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Thread: What file size should I expect from B&W 5X7 negative

  1. #1

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    Question What file size should I expect from B&W 5X7 negative

    I am new to large format and need some advice.

    I shot 4 images with my 5X7 Korona View camera on Ilford B&W film, then sent them off for developing and "enhanced" scanning.

    Upon return, I received the negatives as well as a CD with the images. To my surprise, the scanned negatives were all about 2.1MB files.

    Is this small file size normal? In my mind I was thinking they would be much larger since the negative is so large.

    What am I missing? Help!

  2. #2

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    Re: What file size should I expect from B&W 5X7 negative

    Some questions for you:
    What did the lab promise you could do with the scanned image files (i.e. for web, for printing, etc)
    When you open the files in Photoshop (or whatever), what resolution and bit depth are they?
    What file format are the scanned images in?
    and lastly
    What do you want to do with the scanned image files? If you want to print them, how large do you want to print them (same size, or larger than the actual neg size)?
    How large you expect to print them with an inkjet printer will drive your requirements for how large a scanned image file is needed.

  3. #3

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    Re: What file size should I expect from B&W 5X7 negative

    The simple answer is that with that file size you might as well be using 35mm. Beyond that, the answer is that the file should be as large as you want or need, for what you intend to do with it, usually at 300dpi or better for a print. There is no absolute answer.

    Really, what you have is probably a jpg, which doesn't explain much to us about the real size of the file you have because it's compressed from what ever size the picture really is; it could be incredibly high resolution, mercilessly compressed, or abysmally low resolution not compressed at all: pixel dimensions would tell much more.
    Thanks, but I'd rather just watch:
    Large format: http://flickr.com/michaeldarnton
    Mostly 35mm: http://flickr.com/mdarnton
    You want digital, color, etc?: http://www.flickr.com/photos/stradofear

  4. #4

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    Re: What file size should I expect from B&W 5X7 negative

    The files are 2.1MB on the disc and when opened in Photoshop they are 17MB. Not sure about the bit depth.

    They are .jpeg scans. When saving the file in Photoshop the resulting file size in .jpeg is about the same, 2.1MB. Tiny!

    I was hoping to be able to print up to 30X20 if I wanted to. Is that realistic for 5X7 film?

    I did read another post on the forum and it seemed like the files they had were at least 50MB or more.

    I am confused...

  5. #5

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    Re: What file size should I expect from B&W 5X7 negative

    So that's approximately 17 megapixels @ 8bit (jpeg is 8 bit only). That's enough to print 20x30...cm! Not inches; too little image information for that size. And yes, a 20x30" print from a good 5x7" negative is absolutely possible; even bigger than that.

    Although comparing jpeg file sizes doesn't say much, here's one to give an impression: when I scan a 4x5" in black and white at 3200dpi and save it as jpeg (so 8bit) with the quality setting at 11 (out of 12), I usually end up with a file around 20Mb (Photoshop says it's about 160Mb uncompressed, so roughly 160 megapixels). File size with jpeg depends very heavily on the image, but it's safe to assume that your 2Mb jpeg files are low resolution scans with a fair bit of compression as well; my scans with the same number of megapixels (which happen to be 35mm scans) end up around 5Mb jpegs at quality level 11.

    My guess is the lab scanned your negatives at somewhere around 300dpi. That's not of much use, only for small prints and web viewing.

  6. #6

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    Re: What file size should I expect from B&W 5X7 negative

    Koraks,

    Your example of your scan is exactly what I thought. The 20MB file size should yield a nice size print, vs the 2.1MB file size I have.

    What scanner are you using and what software?

    My question is why does the lab offer an "enhanced" scan when it is such a small file size?

  7. #7

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    Re: What file size should I expect from B&W 5X7 negative

    I use an epson 4990, which may not be state of the art, but it's good enough for 40" prints from 4x5's. I use the stock epson software, which is more than adequate for my purposes.

    Maybe the lab processes their scans to suppress grain and call it 'enhanced'. Either way, most of the labs I checked out only provide small scans for an affordable rate; high res scans usually cost upwards of €20 a piece where I live, maybe (much) more. I don't see the point in that except perhaps for the occasional drum scan of an exceptionally nice negative that needs to be printed wall size. And that's likely to cost much more still. How much did you pay for these scans?

  8. #8

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    Re: What file size should I expect from B&W 5X7 negative

    what are the file's pixel dimensions? Quoting file sizes is not a great indication, other than 2.1MB from a 5x7 neg is not what I'd expect

    in the above example, 4x5 neg scanned at 3200dpi would give you a 12800x16000 pixel file. Printed at 300ppi, that would make a 42"x53" (approx). A 5x7 file scanner at 3200, would obviously be bigger.

    agree with above, low res scans, probably significantly compressed.

  9. #9
    bob carnie's Avatar
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    Re: What file size should I expect from B&W 5X7 negative

    This is normal..

    you are getting back Jpeg for viewing only purposes.

    If you require scans for large prints then you need to specify size of print and your lab will make an appropriate size scan.
    Larger scans will cost you more.

    regards

    Bob
    Quote Originally Posted by rrunnertexas View Post
    I am new to large format and need some advice.

    I shot 4 images with my 5X7 Korona View camera on Ilford B&W film, then sent them off for developing and "enhanced" scanning.

    Upon return, I received the negatives as well as a CD with the images. To my surprise, the scanned negatives were all about 2.1MB files.

    Is this small file size normal? In my mind I was thinking they would be much larger since the negative is so large.

    What am I missing? Help!

  10. #10

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    Re: What file size should I expect from B&W 5X7 negative

    Quote Originally Posted by Nigel Smith View Post
    Quoting file sizes is not a great indication
    It isn't, but the file size that Photoshop displays under the image generally is, as it's uncompressed size. At single channel 8bit depth, it translates more or less directly to the number of (mega)pixels. With the aspect ratio in mind, you can figure out the dimensions in pixels, which should be around 3500x5000 in this instance.

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