Megapixels, Schmegapixels!

Marc

Marc

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I was at a local farm museum yesterday with my camera club, we had some studio lights set up in one of the barns and were doing portraits with one of the old carts as a backdrop in return for donations to the museum.

I set my camera to jpeg in order to speed up the tethered process and was successfully shooting and printing away all day. It was only at the end of the day that I realised the camera was set to jpeg small which was outputting at only 3 megapixels (Someone else was doing the printing). Given that we were doing A4 prints which were coming up very nicely indeed, I was quite impressed!
 
It is surprising what 3MP can do. We all managed when it was the standard!
 
Fair play, I suppose it's the quality of the pixel and not the quantity that counts!
 
The assumption that you need 300ppi for printing is actually wrong. 3Mp will easily (as you have noted) manage an A4 print. I print my A3 images at 150ppi and get great results - yes a bigger image but even close up it looks great. I guess you were printing at between 150ppi and 300ppi. Plenty resolution.
 
EOS_JD said:
The assumption that you need 300ppi for printing is actually wrong. 3Mp will easily (as you have noted) manage an A4 print. I print my A3 images at 150ppi and get great results - yes a bigger image but even close up it looks great. I guess you were shooting at between 150ppi and 300ppi. Pleanty resolution.
Click to expand...

Actually it was 72ppi
 
fabs said:
Actually it was 72ppi
Click to expand...

No one likes a smart arse Marc :p
:D

A great off the cuff experiment
if only more by luck than judgement though :thumbs:
 
fabs said:
I set my camera to jpeg in order to speed up the tethered process and was successfully shooting and printing away all day. It was only at the end of the day that I realised the camera was set to jpeg small which was outputting at only 3 megapixels (Someone else was doing the printing). Given that we were doing A4 prints which were coming up very nicely indeed, I was quite impressed!
Click to expand...

Most people wouldn't know the difference anyway.:)
 
fabs said:
Very true, but I'd like to think that the seven camera club members would. :D
Click to expand...

I was thinking of them in particular! :)

Seriously, I have made about £200 selling a landscape over the past few years that was shot on a (wait for it...) Canon 350D Here (Ferryside sunset #4) http://carregwenimages.com/section135630_283896.html. I printed at A3, and even poster size. One of them is in my hallway, and looks fine.

People don't notice. Especially as in your case it was portraits. People are so pleased at seeing a great shot of themselves (you see, I know you're great) that they ain't going to start pixel-peeping.
 
fabs said:
3Mp out of camera at 72ppi, that's all I know. :shrug:
Click to expand...

The 72ppi is an arbitary figure. If you printed a full 3Mp image, trust me it was as I said. To work out the ppi, look at the number of pixels in the image and divide by the size of the print.

So say 2000 x 1500 pixels (3Mp) and you have an image that is 11.69 x 8.27

So 2000/11.69 = 171ppi
and 1500/8.27 = 181ppi

The image resolution is approx 171ppi (exact figures will be determined more accurately with the number of pixels in your image but this will be close I guess)

The 72ppi you see is not a figure that matters unless you print at 72ppi (and if you did Ps would show the print size as approximately 27.7" x 20.83".

2000/72 = 27.7"
1500/72 = 20.83"

You see what I mean?
 
EOS_JD said:
The 72ppi is an arbitary figure. If you printed a full 3Mp image, trust me it was as I said. To work out the ppi, look at the number of pixels in the image and divide by the size of the print.

So say 2000 x 1500 pixels (3Mp) and you have an image that is 11.69 x 8.27

So 2000/11.69 = 171ppi
and 1500/8.27 = 181ppi

The image resolution is approx 171ppi (exact figures will determine more accurately)

The 72ppi you see is not a figure that matters unless you print at 72ppi (and if you did Ps would show the print size as approximately

2000/72 = 27.7"
1500/72 = 20.83"

So the print size at 72ppi would be 27.7" x 20.83"

You see what I mean?
Click to expand...

Er, yes, of course I see exactly what you mean. :thinking: :D

I'm sure your calculations are spot on. The other guys were doing the printing (I was tethered to the mac and they were printing from Elements on a laptop) so tbh I haven't a clue how they were going about it.
 
Maybe I get over technical but to work it out it's a very simple equation - and actually a very important one if you want to understand how to size prints for the web, print etc. Helps you make informed decisions on how to use images and save at sizes appropriate for your use.

Pixels are the important thing. Lets say your image is 7200 pixels across by 3600 pixels down. Imagine your 72pixels per inch. If you print that image how big will it be? Well easy

Print size (Ps) = Pixels (Px) / Resultion (R) (you do the sum for each axis)

Ps = 7200/72 = 100
Ps = 3600/72 = 50

So it would be 100"x50". Now lets pack those pixels tighter togther to get a higher resolution print. Higher resolution will give better gradations of colour. A print at 72ppi is very low res. Lets use 300ppi

7200/300 = 24
3600/300 = 12

So now we are at 24" x 12"

The digital image you started with is the same image - nothing's changed in the image - just the way you have printed it by packing the pixels closer together.

that's why the 72ppi means nothing when you look at the image - it only maters when you set the print size as that will determine the ppi value.

When printing there are only those three variables.

Px = Ps x R
R = Px/Ps
 
2000/72 means that your image is 2000px long in total, and if you use 72 of those px in every inch, your image will be 27.7 inches long....or maybe I'm wrong and should shut up?! :shrug:
 
Yv said:
Its all total gobbledygook to me too Marc but I do know my 6mp D70s will print fabulously at A2, so not surprised you could do A4 at 3mps at all :clap:
Click to expand...

A lady at work today sat opposite me at lunch and was extolling the virtues of her 8 megapixel cameraphone, so I told her about yesterday. She didn't speak to me again. :lol:

EOS_JD said:
Maybe I get over technical but to work it out it's a very simple equation - and actually a very important one if you want to understand how to size prints for the web, print etc. Helps you make informed decisions on how to use images and save at sizes appropriate for your use.
Click to expand...

It's all good stuff, I'm actually a lot better at the maths stuff than I am the camera tecchy stuff. ;)
 
Slimbert said:
2000/72 means that your image is 2000px long in total, and if you use 72 of those px in every inch, your image will be 27.7 inches long....or maybe I'm wrong and should shut up?! :shrug:
Click to expand...

Correct
 
fabs said:
A lady at work today sat opposite me at lunch and was extolling the virtues of her 8 megapixel cameraphone, so I told her about yesterday. She didn't speak to me again. :lol:



It's all good stuff, I'm actually a lot better at the maths stuff than I am the camera tecchy stuff. ;)
Click to expand...

Added equation I use above :) Really easy once you think about it.
 
EOS_JD said:
Maybe I get over technical but to work it out it's a very simple equation - and actually a very important one if you want to understand how to size prints for the web, print etc. Helps you make informed decisions on how to use images and save at sizes appropriate for your use.

Pixels are the important thing. Lets say your image is 7200 pixels across by 3600 pixels down. Imagine your 72pixels per inch. If you print that image how big will it be? Well easy

Print size (Ps) = Pixels (Px) / Resultion (R) (you do the sum for each axis)

Ps = 7200/72 = 100
Ps = 3600/72 = 50

So it would be 100"x50". Now lets pack those pixels tighter togther to get a higher resolution print. Higher resolution will give better gradations of colour. A print at 72ppi is very low res. Lets use 300ppi

7200/300 = 24
3600/300 = 12

So now we are at 24" x 12"

The digital image you started with is the same image - nothing's changed in the image - just the way you have printed it by packing the pixels closer together.

that's why the 72ppi means nothing when you look at the image - it only maters when you set the print size as that will determine the ppi value.

When printing there are only those three variables.

Px = Ps x R
R = Px/Ps
Click to expand...

Now that (now you've changed your post again :p) explains it all perfectly. :thumbs:
 
fabs said:
Now that (now you've changed your post again :p) explains it all perfectly. :thumbs:
Click to expand...

Does it really or is my explanation pants again :):bonk:
 
Good. it really helps when you realise you don't need the 300ppi that many say you should print at. You would not see any difference in even a 6x4 printed at 240ppi as compared to 300ppi so you can actually save a lot of hard drive space and time (Ps time editing smaller images) by saving the image files you need and working on that.
 
ha ha......

have a 15x12 of an ostrich from south africa from 2006 or so????

3.2 Mp ...looks great.......
 
EOS_JD said:
Maybe I get over technical but to work it out it's a very simple equation - and actually a very important one if you want to understand how to size prints for the web, print etc. Helps you make informed decisions on how to use images and save at sizes appropriate for your use.

Pixels are the important thing. Lets say your image is 7200 pixels across by 3600 pixels down. Imagine your 72pixels per inch. If you print that image how big will it be? Well easy

Print size (Ps) = Pixels (Px) / Resultion (R) (you do the sum for each axis)

Ps = 7200/72 = 100
Ps = 3600/72 = 50

So it would be 100"x50". Now lets pack those pixels tighter togther to get a higher resolution print. Higher resolution will give better gradations of colour. A print at 72ppi is very low res. Lets use 300ppi

7200/300 = 24
3600/300 = 12

So now we are at 24" x 12"

The digital image you started with is the same image - nothing's changed in the image - just the way you have printed it by packing the pixels closer together.

that's why the 72ppi means nothing when you look at the image - it only maters when you set the print size as that will determine the ppi value.

When printing there are only those three variables.

Px = Ps x R
R = Px/Ps
Click to expand...

So... :thinking: If we extrapolate any dead pixels and intersperse the dpi with the ppi do we get a secondary subliminal, yet exponential figure to suggest the resolution of a print at say '123' pica as opposed to the arbitrary dpi figure over the ppi? .... :shrug:
 
Splog said:
So... :thinking: If we extrapolate any dead pixels and intersperse the dpi with the ppi do we get a secondary subliminal, yet exponential figure to suggest the resolution of a print at say '123' pica as opposed to the arbitrary dpi figure over the ppi? .... :shrug:
Click to expand...

dpi is actually a printer resolution not an image resolution so yes.
 
Splog said:
So... :thinking: If we extrapolate any dead pixels and intersperse the dpi with the ppi do we get a secondary subliminal, yet exponential figure to suggest the resolution of a print at say '123' pica as opposed to the arbitrary dpi figure over the ppi? .... :shrug:
Click to expand...

No......I mean yes......I mean.....erm.....I'll just do a funky dance and be done with it! :banana:
 
EOS_JD said:
The assumption that you need 300ppi for printing is actually wrong. 3Mp will easily (as you have noted) manage an A4 print. I print my A3 images at 150ppi and get great results - yes a bigger image but even close up it looks great. I guess you were shooting at between 150ppi and 300ppi. Pleanty resolution.
Click to expand...

I agree with what you have posted later in the thread but "shooting at between 150ppi and 300ppi." ?

On JPEG small I shoot at over 1600ppi :)
 
Not to do with the printing thing- just the original post- but as cameras struggle with noise with more mp packed into the sensors- does it mean that if you use a lower mp as you did in the original post then the images will be less noisy? Or is it more to do with how the sensor is manufactured and unaffected by photo sizes?

If anyone sees what I mean :thinking:
 
Suvv said:
I agree with what you have posted later in the thread but "shooting at between 150ppi and 300ppi." ?

On JPEG small I shoot at over 1600ppi :)
Click to expand...
the word shooting should have been "printing" sorry! But to confirm you don't shoot in ppi. Your image is just pixels and the ppi is a tag that you add when you finally print the image.
 
topcatproduction said:
Not to do with the printing thing- just the original post- but as cameras struggle with noise with more mp packed into the sensors- does it mean that if you use a lower mp as you did in the original post then the images will be less noisy? Or is it more to do with how the sensor is manufactured and unaffected by photo sizes?

If anyone sees what I mean :thinking:
Click to expand...

Noise will look less if you have a large image printed smaller. If you start with a small image the larger you print the more visible noise will be.
 
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