Rule of Thumb for Scanning 35mm slides

[cssaus]

I'm pretty new at all of this and some of the terminology goes a little beyond me.

I'm trying to determine how best to proceed with the scanning of my 35mm slides for archiving onto a 4.7GB DVD.

Essentially my main requirement is for archiving the images off the original slides (some are over 30 years old) but there may be the odd few slides that I might want to print off.

Should I scan them at their original slide size of 1.4"x.9" or upscale them to say 6"x4"? Either way, what Q-factor and DPI setting is recommended to be used if someone later wants to view them either on their PC or large screen LCD/PLASMA TV or print a photo or two?

I'm using a Plustek 7500i scanner with SF V6.6

[degrub]

Q factor only applies for commercial printers. Ignore it.
There are several schools on what ppi to scan at. Some suggest scanning at the native ppi resolution of the sensor, since any ppi above that are interpolated and any below that are downsampled by the scanner driver . If the downsampling is not a factor of 2 of the native sensor resolution, then there is pixel averaging/interpolation. PS and other software may do a better job of both.

THe other school suggests determining the actual resolving capability of the scanner optics and scan at that PPI since anything above that will be noise mostly. i think this is technically correct. If you need more pixels to work with for printing, using an upsampling program to create them from "real" ppi may work better than oversampling.

The reality is that most films, though capable of higher resolving of detail, do not because of many factors - camera shake (hand, shutter, etc), limitations of the lens system, development issues, etc. So scanning with a resolution of 1800 - 3000 ppi can be just fine.

For the scanner you have , i would try some scans at 1800 and 3600 ppi and see which work better for you. You may find the 1800 ppi scans give you everything you want. And for the enlargement you list will give you enough pixels ( assuming 300 ppi to the printer). The LCD TV is not likely to need more than 1024 x 768 pixels or so, and you can downsample to what ever final number of pixels the panel needs. For PC display, many use 72 ppi for the final image resolution.

[cssaus]

For the scanner you have , i would try some scans at 1800 and 3600 ppi and see which work better for you. You may find the 1800 ppi scans give you everything you want. And for the enlargement you list will give you enough pixels ( assuming 300 ppi to the printer). The LCD TV is not likely to need more than 1024 x 768 pixels or so, and you can downsample to what ever final number of pixels the panel needs. For PC display, many use 72 ppi for the final image resolution.

Thanks for your response.

I assume your suggestion is based on scanning the slides with no scaling, leaving them at their original 1.4x.9" sizing.

Your reference to "PPI", do you mean the "DPI" setting?

[degrub]

DPI,PPI yes

yes for the archive copy, then i resample in PS to the output size i need.

[cssaus]

Can you just explain by what you mean by "i resample in PS to the output size i need".

Are you saying you in fact re-scan the slides again for the output size you need?

[degrub]

PS = Photoshop or equivalent image editing program

no rescanning, just re-sampling in PS to get the needed output size.