Quote Originally Posted by Doc W View Post
A friend wants me to do a colour photo of a 'babbling brook" that will be enlarged to 2' x 6' for a poster for her shop window. I can shoot from 6x7 to 8x10 (including 5x7 although I can't seem to find any 5x7 colour film).

Which format would you use for such an application? Negative or reversal? Will 4x5 or even 6x7 do the job and is 8x10 overkill (it certainly is more expensive to scan)?
As others have indicated, use the format that you get the best results from.

2' x 6' is well within the capability of 6x7. If you have the right lens for 4x5, that could be more than enough. If you have a 6x17 back for your 4x5, shoot roll film using that.

I tend to prefer negative film to transparency film unless I intend to project the results (or print Ilfochrome). A babbling brook may offer some extreme brightness ranges, so negative film might be best for that.

I don't have the format choices available to you. With my 6x7 equipment I would shoot two rolls - one Ektar 100, the other Portra 160 - and I would use the results that give me the colour saturation I liked best.