megabyte file issue

Rob, are you resizing on export? If you end up with 5400 x 3600 you must have. Uncheck everything under Image Resizing.

I have an a7RII and the sensor resolution is 7952 x 5304 pixels. So if you have 7830 x 5222 that means the file is very slightly cropped. But that shouldn't matter, there is plenty left.

I don't think any upsampling is necessary here. At 36" by 24" that ends up at 220 ppi (pixels per inch), which will do just fine.

If you have the Photography plan with Photoshop CC 2018 it has a new 'Preserve Details 2.0' resampling algorithm. This allows "upscaling" your camera files with minimal loss in quality to the target paper size and printer dpi. For 24" x 36" @ 300 dpi that would be 7200 x 10800. Just a suggestion if you're not happy with the print results using the native 5222 x 7830 resolution output file.

Best Way To Enlarge Images In Photoshop CC 2018

BTW- 80-85 Quality JPEG file will exhibit no visible loss in quality over 100 setting. Adobe originally provided the 100 Quality setting to minimize buildup of compression artifacts from multiple edit/save operations.With LR's non-destructive editing this is not a concern unless the file has to be edited externally (PS). For that purpose TIFF file format is the best choice.

Jeffrey Friedl's Blog » An Analysis of Lightroom JPEG Export Quality Settings

Robsweeney  wrote Hello all, Admittedly my knowledge in the exporting and printing phase is not great.  That said, my goal is to print a 24 x 36" print at Costco.  In LR6, my photo indicates RAW 7830 x 5222 (I shoot with a Sony 7rII, 42 meg full frame camera).  My goal is to print at highest quality/resolution.  Costco accepts up to 50 mg file.  When I export, the JPG file is less than 7.9 mb, 5400 x 3600.  So my question is: am I at MAXIMUM OPTIMIZATION for printing large?  Should I be exporting in TIFF?  Thank you!

I doubt that 7.9 mb is a problem. Why? Because megabytes of a JPG does not indicate quality. It is a misleading number that causes people to do the wrong thing.

JPG at 7.9 mb is fine. JPG is a compression technology, JPGs are supposed to be a lot smaller than the original RAW.

ADVICE: Go with the 7.9 mb JPG, you won't have any problems.

Do not resize the file on export, leave it at 7830 x 5222. (Uncheck Resize to fit) You'll be needing every pixel for this print size. Export as jpg at 100 quality, and don't worry about file size, which for jpg is not an indicator of image quality.

https://forums.adobe.com/people/Akash%20Sharma wrote The Tiff export would be larger in size and better in quality as well. Since jpeg's are lossy compressed format, you are bound to loose pixels and file size can be a lot smaller than expected. As you've mentioned, exporting the files in tiff format (if your printing service accepts them) and keeping the file size limited to 50 MB would be a good option.

Exporting as jpg does not lose any pixels, but their quality can be reduced. Usually not a problem at 100 quality.

Exporting asTiff would result in a file size much larger than 50 mb, and Limit file size to is only for jpgs.