Vaf 10: Fill & Download for Free

VikasAnvesh Foundation (VAF) is an initiative of the Tata Trusts. Mounted in 2016, the initiative was hived off into a separate legal entity in 2017. VikasAnvesh Foundation (VAF) works with a range of partners across India for identification, characterization, advancement in such issues,Social Work In IndiaTake a Look on some Current social workers in India.akeina-gonmeianil-vermaashif-shaikhashis-modalchingmak-changeklavya-prasadjamila-nishatjohnny-oomenmadhukar-dhasmamoon-akhtarnimesh-sumatiosama-manzarpramod-kulkarniprithibhusan-dekarajesh-shingisarat-dassharbani-das-roysudhir-katiyarsuresh-kumarvandana-gopikumarv-vivekanandanyogesh-jainsource: http://www.socialworkindia.in/

The Canon EOS 6D is just dandy at video. Of course, pretty much every DSLR can do good video. It’s particuarly good in low light, which of course is the main point of the 6D, and full frame in general.Now of course, you’re limited to full HD at 24p or 30p, which isn’t really state of the art. It does 720p60, if you need fast rates. That’s the same as my actual camcorders, and was never a problem. Then again, these days you can get a 4K camera, so it’s dependent on what you want.Anti-Aliasing FilterThe 6D and the 5D mark III came out one after the other, and they’re similar in performance. The 6D has a slight edge on low light, and yet the 5D mk III was always the go-to camera for video. Why? Well, it was the 5D mk II that pretty much established the “stills for video” camera industry, so that’s a part of it. But the other thing is the anti-aliasing filter. The 5D has one, the 6D does not.So what’s that about? It’s based on sampling theory, which I won’t write a book on here, promise! Your camera is taking a real world image and sampling that across 20 million pixels, each pixel a different sample. What happens when a feature in your image is about the size, maybe a little smaller than a pixel? If it’s a still photo, you may see a Moiré pattern (Moiré pattern), which looks a little weird, but may only be noticed when you’re pixel-peeping.But in video, you can get that same Moiré pattern moving all about — it can be very distracting. On practically all DSLRs, this is exacerbated by the fact that you’re using a Bayer sensor. That means that you don’t have 20 million RGB sensors, you have 5 million red, 10 million green, and 5 million blue sensors. So your effective sampling is actually even coarser than you think it is. Older pro camcorders had three separate sensors, one each for red, green, and blue, so they had less of an issue with aliasing than modern cameras.And cameras can stop this by employing a thing called an optical anti-aliasing filter, which helps to remove these Moiré patterns. However, it does that at the cost of a bit of sharpness.As a result of all this, it’s fairly common that a camera mostly intended for stills will leave out the anti-aliasing filter, offering up a bit more resolution that will, occasionally, deliver lovely-or-not-so Moiré patterns. But if the video is strong in this one, it gets the AA filter. Thus, the 6D with no filter, the 5D mk III with the filter.David Stembridge does a pretty good real-world demonstration of this. He’s incorrect that this is related to “rolling shutter”… I’ll cover that next, but he’s absolutely spot-on with his demos of aliased vs. non-aliased shots. He’s reviewing an add-on anti-aliasing filter for the 6D, so you get A/B comparisons. And given the fact of this VAF-6D filter, you actually can buy the 6D first, then figure you’re good, or if the filter is an option.Rolling ShutterOk, so since Mr. Stembridge mentioned it, I’ll talk a little on rolling shutter. This is about what happens in the sensor when you press the button.When you take a still photo, the 6D flips up its mirror. That sends light to the “focal plane”, the place the image focuses. There’s a mechanical shutter there, and it opens to expose the sensor, just as if it were film. After exposed, the sensor is electronically read, a bit or so at a time.But in practical video, you don’t get a mechanical shutter. Movie cameras had a simple rotating shutter that was much simpler and longer lasting than other kinds, but cumbersome. So most still cameras don’t have them. Your focal plane shutter is too slow for video.And so you also have an electronic shutter. That’s not a physical thing so much as some clever software. The sensor in your camera is based on a big array of photodiodes. It can be set to record an image, at which point the photodiodes start detecting photons by releasing an election which then goes in to a special capactor called a charge well. At some point, you want to turn that charge into a voltage, that voltage into a number, and voila, a digital image.The problem with most sensors is that the time it takes to read out the sensor is significant, and there’s no actual processing or memory in most photodiode arrays. If I start an exposure, then stop it and start reading top pixels, the bottom ones are still being exposed. The mechanical shutter is the thing that make the exposure “global”.So to fix this, the camera software starts the exposure at the top of the sensor, but not everywhere. It’s factoring in the time of transfer to the camera. Gradually, pixels from top to bottom get sensitized, capture light, turn off and transfer their image to the camera’s image processor. The photodiodes at the top are working first, and that “rolls” down the sensor until the last one has been exposed. This means that, while every pixel got, say, a 1/125th second exposure, they got this at slightly different times.Here’s a still of a plane with moving props shot with an electronic shutter camera. The bending of the props is obvious… that’s the rolling shutter effect, not a weird plane.In general, large sensors are slower in the same generation than small sensors, higher pixel count slower than lower pixel count, etc. So the tiny 1/4″ or 1/3″ sensors used in camcoders have less of an effect.It’s entirely based on what you’re looking for, if this is any kind of issue. I’ll admit that I really haven ’t noticed it in the practical world.Big Rigs and Other ThingsSince a still camera isn’t usually optimized for video, there are all kinds of different ways to build your own system… if you’re on a tripod. In my experience, I have my 6D either on a tripod or on my Glidecam 2000 when shooting video. Some folks add pro video lenses, some matte boxes, some racks for zoom or focus, etc.I always shoot DSLR video with an external mic, usually with an external recording device like my Tascam DR-60D mk II. The built-in audio recording of a DSLR is probably ok, but the mics are there only for audio sync. They’re uniformly terrible. The external recorder adds higher resolution recording and pro-mic XLR inputs. Of course, you’ll need some pro mics to go with it.You lack a number of software in-viewfinder features in a DSLR: audio meters, focus or exposure peaking, etc. For Canon, you can get a thing called Magic Lantern (Magic Lantern) which really does help.The 6D, like most DSLRs, will stop recording after 29 minutes, 59 seconds. This is due to, well, Europe. Not sure why it needs to affect us, but it does. If you want long, unedited shots, you might want a different camera. But consider: the length of a 35mm roll for a Panasvision camera is usually 10 minutes. Cinematographers have worked around this for years. Action video, on the other hand, might work better with a dedicated camcorder.Dave Rocks OutHere’s a 6D video sample, no anti-aliasing filter. I don’t have much I can post without someone else’s permission, so you have to watch me play:I’m not interested in making your decision for you, just in handing out the information that I know on the subject.Read MoreIs the Canon 6D a Budget Full-Frame Secret Weapon with Mosaic Engineering's New Anti-Aliasing Filter?

I tried to find a simple formula to give you, but I was unable to find it in the “wild”. However, in page 139 and following of Sze (found here: http://www.fulviofrisone.com/attachments/article/486/Semiconductor.Devices_Physics.Technology_Sze.2ndEd_Wiley_2002.pdf) you have the formulas to do the reasoning yourself :-) They are quite complicated and involve both geometrical factors (such as the width of the base) and the doping intensities of B, C and E; as well as the temperature, of course.I presume that what you are asking is if “the BJT still has gain [math]\beta_F\gg 1[/math] in the forward active region” even if the emitter and collector are under the same level of doping.My bet is a “moderate yes” (but I didn’t do the math based in the aforementioned equations) because of the following fact: if, in a circuit — say the common emitter amplifier, — you swap the emitter and collector, there is still a current gain in the device called [math]\beta_R=I_E/I_B[/math] (the R in [math]\beta_R[/math] is from “reverse”, while the F in [math]\beta_F[/math] is from “forward”). In this situation we say that the BJT is operating in the reverse active region. [math]\beta_R[/math] is not [math]\gg 1[/math], though, is only “moderately larger” than 1.In a common small signal BJT, such as 2n2222 or BC548 or BC549, we see [math]\beta_F\approx 200[/math] or so, and [math]\beta_R[/math] around 5~10. And this, note, is with the doping densities reversed; if the doping intensities in E and C are the same then I presume, obviously, that [math]\beta_F=\beta_R[/math] are larger than that reverse gain of 5~10 found in the reversed normal transistor.Below is a Spice model of the 2n2222; the gains are named BF and BR, and their values are 220 and 4, respectively. These are common values, as said..MODEL 2N2222A NPN IS =3.0611E-14 NF =1.00124 BF =220 IKF=0.52  + VAF=104 ISE=7.5E-15 NE =1.41 NR =1.005 BR =4 IKR=0.24  + VAR=28 ISC=1.06525E-11 NC =1.3728 RB =0.13 RE =0.22  + RC =0.12 CJC=9.12E-12 MJC=0.3508 VJC=0.4089  + CJE=27.01E-12 TF =0.325E-9 TR =100E-9 In reality, the design of the BJT (doping, dimensions, geometry) is optimized to imbalance E and C such that [math]\beta_F\gg\beta_R[/math] and [math]\beta_F[/math] is as large as possible.