Questions about printing

[bobiscuit]

I'm going to use the DS Colour Labs website to upload some photos for printing A3 size. Had one test print done with them and I was very happy with the quality .

But as I'm now sending a batch of around 30 images, I need advice:

1) How big should the files be? Most of them are 14MP from my Sony A350, either PNG or TIFF converted from RAW - so there's over 1GB of data here. Should I resize them down at all? Use some JPEG compression?

2) How much sharpening should I use? I usually only sharpen after resizing for the web. Should I get them looking sharp at 100%? Or even sharper?

 

[mrtoad]

i think 300 dpi is the advisable resolution
i dont use raw or tiff...so jpeg is what i submit...normally small prints
and let the file size be as big as i can...
there are some calculations one can do to determine file size but i am not too up on the method
ie
6X4 at 300 dpi = 24x900 = 2.16K...

A3 size is 11.75 x 16.5 x 900 = 17.35k approx by the same method

i think there may be a sticky on this...everyone knows it and i am surprised you havent gotten the flood of tech talk usually associated with these questions

strange world...and good luck

 

[EOS_JD]

To print A3, I suggest you call them and ask what resolution they require. I print my A3s at resolutions down to 150ppi.

If you have a 14Mp image you have 4592 x 3056 pixels. To print A3 at the default resolution you will get 260ppi which is probably higher than you need so just send the defaults saved as JPG images at quality 10.

Regards sharpening, I do but really you need to decide on a per image basis.