listen" to the bad advice you were given above and to learn.

And then you decide whether it is time to sent Harold his 5$ in royalties.

That is how it works.

1) The blur of the not in focus stuff, is the result of the light not converging to a point on the image plane (as displayed on my beautiful illustration below (the red and green lines are light rays that do not converge at the focal point due to reflected light coming from objects in front of or behind the object in focus). the farther your object to lens distance and lens to image plane distance are off of their 'in focus' geometry, the more out of focus they will be. to learn more about lenses, (probalby usefule for this question) look up a book on lenses or find stuff on the web. look up ray diagrams.

2) as mentioned above, look up hyper focal distance. and no it isn't the best way to do it.. the description of your lens.. say a 50mm lens describes the focal length of your lens for items placed at Infinity. really though, everything is never all in focus, the light just converges within acceptable limits of the circle of confusion. IE,, it is acceptably out of focus. try using f/8 for some of your landscape shots, and make sure everything in the forground is not too close. stopping down really only will help increase your depth of field for objects that are fairly close to you, in fact the closer you get the shallower the dof gets. (this is why macro photography is challenging,, the dof is VERY shallow)

3) for land scape shots,, you never really have to shut it down to the smallest aperture just and acceptably small one,, look at hyper focal distance.

4) black and white film will train your eye to look at light,, and try your best to ignore color ,, looking at patterns, contrast, light souce,, etc. the sun straight up creates a non ideal photographic world because it is so bright that shadows are created,, everything is too contrasty. to much light differential. you can still shoot in the sun,, just try to light up your shadows,,, use fill flash or reflectors what have you. (look up flash compensation). TO sum up I shoot black and white when I get that feeling.

Over all I think you could be helped by a good book on lenses,, look up simple lens and light diagrams,, you can and will learn a lot.<div></div>

my lens light diagram above is mildly misleading.. the red is just light paths from the object placed behind the object in focus.. and the green paths are for the object in front. the cyan paths are objects in focus (they converge on the image plane)

this is all showing light reflecting from a point source. an infinite number of point sources would make up an image