Megapixels, Printing, Resolution and Size

Myky D

Myky D

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Hi all,

As a bear of very little brain, I find the above subject utterly bewildering.

I kind of understand the theory of pixelation - that the image consists of pixels, and that the bigger you make it the clearer they become.

However, in terms of practicality, I am completely at sea.

I shoot on a Canon 450D, which is 12mp. Now - I understand that to print you need images to be 300dpi/ppi.

Particularly I have one image that I would like to print heyuage - something akin to perhaps A1 or A0 - basically to cover our living room wall. Is that possible?

I notice that on the Canon software you can save the portrait image at 300dpi at 33.3 x 22.2 inches maximum (without cropping, etc).

Is anyone able to explain it to me, or do you know a decent tutorial that will explain it sufficiently well to someone who finds the plot of most television adverts confusing?

Cheers,

Myky D
 
You do not need to print at 300dpi at all, and should be able to print an A1 image from your 450D no problem so long as you expose correctly and aren't cropping much - or at all if possible!

If you want to be able to stand with your nose to the picture and see all the detail then 300dpi is a must, but in the real world.. you would be viewing your picture from a distance of around 2m.. which means the detail needed is far less :)
 
not wanting to be controversial, but the dpi rating itself appears to be a bit of a red-herrring.
I have read countless 'debates' :D online about the dpi, and how it is communicated across the different brands.
IIRC canon state that the dpi as standard is 72?
the 300dpi which is referred to is their printing resolution, which if I understood is how the printer interprets the pixels rather than the 72 dpi that the screen on your PC shows.

basically I believe the conversation meant that it is irrelevant :D
 
RacingSnake said:
not wanting to be controversial, but the dpi rating itself appears to be a bit of a red-herrring.
I have read countless 'debates' :D online about the dpi, and how it is communicated across the different brands.
IIRC canon state that the dpi as standard is 72?
the 300dpi which is referred to is their printing resolution, which if I understood is how the printer interprets the pixels rather than the 72 dpi that the screen on your PC shows.

basically I believe the conversation meant that it is irrelevant :D
Click to expand...

Hi Racingsnake - in the words of Shakespeare, "WTF?!?!"
 
Was Shakespeare really the originator of WTF?
 
Mine was a trick question; I think you'll find it was in fact Marlowe; uttered just before he got beaten to death in that Deptford alehouse brawl.
 
you want to print at multiples of the printer's native resolution. for my epson R2400 I would print at 360 or 180 dpi for the best quality but really you can set it to anything but 180 is as low as I would go.

by changing the dpi you spread the pixels over a wider area so you can either set the DPI to print at a certain size or interpolate to get a bigger size. when I print A4 from my 5D2 I set dpi to 360 and then the print size of the image (which is smaller than A4) if I print bigger than the size I get at 360dpi I reduce the DPI to get the size of the image.

Myky D said:
I shoot on a Canon 450D, which is 12mp. Now - I understand that to print you need images to be 300dpi/ppi.
Click to expand...
 
Nifkin said:
Was Shakespeare really the originator of WTF?
Click to expand...

No it was actually Marlowe:

DUKE: But prithee, crone, dids't not thou to me venture that 'tis the hour and not the plenitude that we must endeav'r always to hold?!

CRONE: WTF?!

From The Jew Of Malta
 
POAH said:
you want to print at multiples of the printer's native resolution. for my epson R2400 I would print at 360 or 180 dpi for the best quality but really you can set it to anything but 180 is as low as I would go.

by changing the dpi you spread the pixels over a wider area so you can either set the DPI to print at a certain size or interpolate to get a bigger size. when I print A4 from my 5D2 I set dpi to 360 and then the print size of the image (which is smaller than A4) if I print bigger than the size I get at 360dpi I reduce the DPI to get the size of the image.
Click to expand...


Sorry - yes - to clarify - I am not printing at home, but rather want to outsource the printing.
 
Nifkin said:
Mine was a trick question; I think you'll find it was in fact Marlowe; uttered just before he got beaten to death in that Deptford alehouse brawl.
Click to expand...

i read some philip marlowe books as well
 
Back in the olden days, (after Marlowe!) I would print inkjets on a wide format machine. It was always better to use the original file after any retouching, and then let the printer RIP upscale to the final size. Mind you, this was ten years ago so things might have changed, check with the printers.;)
 
Myky D said:
Cheers Purpleclouds. What's the minimum resolution for printing at that size that I could reasonably go down to, then?
Click to expand...

Bill boards are printed at something like 30dpi... but for A1 (without doing any maths at all) then around 150dpi should be fine.

You can upscale your image if needed to give an extra few pixels - printers will do this but you have no control over it! Check out Genuine Fractals or something similar :)
 
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