Sunday, January 31, 2016

More ISO findings.........

To continue my ISO discovery....
I found on my D90 that for close ups, I could safely push to ISO 800 without any real issues.  When you think of it, going to 800 really isn't a stretch - there are some huge numbers coming out now.  (Previous ISO Post)

My next test was to go for an object much further away - maybe about 300 yards.  My central subject is the light on top of the rear navigation light.

For this test, I went with shots at ISO 200, 800 and 1600.  I did three shots with each ISO setting each with different f/stops.  Again, it was almost closed, almost open and one in the middle.  And again, these are 2x2 segments.

And again, it was cold and windy.  For the shots, I used an IR remote never touching the camera.  I also used manual focus.  Some of the shots did not come into focus real well - and it seemed to be a trend.  More on that later.

The ISO 200 shots.

ISO 200   f/stop 6.3    1/640

ISO 200   f/stop 13    1/200

ISO 200   f/stop 29   1/40

The ISO 200 shots show a nice red color and a nice even white color.

Now the ISO 800 shots.

ISO 800   f/stop 5.6    1/4000

ISO 800   f/stop 13   1/800

ISO 800   f/stop 25    1/200

At ISO 800 you can see a real difference between the ISO 200 shots.  The sky looks like it was printed on canvas.  There is definitely some off coloring noise on the whits.  Probably not enough to ruin the shot and maybe rescued in post processing.  Let's see what the ISO at 1600 does.

ISO 1600   f/stop 6.3    1/4000

ISO 1600   f/stop 10   1/2500

ISO 1600   f/stop 29    1/320

Clearly more noise on the close ups.  Let's see what the total photo looks like.  I'll use the smaller f/stops - as those photos appear to be 'better'.

ISO 200

ISO 800

ISO 1600

In the actual photos, for the ISO 1600 I notice a little noise in the building white colors - but that's only because I'm looking for it.  

This was a fun test, but it also demonstrated another aspect of photography I didn't know before.  In all cases, the more open f/stop the less in focus the shot was.  When I first looked at the photo array, I blamed the wind.  I also thought it was the slow shutter speeds.  Well - I was wrong.  Note to self:  Landscape, the aperture setting is more important than speed.  Sometimes when I'm shooting photos, I get more wrapped up in the 'artsy' part and don't think of the basics.  

The good news is I now know more about the limits of my D90.  (I expect the new setup will be much nicer with higher numbers.)  Did I mention, it was really cold out there?

No comments:

Post a Comment