JPEG or JPEG + Raw & convert to DNG + JPEG?

[OogieM]

So I'm scanning using a digital camera about 30K 35mm slides as described in the thread on lessons on scanning here.

The company that makes the SlideSnap recommends only saving JPEG files for the process. They say that for most applications the size savings of the JPEG outweigh any potential loss of information since most slides will not have more information on them than can be captures with a good digital camera system. All my other scanning has been to TIFF files.

I'm trying to decide whether to convert the raw files to DNG and use that plus a JPEG file as a set in the catalog or use JPEG only.

My initial thoughts are to go JPEG only, get them all done and in the catalog and then as the top ones are identified considering re-scanning them and saving both types of files.

The slides include ones taken underwater scuba diving, cave diving, lots of mine are very fine grained kodachrome but lots are also ektachrome, agfachrome and Seattle Filmworks film. For some of the Seattle filmworks ones we have the negative but in many cases all we have are the slides or the prints.

Anyway, I'd like to have a discussion about the issues and tradeoffs on the DNG+JPEG vs JPEG only file types for this project.

 

[Roelof Moorlag]

My initial thoughts are to go JPEG only, get them all done and in the catalog and then as the top ones are identified considering re-scanning them and saving both types of files.

That is what i have done with my negatives and slides about ten years ago. My goal was to have them all digitized first so i could manage them in my catalog. Afterwards i scanned some of them individual with the highest possible quality available on that moment. However, if i wanted that for all my images i would have been busy right now.

 

[Victoria Bampton]

If you're getting your white balance and exposure spot on when you're shooting, then JPEG will do great.

The other option is to shoot JPEG and then convert to lossy DNG. The size is about the same as a JPEG, but it retains a little more editing flexibility. The downside is it's not as well supported as JPEG or TIFF, so it might be an interim stage rather than the archival format.

 

[OogieM]

White balance is set by taking a picture of the LED illumination used in the projector. Camera is set to apeture priority per instructions.

Still debating...