Question on Print Size

[Kit-V]

I have a Canon 60D (18mp, 22.3 X 14.9mm sensor). I plan to start having some of my images printed. Although I understand that there are a variety of factors that will affect maximum print size, I am trying to come up with a guideline (or better yet, a reference chart) to determine maximum print size without visible pixelation at "normal" viewing distances. I might add that I shoot in RAW format at ISO 100-200 (whenever possible). Also, dpi would be 240-300.

Thank you kindly for any guidance.

Kit

[Jim Kasson]

I have a Canon 60D (18mp, 22.3 X 14.9mm sensor). I plan to start having some of my images printed. Although I understand that there are a variety of factors that will affect maximum print size, I am trying to come up with a guideline (or better yet, a reference chart) to determine maximum print size without visible pixelation at "normal" viewing distances. I might add that I shoot in RAW format at ISO 100-200 (whenever possible). Also, dpi would be 240-300.

With decent upsizing software, you won't see pixelation, per se, but you will see quality loss. How much loss is acceptable is something you'll have to decide for yourself. Make some small test prints -- crops -- at the same output scale as you're considering sending to your printing service and have a look.

As to upsizing algorithms,  there's lots to be said, depending on your level of interest and willingness to experiment. What is your editing software now?

Jim

[Bart_van_der_Wolf]

I have a Canon 60D (18mp, 22.3 X 14.9mm sensor). I plan to start having some of my images printed. Although I understand that there are a variety of factors that will affect maximum print size, I am trying to come up with a guideline (or better yet, a reference chart) to determine maximum print size without visible pixelation at "normal" viewing distances. I might add that I shoot in RAW format at ISO 100-200 (whenever possible). Also, dpi would be 240-300.

Thank you kindly for any guidance.

Hi Kit,

It mostly depends on the quality level you need, based on visual acuity, and viewing distance.

I've released a free web-based tool to calculate things like that (and much more).

Section 1. of my tool is all you need to answer your question. Basically you can print your 60D files at 45x30cm (17.7x11.8 inch) size when you need to allow close (normal reading distance) inspection, and e.g. 150x100cm (59x39inch) when viewed from 1 metre (3.28 feet) distance. This assumes uncropped images and normal 20/20 vision.

For the actual output file size, and before output sharpening, you need to use a good resampling tool and resample to the native resolution of the printer that's going to be used, usually 300 or 360 PPI, or even 600 or 720 PPI. Sharpening at that output resolution will give the highest quality results, but do check the actual printer specifications if you use off-site printing facilities.

Cheers,
Bart

[Kit-V]

Jim & Bart,

Thank you for the concise & straightforward responses. BTW, I use Lightroom 5.

Your responses triggering another quick question: When exporting an image to the lab for printing, do I upsample to the lab's printer resolution in Lightroom's Export dialog box? Thank you.

Kit

[Jim Kasson]

Your responses triggering another quick question: When exporting an image to the lab for printing, do I upsample to the lab's printer resolution in Lightroom's Export dialog box? Thank you.

That's not a bad place to start. If your printing service has the expertise, you could let them upsample the native-res image. After upsampling, the image shouid be sharpened for the particular printer and paper. Again, if you're dealing with experts, let them do it. If not, let Lr do it.

As I'm sure Bart will tell you, there are more sophisticated ways to upsample and sharpen for printing than Lr uses, but they aren't bad at either.

Jim

[Kit-V]

Thank you, Jim. I plan to use ProDPI lab. I will definitely check with them. However, there is a part of me that prefers to be as much in control of the process as possible. So, I might opt for letting LR do the upsampling & possibly output sharpening in Nik.

Kit

[Bart_van_der_Wolf]

Thank you, Jim. I plan to use ProDPI lab. I will definitely check with them. However, there is a part of me that prefers to be as much in control of the process as possible. So, I might opt for letting LR do the upsampling & possibly output sharpening in Nik.

Hi Kit,

Lightroom produces a decent upsampling quality. When you are careful with sharpening before upsampling, you'll be able to do more output sharpening after the upsampling. Check with your lab which profile to use for output, then sharpen that final output, and you'll be fine. Just let the Lab know that they should not sharpen again.

Cheers,
Bart

[Kit-V]

Thank you kindly, Bart.

Kit