Understanding print size Vs File Size

photographyman

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Good morning everyone.

Right, please bare with me on this topic.. I have read all the comments and still struggle to understand the printing side of photography.

Recently, I have been looking at selling my photos. So i decided to research the printing requirements of photos ie file dimensions and file sizes. This lead to my head nearly exploding as I would read one site saying the file size was the most important aspect then another one would say the dimensions was the important factor... So, could someone please explain to me in laymen terms the basics of getting photos ready to be printed...

One reason I ask this question as well is i have just started to use lightroom CC. I do very little editing though mainly a touch of contrast, a little sharpening or Black and White conversions. After exporting a file that original was 27MB exported to 2.2MB but the dimensions were over 4000 x 3000 - 300dpi which I believe to be good to print.

I am one of those people who struggles learning by reading but learn so much by doing hence the laymen terms..:)

Please somebody explain this to me... Many thanks in advance.
 
Ah right..thats makes more sense than the articles Ive read so far...haha..

Thanks Admirable
 
The thing that always seems to confuse people is the meaning of dpi with regards to a digital file. A jpg of 4000 by 3000 pixels with a dpi of 300 is exactly the same thing as a jpg of 4000 by 3000 pixels at 150dpi. The dpi of a digital file is akin to the cooking instructions on a pizza box; meaningless until you actually put it in the oven and even then you're free to change it. The dpi of a jpg is just a guide for when you commit it to paper.

Your intended size of your print in inches, combined with the recommended pixels per inch (usually referred to as dpi, but it should really be ppi, and it's usually quoted as 300dpi) will give you your ideal resolution. Going over this pixels per inch will not make a difference as the printer will throw away the extra information (the main penalty is just slowing down upload speeds). Be too far below it and you risk blockiness but even that depends on viewing distance (a billboard might only achieve 10ppi)

So for example, if you want to a 8x6inch print and the printer does a maximum of 300 'dpi', the ideal file will be 2400x1800 pixels. Being close to that should be primary concern. Given the power of modern computers, the size of storage media and internet speeds, just save to a jpg with minimum compression (or a tiff) and don't worry about filesize.
 
Thank you for this easy to understand explaination... Its much appreciated..
 
Interesting... until I got to the PC only bit. How does it do with b&w, Glyn?
I have printer B&W and sizes work ok... just the same, to be hones I've never got a good mono from my printer's. Need time to set them up I think or a new one.
 
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