Thursday, January 28, 2016

Started out with an ISO test, but.....

I had to spend a few days in Chicago for work this week.  I usually drive.  Not much of a fan of flying any more, plus the time between flying and driving is just about the same.  For the drive, I drive past St. Joseph, MI - home of one of the most interesting navigation lights on the Great Lakes.  Usually in the winter there is plenty of ice over the structures that makes for great photographs.  This year not so much.  One of the lights is here: South Light in Winter

The second part of this story revolves around the ISO setting for DSLRs.  For the past two months, I've been researching the new Nikons - getting the itch.  I read one review that said if you have a dinosaur like a D90........  Oh well.

During the research, I've read some crazy ISO setting being used - well over 20k.  What's up with that?  Back in the 35 mm day, 400 was really reaching.  I usually don't stray much past 400 on my shots.  Now I have to ask myself why not?

Stay with me - I'll connect all of this.

Since it is winter, and I'm going past a location that I'm familiar with for photos, why not do an ISO test?  I've seen lots of demos on the web, but none with my dinosaur.  This seems like information I should know.

The set up is I took shots of two subjects, one close (50mm) and one at distance (170 mm).  I used a tripod, manual focus and a Cloudy setting for WB.  The original file is RAW, converted to jpg and then a 2x2 section of a point of focus.  (Remember this when viewing, this is a 2x2 image blown up to what you see on your browser.)  All files were processed the same.  I should also point out it was windy and cold.

The point, again, was to test for noise at higher ISO settings.

The first shots are of a subject at around 10 feet.  The ISO setting are 200 and 800.  The f/stops are open, closed and somewhere in between.

ISO 200   f/stop 4.8    1/1000

ISO 200   f/stop 10    1/320

ISO 200   f/stop 22    1/60

When I first saw these, I expected the detail to be good.  OK.  But I expected the higher speed to be more in focus.  Interesting, but it was windy.  Blame it on Mother nature.

Let's see what they look like at ISO 800.

ISO 800   f/stop 5.6    1/3200

ISO 800   f/stop 10    1/1000

ISO 800   f/stop 22    1/250

For the point of focus or subject, at this distance there really isn't much difference.  So, in this case why would you need to be concerned about an ISO setting?  What I did confirm is that with a slower speed and higher f/stop you get a much clearer photo.  (We all know that!)  Below are the total images.  The goal is a selected speed between 1/250 to 1/350.

ISO 200   f/stop 10    1/320

ISO 800   f/stop 22    1/250

Which is the more all around better photo?  Unless you are going for a DOF effect, the photo at ISO 800 seems to bring more to the table.

Based on what I found out here, I have no problems pushing the ISO to 800.  I didn't go to 1600 because, well - it was cold.  Lousy excuse, but true.  

But what about shots at a greater distance?  That will be published soon.

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