dpi question

[spadeski]

I hope this is the correct place to post this question.

Can anyone help? I've been taking pics for a couple of years now and am at the stage where I would like to start thinking about selling pics as prints. I have been told the minimum print quality/resolution required is 300dpi, My camera's default is 72dpi (it's a Pentax K100d)

I have read the manual from cover to cover but cannot find anything regarding how I can change the dpi 'in camera'. I know it's just an entry level dslr but was assuming this was possible. Is it or do I have to download software to do this when I upload my pictures, or will I have to invest in a more advanced camera that will allow a higher dpi ??

Any help would be greatly recieved

Thanks

[RichardTaylor]

They are just numbers- not helped by a lot of websites.

For practical purposes; Think of it this way for a 10x8" pic:
3000 pixels X 2400 pixels (10x300 and 8x300) is 300 "DPI"

For a 6x4 print it would be 1800x1200 pixels.

So for your Pentax K100 (3008x2000 pixels) the maximum (uncropped). print you could make (if you want 300 DPI) is ~10"x6.6"

[spadeski]

Can I change the default setting in my camera do you know Richard ??

If I wanted to print something, say size A3 or bigger, or wanted a dpi of say 600 would that be possible.

I really am hopeless with numbers so got scared straight away when I saw your calculations for sizes

Thanks

[RichardTaylor]

Not in camera.

Pretty pointless going to 600DPI.

However if you want to print an A3 you can resize your pic in post processing software.

[spadeski]

Thanks Richard, but why is it pointless going to 600dpi ? What post processing software would be best to re-size?

Can anyone point me in the direction of some kind beginner friendly tutorial or information

Thank you

[cleamon]

see this:

Image resolution and DPI explained » Photoshop Ninja

[spadeski]

Thank you cleamon, that will keep me busy for a while

Any other input would be most welcomed folks

Thanks

[BCampbell]

There's some basic confusion happening here that everyone falls prey to.

You want to be concerned with ppi -- you are outputting pixels, not dots. A printer outputs dots, your camera and software output pixels.

So, ignore what your software says about dpi. Leave it alone.

All you need to do is some basic math to find out what size you can print at or what size your image needs to be. Ask you print service what resolution they recommend. Usually 300ppi is high quality (beyond that you run into diminishing returns -- most of us will never need 600ppi). As your print gets larger, the necessarily resolution actually drops a little. 150ppi is usually a minimum for "good" quality, and you can usually go fairly well beyond 8x10 at 150-200ppi. Again, ask your print service.

Then, if your service says that they recommend 200ppi for a 24x30" print, you know that you need 20x200=4000 pixels on the short end and 30x200=6000 pixels on the long end. You can do the math as RichardTaylor shows to get the maximum print size for an image.

[spadeski]

My appreciation all

I think it's begining to sink in