Resolution and quality....

[DavidPalermo]

I use a Nikon D810 and typically crop to a 4x5 aspect ratio.  I cannot print large prints at home and I want to make some large prints - 30x40in or so. 

I'd like to be able to print my files at home in an 8x10in format to look and see what the quality will look at the larger size.  In oter words I want to print as if I were printing a 30x40 but only print part of the image and take a look at the quality before I send the file to my 3rd party printer company.   (they use Epson large format printers - 9600 or 7600 printers.  maybe a P7000 not sure yet.

So, I usually print out of Lightroom and just tell it what size I will print at but I can't print just a partial of the image.  I think I have to export the file to Photoshop  - res the file up to 30x40 and then extract an 8x10 and then go back to Lightroom and make an 8x10 print.  Is that correct?

Thanks!

David

[Mark D Segal]

No - not correct. You can create a crop in LR and send it to print using a resolution of your choosing. You do the cropping in the Develop module and the print resolution in the Print Module. The key to getting a correct prediction of appearance is the size of the crop relative to the resolution - you should design both to avoid as much on-the-fly resampling as possible. May require a bit of calculation.

[DavidPalermo]

Mark:  Yes that makes sense!  But yes I think there will me math involved.  Hmmmm....

; )

Thank you,

David

[Mark D Segal]

Fortunately, it really isn't "math", just "arithmetic" - dividing inches into pixels to derive pixels per inch (or pixels per inch into total pixels to derive inches) and deciding how many pixels you should print (i.e. the crop) to get enough inches at the desired pixels per inch. :-)