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04-03-2012, 05:51 AM   #1
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Largest Print Size with k5?

I had to do some commercial work yesterday for a company that produces lockers etc...

It got me wondering what the largest print would be that they would be able to create from a shot with a K5 without really losing IQ,

04-03-2012, 06:12 AM   #2
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That depends on how closely an image will be inspected. Ideal viewing distance is usually greater than a print's diagonal. So print at 4x6m and view from 8m.

Another way to consider it: The sensor captures an image a bit more than 4500x3000 pixels. Printed at 300 dpi, that's 15x10in; viewed from 20in or further, the dots aren't noticeable. Printed at 150 dpi, just double those dimensions. Et cetera.

So, depending on the viewing distance, you can print from tiny to enormous. Cine frames about the size of an APS-C frame but with less resolution were commonly projected onto screens larger than 30x20ft and viewed from some distance -- occupants of the theatre front rows weren't *really* watching the screen, eh?

Basic rule: Anything seen small enough, or from far enough away, looks good.
04-03-2012, 07:34 AM - 1 Like   #3
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What Rio Rico said. Resolution limits of what the eye can perceive are restricted by the distance between the cones at the back of the eye. Anything which has a circle of confusion smaller than a couple of cones wont be seen by the eye. The resolution limit of the eye depends on whether the image is a dot or a line. The eye can see a line more easily, as it crosses many cones. In John Williams' book called Image Clarity, there was an argument for the eye resolving 30lpmm in a photo at normal viewing distances (hand held photo). It depends on the shape of the image...breaks in a line can be perceived more readily than points.

Less stringent requirements would be 10lpmm quoted in Quality in Photography by Hicks and Schultz. 10lpmm equates to 20 pixels per mm...so the 4500x3000 pixels could be printed on paper 225x150 mm or 9x6 inches, but it depends on the 25cm viewing distance....if you stand twice as far away, you get 20inch viewing distance and 18x12 inch print, a bit more than Rio Rico's estimation. This is all a bit handwavey, and depends heavily on your eyesight. But this is a massive simplification...

You must do a lot correctly to get the full resolution out of the sensor, such as using a tripod or shutter speed in excess of 1/500s to overcome mirror slap/camera shake/object motion. You obviously need a lens which has a higher resolution than the sensor, for an acceptable MTF value, say 50%, with a decent hood on it, and you need a well lit subject with sensible tonal range which offers the requisite detail (not too contrasty, but with good detail). Indeed, you can have a high resolution image with poor contrast and gradation in it. Information in an image =[(resolution) x (range of tones)]....this is where the importance of the subject, lighting, tripod, lens and hood come in. How you post process probably has a large effect on it, with RAW processing requiring the same consideration as developer selection in the old days...high accutance developers are analogous to sharpening, emphasising low resolution detail at the expense of higher frequency information. So you probably want to turn your sharpening down. 50% MTF value at the level of resolution the sensors offer is pretty impossible. The sensors see 120pixels per mm or 60lpmm...I doubt there are many lenses which can achieve this. Hence the need for larger formats.

I've taken a 35mm photo on FP4+ which had a bill-poster advert in the background, about 10cm tall, on a 3m section of wall, showing a phone number on it. The poster is therefore about 1mm on the negative, so the numbering is about 0.1mm on the negative yet you can read the number. I reckon I might have got close to 50lpmm on the negative, with a sufficiently high level of contrast to read something. I was using a Pentax M 100mm 2.8, with the Tak 135 hood, and had a shutter speed around 1/500, using a ME Super (hard to tell what the shutter exactly is with the ME Super). I've only printed it to 5x7, which means the writing is only 0.5mm high, however, there is something neat about taking a loupe to a back lit 5x7 photo and seeing detail in it which couldn't be seen by holding it in the hand. Makes it feel like a world is trapped inside the photo. At some point, I will pony up the cash for some bigger paper and try hanging it on the wall. But this raises the point, for me at least, that its best to print within the resolution limit of the photo, not at it, as it means there is further detail accessible when you put your nose right up to it, sort of a gift for really studying the photo...makes it worth while printing it out, rather than leaving it on a hard drive!

[here is an added conundrum...how close can you get to a print before your eye can outresolve the detail the paper can record? I've just had a look around and it sounds like 600ppi for modern paper which is about 12lp/mm which means no closer than 15cm....this probably corresponds to a normal person's minimum focussing distance.]

Last edited by whojammyflip; 04-03-2012 at 07:45 AM.
04-03-2012, 07:44 AM   #4
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You can also upsample images remarkably well these days in Photoshop to make huge prints that still look good (bigger than you "ought" to be able to make them given the original resolution). No, this of course cannot add new detail, but it can avoid pixelation. We've made large poster-sized prints from our Canon S90 P&S, which has a smaller sensor than the K-5 (and only 10MP) and they look fine. But those are art prints, and might have more leeway than a commercial application, but it just depends on the purpose of it...

04-03-2012, 01:30 PM   #5
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I was thinking, the hunt for resolution is a logarithmic problem. Sometimes problems are additive, in that each step, the returns are equal, whereas in the pursuit of resolution, its multiplicative...so that, if you were taking a picture of a hill, the first increase in resolution would reveal an elephant, then a fly on the elephants knee, then a mite on the fly etc. Most people would stop at the elephant, and be happy with the picture. Certainly, the relevance of the mite on the fly is only something which interests me when I am staring at a wet print (which resolves 60lpmm, not that you need it, but it means its not limited the print detail) through a loupe!

Last edited by whojammyflip; 04-04-2012 at 01:14 AM.
04-03-2012, 05:56 PM   #6
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Pretty big... but its all based on viewing distance of course.

I have gotten the following image published on a large digital billboard that's on one of the main drags within the city.



It of course has some distortion, but while your driving by it looks very sharp and has no jaggies.

It's pretty awesome to see that daily too as you drive by....
04-04-2012, 05:26 AM   #7
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A simple solution to this is to think the performance is limited by the lens at 60lp/mm which would mean a 6X enlargement ratio (for 10lp/mm) at 25cm, or 600x at 25m. Hence a print measuring 600" or 50 feet wide when viewed at 25m would still be excellent quality, as illustrated above.
04-06-2012, 04:53 AM   #8
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The K5 files, after appropriate PP, are just large enough for a 41 cm x 61 cm print size in off-set printing (CMYK) @ +/- 300 dpi (FM screen), that's a double page 'oblong' (also called a 'panoramique') which in reality is a H 21 cm x L 60 cm, to be viewed at usual reading distance. Not bad at all for an APS-C!

04-07-2012, 11:27 AM   #9
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The trouble would be that the lens cannot necessarily deliver what the sensor can record...for instance, a lens restricted to 50lp/mm, with a reasonable level of contrast, gives 6mp of information for aps-c...
04-07-2012, 06:22 PM - 1 Like   #10
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I think the poster is really looking for something a little simpler than the answers being given. Viewing distance is key of course, - a couple of yrs ago I had print made of a corvette shot from my K10 (use a K5 now) printed it at 15x30 came out great. So with the K5 I wouldn't hesitate to go 20x30 or bigger assuming it was a good shot with an iso of 400 or lower.
04-10-2012, 03:10 PM   #11
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i print at 20x30 all the time with no problem.
04-10-2012, 03:19 PM   #12
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I've done 30in x 40in canvas prints of landscapes with no problem at all. Looks good from two feet away.
Joe
02-19-2013, 02:38 PM   #13
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k5 or k30

hello rodin i would like to ask you a question about printing on canvas is it possible to contact me at my email ritualart@optonlone.net
02-19-2013, 05:39 PM   #14
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We do 20x30" from the K5IIs and it looks a little better than the same size from the Nikon D3X. Have not tried bigger yet.

David
02-19-2013, 05:40 PM   #15
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We do 20x30" from the K5IIs and it looks a little better than the same size from the Nikon D3X. Have not tried bigger yet.

David
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