light field camera

• Question:-Why does depth of field increase as you allow less light into the camera?
  Can somebody please explain, in dummies terms, why the depth of field increases with less light?...that is the smaller the aperture, the deeper the DOF. And if you close the aperture, how do you compensate for light loss? By slowing the shutter speed?
  
  Answer:-There are already some good bits of info above. Let me state it simply: depth of field doesn't have anything to do specifically with letting less light in. However, it DOES have to do with the size of the aperture. The smaller the hole, the greater the depth of field. You can take this all the way to using a pinhole, which will focus an image even though there is no lens at all. In effect, the tiny aperture becomes a lens.
  
  It so happens that the smaller the aperture, also the less light reaches the inside of the camera during a given amount of time (when compared to a larger aperture).
• Question:-When is the electrical field of a camera flash the strongest?
  Writing a story where I can fudge the science a bit, but I wanted to get this correct. I'm using a camera flash in the story and (without getting into too much detail) need to know when the electrical field around the thing would be the strongest.
  
  The light charges, then expends the energy. It would seem that the field would peak when the charge was expended, but I'm not strong enough in this science to be certain; it might be most powerful when the charge is at its peak, *before* the light goes off.
  
  Any ideas? Thanks in advance for your attention.
  
  Answer:-There are two different electric fields involved.
  One is the electrical field in the capacitor which stores energy prior to the flash. It is pumped up by a voltage multiplier circuit until it reaches the designed voltage, which is the voltage at which the capacitor stores the amount of energy needed for the flash. It stays at this high level until the flash is triggered.
  The other field is that around the conductors. It is highest at the instant of triggering and rapidly declines to near zero as the charge is in the capacitor is dissipated.
  If the flash is the type where a primary coil is normally charged and then is collapsed at triggering to generate a current in a secondary coil, then the field is high up until the point at which it is triggered. It is the collapsing field, which is always smaller than the primary field, which generates the current in the flash.
• Question:-I am looking for a camera for use during a football game under field lights.?
  He also plays in a band (as the drummer) and I want pics of him. I am concerned about stage lights. I know nothing about cameras and need some help. Thanks so much. I do not want these events to slip by and not have great pics for memories.
  
  Answer:-If you need to shot in poor lighting condition, a DSLR is a must. If you don't know too much about camera, it is not easy to learn how to use a DSLR effectively.
  
  You may consider Canon S5 IS. It has a 12x stabilized zoom lens.
• Question:-How much do you think this new " living picture camera " will change photography significantly ?
  http://www.ibtimes.com/articles/168515/20110623/lytro-camera-no-focus-living-pictures-light-fields.htm
  
  http://www.pcworld.com/article/230966/5_coolest_lytro_light_field_camera_features.html
  
  
  Some photo students are freaking out saying that photographers apparetnly won't be needed no more since you can make stuff in focus and make the light right and stuff like that.
  
  Answer:-NO.
  It will just mean that hopefully we won't be seeing so much out of focus crap on the "what is my photogrpahy like" questions.
  
  It will not help with composition, it will not help with wb, it will not help with subject matter or any number of other things which go towards making a good photograph
  
  
  Photography is more than just getting the subject in focus.
• Question:-Why does increasing the F-Stop on a camera deepen the field of focus.?
  I understand that narrowing the aperture on your lens increases the depth of field, bringing objects in the background more into focus. However, I do not understand why this happens. What physical property of light or of the lens causes this effect?
  
  And a secondary question for anyone who knows. If not, no biggie. Does the same property apply to the human eye? Is the depth of our field of vision shallower in low light than in bright light?
  
  Thank You
  
  Answer:-As was already said the reason that focal length and aperature size affect DOF is the concept of the circle of confusion. Although we talk about DOF as if its a hard line where things on one side are in focus and things on the other are not; thats not how it works. There is an actual focus point where the lines of light converge on the film or sensor and that point is in the greatest focus. In fact its the only point where the image it truely and completely in focus. Outside that point the light rays to not converge exactly on the film of sensor. Any areas that are "acceptably sharp." are said to be inside the depth of field. The more the light has to be bent smaller the area that is acceptably sharp. The center of the lens is where the light rays have to be bent the least so the area that is acceptably sharp is longer. Now on the surface that would make you think you should always shoot at the lowers aperature for the best focus. That also is not true. It will give you the greatest DOF but not necessarily the best sharpness. This is becuase the shape of the aperature also causes light to bend ( diffraction). So the sweet spot on most lenses where they are sharpest I have always been taught is closed down 2 to 3 stops from max aperature. Its also thought aperature geometry effects this sharpness
  If you want to confuse it more there is also the concept of depth of focus/focus spread which deals with how flat a sensor or film has to be in a camera to be able to record the maximum DOF from the lens
  
  Here is a good explanation of DOF
  http://www.bobatkins.com/photography/technical/digitaldof.html
  
  Now if that was confusing the human eye is even more so because yes there is a set focal point and yes pupil size effects this due to diffraction and abberations and there is also a circle of confusion but our brain does not always interpret it that way. It makes accomodations based on what it thinks we should be seeing. Its the same with white balance. Despite the fact that light has different temperatures we see white as white under most lighting conditions the camera needs to be adjusted for light temperature to see true white. Also muscles in the eye change the shape of the lens and eye when out thoughts change what we are looking at so when you are looking at the flower yes the things in the background are out of focus and out of the depth of field but as soon as you think about that and pay attention to it the eye refocuses on that background and you do not notice it was out of focus. We can learn to override this, thats how those pictures that looked like wierd color lines until you changed your focus then you saw an image in them worked. We notice DOF in a picture because even though things were at different distance when we looked though the lens on the print or screen they are the same distance from the eye on that output. We cannot refocus the eye to make the back of the picture come into focus the way we could when we looked at the actual scene. I hope I am not babbling and making this too confusing. When we get older the ability of the eye to change shape lessens, one way to say it is that the eye is less flexible, this is called presbyopia and its what martin is talking about. If you really want to get into it a good book on the way we see is Optics of the human eye By David A. Atchison, George Smith.
• Question:-Are there any camera flashes with a zoom?
  Short version: I want a camera flash with a zoom.
  Long version: A regular camera flash sends light to a wide field of view, which is perfect for photography at low magnification. On the other hand, now that there are digital cameras with zooms beyond 10X, it doesn't make sense for the flash to light up the huge field of view that the camera isn't even looking at. Wouldn't it be cool to adjust the divergence (field of view) of the flash so it would work at higher magnifications and therefore longer distances? If one is available already, let me know.
  
  Answer:-There are indeed flashes that zoom - many of them. I don't konw if one is made for your camera or not, but find your camera at B&H Photo (available through Yahoo! Shopping) and they will show accessories under the camera. Sometimes they show flash units. If not, this is a good site to search anyhow.
• Question:-Looking for a high dof macro camera most often in low light?
  Hi, I have a very specific application in which I need a high depth of field using the macro setting and most often have low light conditions. I can get some more light in the end if that is what I need but that would be inconvenient. I'd also like optical image stabilization, aperture priority and as some insurance, the ability to use a wide angle lens. I was looking at the G7 or G9 but reviews I have read of them say that the macro is no good in low light (although it is great in good lighting conditions). Also looking at the Nikon Coolpix 5000. I'm looking for something in that size range. I'd like to end up with a depth of field of about an inch at a range of around 2-4cms. Thanks
  
  Answer:-I believe you need a (d)SLR with a serious lens. Eventually a special macro lens (like these here: http://www.usa.canon.com/consumer/controller?act=ProductCatIndexAct&fcategoryid=155). DOF becomes lower with bigger aperture and with magnification of image. Since you have low light you might need big aperture which will lower the DOF. A higher ISO setting might help. If you need to work macro (say 1:1, which means image size on senzor equals real image size), again you will loose DOF.
  dSLRs have bigger sensors than compact cameras and usually give usable image quality also with higher ISO --> so you may use narrower aperture and thus longer DOF. But I am afraid your question has no stright answer, at least I do not know it.
  There is also an Adobe PS technique to make more photos, each focused on different distance, then combine them in one image with big DOF. I saw details in a recent Outdoor Photography, I believe. But you need a static subject. Also, if your subject is static put the camera on tripod, use smallest aperture you have (you might need long exposure time) and shoot.
  Good luck!
  Cristian
• Question:-Ran red light in Massachusetts/NH border, camera flashed, question?
  Hi, I just moved up to Massachusetts and live in a town on the border of Massachusetts and New Hampshire. Today, as I was returning from shopping, I was coming up to an intersection when a car came out of left field and got in front of me. He proceeded to go slowly through the light which had turned green then yellow immediately. It was still yellow when I was going through it; after I had already passed the white barrier line, it went to red and the camera flashed. If this helps, I believe it was at the southern border of NH in Plaistow, NH that turns into Haverhill, MA (believe it is called RT. 108). My questions are: does Massachusetts have red light cameras that ticket people and if so, would this warrant me getting a ticket? Also, because I am out of state and don't have a license plate on the front of my car such as people do up here, could I get one anyway?
  Finally, please no criticisms. We all run red lights sometimes and I am not a crazy driver.
  
  Answer:-I've never seen a red light or speeding camera in NH or MA.
  
  What is common, particularly in NH is a strobe light in the red light to get the drivers attention that light is red. These don't take a picture - just there to be sure you notice the red light.
• Question:-Are there any camera flashes with a "zoom"?
  Short version: I want a camera flash with a zoom.
  Long version: A regular camera flash sends light to a wide field of view, which is perfect for photography at low magnification. On the other hand, now that there are digital cameras with zooms beyond 10X, it doesn't make sense for the flash to light up the huge field of view that the camera isn't even looking at. Wouldn't it be cool to adjust the divergence (field of view) of the flash so it would work at higher magnifications and therefore longer distances? If one is available already, let me know.
  
  Answer:-I have an SB-800 flash unit for my Nikon D200. The computer in the flash communicates with the computer in the camera which inturn talks to the computer in the lens.and adjusts for the lens I'm using.
  
  I also have an SB-16B for my 35mm. It while not as sophisticated, it does have a zoom function on the flash head that I can adjust for ultra wide angle, wide angle, normal, meduim telephoto, and telephoto.
  
  You need to get a flash unit made by the camera maker. They match their units so they can communicate various bits of information.
  
  Although you can find some older flash units, like my SB-16B that have a manual adjustment.
• Question:-Good camera high school sports in low light.?
  Requirements ...
  
  1. Sports in low light (high school football field with mediocre lights at night, high school gym with mediocre lights.)
  2. I also want it to be a well rounded camera for portraits, landscape, etc
  
  $1500-$2000ish for body is bearable. I like the price of the Nikon D90. :) ... but don't know if it will handle the above lighting situation.
  
  Just interested in body right now ... glass is a whole 'nother deal.
  
  Answer:-The D90 is an excellent choice as it brings you near-D300 quality at a lower price. The low-light, high-ISO performance is outstanding, and that's what you'd need under the two scenarios you've described.
  
  Currently, I use a D200 for basketball and football, and find myself wishing I could push beyond the self-imposed 1600 ISO ceiling. Anything above that, and the digital noise is really a problem.
  
  On the D90, that problem is history and I'd be able to shoot at ISO 3200 or higher with even better results.
  
  Here's some samples I found on Flickr.com of D90 basketball photos.
  http://www.flickr.com/search/?q=basketball&s=int&cm=nikon%2Fd90&z=t
  
  And here's a photographer who's gotten some great nighttime high school football shots with his D90.
  http://www.flickr.com/photos/terrence_campbell/2941148121/in/set-72157601668152965/
  
  Hope this helps.