EV number for monitor and print

[Donald B]

If I understand you correctly, you are saying that the amount of detail we can see in a print depends not only on the size of the print and the viewing distance (I think everyone probably agrees on those two factors), but also on how brightly lit the print is.

I have never heard anyone suggest that before (except that, of course, if the light is very dim, which does affect acuity of vision).

My impression is that the amount of detail visible is not much dependent on the brightness of the illumination. I look at prints in artificial light or in natural sunlight and I don't see any difference in detail, despite the sunlight being several ev brighter than typical artificial light.

I think what you say is true in general. However, it may breakdown with age. As eyes get old they lose flexibility in the lens so their focus is fixed at one distance (which varies from person to person).

The result is that dim light needs a wider pupil so depth of field diminishes. That can put details out of focus on the retina (at normal viewing distance; what I'm saying doesn't alter the fact that viewing distance alters visibility of detail).

For example, I used to be able to read really fine print in almost any light (I infuriated the doctor at my army medical when I went straight to the printer's name at the bottom of the test chart). Today I can manage small print in bright light but in even quite ordinary indoor light I struggle.

 

[Oldboy 1948]

All I've dug up that I will trust is lighting standards for judging prints in camera club competitions in Australia....

PRINTS

9.18 PRINT ILLUMINATION: The total illumination on a white card placed on the easel on which prints are to be judged shall read an f/stop between 5.6 and 11 (ideally 8) with an accurate exposure meter set at 100 ISO and recording 1/8 second, including the general room illumination comprising 1/4 to 1/3 of the total. For the judging of colour prints the illumination on the easel shall be similar to that used for monochrome prints. The best colour temperature of the light is 5000 degrees Kelvin

9.19 Prints shall be evenly illuminated on the judging easel which should be a dull neutral grey and measure approximately 76cm x 76cm. There must be no distracting glare or reflection near the print and the lighting shall be even, with not more than 10% variation over the area of the easel.

9.20 Extraneous light shall be kept to a minimum.

That from the page at https://www.a-p-s.org.au/index.php/exhibition/aps-nationals

I once built a lighted stand for those judges that had the specified illumination at the time, it then was quoted and measured in another way by measuring the incident light on the stand I made, not on the reflection from a white card, as there's white cards and there's white cards.

Reflected light readings are always hit and miss so for lighting standards incident light measurements are the only way. The incident light reading allowed me to move my meter all over the largest print size area to check that my lighting design kept within the specified 10% variation.

The resulting setup was fairly bright and not the sort of brightness that anyone would use to display prints for casual viewing.

Do some Googling for lighting standards for museums and exhibitions in whatever country you live in and you may turn up something of interest.

Regards.... Guy

Thank you Guy! That means EV8-EV10.

Yesterday we had really bad weather here in my town in Sweden. The maximum EV outdoors was 9 for a few hours....