What is the difference between, for example, a Nikon 50mm DX lens and a Nikon 50 mm FX lens? Both have the same focal length of 50 mm, but why does Nikon produce a DX lens and an FX lens? What is the difference in the lens construction? Is it just the size of the lenses is smaller in DX compared to FX because FX has a larger sensor? Any other differences apart from size, price and weight?
What is the difference between DX format and FX format lenses, and which to choose for what purpose?  What are the pros and cons of both?
Explaining to laypeople why bootstrapping works I recently used bootstrapping to estimate confidence intervals for a project. Someone who doesn't know much about statistics recently asked me to explain why bootstrapping works, i.e., why is it that resampling the same sample over and over gives good results. I realized that although I'd spent a lot of time understanding how to use it, I don't really understand why bootstrapping works.  Specifically: if we are resampling from our sample, how is it that we are learning something about the population rather than only about the sample? There seems to be a leap there which is somewhat counter-intuitive.  I have found a few answers to this question here which I half-understand. Particularly . I am a "consumer" of statistics, not a statistician, and I work with people who know much less about statistics than I do. So, can someone explain, with a minimum of references to theorems, etc., the basic reasoning behind the bootstrap? That is, if you had to explain it to your neighbor, what would you say? Show finite complement topology is, in fact, a topology How to edit Parameters for an Object after it is created? When you first add a cylinder, you have the option to change the number of vertices, etc, but once you do anything else in blender, it seems you no longer can edit those parameters.   Is there a setting anywhere or an add-on that allows these parameters to be edited later on? If not, how easy would such an addon/feature be to create for anyone reading this? Here is my script:  #!/bin/bash  echo "Digite o local em que deseja instalar o IGRAFU(pressione enter para  instalar em  ${HOME}/IGRAFO):" read caminho if test -z $caminho then caminho="${HOME}/IGRAFO" fi echo "O IGRAFU será instalado no diretório: $caminho" mkdir -pv $caminho  mv -v ./* $caminho echo "Pronto!"   At 'read caminho' I may receive from the user a path like ~/somefolder. When the script receives that kind of path both mv and mkdir won't make tilde expansion, so it will try to create a ~/somefolder and not /home/username/somefolder and therefore fail.  How do I ensure that the tilde will be converted into the HOME variable? CSS two divs next to each other I want to put two &lt;div&gt;s next to each other. The right &lt;div&gt; is about 200px; and the left &lt;div&gt; must fill up the rest of the screen width? How can I do this? Where are the review queue counters? The review queue counters have disappeared:        Where are they?  When I did screenshot the Close Votes queue was not empty, if someone think so. Using have gone to / been to / been in I understand the difference between these constructions: "has gone to", "has been to", "has been in":   "has gone to" &mdash; there or on his way to; "has been to" &mdash; someone has been there but he is on his way back; "has been in" &mdash; someone is still there;   But now I am puzzled by next statements:   Have you ever been to / in Greece? &mdash; Yes, it's a very beautiful country; When did you last go to Canada? &mdash; I've never been to Canada.   If I use "has you ever gone to Greece" construction in the first case or "I have never gone to Canada" in the second statement will it be uncorrect? Or just will sound odd? May I say "I have never been in Canada" in the second sentence. Or in these case all of the variants are possible, the problem is in how people usually say it (in what how it perfectly sounds)? I need help to find the Galois Group of $x^5 +1$. I know that it has a 5-cycle and a 4 cycle and is not a subgroup of $A_5$. Thanks! I followed this  to install Ubuntu as dual-boot with Windows 8.1 pre-installed as(UEFI),but I am not able to dual-boot and tried    I first burned an Ubuntu ISO on a blank DVD-R to create the LiveCD. Even with secure boot disabled, when I tried restarting my computer, it never booted to the installation screen, and it just skipped to Windows.  After a lot of skimming, I thought I had to put my computer in Legacy Mode in order to get give my CD/ROM drive priority. I installed Ubuntu and used my existing EFI partition. Ubuntu works, but Windows doesn't, probably because my laptop is stuck in Legacy Mode. I tried switching back to UEFI using boot-repair on the Linux Terminal, and going into Advanced Properties -> Grub Location -> Ticking the checkbox for EFI, but it says I need to be in an EFI session, and now I'm just really lost and confused at what I've all done. I can see my Windows8.1 OS on a partition but I want to dual-boot Windows 8.1 along with Ubuntu?   Did I just brick my computer? Why can't Chromium suddenly access any partition except for /home? Can I fetch the value of a non-standard CSS property via Javascript? Some months ago I posted  about exporting Sentinel 1 scenes from a collection and was successful with help from .   I now have a new region of interest, which sits on the overlap between 2 scene footprints (sequential images in descending orbit). When I make a mosaic of the 2 scenes I get a small no data gap and lack of alignment between the 2 images:  // Create a geometry representing an export region. var roi = ee.Geometry.Rectangle([-62.67, -8.31, -63.25, -8.85]); var zoomPoint = ee.Geometry.Point([-62.35, -8.06])  // Load the Sentinel-1 ImageCollection. var sentinel1 = ee.ImageCollection('COPERNICUS/S1_GRD') .filterBounds(roi);   // Filter by metadata properties. var IW_H = sentinel1  // Filter to get images with VV and VH dual polarization. .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV')) .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'))  // Filter to get images collected in interferometric wide swath mode. .filter(ee.Filter.eq('instrumentMode', 'IW'))  // Filter IWs to get High res. .filter(ee.Filter.eq('resolution', 'H'))  // Filter IW-Highs to get 10m res .filter(ee.Filter.eq('resolution_meters', 10));  // Filter to get images from different look angles var col_desc = IW_H.filter(ee.Filter.eq('orbitProperties_pass', 'DESCENDING'));  // Spatially mosaic the images in the collection and display var col = col_desc.mosaic(); var colVV = col.select(0) Map.addLayer(colVV, {min:-17, max:-3}, "VV"); Map.centerObject(zoomPoint, 20);   What am I missing?  Are these scenes not acquired sequentially? For some reason I can't boot my system. I get an error akin to Operating System Not Found.   I tried bootrepair, and that didn't work. So then I decided I would just save my personal files, wipe everything, and reinstall.   But in the live session, when I go to the /home directory, my username folder isn't there, instead it goes to the Live CD's desktop and other directories. Is there some other error occurring? Is there a way to recover the files? If there are injective homomorphisms between two groups in both directions, are they isomorphic? If I have two groups, $G$ and $H$ and two injective homomorphisms $\phi:G \to H$ and $\psi: H \to G$, then by the first isomorphism theorem applied to $\phi$, we have that $G \cong \mathrm{Im} (\phi)$, a subgroup of $H$. Similarly, $H$ is isomorphic to a subgroup of $G$. For finite groups, this guarantees that $G \cong H$ but does this hold for infinite groups?  Weird things can happen for infinite groups, e.g $n\mathbb Z \subsetneq \mathbb Z$ but $n \mathbb Z \cong \mathbb Z$. I'm wondering if this kind of thing stops an isomorphism from occurring.  I think this question generalises to rings, modules, fields and so on. Can this be answered for all of these structures? How to read a line from the console in C? What is the simplest way to read a full line in a C console program The text entered might have a variable length and we can't make any assumption about its content. Let $H$ be a subgroup of $G$ with $[G:H]=n$ and $G$ finite.  Let $G$ act on left cosets of $H$ by left multiplication.  Let $N$ be the kernel of the action.  Show that $[G:N]$ divides $n!$.  Ok so I have a theorem that says that if $G$ is simple then it embeds into $S_n$.  So if $G$ is simple than I'm done because $G$ divides $n!$ and thus $N$ divides $n!$ and hence $[G:N]$ divides $n!$.  Now I also know that $N$ is the largest normal subgroup of $G$ contained in $H$.  Thus if $G$ isn't simple then it contains some non-trivial normal subgroup $K$ and thus $K\cap H$ is normal in $H$ and by the 2nd Iso Theorem $H/K\cap H\cong KH/H$...    As you can see I'm not sure where to go from here. I was hoping to prove that $K\cap H$ wasn't trivial and thus that $N$ couldn't be trivial since it must contain $K\cap H$, but I'm not sure I can, and even if I could I'm not sure that would help me in showing that $[G:N]$ is small enough to divide $n!$.  Can anyone give some guidance?  Thanks. I'm at roughly 67% completion of the Alola Dex, with ~200 caught, ~290 seen. After scanning QR codes, I've caught a Swinub and Cyndaquil. However, neither were registered in the Pokédex, since neither are Pokémon in the Alola Dex. This brought up the following question:  When will I unlock the National Dex?   Do I need to have seen all the Pokémon in the Alola Dex? Do I need to complete some specific quest, like catching/defeating the Ultra Beasts? How can I get id,class or name attr an element with jquery Crossthread operation not valid... - VB.NET Remove Reviewer and Steward badges Badges should encourage good behaviour. But what when a badge encourages more bad behaviour than good?  We hear it all the time - robo reviewers, badge-hunters. The review system fights with that users that only want badges and not want to help.  There are many suggestions how to find such robo-reviewers or how to make it difficult to robo-review. But why not cut them off at the source? Don't make them want to review for badges at all.  Remove the Reviewer and Steward badges! The Custodian Bronze badge should suffice to bring a user to the review system. And we really only want users doing reviews who want to help and not doing it for the badges.