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Thread: OK, how many mega-pixels equals a LF negative?

  1. #1

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    OK, how many mega-pixels equals a LF negative?

    Although I do own a digital camera, I am tired of friends that know about my add iction to LF photography telling me about the next break-through in the digital world, and how it just makes film more obsolete. Just as a comparison, can some one guesstimate what a quality 8x10 negative contains compared to a digital imag e file?

  2. #2

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    OK, how many mega-pixels equals a LF negative?

    Even a non quality 8x10 film image has probably somewhere in the range of 600MB to a gigabyte (1,000Mb) worth of information. But in reality such comparisons are pointless. Each medium has its own unique assets and drawbacks.

  3. #3

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    OK, how many mega-pixels equals a LF negative?

    Ellis: with how much color depth? My estimates are closer to a bujillion.

  4. #4

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    OK, how many mega-pixels equals a LF negative?

    I've heard numbers up to 20MP for a 35mm frame, but even if we cosider that wildly optimistic (I don't) we're still stuck with at least 14MP as a bare minimum to reach 60lp/mm (we actually need even more, but this gets us in the ballpark and gives the digital people a chance). Cosidering the square area only gives us (80/1.5)x14MP = 742MP minimum (1GB using the 20MP figure). This gives us the raw capacity of the recording media only, and does not account for diffraction, circle of confusion, film plane accuracy, etc... Even having said this I'm sure that there are people here scanning 8x10 on a drum who can probably state that a 300MB file extracts 90% of the information on an 8x10 chrome - I haven't yet had that experience (unfortunately).

  5. #5

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    OK, how many mega-pixels equals a LF negative?

    As Ellis says, there are a lot of variables, not the least of which is color depth. The DCS 460 camera that I use has an array that is approx. 1 sq. in. From that, the system creates a 17 Meg. file, but that is with only 8 bits of color. To match an 8x10 chrome, my best guess would be 2 - 3 Gig.

  6. #6

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    OK, how many mega-pixels equals a LF negative?

    Between 400 - 500 mega pixels. The newest 4-5 megapixel cams can make an OK 8X10. An 8X10 resolved to 60 lp/mm can generate an acceptable 80X100" print at 10X That's 100 of the little 4-5 megapixel chips.
    He is no fool who gives what he cannot keep..to gain that which he cannot lose. Jim Elliot, 1949

  7. #7

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    OK, how many mega-pixels equals a LF negative?

    Does it depends on the resolution (pixels/inch) when scaning the negative? i.e at resolution = 300.. we will have 8*300=2400 and 10*300= 3000 ..now 3000*2400=7200000 which is which is 7.2Mb...seems way too low..because photoshop said it's a 20.6 Mb file....any opinion?

  8. #8

    OK, how many mega-pixels equals a LF negative?

    Based on my estimate of roughly 175 thousand angels on the head of a pin (that is, 175 kilo-angels), 17.3 pinheads/pixel and 400 pixels/inch, it is approximately 17 million bakers dozen pixel- pinheads per picoliter.

    Nathan

  9. #9

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    OK, how many mega-pixels equals a LF negative?

    the number of grains contained in a particular piece of film is not actually very relevant in determining the amount of useable information for scanning purposes. the reason is that as you zoom in on an image (with increasing scanning resolution) you reach the limits of the optical photographing process long before you reach the film grain. in other words, no camera/lens combination in the world is sharp enough to resolve lines down to the sharpness of the film. the sharpest line you could ever get on film would be a gradient ten or twenty grains wide; you would never see a line or any other detail that was one grain in dimension. so for scanning purposes, all you ever need to scan to is the sharpness of the lens; scanning all the way to the film grain just gets you a really large fuzzy, file.

    the lens/camera systems in 35mm are much sharper than for 4x5, which in turn are sharper than 8x10 (due to lens sharpness, proximity of film to lens, flatness of film, thickness of film, and other factors). so you'd want to scan a 35mm original at higher resolution than a LF original.

    for 35mm a 4000 dpi scan (100 MB in 8-bit color format) will take you past the sharpness of the lens and pull out all available information. for grainy films this number will be substantially lower.

    for 4x5, 2400 dpi (a 300 MB file in 8-bit format) will pull out all useable information from the sharpest films. i'm not sure for 8x10, but i suspect it'd be in the 600 MB to 1 GB range.

    so, digital backs are nowhere NEAR to producing the sharpness you can get from film. but, their far greater tonal range can produce some amazing images that would be difficult to match on film, so as everyone else has said here, each medium has its advantages...

    ~chris jordan (Seattle)

    www.chrisjordanphoto.com

  10. #10
    Andy Eads
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    OK, how many mega-pixels equals a LF negative?

    From a technical standpoint the question could be posed in these terms: if you need to distinguish if a spot on the wall of the nuclear waste tank is a hexagonal bolt head or a round paint spot, how many pixels do you need to reliably determine the shape of the object? Or, what is the optimum lens, format size and film to do the same? This is not an academic exercise. Much of what passes for sharp digital imagery is a mathematical construct that pleases the eye but is filled with empty resolution. Not that it matters too much for landscape photography, but it is an issue if we intend to use digital to accurately document a thing or an event. One measure I have never seen defined is how small a difference between two colors (or two shades of gray) can a system capture. I suspect this figure of merit could be expressed in CIE terms. If film and digital can record differences smaller than human perception, the question is moot. If not, we have a basis for comparison. It also appears that the colors recorded in a digital system (the color space) are for the convenience of the computer, not necessarily allocated optimally for human vision. The color information recorded by film may be better suited for our eyes, especially color transparency film.

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