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Nikkor

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Posts posted by Nikkor

  1. 1920x1080p H264 is up-sampled by the camera means that the "true resolution" is?

    do you mean that h264 1920x1080p is sub HD but upscaled at 1920x1080p? I want not buy one of this cameras if this is true, can you explain it better? thanks.

     

    thx

    That sounds ridiculous, you wanted to use h264, what quality were you expecting anyway?

     

    Look at this list, there you can see the actual resolution of the sensor read outs https://docs.google.com/spreadsheet/ccc?key=0AgQ2MOkAZTFHdFFIcFp1d0R5TzVPTVJXOEVyUndteGc#gid=5

     

    until now it was pretty simple, everycamera that skips lines records it's full sensor x and y resolution divided by 3. That output is taken and upscaled to 1920x1080.

     

    The only camera that does real full hd are the gh2 and gh3 (and I'm not really secure about that).

  2. About the 3x zoom without aliasting, you can do that on the 7D but only in raw (maybe also h264 but can't guarantee that). It was 30fps only but maybe they already fixed that.

    Personally I would go with the 7D, raw is amazing.

  3. Enhorabuena ya sabes lo que son los f stops , if you have watched the video you will have learned that f stops refer to "amount of light".

     

    Now you have to understand that that amound of light is projected on an image circle. 

    Imagine that the amount of light is "number of photons", you use the same fullframe lens on a full frame camera and on 2x crop sensor.

    Inside that image circle we have two rectangles, a big one (the full frame sensor) with an area of 40 and a small one (the 2x crop sensor) with an area of 10. Now you know that actually a 2x crop sensor has 1/4 times the area of a full frame.

    The amount of light is 40 photons on the full frame, they spread uniformly around the sensor area. How many photons do we have per area unit? 40 photons/40 area units = 1 photon/area unit. How many photons will the 2x crop sensor recieve? 1photon/area unit * 10 area units= 10 photons.

    Imagine that both cameras are 10pixel cameras (the same as 10mega pixels, just 10*6 times less pixels).

    So how many photons do we have per pixel?

    Full frame-> 40photons/10pixels=4 photons/pixel

    2x Crop -> 10photons/10pixels=1photons/pixel

     

    Which sensor do you think will have less noise?

     

    But what has this to do with the number of my f stops, i have written on my lens "25mm f2" so on my 2x crop camera this is a 50mm f2 lens, stop talking bullshit

     

    Ok imagine , in the example before, we were talking about a 25mm lens, your famous equivalent 50mm f2 lens. On full frame we will need a real 50mm f2 lens, this will give us the same view angle as the 25mm f2 on your 2x crop. Since it's the same f stop, we will have the same amount of light, 40photons, and therefore we will have the same 4photons per pixel.

     

    So now we have the same image, one with 40photons, and one with 10. If f stops refer to amount of light, howcome on one images there are 4 times more photons than on the other? HOW CAN THIS BE? THERE IS WRITTEN F2 ON MY LENS, F2.

    That's because f stop, is just a number, focal length / aparent aperture diameter, and focal length written on the lens is always the same because it's the actual distance between the planes.

     

    I ALSO WANT 40 photons on my sensor

     

    That means you want 4 times more light, I hope you watched the video with attention, every f stop means twice the light, so we will need to look for a bigger aperture. So we will go down in the numbers, from f2 to f1.4, now we have 20 photons, we want more, f 1.4 to f 1, 40photons. So you will need a 25mm f1 to have the same performance as a 50mm f2 on a full frame.

     

    Where is my Depth of field, its gone.

     

    Welcome to the world of phisics.

     

    Now I understand why there are C mount lenses labeled 25mm f0.95 like this one:

    http://www.ebay.com/bhp/c-mount-lens-angenieux

    http://www.flickr.com/photos/wendine/sets/72157622080643184/

    https://vimeo.com/9435241

     

    Yep, in the age of film everything was a little bit more clear, if you were on 8mm f0.95 wasn't so special, but the 50mm f0.7 Kubrick http://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7 used on Barry Lyndon was a very special one. I mean, if this thing I'm trying to explain were fake, Kubrick just would have taken an 8mm camera with an 25mm f0.95 instead of using that very expensive lens. Don't you think so?

     

    If you still don't bellieve me try to compare the same image taken with the same generation full frame camera and a 2x crop camera. On full frame you will use a 50mm @f5.6 (cheapest lens out there will do this) and on 2x crop a 25mm @ f2.8 (common zoom lens range). They will have to have the same megapixles (this will be the hardest part), on the 2x crop use iso 100 and on the full frame use iso 400, you should see that they perfom equally. Same depth of field you will notice.

     

    Just to make sure you don't refer to the super biased article, comparing the omd-5 to a 5d classic.

    http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/(appareil1)/842%7C0/(brand)/Panasonic/(appareil2)/834%7C0/(brand2)/Nikon/(appareil3)/795%7C0/(brand3)/Canon

     

    If you go to the SNR comparsion you will see that iso 100 on the gh3 has the same SNR as a mkiii or d600 at iso 400, therefore the same noise.

    Now try to go and buy equivalent lenses to a 50mm 1.2, 85mm 1.4, 135 f2 on a 2x crop sensor. They don't exist...

  4. I must take exception with the statement, "The problem is, F2.8 on Micro Four Thirds is equivalent to about F5.6 on full frame in terms of depth of field control and low light performance, so the 12-35mm F2.8 and Canon 24-70mm F2.8 is not really a like-for-like comparison, and a 24-70mm F5.6 for full frame would be much smaller than the Canon 24-70mm F2.8."  Yes, in depth of field control.  No, in low light performance.  F2.8 is F2.8 on any sensor, Period, end of discussion.   Some sensors do have more sensitivity to light.

     

    http://frugalfilmmakers.com/2013/08/11/21st-century-camera/

    Imagine you put an 35mm 1.4 on a 1.6x tele converter, is it still 1.4? It's not.

    Now put the same lens on an APS-C canon, you will have the same image with what you call 1.4.

    Imagine both have the same megapixels, you will have exactly the same amount of light  on the pixels, but the FF is around f2.2 (do the math right if you want).

    So unless the small aps-c pixels are much better than the FF ones, the aps-c equivalent in terms of performance to full frame would be f2.2. The lens is still 1.4.

  5. A mi la primera me salió rana, la segunda funciona perfectamente. Esperemos que tengas suerte, no se como andará el tema de las devoluciones en Venezuela ^^.

    Recuerda (ya se que dices que lo tienes claro) que la que necesitas es la 1000x, la 600x o 800x no valen (al menos las de Komputerbay, son bastante más lentas de lo anunciado)

     

    Por cierto, tienes otra cámara? Es por si no lo tienes claro del todo,un compañero mejicano preguntaba hace poco si la 50d le podía hacer también el apaño como cámara principal (usando video comprimido h264). Le recomendé que no hiciera tal cosa por que el raw gasta baterías que da gusto, ,el h264 que saca la cámara es bastante malo,necesitas un ordenador (computadora) potente, no graba sonido, y porque es un proceso que quizás no merezca la pena para cierto tipo de contenido.

    Ahora bien, hace poco era impensable tener acceso a tanta calidad, especialmente en temas de color. La verdad es que se pueden hacer cosas muy pero que muy lindas, de cine totalmente.

     

    Si tienes cualquier duda acerca  de la 50d no dudes en mandarme un privado. 

     

    Saludos!

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