Initial Calculations
While using film within your photographic practice you inevitably get to the question, what do I do with the film once it is processed? The two options I contemplated were printing them in a darkroom using a traditional gelatin silver based process or scan the film and print digitally. I decided on the latter option, digital printing, as the cost to setting up a darkroom is expensive and there are no longer any darkroom rental facilities available in my area. Also having taught both print and digital printing I appreciate the advantages of the digital editing process. Scanning on the other hand is something I have done very infrequently and have never given much thought too. As such this was an area of the process that I wanted to explore as I have never been completely satisfied with the result I have obtained previously.
There are many ways to scan or digitize film, you can scan it using an assortment of different devices or photograph the film with a digital camera. The two methods of digitizing my negatives I have been exploring are scanning the negatives with an Epson V750 flatbed scanner and photographing them with a Canon 5D Mark III digital camera. The reason I decided on these two processes was they are commonly used, from a monetary perspective they are not expensive, and they are purported to give excellent results. This write up will look at my calculations for scanning on the Epson V750 flatbed scanner.
PRINT SIZE
Before I began digitizing the negatives I decided on a print output size, the film I am scanning is 4x5 black and white negative film. There is an art to scanning but simple formulas can help you decide how much resolution you need for different types of images (Fraser, 2009). So I am going to use a number of different formulas below that I have used for years to figure out, viewing distance of the print, and resolution.
I am going to print on two different devices an Epson Pro 9900 printer which has a maximum width of 44 inches. The second is the HP Latex 110 printer that has a maximum width of 54 inches, but the RIP software will allow me to tile and print the images on multiple vinyl wall wraps. So for the Epson I am going to print images 44x54 inches wide and on the HP I plan to double the size of the image and print on two vinyl panels, 88x108 inches wide. I want to make sure that the dimensions of the potential gallery space will allow for such a large print (See Print Viewing Distance below).
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PRINT VIEWING DISTANCE
There is two different sizes that I would like to print 44"x54" and 88"x108" prints.
88"x108" prints have an optimal viewing distance of 17.41' feet
44"x54" prints have an optimal viewing distance of 8.7' feet
The formula below is my calculations to determine the optimal viewing distance for the prints. The formula calculates the diagonal length of the print, then the diagonal length allows me to calculate the optimal viewing distance.
44"x54" Print
44 squared is 1936 x 54 squared is 2916
(1936 + 2916) = 4852
Square root of 4852 = 69.66" which is the diagonal length of the print.
Formula For Optimal Viewing Distance Of Print
69.66" x 1.5 = 104.5" or 8.7 feet
88"x108" Print
88 squared is 7744 x 108 squared is 11664
(7744 + 11664) = 19408
Square root of 19408 = 139.31" which is the diagonal length of the print.
Formula For Optimal Viewing Distance Of Print
139.31" x 1.5 = 208.97" or 17.41 feet
The gallery space, Studio Sixty Six, will only support two image at 88"x108" inches as there is only two spaces with that viewing distance depth. The space will also allow for proper viewing of the 44”x54” prints. My other concern is the resolution needed to scan the image. I know that at 24" inches the minimum print resolution needed is 143 dpi to provide the illusion of continuous tone to an observer with 20/20 vision (Fraser Image Sharpening). This is a base level of dots per inch needed but I would like the image to be appear to be a continuous tone at a closer range (see Image Resolution and Resolution For Scanning below for the calculations).
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IMAGE RESOLUTION
The Epson printers maximum dpi (dots per inch) is 1440 (Epson, 2019) and the HP is 1200 (HP, 2019). The ppi (pixels per inch) resolution of images printer print at can be no better than half the specified dpi of the printer (Clarkvision, 2013). This translates into a maximum ppi of 720 and 600 respectively for each printer. From years of testing I know I can print all my images at half of that so I use 360 ppi half of Epson's pixels per inch.
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RESOLUTION FOR SCANNING
Knowing that I plan to print at 360 ppi and output at 88x108 inches, I use this formula to figure out my scanning resolution.
88"x108" Print
(88x360) = 31680
(108x360) = 38880
Using the longest dimension of the negative to determine the scanning resolution:
38880/5 = 7776 dpi
44"x54" Print
(44x360) = 15840
(54x360) = 19440
Using the longest dimension of the negative to determine the scanning resolution:
38880/5 = 3888 dpi
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The Epson V750 Flatbed Scanner has a maximum resolution of 4800 dpi (Epson Scan, 2019) it will not scan at 7776 dpi for the 88"x108" prints. So I will have to interpolate the image, which will add information that does not exsist in the orignial image (Fraser, 2003) or decrease the resolution of the image to get a print of that size. This I will have to test and see if it will work or I can scan for the 44"x54" print size.
Citations
Burke, A. (2017) Drum vs Flatbed Scanner - Side by Side Comparison. Available at: https://www.alexburkephoto.com/blog/2017/12/15/drum-vs-flatbed-scanner-side-by-side-comparison [Accessed 04 August 2019]
Clark Vision. (2013) ppi of Printer . Available at: https://clarkvision.com/articles/printer-ppi/ [Accessed 04 August 2019]
Kennedy, S. (2018) Epson V750 for 4×5 or Drumscan?. Available at: http://www.simonkennedy.net/blog/architectural-photography-2/4x5-flatbed-vs-drum-scan/ [Accessed 04 August 2019]
Epson (2019) Epson 9900 Printer Specs. Available at: https://files.support.epson.com/pdf/pro79_/pro79_ug.pdf [Accessed 01 August 2019]
Epson Scan (2019) Epson V750 Specs. Available at: https://www.filmscanner.info/en/EpsonPerfectionV750Pro.html [Accessed 03 August 2019]
HP (2019) HP 110 Latex Printer Specs. Available at: http://h10032.www1.hp.com/ctg/Manual/c04721790 [Accessed 01 August 2019]
Fraser, B. (2009) Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom [Online] Available at: https://bookshelf.vitalsource.com/#/books/9780321679369/cfi/6/8!/4/704/2@0:0 [Accessed 01 August 2019]
Watson, K. W., (2019) All About Scanning Photos. Available at: http://www.rideau-info.com/photos/scanning.html [Accessed 03 August 2019]