DOF, sharpness, and distance to subject question


No longer a newbie, moving up!
Dec 24, 2010
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First of all, I have tried to do significantly less posting and more searching and reading. I have learned and grown so much and wanted to say a huge thank you to those who are consistently helpful to posters with questions. Being able to search through old threads has been most beneficial.

(Grr- accidentally hit "enter"- sorry if you're reading just the above and it makes no sense- standby- editing!)

I have read time and time again on here NOT to shoot wide open on a lens with a large aperture. I have a 50mm f/1.4 and have been reading and shooting and reading and shooting. I am attempting to really and truly *know* the lens intuitively at smaller apertures before I try opening it up. (Don't get me wrong, I've played at all ends of it, but I understand that it's going to be soft wide open, I understand that its DOF is super tiny at 1.4, and I'm trying to get a better handle on other apertures of it before I go anywhere near that end.)

"o hey tyler" and "pgriz" were very helpful in other posts with understanding focal lengths and focal length calculator.

This brings me to my question- If I am shooting a subject from a distance of approximately 4 feet, and using an aperture between f/4 and f/6.4, are there any considerations I need to think about that I may be missing now? To elaborate- at an aperture of f/4 and a camera-to-subject distance of 4 feet, the calculator says I have a focal area between 3.86 feet and 4.16 feet, or an area of about 0.3 feet (4"). If I am shooting from 4 feet at an aperture of f/6.4 it says my focal area is 3.78-4.25 feet, or about 0.48 feet (6"). My camera-to-subject distance is flexible but I will be working in a small room, so the closest distance would be about 4', and the max would be about 8'. I am wanting to capture details and delicate features, so a focal area/depth of 4" to 6" will be perfect. What would you all advise that maybe I am not factoring in? Is one going to be super sharp or crisp over the other? Is f/4 still too open and destined to be soft? I did take some practice shots this evening and I do see an ever-so-slight difference in crispness- but then again my shutter speed was a bit faster with the aperture opened up more so shake may have been a slight factor. (Sorry I don't have any test images to post).

It looks like I could even stop down to about f/11 and still have a pretty narrow DOF (less than 1'). I guess I am just looking for some feedback and advice. Obviously I will do some test shots and see what works best, but I don't want to preview images on my camera and maybe not realize that they are a bit soft until it's time to post process. So, experts- any words of wisdom? Advice?
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im thinking she is saying that she has heard people say how if you say have a 35mm f1.4 lens that at 1.4 your shots are going to be soft. because its not at the optimum setting for the lens itself. basically don't shoot at the most extreme f factor on each end of the lens. and she's asking if at f4 is that too wide open to get the best photo, based on the distance away from the subject. or at least thats how im hearing the question.
Most large aperture lenses are sharp from about 2.8 onward. The photos will have probably very little difference in sharpness at the center of focus, however at the smaller aperture there will be more of the subject in focus.

Also; no one said to not shoot wide open. They said to not shoot wide open until you know what you're doing.
12- I think he replied while I was editing ( I hit enter and only the first part showed up initially). You are understanding my question correctly. Also, your response was your 666 post on the forum- not sure why I noticed that- weird. :) Hope I didn't over-complicate the question, I just want to know if there's anything I'm not taking into account or if I should try something completely different.

Dave- Thank you! That does lead me the right direction (what you said about most being sharp above 2.8).
If you have an iphone or an android, download a DOF calculator. It will answer a ton of questions and take a bunch of guesswork out for beginners. Trial and error will prevail.
Well, one thing you must realize is that that 4" to 6" depth of field extends, in the simplest possible wording, "straight out" from the camera, with the back of the camera being parallel to a subject. And you asked what you might be missing...well, what you might be missing is that, if you aim the camera downward, let's say at a table, and there is an "angle" of let's just say 30 degrees to the back of the camera, that 4 to 6 inch depth of field will be "distributed" in such a manner that ANYTHING that projects upward from the table, like say the top of a salt shaker, might very well be OUT of the depth of field zone. Sad, but true.

This is why a view camera, with a movable, "tiltable" front standard is so,so useful in close-up and table-top photography. With a fixed-lens camera, with a fixed back, like your d-slr, the 4 to 6 inches of depth of field is calculated with the supposition that the camera's back will be in perfect parallel with the subject area.

Let me put it this way: between 4 and 6 feet, with a 50mm lens,apertures in the range of of f/4 and f/6.4, provide little DOF, and CRITICAL focusing is essential. If the camera is "looking up" or "looking down" at a person's face, that "four inches" of DOF is an illusion, a farce, a fable--a place where reality and theory part ways...If you really want to be able to photograph freely, you need to use apertures like f/8 to f/13 at this close distance range of 4 to 6 feet.
Derrel- thank you for your reply. I do understand what you mean by the angle, and plan on shooting parallel to my subject. (it would help if I elaborated I guess- I'm doing a newborn shoot tomorrow for the experience only and am wanting the most shallow DOF I can use for eyelashes, ears, lips, toes (not all at once) while still having my subject (specific body part) be sharp and not have softness due to too large an aperture. The space constraints are due to the layout of their home and best lighting. I am trying to slow down, take my time, and really compose my shots.

Again thank you to everyone who has been so helpful. It can be so discouraging to read through threads and see the nasty remarks and condescending comments some people freely wield. Heck I've probably said something I shouldn't have a time or two as well but I've realized how crappy that is to do. I hope to continue learning and growing from this valuable forum! Thank you again.
There's no hard rules... it's perfectly fine to shoot portraits at 1.4 as long as you can manage the DOF problems--the contrast and sharpness isn't the best wide open, but that's often flattering in a portrait. Before the advent of digital manipulations photographers used to use filters to, GASP, soften their images. Sharpness is overrated.
The sercret to those wide open shots is that the blur makes sense. Say you focus on the eyes of a baby. For that to make sense in the picture, the viewers focus has to be drawn to the eyes. If it's drawn to another part of the baby it will come across as a blurry picture. That's why people tell beginners to close the aperature down some until they learn to apply that shallow depth of field to the framing of the image.
I can't grab the code off Flickr nor can I see the exif data (posting from phone at my fire station), but here is a shot I uploaded from phone to photobucket (which doesn't preserve the best quality so take it with a grain of salt). iirc I took this one pretty darn open and was tickled pink at the results when printed. I think I have a pretty good understanding of it, but never know what it is I don't know, if that makes sense.

I think you're getting there. The image of the baby's foot definitely captures the ability of a shallow DOF to direct our attention to what you want us to see.

The challenge in getting "everything in focus", as you've been learning, is that the relatively high f/numbers (F/8 through f/22) all limit the amount of light, forcing you either to go to very slow shutter speeds, or requiring additional amount of light in the form of flash or other lighting equipment. Of course, you can also boost the ISO, but at the cost of increasing the noise in the image, and reducing your dynamic range. The answer to the above problem is the one you'll hate: "It depends".

If your shooting situation is static (still life or non-moving subjects), then using a tripod, augmented by various off-camera flashes and accessories will work. This then becomes the "studio" solution.

If your shooting situation is more dynamic (still indoors, but you're moving around and the subjects are moving around), then an on-camera flash becomes more appropriate. At this point, the choice of whether you use bounce flash or other method of softening the flash depends on the size, color and configuration of the space/room you're in.

If you are shooting moving around in an enclosed space, another option is to use strategically positioned flashes or other lighting sources that will illuminate the room pretty evenly, but now you have two challenges: to aim your camera so that the bright parts of the room don't show up in your images, and to deal with the appearance of omnidirectional light (relatively flat). While this technique is doable, it takes a lot of practice.

As you have already learned, you're always balancing aperture (with its relation to DOF), with shutter speed (too low, and you get hand-shake blur), with ISO (little noise or lots of it), distance (closer in means less DOF), and light (there's never enough of it!!!).
A factor you may not be aware of is that the distribution of the DoF in front of, and behind the point of focus can also change.

In your example of the 50 mm lens @ f/4 and a 4' focus point distance the DoF distribution is 48% in front of, and 52% behind the point of focus. However, by changing just the lens aperture to f/11 the DoF distribution then becomes 45%/55%.
I know that's not a big change, but as focus point distance increases, so does the change in DoF distribution with changes in lens aperture, which is why I brought it to your attention.
Good call, Keith! You beat me to it.. I was thinking that info needed to be added to this post as I was reading it. A lot of people don't realize that depending on where you focus, less than half of the usable DOF is going to actually be on the subject. When you are already dealing in inches, that can be very important.

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