Hi Ray,
No argument about your points.
On the other hand, I feel that once the image quality is good enough it is more about printing craft.
Let's give an example:
I was shooting with my 24 MP full frame standing on the top of (very) small ridge, that position gave me an acceptable composition. I was shoot some trees in full autumn shroud and it was a bit dark. It was also windy, so I wanted to be able to use a bit shorter shutter time. First I made some shots with the 24 MP full frame I had a Sony Alpha 900. With that camera I used a Sony Alpha 70-300/4.5-5.6 lens. The Alpha 900 lacks live view, so I felt a need to stop down a bit for accurate focus. I raised ISO a tiny bit, but the A900 is not that good at high ISO.
Next, I felt that I could use the Sony SLT 55 I also had. I bought that camera mostly for it having live view. It had 16 MP on APS-C. The sensor on the SLT 55 is a bit newer so I could use a bit higher ISO. Also, the crop frame allowed me to use the Sony 24-70/2.8 which is very good on the APS-C crop. So, LV, better sensor and better lens gave a significant advantage for the 16 MP sensor.
So, I made an A2 print from both. Not a lot of difference between the prints. Visible pixel peeping with the naked eye? Nay, not really. Looking with a loupe? Yes I think so.
As predicted, the 16 MP image had less motion blur, so it made it to the wall.
Another example:
When I got into medium format I had 39 MP on 49x37 mm. I have made a few comparison prints, still at A2, and I don't think I could observe any difference in image quality between 24 MP APS-C and the 39 MP MFD with the naked eyed. Using a loupe it was very obvious.
A final example:
I was bitching about LR producing some zipper artefacts on one of my A7rII images. One of the printing experts here at LuLa, Mark D Segal, checked out my files and agreed on my findings, but noted that he doubted it was visible in print. He made a large print from a small crop, corresonding to 29.5" x 44.2". He could not see the zipper artefacts with the naked eye, but has observed them with a 10X loupe.
Impressed by Mark's comments I made an even larger print corresponding to 38" x 48". Looking at short distance with out glasses I could see the jagginess (I am short sighted) but I could not see them with corrective glasses at short distance. Looking at 50 cm with correcting glasses I could not observe them.
So, human eyesight is a factor.
At 50 cm (20") viewing distance 20/20 vision corresponds to 180 PPI and I think that 50 cm is quite a close viewing distance for a large print. Many folks have better eyesight than 20/20, of course.
But, I would say that if you have 180 PPI and process decently well you will end up with a good print.
Best regards
Erik
Hi Erik,
Let's be more precise here. There are 3 main aspects of the 'quality' of a print; image quality, paper quality, and ink quality.
Image quality involves many factors, including eye-catching illumination of the subject, clean shadows which the eye would have seen in the real scene, interesting, pleasing or eye-catching composition, interesting color combinations, and realistic detail visible from a relatively close distance, depending on the size of the print.
If the image quality is deficient in any one of those factors, then disappointment can result, depending again on the style and nature of the image. Certain types of images simply don't require eye-catching resolution, such as a misty scene of distant hills. Some images don't benefit from clean and detailed shadows when the detail in the shadows is distracting or irrelevant. Sometimes dark, or even black shadows are preferable.
From my own personal experience and testing, I have found that at least a 50% increase in pixel count is required to get a worthwhile or noticeable increase in resolution, using the same lenses with the same format.
