How to choose f-stop / depth of field? I am fairly new to photography and I have read many "beginners guides" and watched youtube tutorials. One thing that remains elusive to me is how to properly pick what f-stop to use.   I use a 35mm, 55mm f1.8, and a 24-70mm f4 lens with my Sony A7.   For portraits, I generally try to pick lower f-stop like between (1.8-6f). For more general use like taking pictures of animals I usually pick between (6f-10f).   The issue I primarily run into is that when I take a picture with a lower f-stop, it looks great in my viewfinder. However when I go home to load it on a larger screen, I find that a lot of elements I am trying to capture is actually out of focus.   How do I know how much room I have to play with before a subject goes out of focus? It seems to change with f stop, how close I am to the subject(s), and the focal length I am using.   I understand the concept that I am basically focusing on a "slice" of space in front of me and when I lower the f-stop, this slice of space becomes narrower. I can't figure it out and I end up getting disappointed when I view the pictures on a large screen.
Is there a 'rule of thumb' that I can use to estimate depth of field while shooting? I can use a DoF calculator, or crunch the heavy math by hand if I really want to know exactly what my DoF is going to be... but most of the time knowing exactly is actually overkill, and taking the time to pull out a DoF calculator is impractical. I'm wondering if anyone knows of a 'rule of thumb' that is common for quickly figuring out a rough estimate of what my DoF will be when I'm in the field...
SUB-TREE WITHIN A TREE in MySQL  In my MYSQL Database COMPANY, I have a Table: Employee with recursive association, an employee can be boss of other employee. A self relationship of kind (SuperVisor (1)- SuperVisee (∞) ).     Query to Create Table:    CREATE TABLE IF NOT EXISTS `Employee` (   `SSN` varchar(64) NOT NULL,   `Name` varchar(64) DEFAULT NULL,   `Designation` varchar(128) NOT NULL,   `MSSN` varchar(64) NOT NULL,    PRIMARY KEY (`SSN`),   CONSTRAINT `FK_Manager_Employee`                 FOREIGN KEY (`MSSN`) REFERENCES Employee(SSN) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;   I have inserted a set of tuples (Query):    INSERT INTO Employee VALUES   ("1", "A", "OWNER",  "1"),     ("2", "B", "BOSS",   "1"), # Employees under OWNER   ("3", "F", "BOSS",   "1"),   ("4", "C", "BOSS",   "2"), # Employees under B  ("5", "H", "BOSS",   "2"),   ("6", "L", "WORKER", "2"),   ("7", "I", "BOSS",   "2"),   # Remaining Leaf nodes     ("8", "K", "WORKER", "3"), # Employee under F        ("9", "J", "WORKER", "7"), # Employee under I        ("10","G", "WORKER", "5"), # Employee under H   ("11","D", "WORKER", "4"), # Employee under C  ("12","E", "WORKER", "4")     The inserted rows has following Tree-Hierarchical-Relationship:                A     &lt;---ROOT-OWNER         /|\                     / A \               B     F      //| \    \              // |  \    K        / | |   \                       I  L H    C         /     |   / \  J     G  D   E   I written a query to find relationship:    SELECT  SUPERVISOR.name AS SuperVisor,          GROUP_CONCAT(SUPERVISEE.name  ORDER BY SUPERVISEE.name ) AS SuperVisee,          COUNT(*)   FROM Employee AS SUPERVISOR    INNER JOIN Employee SUPERVISEE ON  SUPERVISOR.SSN = SUPERVISEE.MSSN  GROUP BY SuperVisor;   And output is:    +------------+------------+----------+ | SuperVisor | SuperVisee | COUNT(*) | +------------+------------+----------+ | A          | A,B,F      |        3 | | B          | C,H,I,L    |        4 | | C          | D,E        |        2 | | F          | K          |        1 | | H          | G          |        1 | | I          | J          |        1 | +------------+------------+----------+ 6 rows in set (0.00 sec)   [QUESTION] Instead of complete Hierarchical Tree, I need a SUB-TREE from a point (selective) e.g.: If input argument is B then output should be as below...  +------------+------------+----------+ | SuperVisor | SuperVisee | COUNT(*) | +------------+------------+----------+ | B          | C,H,I,L    |        4 | | C          | D,E        |        2 | | H          | G          |        1 | | I          | J          |        1 | +------------+------------+----------+      Please help me on this. If not query, a stored-procedure can be helpful. I tried, but all efforts were useless! Limit of a particular variety of infinite product/series How should references in non-Latin script language be treated in English paper? Let's say I want to cite a Russian text in my own paper which is written in English. Should I:   reference it as is, in the original Cyrillic alphabet, although the readers won't be able even to pronounce it? transliterate the authors' names, while keeping the rest as is? transliterate the names and translate the title of the work, journal name, etc. into English? I have read in a book that the limit of the ratio of consequent Fibonacci numbers is the golden ratio. However, it was just mentioned thus not justified. So, my question is how would you derive the following limit: $$\lim_{x\to\infty}{\frac{F_n}{F_{n+1}}}=?$$ Where $F_n$ is the nth Fibonacci number? I can't browse to any website using Safari; yet, Google Chrome and Firefox are working fine. The Mac App Store also reports that it cannot connect.  I am running OSX 10.7.2 on a 2011 MacBook Pro. How to set HttpResponse timeout for Android in Java I have created the following function for checking the connection status:  private void checkConnectionStatus() {     HttpClient httpClient = new DefaultHttpClient();      try {       String url = "http://xxx.xxx.xxx.xxx:8000/GaitLink/"                    + strSessionString + "/ConnectionStatus";       Log.d("phobos", "performing get " + url);       HttpGet method = new HttpGet(new URI(url));       HttpResponse response = httpClient.execute(method);        if (response != null) {         String result = getResponse(response.getEntity());         ...   When I shut down the server for testing the execution waits a long time at line  HttpResponse response = httpClient.execute(method);   Does anyone know how to set the timeout in order to avoid waiting too long?  Thanks! How to send an SMS in iOS 10 Why do I have to press Ctrl+D twice to close stdin? Rotate (group) objects outwards on spherical particle system? I just bought a  game (Forza 4) for my Xbox 360 (bought in the US). When I tried to play the game, it wouldn't load because of region issue. Is there a legal way to solve this (no crack)? I am starting to learn using blender, and at some point I managed to do something to the 3D view camera.  Usually the camera orbits around an object, but now the rotation seems to happen (atleast very close to) around the "camera's origin". Neither the input setting in "User Preferences", the pivot point selection nor Ctrl-Alt-Shift-C (as suggested on some forum) do anything to the issue. I've created a bash script but when I try to execute it, I get   #!/bin/bash no such file or directory   I need to run the command: bash script.sh for it to work.  How can I fix this? Sometimes I use, $PROJECT_HOME/* to delete all files in the project. When the environment variable, PROJECT_HOME is not set (because I did su and the new user doesn't have this environment variable set), it starts deleting all files from the root folder. This is apocalyptic.  How can I configure bash to throw error, when I use an undefined environment variable in the shell? What is the difference between user and service account? I would like to know difference between user and service account.  I know that e.g. Jenkins installed to ubuntu is not a user, .    What is use of service account? When we need them? How can I create service account? I am trying to under stand how to build a barrel shifter using multiplexers. I understand how the barrel shifter works but I don't get how you decide the number of multiplexers to use, and how the shifting is done with the multiplexer basically.  So far wikipedia doen't help much. And the best I have so far is   But it does not really answer my question. Two mice heterozygote and black are reproduced. Find the probability of getting the filium dark and heterozygote if p is prime then 1920 divides $p^4-10p^2+9$ This is a variation of the  questioned some time ago.  For a complex Hilbert space $H$ let $T: H \rightarrow H$ be a bounded operator. We call that $T$ is a trace-class operator if the following sum  $$\sum_{i}{\langle |T|e_{i}, e_{i} \rangle} &lt; \infty$$  converges, where $|T| = (T T^{*})^{\frac{1}{2}}$ is the absolute value of the operator.  Assume that  $$\sum_{i}{\langle Te_{i}, e_{i} \rangle}$$  converges for any basis in the space $H$. How to prove that if the aformentioned property holds then the operator is a trace class operator?  The progress on the problem is the following: Given an arbitrary bounded operator $T: H \rightarrow H$, one can use the following decomposition $$T = \big( \frac{T + T^{*}}{2} \big) ^{*} + i \big( \frac{T^{*} - T}{2i} \big) ^{*}$$  The latter line gives the decomposition $$T = A + i B$$ where $A, B$ are normal operators.  For the normal operators we can apply the spectral theorem that proposes that $T$ is unitary equivalent to  $$(UT U^{-1})(f(x)) = g(x) f(x)$$  where  $$U: H \rightarrow L^{2}(X, \mu)$$ $$g \in L^{\infty}(X, \mu)$$  Though this decomposition classify the operator in a broad sence, i see no direct way to conclude the statement. Are the any hints that may extend the previous argument? If not, are there any ways to conclude the statement? I constantly stay up to date with each new release of Blender, but this means my preferences are wiped clean each time. How do I export/import these preferences to avoid loosing my carefully crafted set up each time? Why is the Sun approximated as a black body at ~ 5800 K? Apparently spectral solar radiation is approximated by a black body at 5800 K. The spectral black body distribution (Planck distribution) is shown below (from Incropera, Fundamentals of Heat and Mass Transfer), with different temperatures including solar radiation at 5800 K.     The heat flux on an Earth surface perpendicular to sun rays (i.e., the solar constant), is roughly 1.36 kilowatts per square meter. Is this simply the integral of the above distribution? Why is the sun approximated as a black body at 5800 K? Does this mean that the surface of the sun which is emitting radiation has a temperature of 5800 K? That seems kind of low. Is solar radiation approximated as a black body at 5800 K only on Earth, or is it the same everywhere? Why don't atmospheric effects and scattering change measurements of the solar spectrum on Earth?   EDIT:  The solar constant is approximated by considering the Stefan-Boltzmann law (i.e., the integration of the spectral solar emission), the size of the sun, and the distance from the sun to Earth. A good derivation is shown here: