Question: My wife is a photographer (Nikon D700, edits in Win7 Adobe CS5 suite) and mentioned yesterday that she's out of hard drive space. When I inspected, I found *GIGANTIC* .TIF files on her drive, ranging anywhere in size from 100MB to 4 ***GIGABYTES***.

I told her to save her final edits off as JPEGS and delete the .TIFs, but she said she can't do that for two reasons: 

* Her printing companies require TIF format
* If her clients want a picture redone or resized, she can't go back
to the JPEG as effectively as she could have with the tif format.

Both of these reasons seem more like the product of workflow issues to me, but I don't know enough about the art to make that call. As the financier of her operation, I have a few questions for the community:

1) Are file sizes like this normal? Is there a more friendly format that she can work in that doesn't require me to buy a new hard drive every few weeks? 

2) Is it possible that there is a knowledge gap somewhere and that she's missing a crucial step in her workflow? She demonstrated for me, and I watched in disbelief as a brand new 10 MB raw file without any edits turned into a *105 MB* TIF file.

I ask because these file sizes seem absolutely ridiculous to me. At this rate, she'll practically have to add a hard drive surcharge to every one of her shoots from now on...

Thanks in advance!

Answer: 
Saving TIFF files doesn't make sense to me. The original RAW is more space-efficient, and of course contains all the inforation to be had. I save the original RAW file and one or more post-processed JPG results. If I want to go back and make a version that's a little darker, more snappy contrast, more detail in the clouds, or whatever, I do that by going back to the RAW file and then making another JPG with the desired tradeoffs.

I'm guessing she is saving the data in 16 bit TIFF files. That is going to be a lot bigger than the RAW for two reasons. First, the RAW contains only one color per pixel. TIFF contains all three with the other two invented somehow from the RAW information. They don't contain any more information, but do take up at least 3x the space. Second, 16 bits is more per color per pixel than RAW data, at least currently. The Nikon D3S produces 14 bits/pixel raw, and I don't think other common cameras do more than that, most less. You don't gain any information by expanding the 14 or 12 bits of raw data into 16 bits, just more wasted space.

So basically a 16 bit TIFF file expands the raw 12 or 14 bits/pixel into 48 bits/pixel without any advantage in information content.

If the printer insists on TIFF file, probably to avoid JPG compression artifacts, send them a 8 bit TIFF file after the post processing. Personally I find JPG files with lossless compression disabled to the extent possible (often done with something like a "quality" setting at 100%) don't have visible compression artifact even when pixel peeping. That is how I store my post-processed images. If someone wanted a TIFF version of one of my pictures, I'd probably just make a TIFF version from the high quality JPG file.

I just checked one of my pictures at random. D025-1756 (for my reference) is 4288 x 2844 (12.2 Mpix) pixels in size. The RAW file is 25.9 Mbytes. The post-processed JPG is 4266 x 2844 pixels and 8.1 Mbytes. A 8 bit TIFF version with forward differencing and LZW compression of the JPG, which contains exactly the same information, is 18.9 Mbyte on the disk.

The details will vary from picture to picture, but the statistics for the above picture seem to be typical in my experience.
TIFF files saved with Perfectly Clear plugin for Lightroom in 16-bit format are 140 MB (from ~20-24 MB RAW files). Will definitely use 8-bit conversion in future!