I have an older Pentax MZ-50 camera that came with a SIGMA 100-300mm lens. Can I get an adaptor so the lens will work with my Canon EOS 1100D?  If so, where can I get one from? Any help would be greatly appreciated.  Cheers,
My dad has an old Sears KS-2 + 50mm f/1.7, which from a bit of research seems to use a Pentax K-mount.  I've looked around a bit and found a , which says it supports af-confirmation, and costs ~$30 US.  Has anyone tried using an adapter ring like this, and if so, would you recommend doing so?  I am perfectly happy with shooting manual, but I'm curious about the quality of older lenses.  I'm assuming that if I use older primes the optical quality will be fine, and it looks like the build quality of the older lenses is much better that similarly priced new lenses.
Proof that there are infinitely many prime numbers starting with a given digit string To prove the following fact: given any sequence of digits in any base, eg 314159265358979323 base 10, there are infinitely many primes that start with these digits,eg when expressed in decimal they start with 314159265358979323. I think using a prime number theorem will be helpful . But I am still not getting a point of how to start the proof. Does the Hong Kong metro map give interchange direction suggestions? On the , some of the interchange symbols have little lines and half-circles in them. They're a bit small to read on some maps, but if you zoom in they get a big clearer:    Are these suggestions for where to change depending on the direction you're going + changing to? Or do they have some other meaning?  .  Bonus marks - Assuming I am right that that these are direction interchange suggestions, what does it mean if it's an empty circle, or a "T" in one? How does QGIS Zonal Statistics handle partially overlapping pixels? I just read this very insightful post , where the author stated that the variance of $\hat\beta$ is:  $$\text{var}(\hat\beta) = \sigma^2(\textbf{X}^\prime \textbf{X})^{-1}.$$  I couldn't figure out why it is like this. Can anyone elaborate a bit? I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic knowledge of quantum mechanics. I know that Schrödinger's equation is deterministic. However, quantum mechanics is much deeper than that and I would like to learn more. If this question is not clearly answerable at this point than can anyone point out some recognized sources that try to answer this question. I would appreciate it if the source is scientific and more specifically, is related to quantum theory. What time zone do SO's servers operate in? What time zone do Stack Overflow's servers operate in?  I noticed that it couldn't be my time zone, or the ones before me (I'm in North American Eastern Time), because I logged into SO earlier today (around 12 pm), then I logged in just a few minutes ago (around 8 pm), then about a minute later I got the Fanatic badge (yay me!). Reverse String order Unable to change payment information to NONE in iOS Appstore These questions are really bothering me. Any help would be much appreciated.  Let $p$ be prime  a) If $(G, \oplus)$ has order $2p$, prove that every proper subgroup of $(G, \oplus)$ is cyclic  b) If $(G, \oplus)$ has order $p^2$, prove that $(G, \oplus)$ has a subgroup of order $p$ Placing math environments inside math environments I have a macro which appears throughout my document in various places:  \newcommand{\placefraction}[2]{     $\frac{#1}{#2}$ }   Sometimes it is placed with regular text. Sometimes it is placed within other math modes. However, the document won't compile if it is placed inside another math mode.  None of my math ever appears in displayed formulas, it is always part of the paragraph.   How can I have a macro which sometimes appears inside math mode, sometimes outside, but itself contains math mode? A list of inconveniences between quantum mechanics and (general) relativity? Possible Duplicate:          I know that I have to find the number of factors of $5$'s, $25$'s, $125$'s etc. in order to do this. But how can you derive such a formula for any number $n$? Detecting current iPhone input language How to find the smallest $n$ such that $n^a\equiv 1 \pmod p$ Given a prime $p$ and number $a$, how do I find the smallest $n$ such that $n^a\equiv 1 \pmod p$? Is there a non trial-and-error method?  Edit: obviously removing $n=1$! This is a general question that was asked indirectly multiple times in here, but it lacks a single authoritative answer. It would be great to have a detailed answer to this for the reference.  , the proportion of correct classifications among all classifications, is very simple and very "intuitive" measure, yet it may be a . Why does our intuition misguide us here and are there any other problems with this measure? What is the difference between String and string in C#? Example (note the case):  string s = "Hello world!"; String s = "Hello world!";   What are the guidelines for the use of each? And what are the differences? Symbols of derivatives Remote Desktop Session Black after Minimize PROBLEM: When I minimize a remote desktop session and restore it, the remote desktop screen shows up black. This only happens when connecting to a particular computer.   DETAILS: If I start clicking around in the black area, portions of the screen will start redrawing and showing up correctly. For example, if I leave a window open in the remote session and click where that window is located on the remote computer, then that window--and only that window--will redraw, and sometimes a portion of that window won't redraw (usually the toolbar).  And to clarify--the window only has to be minimized momentarily, so it doesn't seem to be a timeout issue. Clicking or typing in the remote session still causes the remote computer to respond appropriately. Disconnecting from the session and reconnecting restores the whole screen image, as does clicking all over the place in the black image (causing each section to redraw).  CONFIGURATION: This problem only happens for me when connecting to a particular computer (a W2K Server box configured to allow remote administration) and only with certain client computers. I've tried 7 different client computers with various versions of Remote Desktop (the OSes were: Win2K, Server 2003, Server 2008, Windows 7 RC, 3 XP) and two of them exhibit the problem (one is one of the XP boxes and the other is Windows 7). Those same computers can RDP to other computers without problem.  RESOLUTION ATTEMPTS: I have tried the following:   Disable the LOCAL screen saver as mentioned on  Turned off bitmap caching in the client, as mentioned on many forums. Updated to version 6.1 of the remote desktop client Using mRemote (I doubted this would work since it uses MS's code for connecting to RDP servers) Turning off all video acceleration.   QUESTION: Any ideas on what is causing this? The plugin generated X characters of unexpected output during activation (WordPress) How do I do a case-insensitive string comparison?