Film Scanning - Optimum resolutions for different film types

[Craig Arnold]

For the scanning gurus.

I mostly use the C41 BW films, Ilford XP2 and Kodak BW400CN.

Because:

• 400 ISO
• Easy to get processed in a high-street lab.
• Allegedly good for scanning.

I am (still) considering purchasing a MF outfit, and because I can't afford a Coolscan 9000 am wondering what resolution scans I should pay for. The labs seem to base their prices on the final output size (I guess they have to base it on something), but clearly there is no point in paying for a 100Mb scan when a 20Mb scan will do the same job with the film I happen to be using.

So here is my question: At what point does one reach severely diminishing returns with a given film type?

Is there any point in scanning XP2 at 4000dpi? Will everything beyond 2000dpi be just extra grain/noise? My intuition says that for ISO400 films there is probably little extra detail in the 4000dpi scan compared to a 2000dpi scan. With Velvia50 I would expect there is extra detail beyond even 4000dpi.

Does anyone have a handy matrix for optimum scan resolutions for different film types? [Or have I just got hold of the wrong end of the stick with this notion?]

It also has longer term purchasing implications, for example if I do 90% of my shooting with BW ISO 400 films (C41 or silver), it may be that there is no real point in getting a Coolscan9000 over a V750 for example. The V750 is reported as having a 2500dpi optical resolution, if the film only needs 2000dpi then I can spend the money I might have spent on some extra lenses, or a holiday, gift for the wife, etc.

Thanks in advance.
Craig

[JohnBrew]

Craig, I'm not sure if this will help, but this is my experience: I have a Minolta 5400 scanner. When I used SilverFast software with this scanner I scanned @ 4000 and got very acceptable performance and found I didn't need the top 5400 dpi. When I changed platforms and had to change to Vuescan software I discovered you really can't dial in what dpi you scan. I was given a choice of Auto, 5400 or 2700. Through experimentation I found more detail in the 5400 scans over the 2700. So in my case 2700, while acceptable, wasn't quite good enough.
Your question does hold further interest however, since I also shoot MF and I would like to know how well the Epson V750 does at it's maximum dpi with 120 negs.
Hopefully someone else will chime in here...

[Czornyj]

Your question does hold further interest however, since I also shoot MF and I would like to know how well the Epson V750 does at it's maximum dpi with 120 negs.

Take a look at this:
http://www.photo-i.co.uk/Reviews/interacti...V750/page_5.htm

[digitaldog]

So here is my question: At what point does one reach severely diminishing returns with a given film type?

I've heard various figures over the years. Much depends on the type and quality of scanner. When I worked with pretty high end desktop drum scanners (oil mounting the film), we felt the spec, 4000-5000ppi was sufficient to resolve down to the grain (IOW, more resolution didn't buy you anything).

That said, a 4000ppi scan of a CCD, desktop scanner and 4000ppi off a PMT drum were quite different in terms of quality and useable data!

[aeroektar]

That said, a 4000ppi scan of a CCD, desktop scanner and 4000ppi off a PMT drum were quite different in terms of quality and useable data!

Having owned both ccd (modified Minolta Dimage Pro/scanhancer/LEK mods) and drum (Howtek 4500), this is very true. IMO, device capability is equally important as the scanning resolution. For some that difference matters, others not. I'm in the process of redoing a whole body of work that was originally ccd scanned. I did some tests on the same images w/ the drum scanner and the difference is disturbingly noticeable to me. But that's just my take...live and learn.

[Czornyj]

Having owned both ccd (modified Minolta Dimage Pro/scanhancer/LEK mods) and drum (Howtek 4500), this is very true. IMO, device capability is equally important as the scanning resolution. For some that difference matters, others not. I'm in the process of redoing a whole body of work that was originally ccd scanned. I did some tests on the same images w/ the drum scanner and the difference is disturbingly noticeable to me. But that's just my take...live and learn.

I have 9000ED and I also hate it. The resolution is more than sufficient, the DR is ok, but there's still a flare that affects the dark areas that are close to bright parts.

[Wally]

FWIW I have found that even my cheapy Epson 4490 flatbed does a far better job than a Min-Lab will do with scanning. This is even more true with B&W negs. I scan my medium format negs at 2400 DPI with my 4490 and that is plenty of resolution. Remember with medium format negs you have a much larger negative than 35mm film so you do not have to enlarge the file nearly the same amount to get the same size print.

You will find that a flatned scanner will quickly pay for itself over having lab scans, and when you get that once in a lifetime shot you can always get a high qulity drum scan made