If I take a picture of a flat surface perpendicular to the direction of the lens (i.e. the surface is facing directly at the camera), and I focus on the center, are the points off center in perfect focus, since they are further from the lens than the center point?  Alternatively, do camera lenses have a way to account for this?  If in fact the points off center are slightly out of focus, couldn't this have a significant effect on achieving focus across the entire surface, especially if the camera were close to the object?  Thanks to anyone who can shed some light on this.
This is something I just realised I don't entirely know the answer to, so I'm going to ask it here as I think it's interesting.  In most non-scientific writing on depth of field, diagrams generally show camera and subjects as being perfectly parallel, e.g.    However, is this a more accurate representation of the focal plane?    Are there ways to optically alter the shape of the focal plane?  Note: Obviously these diagrams are two dimensional, but I'm assuming in the second diagram the shape would be spherical with the sensor at the center.
Incorrect query filter according to the requirement My requirement wholly depends on the QUERY.  I am filtering my gridview on the basis of three parameters.   Project_name (Always required) Date (Not always) Vehicle_No (Not always)   So, what my requirement is,      With project_name either any one can be used for filtering my gridview.   Currently my debugged query works exactly fine for any two parameters.  Below is my debugged query:-  SELECT DISTINCT sv.mkey, vehicle_no,                TO_CHAR (date_in, 'dd-MM-yyyy')             || ' &amp; '             || time_in vehicleindate_time,                TO_CHAR (date_out, 'dd-MM-yyyy')             || ' &amp; '             || time_out vehicleoutdate_time,             gate_no_in || ' &amp; ' || gate_no_out ingate_outgateno,             gd.good_type goods_type, net_weight netweight,                TO_CHAR (challan_date, 'dd-MM-yyyy')             || ' &amp; '             || challan_no challandate_no,             remark_in remarkin, NULL receipt_no, date_in        FROM xxcus.xxgid_supinv sv,             xxcus.xx_supinv_goodtype gd,             xxcus.xxacl_xxgid_user_mst ms       WHERE (gd.good_type_code(+) = sv.good_type)         AND (       sv.project_id = '1368'                 AND TO_CHAR (date_in, 'dd-MM-yyyy') = '26-11-2015'              OR vehicle_no = '0'             )         AND sv.delete_flag = 'N'    ORDER BY date_in DESC, vehicle_no   The above query shows me the exact result for project_name and Date which I entered.  But when I add the third parameter say Vehicle_no it doesn't show the data for that exact vehicle_no it still shows me the same data which I looked for 2 parameters.  I am using Oracle for the database.  LATEST UPDATE WHICH IS NOT WORKING  I am confused as how to deal with the query, as Balazs' solution was working fine when I selected, Project_name, Date and then vehicle_no (not necessary). But it was not fetching proper result when I took first as Project_name, and Vehicle_no. Any guesses why?     The issue  is when I only filter with Project_name and Vehicle_no the date_column value comes as 0 so it doesn't show me any row, which is incorrect as I have data for that Project_name and Vehicle_no.   I have used Balaz's second query for the solution which is below  WHERE (gd.good_type_code(+) = sv.good_type)     AND (       sv.project_id = '1368'             AND TO_CHAR (date_in, 'dd-MM-yyyy') = '26-11-2015'          AND vehicle_no = decode(:vehicle_no, '0', vehicle_no, :vehicle_no)         ) Exporting feature class into multiple feature classes based on field values using ArcGIS Desktop? I have a feature class with over 2,000 features, and I need to make them all individual feature classes based on a field.   Is there a way to do this? While reading a question here whose answer was Stephen Baxter's &quot;Light of Other Days&quot; book, it reminded me of a short story I read with a similar idea. Probably read at least 30-40 years ago, in English. The fact that the Government has invented a device that can view the past is made public (by a whistleblower, I believe). Historians go nuts besieging the government to look at their favorite time periods to reveal the truth about various historical &quot;facts&quot; and or &quot;mysteries&quot; (Who shot JFK? Who was Jack the Ripper? Was Helen of Troy really that beautiful? Did Jesus exist? etc, etc.) And the government is stonewalls most of them and claims it's expensive to operate, hard to control to get exact time/location, etc. So someone (maybe the whistleblower?), knowing it's possible, does math/construction and builds his own version, and realizes it's easy to make, cheap to operate, and easy to use. So he makes plans to stick it to the government by releasing the info. Maybe he tries to force the government to release the info, or they realize he has made it, so they grab him and try to convince him to stop. But he is not convinced until they tell him, it can't see back very far (maybe just a few days/weeks, because it needs exponentially more power the further you look back.) Finally the agents tell him: &quot;Don't you see, you can use it to see what's happening just a few minutes ago, or even now. Your company can't make widgets? Zoom in on your competitors and see how they make them. Think your wife is fooling around on you? Zoom in on her and track her to see if she is. Your pretty neighbor is taking a bath now? Zoom in and watch her... These devices mean no one will have any privacy now.&quot; At which point he tells them it's already too late. They kept him there so long that the letters he mailed will already be delivered to various newspapers, scientists, historians, etc. I know that $S_n$ is generated by a number of things, like all transpositions, all transpositions of the form $(1\,a)$, the transpositions $(1\,2),(2\,3),\dots,(n-1\, n)$, and  just the two elements $(123\dots n),(1\,2)$.      Suppose $n$ is prime. If you just have $(123\dots n)$ and some arbitrary transposition $(a\, b)$, how does this also generate $S_n$?    Can you somehow get to $(1\,2)$ or reduce it to some other previous case? Testing whether two regression coefficients are significantly different (in R ideally) If this is a duplicate question, please point to the right way, but the similar questions I've found here haven't been sufficiently similar. Suppose I estimate the model $$Y=\alpha + \beta X + u$$  and find that $\beta&gt;0$. However, it turns out that $X=X_1+X_2$, and I suspect $\partial Y/\partial X_1 \ne \partial Y / \partial X_2$, and in particular, that $\partial Y/\partial X_1 &gt; \partial Y / \partial X_2$. So I estimate the model $$Y=\alpha + \beta_1 X_1 + \beta_2 X_2 +u$$and find significant evidence for $\beta_1,\beta_2&gt;0$. How can I then test whether $\beta_1&gt; \beta_2$? I considered running another regression $$Y=\alpha +\gamma(X_1 - X_2) + u$$ And testing whether $\gamma&gt;0$. Is this the best way?  Also, I need to generalize the answer to many variables, i.e. suppose we have $$Y=\alpha + \beta^1 X^1 + \beta ^2 X^2 + \dots + \beta^nX^n + u$$ where for each $j=1,\dots,n$, $X^j=X_1^j+X_2^j$, and I would like to test for each $j$ whether $\partial Y/\partial X_1^j \ne \partial Y / \partial X_2^j$.  By the way, I am primarily working in R. iOS Launching Settings -> Restrictions URL Scheme Control 220V AC line using MCU When do the differences between APS-C and full frame sensors matter, and why? Can a JavaScript object have a prototype chain, but also be a function? function a () {     return "foo"; }  a.b = function () {     return "bar"; }  function c () { }; c.prototype = a;  var d = new c(); d.b(); // returns "bar" d(); // throws exception, d is not a function   Is there some way for d to be a function, and yet still inherit properties from a? unsigned int vs. size_t Is there a robust command line tool for processing csv files? More Generating Functions problems I have a large amount of duplicate records (25.000) in an even larger table (250.000 records). I've done the detection using the reporting function. The criteria I used to detect the duplicates were 3 fields (unique account identifier, unique user identifier and date). Based on a list of criteria, I would like to either merge or delete these records. I've got a handle on the logic associated with the merging and the deleting but what I'm having trouble with is defining the duplicate detection process.   I'm looking at either creating a custom object to take care of the detection or dumping the records into an SQL database and taking care of it offline. Any thoughts on which one of the two is the best approach?  Edit:  After reading the first comment, I think the more appropriate question would be "How do I approach the problem in SOQL".  The object I'm working with is the Event object and I'm really only looking at the standard fields, AccountId, OwnerId and ActivityDate. From what I've found online, there's no easy way to find records that have the same value for these three fields. I think it could be accomplished by nesting SOQL queries but I'd like to use a different approach if at all possible. Check ping statistics without stopping Is there a way to tell ping to show its usual termination statistics without stopping the execution?  For instance, I'd like to quickly view:  --- 8.8.8.8 ping statistics --- 2410 packets transmitted, 2274 received, +27 errors, 5% packet loss, time 2412839ms rtt min/avg/max/mdev = 26.103/48.917/639.493/52.093 ms, pipe 3   without having to stop the program, thus losing the accumulated data. Let $G$ be a finite group and $F$ a field with $\mathrm{char}(F)=0$ or coprime to $|G|$. Let $V$ be a $FG$-module in a way that every $ FG$-homomorphism $ f : V \to V $ is given by $f(x)= \lambda x $. Then $V$ is irreducible.   I already managed to proof this by contradiction, using Maschke's Theorem. We can  write $V$ as $U\oplus W$ and get a $FG$-homomorphism $\pi:U\oplus W \to U\oplus W$, $\pi (u+w)=u$, then $\pi(u+w)=\lambda (u+w)=u $ then either $U$ or $W$ are trivial and thus $V$ is irreducible.  My question is if this statements still holds if the characterictic of $F$ divides the order of $G$, since I only used this fact in my proof to use Maschke's theorem. Free way to clone HDD to SSD? Is there a free way to clone a full Windows 7 installation from HDD to SSD? (The free part is important, I know I can pay for Acronis True Image.)      SSDs are usually much smaller than HDDs which complicates matters. For instance, I have about 50GB data, my new SSD is 80GB but I still can't use Windows clone/restore system if my HDD is something like 300GB.  Therefore, I'm looking for a third party tool that will be able to:   Create a clone of my C: partition Store it onto an external USB drive Boot from some rescue / restore CD Load the image onto the new SSD   Acronis True Image seems like a tool that should support this but it's a paid-for software and the trial version cannot create clones. Acronis Migrate Easy is a fully functional tria for 15 days but need both the HDD and SSD connected at the same time which is a bit of a problem for me as a laptop user.  P.S. I almost got there combining Windows image backup combined with Acronis True Image restore CD (which can load .vhd's) but was not able to boot as some boot information were probably lost and could not be repaired using the Win7 installation DVD. Given a sample of n units out of a population of N, population median can be estimated by the sample median.  How can we get the variance of this estimator? If I seem tired, can I say: "I haven't slept last night"? If not, why have I been told that we use present perfect for actions that have present effects? How do I survive in the Nether? Whenever I travel to the Nether in Minecraft, I almost instantly get blasted to smithereens and chopped up into little pieces.  How do I survive in the Nether, at least long enough to build some sort of shelter and get situated? Can you turn weather off in Minecraft?