what should the resolution be when saving files from Light room?

[supercool2]

I noticed when exporting photos (saving them to my hard drive, etc.. for printing later ) the resolution in LR says for pixels per inch, 600 but gives me the ability to change that number. I dont know what that number is supposed to be for printing in highest quality.
That number might have been put in their by accident, or its what is defualt. I dont know. But I have been leaving alone. I also notice that when Im printing from my computer picasa and/or my printer settings will let me choose a ppi number. Right now that setting is for 300. Sometimes I will write text on my pictures in picasa (since I dont know how to do that in any other program) or make a picture collsge in picasa, and need to print out a picture from there. That is how I noticed the 300 ppi on there .

I am new to re-sizing, picture quality, and even having them print ready too like when it comes to not having to crop it when ordering prints in certain sizes. So if there is a book or articles explaining those things , that you can reccomend I'd love to know. Because very soon I will be trying to catch up on printing all the photos I have ever taken of my kids and a few misc. stuff as well . And when on costco online usually for half the pictures, depending on which sizes Im wanting it will require me to set how I want it cropped. Having it ready to go so its croped for any size epuld be a time saver. Unless Im misunderstand something I read somewhere and it's not possible to do that (?) Thanks

 

[KmH]

The thread has been moved to a more appropriate forum.

You need to consider that ppi and the image pixel dimensions determine print size - pixels / ppi = inches (because the pixel units cancel).
For electronic display, ppi is meaningless and has no effect on image or file size.
For electronic display, the image pixel dimension are the only meaningful numbers, but many electronic displays automatically re-size images to large for the electronic display page.

For example: the native image resolution (not print resolution) of your D600 is 6,016 × 4,016 px. (Note the native aspect ration of your D600 and D7100 image sensors is 3:2)
6016 px / 300 ppi = 20.05" The long side of a print would be 20.05 inches long. 4016 px/ 300 ppi = 13.39"
6016 px / 600 ppi = 10.026" The long side of a print would be 1/2 as long, only 10.02 inches long.

Doing some basic algebra we can determine that:
pixels / ppi = inches
inches x ppi = pixels
pixels / inches = ppi

So if the long side of your photo is 6016 pixels and you want a print that has a long side of 10 inches - 6016 px / 10 inches = 601.6 ppi.

If you want to make a print having an aspect ratio different than the native aspect ratio of your cameras, you need to crop some from the original image to make it the aspect ratio of the print size you want to make, or have made.

 

[supercool2]

Thank you for the detailed info. Im sure you explsined it well. Maybe I really am stupid....but I cant understand any of that ;-( I might need some kind of book and to read your explanation over&over in hopes a light bulb will go off and I might get it. I do like the chart. I think that helped .

But by looking at that chart does that mean with the kind of cameras I own I can't get good high resolution pictures if I want super giant prints? I like printing in 11x14,16x20, 20x30 + but havnt tried bigger than 20x30 yet. And later I plan to get much bigger prints than those to display on my walls. I want those large prints to be high quality . Once I had taken some pictures with the D600 and thought I had it on raw. I accidentally hit the wrong button that day, not knowing it got switched to a small or medium jpg. I was disappointed because I didnt know how that would degrade my pictures, in adfition to after editing them. They were of my kids , my husband&I and one of me . The one of me nursing my son was special to me and I wanted to print it as a 20x30 but the largest I could go was a 16x20 before the low resolution warning came up . This was during the ordering process on costco online. However, there was a different photo from 4hat same "session" . I was able to print in the 20x30 size. Even though it wasn't the sharpest, (unless its my imagination, I can tell a difference in quality compared to the 24 megapixel pictures shot from raw and those) it still looks good and I don't think the resolution warning popped up for that one. I dont know if this has anything to do with it, but the other photo (the nursing one) I did have to do a lot of editing (healing tool, brushes in LR) because there was a horrible little triangular shaped shadow (looked like smudge was on lens) on one cheek and I had dark circles under my eyes. I did not do any cropping because it was actually shot framed way too close around me (Ihad a family member shoot it for me) so even if I did want to crop it in post processing, I would have chopped some of my head off .
Its important to me to be able to print very large prints so I feel I need to know how to save the files correctly. I hope my camera is good enough for larger prints ? I thought 24 megapixels would be more than enough for really big prints. Unless my idea of big prints are really super giant .

 

[Big Mike]

The PPI resolution number isn't the important number. That number basically tell a computer how large to display the image on a screen.

The more important numbers are the pixel dimensions. The more pixels the image has, the easier it will be to print at a larger size...provided that they are quality (good looking) pixels.

The rule of thumb for photographic prints is that you want 300 pixels per linear inch on the print. So if you are printing a 4x6, you would set your pixel dimensions to 1800x1200. If you are printing an 8x10, you would want 2400x3000. Notice that an 8x10 print is a 4:5 ratio where as the 4x6 print (and the files out of the camera) are a 2:3 ratio. This means that if you want to print anything other than a 2:3 ratio, you will need to crop (or have blank space).

I see that your camera's max resolution is 6016 × 4016. So if we use our rule of thumb, we could easily make a high quality print up to 20" wide.

But, the 300 pixel rule isn't a hard rule. Many people use something like 240 pixels per linear inch, or 150 or even 100. So at 100 pixels, you could print up to 60" with a file right out of the camera.

Of course, the quality will go down as you use the same number of pixels to make larger prints...but it's not necessarily something that you'll see (unless you really look for it). The part that most people forget, is what we call proper viewing distance. For example, a 4x6 or 5x7 should be really sharp when you are holding it, but a 50" wide print is meant to be hung on a wall and viewed from several feet away....and the further away you view the image from, the less resolution you actually need. As an example, think of roadside bill boards. They might be 30-50 feet wide...and many of the photos on them, were probably shot with cameras that have less pixels than your camera has. And if you get up close to a billboard, it probably look terrible, but that doesn't matter because it meant to be viewed from 100 feet away.

So really, you can print as large as you want and it would probably look OK (provided the photo was good in the first place)....you just have to factor in how far away you will be (should be) when viewing it.

Also, you aren't stuck with 6016 × 4016 pixels. When you export from Lightroom, you can change the pixel dimensions. First you should crop to the ratio that you want, then in the export dialog, set the pixel dimensions that you want. You can make it larger or smaller than your camera's native resolution....and if you make it bigger, the program will have to add 'made up' pixels. Adding made up pixels will decrease the quality of the image, but you can increase it quite a bit before it becomes a problem. You might be able to get away with doubling it, if you had to.

So, it's a bit of a balance between adding pixels and using a lower pixels per inch of print. For a large wall print, I'd probably shoot for something like 150-200 pixels per inch of print, and then set my pixels dimensions accordingly.

Also, the printing medium can be a factor as well. For example, canvas prints are very popular, and one thing about canvas is that the texture can allow you to get away with fewer pixels. I have a 50x30 gallery wrap canvas print on my wall at home. The print wraps around the edges so the file was actually sized for just over 54" x 34". The photo was shot with an 8MP digital camera....and the print looks spectacular, if I do say so myself.

I don't know that there are hard rules that we can give you...because a lot of it depends on your own personal standard or expectation of quality and the quality of the photo. For example, when I'm shooting landscape photos, I do everything I can to maximize sharpness, because that will make for better looking images, especially if blown up into large prints.

This is something that you'll likely have to learn via experience. Go ahead and have some prints made and see if you like them or not.

And don't be afraid to try different labs. You mentioned Costco, and they usually do a decent job (for a great price) buy they are still a 'consumer' lab, not necessarily a high end 'professional' level print lab.

 

[hirejn]

Just make it 240 when exporting for print. If you want to know the maximum size your camera can print, divide each dimension in pixels by the dpi. Photos need only about 150 dpi for photo resolution at average viewing distances. So if you have a 3,000 x 2,000 image, the max print size at photo resolution is 3,000/150 x 2,000/150, or 20 x 13.3. You can still get a print at 100 dpi, which is the minimum for professional labs. That would give you a 20x30 from a 6-megapixel camera, so you can see you need fewer megapixels than you think.

 

[supercool2]

Let me know if understood this correct. So if I reduce the pixel number per inch, I can make a bigger print, *but* the quality will go down so I should play around with it, and see what I like ? Im picky and like to have the sharpest looking pictures possible , small OR big. So I will probably go easy on reducing the ppi for print . I bookmarked this page so I can come back and print the info out, to re-read later and hopefully can understand it better later on as I learn more.

 

[supercool2]

I will experiment with aspect ratios on he computer (to try to match the ratios given to me below in the chart) and see what happens. It should help me learn and hopefully a lightbulb will go off . So thank you. Doing stuff on a computer for photos is new to me. I used to just take the picture and that was it. SomI'm evolving from that to learning LR and now how to properly save files for printing , and do things on a computer etc.....

I have ordered from mpix before. And I know of a few other places. I just have been using costco because I like the instant gratification of picking them up in person. They have only been phtos of myself, my kids, pr pictures Ive done free foa few people. Who by the way were very happy with their pictures. If I were being paid a lot of $ to take someone's pictures I probably wouldnt use them. But I have been told by the people who work there that a lot of local professional photographers use them. Also, they have really given great results so far. The only time they came out bad, was when I didnt know to turn off the auto correct choice. Before I got my membership there, I actuslly only ordered from smugmug because I refused to use snyone else, like walmart walgreens, etc.. I took some pictures of my kids in 2009 and walmart refused to let me print them because they said they were professional when they were not. So I got mad and stopped using them all together, lol.