Why would a photographer use ISO 800 outdoors in daylight?
Asked 12/3/2012
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I saw a Reuters image shot at 135mm, f/2.8, 1/500s, ISO 800. At first glance it looks like bright daylight, so I wondered why the photographer didn’t use a lower ISO and a slower shutter speed instead, such as ISO 200 at 1/125s, for potentially less noise. In what situations does it make sense to use a relatively high ISO outdoors, and what might explain these settings in this case?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
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The standard answer most time this is asked is don't assume everything was done for a reason, the camera may have already been set to ISO 800 and the photographer might not have had time to change it.
However, this image looks like bright daylight and so ISO 800 seems way off, but in this case the image brightness is a bit misleading, 1/500s f/2.8 ISO 800 corresponds to an ISO 100 exposure value (EV) of 9 - about the same you get a night time sports venues! This was likely shot very early in the morning, or late at night.
Looking at the other settings we note:
- 1.3x crop camera was used
- focal length was 135mm
Applying the standard 1/focal-length rule for shutter speed and accounting for the crop factor would recommend shooting at 1/175. I prefer a 100% margin for safety when dealing with camera shake (resolution has grown massively since the rule was popularized) which would give you 1/350s, not far off what the photographer used.
So given the image was shot in fairly low light it looks like the settings were about right for those conditions (not taking into account image stabilisation if available).
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
13y ago
0
Generated from our catalog & community — verify before relying on it.
Yes—there are good reasons. A higher ISO lets you use a faster shutter speed, which can reduce blur from subject movement, wind-blown clothing, and camera shake. At 135mm on a 1.3x crop body, 1/125s would be fairly risky handheld; 1/500s gives a much better safety margin and also freezes motion more effectively.
Also, the scene may not have been as bright as it looks. The exposure of 1/500s at f/2.8 and ISO 800 corresponds to fairly dim light, more like early morning, late evening, or otherwise subdued conditions rather than strong midday sun.
And sometimes there is no deeper reason: the camera may already have been set to ISO 800 and the photographer may not have had time to change it.
So while ISO 200 and 1/125s could give the same overall brightness, it would not necessarily give the same sharpness. In outdoor shooting, especially with longer focal lengths and moving subjects, using a higher ISO to keep shutter speed up is often the better tradeoff.
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