print size vs megapixels vs quality question

Qarik

I printed out an 11x14 shot through smug mug. It turned out okay but a little more grainy then i was expecting. I went back and retraced my cropping/settings on this picture. It appears the shot was heavily cropped..I only have maybe 6 megapixels in the shot.

Well that is my 1st question..for say family portrait..is there some kind of rule of thumb with regard to number megapixels and print size? Is 6 mpixels too little for an 11x14?

And what compression quality do you use for jpegs? I was using 80% and 240dots per inch. The jpeg looked fairly close to the lightroom shot. I think I will up it to 300 dots per inch and 100% for quality.

I also recall seeing a smugmug option in some control panel "sharpen for printing" or something like that...I might be imagining things though.

pathfinder

Qarik wrote:

I printed out an 11x14 shot through smug mug. It turned out okay but a little more grainy then i was expecting. I went back and retraced my cropping/settings on this picture. It appears the shot was heavily cropped..I only have maybe 6 megapixels in the shot.

Well that is my 1st question..for say family portrait..is there some kind of rule of thumb with regard to number megapixels and print size? Is 6 mpixels too little for an 11x14?

And what compression quality do you use for jpegs? I was using 80% and 240dots per inch. The jpeg looked fairly close to the lightroom shot. I think I will up it to 300 dots per inch and 100% for quality.

I also recall seeing a smugmug option in some control panel "sharpen for printing" or something like that...I might be imagining things though.

300 pixels per inch X 11 inches = 3300 pixels for the short dimension

300 pixels per inch x 14 inches = 4200 pixels for the long dimension


3300 x 4200 = 13, 860,000 pixels or ~ 14 Mbytes

So 6MPxls is a bit short without uprezzing. But if your shoot in RAW, it is easy to uprez a bit in Adobe RAW converter before popping your image into Photoshop.

Having said that, lots of folks have printed images at 11x14 from a 6 Mpxl camera. I have a number of images from a Canon 10D that was 6,5 MPxls
This image came from my Canon 10D several years ago. I have it framed on the wall in my home at 11x14 inches and it is grainless



The secret is the quality of the pixels and avoiding cropping the image if you can.

What was the ISO your image was shot at?


Here is a tute I wrote about Resolution and printing.

I save jpgs at a Image quality of 10 in Photoshop, or 90% in LR2. I prefer to print at 300 pixels per inch, but have seen a number of fine prints printed at 180 ppi. Remember, ppi does not equal dots per inch from your printer. EACH pixel may be represented by 5 - 10 dots per inch out of an inkjet printer.

I usually print from Lightroom2 now, I like it better than the dialogues in Photoshop, and sharpen maximally in the printing module in Lightroom. I also do capture sharpening in LR2 RAW processing or in ACR 5+ before introducing my file to Photoshop.