Changing ISO question

Sorin

I didn't want to clog up another thread with this question, so I brought it here. I was looking at some outdoor wildlife shots here. The photographer nicely added in all technique info which is quite helpful. The one thing that stuck out to me was that the ISO was so high for outdoor daylight shots (I recall one at ISO 1250), and the f/stop was varying from f/16-22. Why? It seems so backwards. If your f/stop can be dropped and your ISO dropped, why wouldn't you take advantage of that? What am I missing?

basflt

high shutterspeed , perhaps ?

Richard

The only thing that occurs to me is that the shooter was trying to maximize depth of field. Were there several points of interest at different distances?

ziggy53

Sorin wrote: »

.... The one thing that stuck out to me was that the ISO was so high for outdoor daylight shots (I recall one at ISO 1250), and the f/stop was varying from f/16-22. Why? It seems so backwards. If your f/stop can be dropped and your ISO dropped, why wouldn't you take advantage of that? What am I missing?

You need to take into consideration all the elements the photographer was trying to achieve.

In the case of:

http://dgrin.com/showpost.php?p=1629255&postcount=1

... I believe that Maxis needed the higher ISO to allow the particular DOF as well as an acceptable shutter speed to stop the birds' actions. Remember, this is an 800mm lens that has pretty shallow DOF, as evidenced by the background bokeh.

In the case of:

http://dgrin.com/showpost.php?p=1628706&postcount=1

... Harry is using ISOs 500 through 1250 to provide similar qualities for his long focal lengths and long effective focal lengths; a particular DOF and acceptable shutter speed for the subject.

Time-of-day has additional bearing as well as time-of-year (to a somewhat lesser degree). Shooting early and late in the day allows some spectacular sunlight, but at diminished levels.

Sorin

Aahh, the long focal length. I am not used to how large lenses work re: DOF. Thanks for explaining.