Sunday, September 20, 2009

4000dpi Medium Format Scan vs. 2000dpi Scan

Today I would like to compare 4000dpi vs 2000dpi scans. Tree shots are perfectly suited for sharpness comparisons. The shot was made by my friend Philipp with a Zeiss 50mm lens on Fuji Velvia 50 probably at EV 14, which is f/11 at 1/125s. It was shot hand-held. Its a beautiful subject in beautiful light. And the slight underexposure and vignetting helps to keep the attraction centered to the main subject. In 100% view the image is sharp, but not extremely sharp. It is a typical medium format sharpness. The image above shows the original scan rotated by 0.4 degrees and scaled to 5 percent. It was rotated in order to keep the black frame lines straight.
I used the original, non-rotated file and an image downsampled to 2000dpi (also not rotated) for the first comparison. I compared the original version at 100% and the downsampled file at a 200 % view and it was impossible to see a difference. I also did not see any difference between the 400 percent and 200 percent view.
Then I brought rotating into play. I rotated the original file and I rotated the downsampled file by the same amount. Then I enlarged both versions to 200 and 400 percent respectively and was finally able to see a difference (mouse over for the 2000 dpi version):

It is mainly the film grain which makes the first image appear sharper. No real details are lost but anyway the 2000dpi looks less sharp. Please consider that this is not a 100 % view but a 200 % and 400 % view. It is hard to see anything at 100 % here. I recommend 2000dpi scans when file size is critical and the shot is not extremely sharp from the beginning. You will still get top-quality compared to an image from a digital camera or a scan from 135 film. You will still get a good quality after rotating or other transforming but the quality of a transformed 4000dpi scan is clearly better - at least when you plan to make huge prints of it.


  1. I'm curious, what scanner are you using?

    Thank you


  2. This is meaningless unless your scanner is capable of resolving 4000 dpi. That's why we need to know what scanner was used.