QT; laughing out loud but thank you for reinforcing my point -- although you go in the opposite direction. Is there a webcam that is 12 14 or 16 bit per channel capable?
QT; laughing out loud but thank you for reinforcing my point -- although you go in the opposite direction. Is there a webcam that is 12 14 or 16 bit per channel capable?
I can resolve lettering that is less than 1/10 of a mm tall on a 4x5 negative, close to the edge of the image circle. That is with an old camera and a single coated lens. If you assume that it takes at least 10 rows of pixels to resolve a letter, then a 35mm negative is about 10 meg. That would put 8x10 over 500.
Research done at Cornell would tend to support this.
http://www.library.cornell.edu/preservation/tutorial/conversion
I just played with shooting a full unfolded sheet of newspaper with a Argus C3 and resolved lettering (on a drug store print) that was about .09mm tall on the negative.
http://truckgenerator.com/subdomain/sueandneal/new_page_9.htm
I think using legibility as a benchmark is better than debating the validity of MTF.
Most average people would tend to agree that a medium that retained legibility at a given reproduction ratio contained more information than one that didn't.
"FWIW, I just produced a 14 x 44 foot billboard - they print these at 9 dpi"
What, you mean people don't climb up to the billboard with a loupe, to examine the details and check for grain?
(4000 ppi)(4 in)(4000 ppi)(5 in) = 320 Mpixels
(4000 ppi)(8 in)(4000 ppi)(10 in) = 1280 Mpixels
To make such a high-res scan may be a little overkill, since you can get a very sharp image by printing out at 300-400 dpi. I doubt that most of us could tell the difference, once a print gets up past 360 dpi.
So let's say you scan at 4000 ppi, and print at 400 dpi. That means your print will be a 10x enlargement, an 80x100 inch image. That may be larger than you can output to any affordable printer, or hang on the wall in your home, for that matter.
If you only want a 16x20 print, that's a 2x enlargement: you could scan at 800 ppi, and print out at 400 dpi. The 800 ppi file would be 146 megabytes for color, 49 megabytes for B&W.
If you scan at 1600 ppi and crop a little, you still have plenty of pixels to toss out, and still make a very fine 16x20 image. The size of that 1600 ppi file would be 586 Megabytes for color, 195 for B&W.
A 1200 ppi file, allowing a 3x enlargment, would be 330 megabytes for color, and 110 megabytes for B&W.
You can print out to fine art paper, or print a negative onto a transparency material, and make Platinum/Palladium prints, or other alternative process. You can also remove blemishes & dust spots, and control contrast & brightness to an almost infinite degree, without using a single sheet of paper.
"FWIW, I just produced a 14 x 44 foot billboard - they print these at 9 dpi"
Lear: O reason not the need: our basest Beggers Are in the poorest thing superfluous. Allow not Nature, more then Nature needs: Mans life is cheape as Beastes.
is that what they mean by "beaste boyes"?
There are in fact three questions within this question, depending on what you are trying to do:
1) How many pixels in a digital camera would give an image of the same apparent quality as a LF print.
2) How many pixels must we scan a LF neg. so that the digital print looks subjectively "as good as" the chemical print.
3) How many pixels are required to capture every detail on the LF neg.
In recent times I have done some investgation on 1). The figures quoted for the digital resolution of a camera to match 35mm seem to lie around 10 Mpixel. So if we expand this to LF sizes
4x5 = approx 15 times 35mm size = 150 Mpixel
8x10 = approx 60 times 35mm size = 600 Mpixel
Of course one could argue that the relationship of LF and 35mm is not a simple linear one, so that the above figures are optimistic or pessimistic.
Ken,
You know that, and I know that. But the poster asked how many mega pixels would a camera have to deliver to match the resolution of 4X5 and 8X10 Velvia(the old iso 50)?
The point is, there's a hell of a lot of information on a piece of 8x10 film. Whether or not it is all usable information is where the religious arguments start. Personally, I agree with you - I've never scanned anything to the file sizes I'm talking about (at 16bit, grayscale, that's 640MB for the 4x5, and 2.5GB for 8x10. It would take my drum scanner over 5 hours to scan an 8x10 at that resolution!)
Personally, I have to have a really first class image, both aesthetically and technically, before I'll go higher than a 10x enlargement on any film, 35mm to 4x5 (sorry, I'm too old and weak to haul 8x10 equipment up and down the mountains anymore ;-).
Bruce Watson
hmmm...someone asked if anyone would post a straigt answer... I'll try.
The question was pretty straight forward: "how many mega pixels would a camera have to deliver to match the resolution of 4X5 and 8X10 Velvia(the old iso 50)?"
The answer is equally straight forward...
PPI = 2R*25.4 (ok 50.8R for the sticklers out there).
Where R is the resolving power of the film expressed in line-pairs per mm.
Its a simple application of the Nyquist Theorem... paraphrased, in a digital system, the sampling rate needed to reproduce an analog signal is 2 times the frequency of that signal. In this case the resolving power of the film is the frequency.
I don't know the resolving power of Velvia 50, but I would guess its somewhere between 100-150 lpmm, so a digital sensor that exactly replicated its resolving power would need between 5000 and 7550 ppi... so, at least 500MP for 4x5.
Of course, the real goal is to produce the same results in the final product. The question becomes, in a particular digital system, how much resolution is required in the capture media to produce results with the same apparent resolution in the final product as a film based system that uses film X as the capture media?
To answer this, you need to also know the impacts of the print production methods on resolution. In a traditionaly enlarged photo print, the paper and the enlarging system (and even the chemistry) have resultion factors that are part of the overall equation. Digital printing is completely different, but each technique has its own set of resolution impacting attributes. Thus, to get the same resolution in the final print, the resolution required of the capture media will be different between film and digital systems.
Hogarth - You are right ! I missed the question itself. Oops ! :-)
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