Howie1a wrote:
I have used the following all worked good and gave great pictures a, Nikon D 40-50-70-80-100, D 40x-60-200-, and D 3200 as well as a D300 all with 6 to 24 MG pix why do you need to go with a larger Megpx Ken Rockwell say's 6 is enough. What is your thoughts ?? I could be happy with my D 100 with a larger screen Howie1a
This is one of the few times I agree with KR. He is absolutely correct. I've printed images from a Nikon 70S, a 6.1 mp camera, to 40x60, and sold them, with zero complaints about loss of resolution
The rationale is easy to understand. You've been to a multiplex theater. The Sony 4K screening rooms are about as good as it gets, other than IMax. Your typical screen could be from 40 ft to 60 ft wide. The 4K standard for resolution is 8.8 mp. You don't need a lot of pixels to print big - that is a myth. In fact, your ppi requirement diminishes as the print size gets bigger, because a larger print (or projected image) implies a greater viewing distance, and your eyes can only resolve so much detail, and that diminishes as the viewing distance increases.
You must have seen the iPhone 5 and 6 billboards around town which displayed an image taken with the phone to billboard size. There was no software magic used to do that. It was pure physiology. Our vision can't see minute details at a distance of 30 ft or greater. But there is a great impression of sharpness. A 40x60 image requires 32 ppi for the appearance of acceptable sharpness. The 6 mp camera, if you use an image uncropped, will give you 75 ppi at that print size, about 2.5X more resolution than is actually needed. So for the obsessive photographers in the crowd who insist on taking out their loupes and examining the dot pattern on a print, 6 mp may not be up to their standards, but certainly you have more than you need.
This site explains how this all works, and provides the mathematical formulas to figure it out, or a quick calculator if you don't want to do the math:
http://www.photokaboom.com/photography/learn/printing/resolution/1_which_resolution_print_size_viewing_distance.htmThe primary benefit of having more pixels, provided you lenses are sharp, is to be able to crop more without too much loss of image quality.
So, without a doubt, Mr. Rockwell is 100% on target. You don't need more mp to print larger, you need enough, which is 6mp, and some good technique and sharp lenses.
Hope this makes sense to you and answers your questions. Most follow the herd and buy into the notion that you need more mp for bigger images. You don't.