sosider wrote:
I've got some 3000 slides to scan and while .tif has been around for some time I was hoping to be able to get some compression to save on file space.
There's nothing to stop you from considering TIFF, because you have several options for compressing it without loss of quality. However, there's a lot of traditional advice being given out and some of it needs adjusting for today's workflows.
TIFF vs PSD: The TIFF format can store just about anything PSD format can (layers, Smart Objects, effects, etc.), and it's more open, so using TIFF can potentially let you open the files in the future using many applications other than Photoshop or Lightroom.
TIFF compression: When you Save As a TIFF in Photoshop (or export TIFF in Lightroom), you get some compression options. The traditional advice is to use LZW compression. That was excellent advice for the 8-bit age, but now that 16 bit files are both recommended and common there are better ways. Adobe provides a ZIP compression option for TIFF and that compresses even more than LZW. There is another very serious reason not to use LZW if you work with 16-bit files: In some cases applying LZW to a 16-bit TIFF can actually make it much larger!
An example I just tried with a 16 bits/channel TIFF:
Uncompressed - 107.5MB
Compressed with LZW - 121.3MB
Compressed with ZIP - 96.2MB
The disadvantage of ZIP is it takes the longest to open and save. If you're working on an image a lot you might temporarily use PSD. PSD is actually compressed, but you don't have any control over it.