Help! Can I print a 24x36"

[Vincenzo]

Hey! I'm using a T1i so it has 15.1mp and I'm going to be taking 4-5 shots (Interior) for a job that will need to be printed at (B+W, then Laminated).

I'm wondering does my camera have sufficient enough resolution to print that big? I'll be using a tripod so I could shoot at 100iso so there will be less grain and maybe that would help. But what about sharpness blowing it up that big?


:S

Thanks!
Vince

[Colin Southern]

Hi Vince,

This is a much mis-understood area.

Basically, you can print any size you like from a camera of any resolution; the variable becomes one of viewing distance.

The T1i has a sensor pixel count of 4752 x 3168, which equates to 132 ppi for a 36 x 24" print which will be just fine at a normal viewing distance.

[Vincenzo]

Colin thanks a bunch, that makes perfect sense! However It's usually better to print at 300dpi or ppi? I guess that's if your sticking ur nose to the photo..

I was thinking maybe i should rent the 5dmk2 just for the one day shoot to high-res but it seems like i'd rather pocket that extra money and use my own cam.

[jeeperman]

I would save your money. As Colin said your camera is plenty capable. I use a 10.2 MP camera currently and often print 20 X 30 without any visible issues even up close, least not to any significant degree.

[Vincenzo]

great, thanks a lot guys

[revi]

Just one point to keep in mind: you might want to avoid cropping of your image, as your resolution is sufficient, but not that excessive that you can throw away half the pixels.

The '300 dpi' figure comes from press use, and might be related to what a person with normal eyesight can distinguish on a printed page at normal viewing distance (note the 2x 'normal' in there ). Double the viewing distance, and you would need only half the resolution.

[Colin Southern]

Colin thanks a bunch, that makes perfect sense! However It's usually better to print at 300dpi or ppi? I guess that's if your sticking ur nose to the photo..

I was thinking maybe i should rent the 5dmk2 just for the one day shoot to high-res but it seems like i'd rather pocket that extra money and use my own cam.

There is an old joke that "the viewing distance for photographers is limited only by the length of their noses"

300 to 360 dpi is typical magazine quality, but overkill for most situations. A square inch is pretty hard to visualise, so lets visualise a square millimeter instead ... so 132ppi divided by 25.4 = 5.2. Square that to go from linear to area and we get 27. Could your eyes resolve up to 27 tone changes per square millimeter at a sensible viewing distance? (mine can't). At 360ppi that rises to a (ridiculous?) 200.

Because prints are two dimensional, you actually need four times the number of pixels to double the resolution - so even renting a 5D2 for the day still only gets you to 156 ppi (I too would suggest saving your money). For what it's worth, I have 22 x 44" landscapes hanging on my gallery wall that were shot with a 20D - and they look just fine. It's all about the viewing distance

[Vincenzo]

Haha great joke

so even renting a 5D2 for the day still only gets you to 156 ppi

That's crazy, we'll im settled then. I'm going to use my camera.

[Colin Southern]

Haha great joke

It's 1/2 joke in all honesty. Case in point ... I'll slave over a photo - pushing pixels at 100% to get them perfect - and then show the final picture to the kids. Typically, the reaction is "cool photo dad - when are we going out?" That pretty much sums it up - we're concerned about how every pixel looks - the customer / non-photographer is only interested in how the whole image looks. The day I realised that was the day my photography changed forever.

[Vincenzo]

yeah Colin I totally hear you on that. I've noticed the same thing with artwork (I'm primarily an illustrator).

I just thought about it and if I really did want a huge file, I could stitch a few photos. Microsoft Ice is free and amazing I've used it a few times. But I probably wont just always good to remember as an option.

-V

[Dave Humphries]

No one has mentioned (in the replies above) the lens quality - or, far more importantly, the RAW workflow and good sharpening techniques.

But I just fixed that

I know it wasn't the originl question, but it will have more effect on the results than the camera body.

[Vincenzo]

Yeah i usually never print, so i guess for sharpening I'll use the "Sharpen for Print" in lightroom?

[darekk]

I 've never printed any image, but theoretically to keep given resolution (for example 300 ppi) you can calculate image dimensions this way:

(for 4.752 x 3.168 MP sensor)

width:
2.54 * 4752 / 300 = 40.23 cm
4752 / 300 = 15.84 in
height:
2.54 * 3168 / 300 = 26.82 cm
3168 / 300 = 10.56 in

or when you have only sensor dimensions in mm (22.3 x 14.9 mm)

width:
2540 / 300 * square root of (15.1 * 22.3 / 14.9) = 40.25 cm
1000 / 300 * square root of (15.1 * 22.3 / 14.9) = 15.85 in

height:
2540 / 300 * square root of (15.1 * 14.9 / 22.3) = 26.89 cm
1000 / 300 * square root of (15.1 * 14.9 / 22.3) = 10.59 in

There are many calculators all over the internet performing such computations, but the best one is my calculator:
http://darekk.com/kalkulator/calculator-javascript
Simply write down your formula, for example
2.54 * 4752 / 300 or
2540 / 300 * Math.sqrt(15.1 * 14.9 / 22.3)
and press Calculate.

(you can do it also using this calculator:
http://darekk.com/kalkulator/matryca-rozdzielczosc
but it is not in english, print dimensions are green)

[Sunray]

Hi,

a friend of mine took a picture of radiotelescope "Astropeiler" with 15MP. It was printed on canvas, size 3x4 METRES.
Yes, you can see every pixel even CAs when viewed within nose range. The picture did hang behind a stage. Minimum viewing distance for public was about three meters. Even at a viewing distance of two meters it already looked perfect.

Robert

[darekk]

300ppi = 11.81 pixels / mm (5.91 lp / mm)

Then actually 254 ppi (not 300) coresponds to that human eye resolution 5 lp / mm at 25 cm distance
(http://en.wikipedia.org/wiki/Circle_of_confusion)
5 lp / mm = 10 pixels / mm = 254 ppi

At 2 meters 5 lp could be on 2000 / 250 larger area (= 8 mm instead of 1 mm):
5 lp / (2000 / 250 mm) = 0.625 lp / mm = 1.25 pixels / mm = 31.75 ppi at the verge of human eye resolution at 2 meters (?)

width:
2.54 * 4752 / 31.75 = 380 cm = 3.80 m
height:
2.54 * 3168 / 31.75 = 253 cm = 2.53 m

3.8x2.5 m print and 2 adjanced pixels are on the verge of eye resolution at the distance of 2 m !!! This is enormously large. Very strange.

--------------------

Some of people assume pixel spacing of 1 arc-minute (θ = 0.000290888 rad, 30 cycles per degree CPD like Snellen, 30 lp/degree, about 6.9 lp/mm at the distance of 25 cm)
http://www.scss.com.au/family/andrew/camera/resolution/

Distance between 2 points:
c = 2 * d * tan(θ / 2)
where d is the viewing distance

c = 2 * 250 mm * tan(0.000290888 rad / 2) = 0.072722 mm (= about 6.9 lp/mm)

PPI = 1 / (c / 25.4)
1 / (2 * tan(0.000290888 rad / 2)) = 3438 -->

PPI = 3438 / (d / 25.4) [mm]

For example:
PPI = 3438 / (2000 mm / 25.4) = 43.66 ppi
or:
PPI = 6.9 lp / (2000 / 250 mm) = 0.8625 lp / mm = 1.725 pixels / mm = 43.82 ppi
( PPI = 6.9 lp / (2000 / 250 mm) * 2 * 25.4 = 43.82 ppi )

[Colin Southern]

Hi,

a friend of mine took a picture of radiotelescope "Astropeiler" with 15MP. It was printed on canvas, size 3x4 METRES.
Yes, you can see every pixel even CAs when viewed within nose range. The picture did hang behind a stage. Minimum viewing distance for public was about three meters. Even at a viewing distance of two meters it already looked perfect.

Robert

Exactly. I think a lot of people are too caught up inspecting the bark of 1 tree that they forget to stand back and enjoy the forrest!