Why do most professional photographers prefer to use their SLRs optical viewfinder? I have heard again and again that using the digital viewfinder on your SLR is a big no-no and that you should always use the optical viewfinder when framing a shot.  Why?
What are the advantages of using the optical viewfinder over live preview to take photos on a DSLR? Forgive this novice question, I am basically a complete newbie to photography.  Really, all I've ever used for most my of short life have been point-and-shoots; I've only recently started to pick up some curiosity.  Anyway, from what I've gathered, reading through many of the  questions, most serious photographers use the optical viewfinder as their primary tool to determine what makes a good shot.  Live-preview isn't used much at all; it seems its help is to primarily set up the shot.  Reading a Wikipedia article seems to confirm this view, adding that      [l]ive preview in DSLRs does not typically serve as their principal means of framing and previewing before taking a photograph, with this function still being mainly performed with optical viewfinder. While initially largely a novelty feature, live-preview functionality has become more common on DSLR cameras...    My questions are:   What are the myriad advantages of using the viewfinder over live preview, what does it help one accomplish in achieving the goals of photography? What are some interesting ways serious photographers use live preview to take better shots they might have otherwise missed?
Prove that for all integers $n$, $n \geq 1$,   $$1 + 3 + 5 + \cdots + (2n - 1) = n\cdot n$$   How would I go about proving this? Why is mathematical induction a valid proof technique? What's a concise way to check that environment variables are set in a Unix shell script? Search for a string in all tables, rows and columns of a DB Script to Notify me when something happens on a shared directory The situation is:  I have a shared directories from many other machines where other users work on.  I need to be notified whenever a user create, modify or delete a directory or file from his local directory which I share using smb...  It looks like the folder actions in the MAC systems..  Is there a software that do that?!  If there is no such application, any help in writing a script for that is appreciated..  Thanks in advanced... Migrate database from Postgres to MySQL Is the set of all unitary matrices in $M_2(\mathbb{C})$ is compact? I can show that as determinant map is continuous so unitary matrices are closed but how to show they are bounded?   Please help. How can I minimize Thunderbird 60.2.1 to tray after "MinimizeToTray revived" add-on stopped working? After update, my Thunderbird stopped getting minimized with the "MinimizeToTray revived" add-on. Is there any way to minimize my Thunderbird? Any other add-on that works with the new version? Found a similar question , but with some minor differences. Is it archaic to use have you in sentences such as this:     John : I think we can see it with a specially crafted telescope.   Mary : Have you such a telescope?   instead of     Mary : Do you have such a telescope?   Is it still used in official and casual conversations? What are the advantages of a custom ROM over rooted stock? Which style is preferred? Is there a good reason for one vs. the other?  Thanks in advance!  1) cmds.each do |cmd|    end  2) cmds.each { |cmd|    }   Example code:  cmds = [ "create", "update", "list", "help" ]  # Block style one # cmds.each do |cmd|   puts "loop1, cmd: #{cmd}" end  # Block style two # cmds.each { |cmd|   puts "loop2, cmd: #{cmd}" } PCA and proportion of variance explained I'm just going to throw this out there, but Google indexes Stack Overflow really quickly Statements equivalent to the Axiom of Choice The Axiom of Choice reads:     The product of a collection of non-empty sets is non-empty.   As you know well, this axiom is equivalent to many other statements. A few examples (probably the most known) are the following:   Zorn's lemma: Let $(P,\ge)$ be a poset in which every chain has an upper bound. Then $P$ has a maximal element.   This is used in a number of different places to prove very powerful theorems. A couple of examples I can think of right now are: the proof that every ring has a maximal ideal (commutative algebra) and the  (functional analysis).   Well ordering theorem: Every set can be well-ordered (i.e. it admits a total order such that every subset has a least element). Tychonoff's theorem: Every product of compact topological spaces is compact.   This is used for example in the proof of  (again functional analysis).   gives various more. Among them:   Tarski's theorem: If $A$ is an infinite set, then there is a bijection $A\to A\times A$.   (As @Wicht dutifully commented, Tarski's theorem is the name given to the implication $|A|=A\times A \Rightarrow$ Axiom of Choice, while the other implication was known before the proof of this fact by Tarski.)   Every vector space has a basis.   My question is: what are other useful statements which are equivalent to the axiom of choice? Where are they used, and to prove what?  P.s.: By "useful statements" I mean either statements which are important theorems by themselves (as Tychonoff's theorem) or that are directly used in (simple versions of) the proof of important theorems (as Zorn's lemma). I'm working on a map in Bedrock Edition, and I need to have a command block at the end that says "Congratulations [player], you win!" Because it's a map, I cant just have it say a specific player's name, and I've seen maps that do exactly what I want mine to do. How do I format the command to allow this? How do I find least cost path over a DEM based on slope magnitude and direction? What sort of algorithms can I use to find a least cost path through a DEM where it costs more to traverse a cell going downhill or uphill than it does to follow the contour of the land?  All the examples I've seen involve creating a least cost surface where the magnitude of the slope is part of the cost - but the direction isn't.    Additionally, the examples assume the cost to travel through a cell does not depend on the direction of travel. Schur's theorem and numbers Can you give a proof for bounds of  $S(r)$? Please suggest me articles to have better idea of Schur's theorem (Ramsey theory). As title, what is the difference between a   and ~?  I see no differences after the compilation.  MWE:  \documentclass[a4paper]{article}  \usepackage[english]{babel} \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{graphicx} \usepackage[colorinlistoftodos]{todonotes}  \title{Your Paper}  \author{You}  \date{\today}  \begin{document} \maketitle  I am cool.  I~am~cool.  \end{document} How to show $x_1,x_2, \dots ,x_n \geq 0 $ and $ x_1 + x_2 + \dots + x_n \leq \frac{1}{2} \implies (1-x_1)(1-x_2) \cdots (1-x_n) \geq \frac{1}{2}$ How to show  $x_1,x_2, \dots ,x_n \geq 0 $ and $ x_1 + x_2 + \dots + x_n \leq \frac{1}{2} \implies (1-x_1)(1-x_2) \cdots (1-x_n) \geq \frac{1}{2}$ Writing a git post-receive hook to deal with a specific branch