[Andy Harris]

Finally I got a slide scanner (Canon 4400F) for Crimbo and can get round to scanning in years worth of slides. The whole resolution, dpi thing has always been confusing and I'm hoping there's some simple advice out there.

Basically I want to get the choice images on the PC for posterity and to potentially print up to A4 in one of them fangled on line book things. So what dpi / resolution should I be scanning at? I'm not too bothered about doctoring them further as it's going to take me long enough to scan them in the 1st place.

Basically I just want to set the software up once and scan away. The only thing i'll need to alter is between colour and B&W positive for my Agfa scala slides.

Any advice, hints, tips appreciated.

[Andy Harris]

i did find a previous post by JB and cofe but I'm none the wiser. JB was reccomending scanning at a max of 2900dpi for up to A4. Now i appreciate the scanner i have is not dedicated for slides but for my needs I'll be pretty happy. If I set 2900dpi on A4 the file size for 1 slide is 775mb! A little excessive me thinks.

Now either I'm doing something wrong or my scanner is completely different.

The manual itself reccomends output settings of 300dpi max and in some cases for v.high quality printers 600dpi (8.3 & 33mb per scan respectively).

[Johnny Brown]

You need to get your head around input resolution and output resolution - slides are small, pints are big.

Working backwards then, 250-300 ppi is fine for output, ie printing, you won't see the pixels at that even with your nose on the print.
So at 12" long edge [for A4 roughly] you'll need a file with 3600 pixels long edge [12inches x 300 pixels per inch].

Your actual slide's long edge is only 36mm/ 1.42", so to scan for a 12" print you need to squeeze all those 3600 pixels out of that.

3600pixels/1.42"= 2535 ppi - hence 2900 ppi.

My old slide scanner had a max optical res of 2900 ppi, so I went with that. I would check the max OPTICAL resolution of the scanner and do the same, its unlikely to be more than 4000ppi. A tiff file size of 33Mb sounds about right.

[dave]

just check where you're intending to get them printed and find out what the output resolution is. most commercial printers photo output like JB says are in the 250-300 ppi range (for example peak imaging is 254, photobox is 300).

if you want to make it a quick job and handle small filesizes, you could always do quick low-res scans for the internet use (say 1200dpi scans) and then only scan the stuff you want to print big further down the line. at least then you'd be scanning printable images individually (and thus making all the relevent adjustments you'll need to get cracking prints) rather than doing the one-size-fits-all approach which you're bound to have some slides which just look wack on whatever your "standard" settings turn out to be.