8ft x 4ft poster...but how many dots per inch for images?

[Thali-Hoo]

I've read a online somewhere a while back that the bigger the end product, the less the amount of dots per inch needed. is this true? if so, when do I start changing from 300dpi for A3 sizes to smaller DPI's on larger size prints?

is there a way to calculate this? I'm always thinking it might for spending less ink on the larger size prints, etc

and what should I use for a 8x4ft poster when:

1. people are gonna see it up close

2. when the closest they get would be about 4-5 feet away

with this particular poster, people are gonna be up close.

thanks for any info

[Posted June 2009 and now locked. Please start a new thread.]

[Eugene Tyson]

This might not even be taking into account they are actually printing it as a halftone.

I'd really like to see the poster to see what way it will be screen printed?

[rob day]

(working in inches)

1/((distance x 0.000291) / 2) = ppi

Seen as you're viewing from 4 feet away (48 inches)

You need

1/((48 x 0.000291) / 2) = 143 ppi for final size

Do I get to wear my glasses?

[Eugene Tyson]

Yes - but you have to stand at least one extra foot away.