Poster sized / lower res???

I've been getting pictures up to 8x10 "developed" at Sam's club and have been very happy with them.

I was looking on their site and they now offer poster size prints up to 36x48. These aren't cheap so I don't plan on getting any, but I noticed they said something that didn't make sense to me. Maybe someone here could explain.

Their site says that poster prints require less resolution in the picture to produce the poster. They say a picture that can produce a 16x20 or larger poster might not have the resolution to print a 8x10 or smaller photo.

Certainly these are different printing processes, but I just found it really weird. Has anyone tried to get any of these, or similar, posters made? Any good results?

Later,
Michael

It is taking a long time to get an answer. I'd be interested in the answer myself.

From what I've read, it's all about the number of megapixels that the picture was shot with. You really only need a camera that will shoot at a minimum of 4 Mp to generate an 8x10" photo. For a 16x20", you need a minimum of 8Mp, and for a 24x36" you need a 10-12 Mp camera.

So I don't know what they mean by "resolution" in that term. Sounds kind of backwards the way you stated. I mean if a "perfect" 16x20 pic is created, makes no sense that you can't also make smaller pictures of it. It almost sounds like their talking about "image ratio" ... hmmm...

The difference is that you expect to view an 8x10 at arms length or closer while you would typically look at a poster from a little farther away. Normally you probably want your prints at around 300 DPI, but I think you can get away with 150 or even 100 DPI for the posters.
The easy answer is to get a comparatively cheap 8x10 printed as a cropped portion of the image you want to make the poster to see how it would look. If its good enough for you then get them to print the big version.

In normal photography terms, a 48*32in poster would typically be viewed from about 24in away, where as a 10.67*8in print (same aspect ratio) would typically be viewed from about 16in away. Thus the smaller print needs to be printed at a 50% higher dpi than the larger print. Conversely, the larger print would require 3 times as many pixels in each direction for the same definition at those distances.

When your printer talks of posters, I suspect he/she isn't talking about photographic quality prints, but a much lower 'poster' quality. People are usually much more tolerant of low resolution in something they regard as a poster (eg for a shop display) than a work of art to be viewed in a gallery on on the loungeroom wall. For posters, you might even be able to get away with fewer pixels than for the smaller 'photo quality' print.

Cheers

mlfrancis wrote in post #14806
I've been getting pictures up to 8x10 "developed" at Sam's club and have been very happy with them.

The correct term is usually considered to be "printed" rather than "developed" for just making prints.

Exposed film must be developed before it becomes either a negative or a slide (depending on the film type).