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Thread ID: 42158	2004-02-02 08:46:00	Off Topic: 35mm slides - what resolution to scan?	tbacon_nz (865)	Press F1

Post ID	Timestamp	Content	User
212359	2004-02-02 08:46:00	I have a bunch of 25 year-old 35mm Kodachrome slides that I want to convert to 10 x 15 prints and mount and display on the wall. What is the minimum resolution to scan the slides at to get a satisfactory enlargement to that size? Can anyone suggest a commercial operation in Auckland that could handle the whole thing for me? Ta, Tony Bacon	tbacon_nz (865)
212360	2004-02-02 08:54:00	If you want quality a drum scanner is the best. There must be an outfit with one in Auckland.	mikebartnz (21)
212361	2004-02-03 00:05:00	Many photographic shops which do their own processing will have a film scanner which will have "good enough" resolution . They'll happily show you samples of the results . However, if they show you a flatbed scanner they use, look elsewhere . ;-) You need thousands of ppi rather than hundreds . Drum scanners get very good results . That will be very expensive . That's worth it if you are producing separations for an expensive "art" magazine .	Graham L (2)
212362	2004-02-03 00:30:00	Thanks GrahamL, you've confirmed my opinion. I went into a local copy shop who were going to scan them at 300dpi, which struck me as waaaay to low. They were adamant that would be sufficient. Tony	tbacon_nz (865)
212363	2004-02-03 00:40:00	if you think about the numbers....... 300DPI on a slide of about one inch give 300 dot per photo width. 300 dots per photo width on a 8 inch print gives 37 DPI on the print which will look like crap :-) if you want 300 DPI on a 8 inch print then you need to scan at 2400 DPI hope this gives you some numbers to think about.	robsonde (120)
212364	2004-02-03 00:50:00	"35mm scanner" to Google. :D The links "Prime film 35mm scanning"and "Digital Scanner reviews" will show you the sort of thing you want them to use. That first one says that 1800 ppi is running out steam at 5"x7".	Graham L (2)
212365	2004-02-03 00:52:00	That's the sort of resolution I'd been thinking about. If I can find a friend/neighbour/whatever with a semi-decent scanner with a slide attachment, will that do the job? My scanner is quite old and has no slide attachment. I'm happy to touch up/crop the photos and transfer them to CD. Tony	tbacon_nz (865)
212366	2004-02-03 01:01:00	A lot of flatbeds don't really have enough "real" resolution . (It's cheaper to interpolate;-)) . But some do . The final test is how it looks to you . A photographic notcopy business will have the right gear . (and know what they're doing) .	Graham L (2)
212367	2004-02-03 06:23:00	I have a lot of old slides that I'm digitising myself. 300 dpm is far too low a resolution. I find that 1200dpi does Ok. It depends (at least in my case) on the quality of the original slide. I find that going higher than 1200dpi often (in fact usually) doesn't give a better result. I try to judge whether the inherent fuzziness of old slides shows up first or whether it is the pixelation due to scanning at inadequate resolution. I use Adobe Photoshop to display the scanned results, and as a matter of practice enlarge them (or zoom in) to see whether undue pixelation shows up first or whether slide fuzzinessshows up first. For most of my slides 1200 dpi seems adequate. I just scanned a Kodak 35mm at 1200 dpi using flatbed scanner Canoscan 5000F, computer Athlon 2000+ with 512mb ram. It took 4 mins 15 secs and when saved (tiff format) had a file size of 74,173kb. Compare this with my digital camera Canon G3 which even at highish resolution produces file size of around 3,000kb. My scanner (claims it is) capable of a maximum output resolution of 2400 dpi, which gives a saved tiff file of 289.7 mb, approaching the reasonable limit of my existing ram. I can print (on deskjet) the digital camera shots on A4 paper and produce a result with no pixelation. There is no loss of quality detectable if I print the scanned slide file on A4. I haven't calculated at what paper size the pixellation would start to show up, by if you are only using 150mm by 100mm paper I think that scanning at around 600 to 750 dpi would be fine. Couple of further points though. Good drum scanners are capable of much higher resoultion than flatbeds, and are correspondingly more expensive. A commercial outfit has to cover its costs and would charge you accordingly. So do you want to pay for a higher degree of resolution than you indicate that you want. I have had problems with commercial shops in the past, although some are OK. But overall I generally find it better to do the job myself. But at 4 mins 15 secs I might be doing it for a long time…. So should I pay someone else to spend their time instead? As Voltaire remarked in a somewhat different context - C'est une grande question. Hope these remarks are of some help.	rugila (214)
212368	2004-02-03 10:09:00	Thanks Rugila, that has been a great help. 1200 dpi was what my instinct was pointing me at - all I have to now is find someone to do the scanning! Tony	tbacon_nz (865)
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