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Sorry I have a question about printing (which is not really about the camera) hope thats ok. 

I use to always export my photos at 100 quality and leave everything else unchecked on lightroom with 300ppi to print any sizes. 

However recently I've been told that I should check the pixels on the long edge and divide by 300 to work out the max print size. If its not enough, I should reduce the ppi say to 150 to allow the image to print bigger. 

For example : if the long edge by default from the SL2 shoots out 8368 pixels, at 300ppi it can go to 27.89 inches but at 150ppi it can go to 55.79 inches. 

This makes no sense to me, given the same photo why am I getting a better print if the pixels are further apart? Given that the pixels were set by the sensor when the shot was taken? 

Would appreciate it if someone could explain. 

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You're opening a can of worms here.... And it'll probably get moved anyway, but here goes.

1. While pixel count and print resolution both have an impact on output size they should be treated differently. PPI (pixels per inch) for the camera and DPI (dots per inch) for the printer (or PPI again for a screen).

2. Camera resolution affects how much detail is in the image, yes but that in itself does not determine the maximum output. For that you need to divide by the amount of resolution you can perceive (or the amount of detail you want to see.). The quality of your eyesight, the viewing medium and the viewing distance are just three of many parameters that will affect image size. And many subjects don't even have a lot of resolution. A portrait can print bigger than a landscape at the same ppi because we don't want to see as much detail... 

3. Not all printers require 300 dpi. This is from the line printing days when commercial printers printed in 150 dpi line pairs (300dpi file). But an Epson wants a 360dpi file (but actually has many more ink nozzles than that). Canon at 300dpi. I one had a dye thermal printer that NEEDED a 308dpi file. Or the results were mush. You should send your printer a file at the print rate it likes for maximum quality. There's also dither on modern printers. Another topic but basically the inks bleed and mix to form a more even look on the paper. There's also the relationship between printer and paper to consider as that affects maximum size as well.

4. So, say your visual acuity is average, then you're probably good for a 240ppi viewing resolution for a handheld print. A 6000 pixel file will give you a 25" print. But you'd resize and send your Epson printer a 9000 pixel file to get that 25" print so you're getting the print resolution to match the printers ink heads. But if it were a scene with a lot of negative space you might be able to triple that.... i think you can see where this is going.

5. Lightroom when using the print module will do most of the PPI to DPI stuff for you so, to answer your question, no you don't need to worry. Just shoot at max quality and let Lightroom do its thing. Just use the profiles that are available for your paper/printer and you're golden.

7. I print at a commercial level for photographers and artists and before that I printed b&w and Cibachromes professionally. The above is a vastly simplified version of what happens during printing. Like, just a scratch. I can say this. A LOT of information on the web and from well meaning colleagues is here say and best ignored.

8. Everyone's needs are a bit different. What you may think is unacceptable might be brilliant, for me, or vice versa. That's why fine art printers work with their clients to tailor the work to the artist. It costs more, but that's how you get the best....

9. We haven't touched (thankfully) on colour management....

Gordon

Edited by FlashGordonPhotography
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Yup. Definitely a can of worms here.

PPI/DPI is also dependent on paper type. Different paper require different levels of over-sharpening to account of the loss in acuity because of the way the ink gets absorbed by the paper. Back in the early days before LR had a mature print module with output sharpening, it was pretty standard to upscale manually and perform the necessary over-sharpening in photoshop.

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Just to add to that from my point of view as a journalist and editor -- magazines and books usually require 300 dpi while newspapers are happy with 200 dpi. If you want to make a print for your own use, 200 dpi will probably be fine.

Depending on software, you can change pixel dimensions to inches or centimetres so you can work out the size you can print to at a given resolution. 

If you have a Mac, Graphic Converter is a good piece of software to use. See: https://www.lemkesoft.de/en/products/graphicconverter/

 

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Thanks for all the info ! Its been really helpful! 

I'm only printing with online printing companies like mypicture.com and they dont really have any info on the export settings required. It also seems like no matter the setting, they still allow to me to choose whatever size I want to print to. 

So in general, my understanding is that I could ignore everything as long as I dont resize :) So I could get away with just cropping to the right ratio and leave it right. 

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9 hours ago, Ktsa5239 said:

So in general, my understanding is that I could ignore everything as long as I dont resize :) So I could get away with just cropping to the right ratio and leave it right. 

Exactly. Send them a file at full resolution and let them figure it out.

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  • 3 weeks later...
On 8/16/2021 at 12:07 AM, FlashGordonPhotography said:

You're opening a can of worms here.... And it'll probably get moved anyway, but here goes.

1. While pixel count and print resolution both have an impact on output size they should be treated differently. PPI (pixels per inch) for the camera and DPI (dots per inch) for the printer (or PPI again for a screen).

2. Camera resolution affects how much detail is in the image, yes but that in itself does not determine the maximum output. For that you need to divide by the amount of resolution you can perceive (or the amount of detail you want to see.). The quality of your eyesight, the viewing medium and the viewing distance are just three of many parameters that will affect image size. And many subjects don't even have a lot of resolution. A portrait can print bigger than a landscape at the same ppi because we don't want to see as much detail... 

3. Not all printers require 300 dpi. This is from the line printing days when commercial printers printed in 150 dpi line pairs (300dpi file). But an Epson wants a 360dpi file (but actually has many more ink nozzles than that). Canon at 300dpi. I one had a dye thermal printer that NEEDED a 308dpi file. Or the results were mush. You should send your printer a file at the print rate it likes for maximum quality. There's also dither on modern printers. Another topic but basically the inks bleed and mix to form a more even look on the paper. There's also the relationship between printer and paper to consider as that affects maximum size as well.

Gordon

Thanks. 

But where is contrast change? My monitor can deliver far more contrast than a paper print.

I lower the contrast of the digital picture in PS. By adjustment -> curves and then move the left button upwards to around 15.

I use a not so very actual Epson printer (1500W) and print A3+ maximally, at most A4.

Edited by jankap
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On 9/7/2021 at 3:35 AM, jankap said:

Thanks. 

But where is contrast change? My monitor can deliver far more contrast than a paper print.

I lower the contrast of the digital picture in PS. By adjustment -> curves and then move the left button upwards to around 15.

I use a not so very actual Epson printer (1500W) and print A3+ maximally, at most A4.

Well, we were talking about print resolution and how it relates to print size, so I omitted many other considerations. printing is a big topic at the highest level.

Likely though it's a profile/paper choice that has required your need to lower contrast in LR. Generally printers have wider gamuts than screens.

Gordon

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