Pete B
Well-known
I read on a forum that the published resolution for the 8100i of 7200ppi is achieved using interpolation, so there is little point in scanning greater than 3600ppi (the actual scanner resolution) as it merely gives you bloated files. Is this correct?
Pete
Pete
nukecoke
⚛Yashica
I have a PlusTek 7200 and I never use any setting higher than 2400. They just look more smeared and are unnecessarily large at higher settings.
ptpdprinter
Veteran
According to filmscanner.info, the actual resolution of the Plustek 8100i is 3800, but you have to scan at 7200 to get that. If you scan at lower than 7200, you'll get something lower than 3800 (probably proportionally).
Pete B
Well-known
Pete B
Well-known
Ah, :bang:
That's what I have been doing. I was doing so to gain as much information as possible before downsizing to about 2000 pixels along the long edge. Is this a waste of time?
Pete
cz23
-
Pete, I think it would require unnecessary time, but I've never seen information on how high to scan for final resolutions lower than the optimum of 3800. I'd love a formula for that. Scanning at 7200 takes a while.
John
John
flagellum
Established
I can't say I know the true DPI resolution at lower settings, but I scan at 3600dpi optical resolution with the 8100 and I get ~15mp files that print nicely up to 11x17. I'd say just scan at 3600dpi or and only go up to 7200 if you really need it.
mod2001
Old school modernist
Here you are: http://plustek.com/plustekdoc/How to apply a proper scanning solution on your film scanner.pdf
According to Plustek you get around 4100dpi with the 7200 setting and 2900dpi with a scan at 3600dpi.
Jürgen
Bille
Well-known
I think the scanner outperforms 35mm film. Full res gave me bigger grain but not more detail in the image.
Huss
Veteran
From plustek.com:
"Ok now here is a dirty trick all manufacturers play. They don’t tell you what the measured resolution of the scanner is. They don’t tell you because the measured resolution will almost never be the same as the Optical Resolution. In many cases the Measured Resolution is only 50% of the Optical Resolution. So how could a 6400 dpi scanner only have a resolution of 2000 dpi? Simple. The optics in any scanner are the limiting factor when it comes to resolution. It’s no different than with your camera. It’s the reason some camera lenses cost $2000 and others cost $200. Typically the more expensive camera lenses are “sharper” and have higher resolution than the lower cost
lenses. It’s the same thing with a scanner. Scanner manufacturers need to make a compromise between cost and quality, and quality optics are expensive!"
And from filmscanner.info :
http://www.filmscanner.info/en/Aufloesung.html
"Unfortunately, it often occurs that a producer introduces a scanner into the market with a resolution of 7200 dpi, but in the practice, not even the half of this resolution is achieved. "
"Ok now here is a dirty trick all manufacturers play. They don’t tell you what the measured resolution of the scanner is. They don’t tell you because the measured resolution will almost never be the same as the Optical Resolution. In many cases the Measured Resolution is only 50% of the Optical Resolution. So how could a 6400 dpi scanner only have a resolution of 2000 dpi? Simple. The optics in any scanner are the limiting factor when it comes to resolution. It’s no different than with your camera. It’s the reason some camera lenses cost $2000 and others cost $200. Typically the more expensive camera lenses are “sharper” and have higher resolution than the lower cost
lenses. It’s the same thing with a scanner. Scanner manufacturers need to make a compromise between cost and quality, and quality optics are expensive!"
And from filmscanner.info :
http://www.filmscanner.info/en/Aufloesung.html
"Unfortunately, it often occurs that a producer introduces a scanner into the market with a resolution of 7200 dpi, but in the practice, not even the half of this resolution is achieved. "
Huss
Veteran
Lab test of the Plustek 8100i:
http://www.filmscanner.info/en/PlustekOpticFilm8100.html
"The effectively recoverable resolution is at about 3800 ppi. That is only about 53% of the optical resolution announced by the manufacturer, but nevertheless 3800 ppi are a pleasing high value. Otherwise such resolution values are only reachable by distinctively higher priced scanners. You can read more about that about in our test review of the Plustek OpticFilm 7400.
At this point it shall be mentioned that one has to scan at 7200 ppi to get the highest available effective resolution. One just can't directly scan with 3800 ppi because then the realized effective resolution is further decreased. So to keep the file-size preferably low one should scan using 7200 ppi and calculate the digital image afterwards down to 3800 ppi by using an image processing program. Also this is necessary because scans at 7200 dpi result in lower image-files of 210 megabyte, however in deed in the image-file are only about 60 Megabyte of information; the remaining 150 megabyte consist of double and three times pixels. The removal of these is the task of image processing programs after the scanning."
http://www.filmscanner.info/en/PlustekOpticFilm8100.html
"The effectively recoverable resolution is at about 3800 ppi. That is only about 53% of the optical resolution announced by the manufacturer, but nevertheless 3800 ppi are a pleasing high value. Otherwise such resolution values are only reachable by distinctively higher priced scanners. You can read more about that about in our test review of the Plustek OpticFilm 7400.
At this point it shall be mentioned that one has to scan at 7200 ppi to get the highest available effective resolution. One just can't directly scan with 3800 ppi because then the realized effective resolution is further decreased. So to keep the file-size preferably low one should scan using 7200 ppi and calculate the digital image afterwards down to 3800 ppi by using an image processing program. Also this is necessary because scans at 7200 dpi result in lower image-files of 210 megabyte, however in deed in the image-file are only about 60 Megabyte of information; the remaining 150 megabyte consist of double and three times pixels. The removal of these is the task of image processing programs after the scanning."
cz23
-
Thank you, Jürgen. Very helpful.
Pete B
Well-known
Yes, thank you to all for taking the time to respond. It sounds as though scanning at full res doesn't artificially up res the file through interpolation. Scanning at full res is required to gain the max resolution file, as seems obvious 
I'm having building work done now, but when I'm in a position to, I'll run some tests to see if I can see any practical difference between scanning at a lower res, and scanning at a high res then downsizing in software for display on a monitor. I suspect I won't, and that will save me a lot of time and storage.
Thanks again.
Pete
I'm having building work done now, but when I'm in a position to, I'll run some tests to see if I can see any practical difference between scanning at a lower res, and scanning at a high res then downsizing in software for display on a monitor. I suspect I won't, and that will save me a lot of time and storage.
Thanks again.
Pete
michaelwj
----------------
I typically scan at 3600 on my 8100. I scanned some negatives at both resolution and made prints up to 11 x 14 and couldn't tell the difference so I left it at 3600.
Pete B
Well-known
That's interesting. Thanks, Michael.
Pete
Pete
mod2001
Old school modernist
Same here, but I shoot mainly >= 400 ISO, maybe there's a slight difference with an Ektar 100 or Pan F for example.
Jürgen
David_Manning
Well-known
Forgive me for including an image...I'm only including for technical merits.
I scan film with the Plustek 7600i, at 3600. There is plenty of image data to print large, good dynamic range (you can scan twice for more). It's great with B&W and color.
This image is a 35mm from from cheap 200ISO Fujifilm print film, shot with a Contax T3 wide open at F2.8:
[url=https://flic.kr/p/22Co9S9]
Park Service Ranger by David Manning, on Flickr[/URL]
I scan film with the Plustek 7600i, at 3600. There is plenty of image data to print large, good dynamic range (you can scan twice for more). It's great with B&W and color.
This image is a 35mm from from cheap 200ISO Fujifilm print film, shot with a Contax T3 wide open at F2.8:
[url=https://flic.kr/p/22Co9S9]
Park Service Ranger by David Manning, on Flickr[/URL]
Pete B
Well-known
Lovely shot, David, and nicely scanned.
Pete
Pete
ptpdprinter
Veteran
If you are only scanning for the web, then there is no need to spend the time on scanning for maximum resolution. On the other hand, if you are printing, then the extra time is well spent.