DanCulleton

No!

Bayou

Ignore this advice. It's completely wrong.

Bayou

No, nothing but drawbacks.

burkphoto Loc: High Point, NC

Lightroom Classic will preserve your original files, NO MATTER WHAT THE FORMAT. Only when you export, print, send to web, or make a book or slide show is the image converted using the changes you make in Adobe Camera Raw, the engine of the Develop module in Lightroom Classic (LrC).

When you "Import" a file into LrC, it stays where you put it before or during the import. LrC gives you a choice.

When you "Develop" an image from that file, Lightroom creates a PROXY of the original for display, and applies your changes to the proxy as you work, so you can see them on your calibrated and custom ICC-profiled monitor. At the same time, it automatically saves the "instructions" to make all those changes into its "catalog," (a database). It may, optionally, save those same change instructions to a "sidecar" file. That file can be used in Photoshop with your original.

When you export, print, send to web, or make a book or slide show from LrC, the image is finally produced for use at whatever pixel resolution and dimensional size you specify, and with the ICC profile and the file format you specify if exporting.

INTERNALLY in LrC, no matter what file type you started with, it is converted to a high bit depth file (16-bits) and a wide gamut color space such as ProPhoto RGB. This allows maximum smoothness to gradients like blue sky, and shadow edges in portraits. LrC applies all editing changes and color gamut conversions when the file leaves LrC.

Your original is NEVER changed in LrC. It is copied, altered, and then exported, or printed, or sent to the web, or made into a book or presented as a slide show.

To those of you who say there is no benefit to converting from JPEG to TIFF, I ask, "Why does every advanced parametric editing tool do essentially that, behind the scenes?" If you are not using Lightroom Classic, Kodak DP2 lab software, or some other completely non-destructive editor, then you can MANUALLY create the same sort of process as I outlined in an earlier post here.

What this will not do:

You cannot use this process to "add back" any detail or brightness information that was not in the JPEG (or other type of file).

If the camera threw it away or could not stuff tonal information into a raw file because it was not in the exposure, you won't be able to fix that. But if a JPEG file requires subtle exposure and MINOR white balance adjustments to make it look better, LrC or Adobe Camera Raw in Photoshop or Bridge can do a great job of that.

mwsilvers Loc: Central New Jersey

If you were to convert to TIFF format from a JPG file everything you indicated above would be inaccurate. Converting from an already compressed JPEG can't invent pixels that are not already there. There would be absolutely no advantage to a TIFF to JPEG conversion.

I suspect, and hope, you may have misunderstood the OP's original question.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Indeed, conversion from 8 bit to 16 bit for editing purposes is valuable. But as long as you use a good editor, that software will do the conversion for you so there is no benefit to doing the conversion before sending the file to the editor. The key here is 'behind the scenes'.

Were I doing my editing in IrfanView, there were some benefit to conversion first, but as I do all but the most basic edits in Lightroom/Photoshop, conversion to tif is a useless extra step. (In my early digital days I managed to do some color balancing in IrfanView [sort of], but it was a LOT of work. It's SO much easier [and so much more precise] in Lightroom and equivalents).

The OP did not specify the purpose of conversion, so without considering the effect on editing, there is no benefit to conversion from the original format.

AzPicLady Loc: Behind the camera!

I save all my BEST photos as TIFFs. It takes up more space, but I've always believed it's safer, as they aren't so prone to deteriorate. I can always resave as JPEG for sending out.

DirtFarmer Loc: Escaped from the NYC area, back to MA

A common misconception.

jpgs do not deteriorate. At least they do not deteriorate any faster than any other digital file.

Bit rot is real, but it doesn't depend on file format. It depends much more on the medium.

A jpg can deteriorate by being re-compressed, but the effect is not large if the compression is reasonably small. See https://www.uglyhedgehog.com/user-page?upnum=3000

OTOH, if it makes you happy, it won't hurt anything.

SuperflyTNT Loc: Manassas VA

Says who? Actually most labs prefer JPEG.

CHG_CANON Loc: the Windy City

A number of false digital photography bromides have been regurgitated onto this thread. Alas, will any of those laboring under these false understandings be shown the light?

BigDaddy Loc: Pittsburgh, PA

Digital files normally (never) deteriorate unless you force them, or a computer error happens, in which case it matters not what format your file is in, it will "deteriorate." If you insist on saving a jpg file over top of itself, over, and over again, it will then deteriorate, or, if you tell your jpg compressor to apply LARGE amounts of compression, it will degrade. Photographers should know about all of this, it is pertinent to digital photography.

jlg1000 Loc: Uruguay / South America

How do they deteriorate?

Humidity?
File eating fungus?

PHRubin Loc: Nashville TN USA

Please explain. What is reversible? Certainly not the reduction from 12 bit to 8 bit.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Yes, deterioration by corruption can happen to any format. Deterioration by normal opening and closing is not a thing, even with jpgs using lossy compression because opening and closing does not go through another compression.

Again: https://www.uglyhedgehog.com/user-page?upnum=3000

In my tests the jpg would change on successive re-saves (re-compressions) to a point, after which it reached saturation and showed no further change. Not something I expected, but that's the way it worked. Saturation happens sooner for large compression and later for small compression. Some images took 600 re-saves. Some took 5.

CHG_CANON Loc: the Windy City

Re-read the emphasized section again. Think about what you're asking. Does WinZip discard data when compressing files? If you try WinZip or similar software against a JPEG, does the file get smaller? Creating a JPEG from another format will mostly likely involve removal of data, for sure when the source file has a higher bit depth than 8-bit. But, as an 8-bit file, the JPEG is just a compressed storage format that is fully expanded when displayed. If you're still unsure, do your own research.