I have LR 5 on a Windows 10 and have been using it for years.
Up to now, I've only had 5x7 4x6 prints made. Cropping to that specific size gave me what I wanted.
I would export as a .jpg w/ 300dpi and be very happy with the results that were printed at Costco.
Now, I want to have a local Pro Lab print one of my photos at a very large size 38 7/8 inch X 27 inch.
I have cropped the photo because the raw photo is..flat and rectangular. The crop rotates the photo slightly
and obviously cuts out some edges in order to center the focal point. It is cut down to a 5x7 size that would only allow me to max out at maybe 8x12 (so says the Lab). I have the file as a .DNG and can export in whatever format LR will allow me to.
But how do I export in the best way for printing in such a large size?
Everything I have been able to find says to use a Custom Crop...but what Aspect Ratio do I put in?
If I put 38.875x27 it shows up as 3.8875 x 2.7, and I'm sure that's not what I need.
The Lab told me to use Photoshop and it would be able to export at any size I chose, but I'm not sure I am willing to sign up for Photoshop just to do this.
Help please for a pretty much noob that has some idea how to do some stuff!
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Export as a TIFF.
What are the max number of pixels in that exported (cropped) TIFF, that's what is necessary to know.
We need to know how you'll divide all the pixels (let's use one dimenstion) to 38.X inches. Ideally you want about 200 pixels per inch for a print, no need for more but if you end up with more, no problem.
The original dimensions of the pic are 4928x3264, cropped I'm getting 4045x2816.
Based on 200 pixels/in, best would be 20x14. Is that what we're saying here?
How bad would this look at 39x27? Half as many pixels as we'd like for good quality.
At 300dpi the lab is saying 13x9 would be the best/max print size...
4045 divided by 39 comes out to 104PPI which isn't really enough ideally for this print size. You'll either have to interpolate when you render (making pixels up) or get a smaller print or live with this when viewing the print at viewing distance. Your call.
I can't tell you how bad because I don't know anything about the output device or how picky you may be, or if you'll view this at ideal viewing distance. As the late great Bruce Fraser once wrote: "The ideal viewing distance of a photographer is based on the length of his nose"
A print that large wouldn't be viewed this way but hopefully you get the idea and humor.
The lab says 300 DPI (they mean 300 pixels per inch of your data) and again, I think you can easily get away with 200 PPI (some might suggest 180 PPI), so do the math and maybe consider a 20 inch print from those 4045 pixels.
Yah, I understand. Its definitely not ideal. I have a very large frame that I bought for cheap that I want to put this picture in. So the print size isn't negotiable. The print will be viewed mostly from several feet away up to 50ft away. So my nose can be pretty long.
So go ahead knowing that you'll end up with 104PPI, you may wish to 'size' the print for the lab so they understand you want output that is X by X at 104PPI or maybe try resampling when you export the image to 200 (more is pointless), Lightroom Classic does a pretty good job of doing this from raw. You can include output sharpening and such when you export which can help.
The important thing is for the lab to know exactly what size you want, no matter with the resoution tag upon export applies. And that you don't ideally want them to resample any more (if possible, some labs just don't listen to cusomers).
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Select the file and go to menu Photo> Enhance. This applies both Raw Details to increase the image detail AND increases the pixel dimensions by 2x (4x megapixels) using an algorrithm that retains more image detail. You could also use the Export module Image sizing to increase the file to 300 dpi at 38 7/8 inch X 27 inch. However, photo lab RIPs will probably do a better job of the upscaling and output sharpening so I would just export the Ehanced DNG file without resizing and send that to the photo lab. TIFF is best, but many labs want JPEG files.