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Old Mar 5, 2007, 10:45 PM   #1
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While Scott posted an excellent web page from Tamron that showed the differences in the view produced by various focal length, I thought some real-world examples might be nice, giving an idea of what you might see. So I spent a few minutes at lunch playing with my K10 and three lenses - the kit lens, the DA 50-200 and the A*300, taking pictures from one spot and using different focal lengths. These were all taken in raw and are full frame, resized to fit here. If I were really processing these I would straighten the horizonal lines, and probably crop a number of them (both of which would have changed the fieldof view), but I wanted to leave them exactly what the camera saw (you can see my pictures always need some pp work).

This first picture shows where I was sitting - at the top of a grandstand (see white arrow). It was taken with the kit lens at 45mm, what seemed to be pretty close to what my eye saw.
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Old Mar 5, 2007, 10:46 PM   #2
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Kit lens, 18mm:
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Old Mar 5, 2007, 10:47 PM   #3
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After thinking about what people said below, and also trying to organize my own thoughts, I went out yesterday and re-took the shots (the day wasn't as good - the marine layer hadn't fully burned off at lunch time).

Focal length changes both magnification and field of view, at the same time. I'm not sure I'm able to exactly explain what I want to say/show. But it seems to me that what a focal length does to a subject changes as your distance to the subject changes. I shot two series of pictures that show different application - one a far distant object that I zoomed in on, and one where the subject was much closer - which seems different to me (different application). I've only processed one of the series - I thought my computer was ready so we drove over the hill to where it was, only to find out that they had only fixed one of the problems (they ended up replacing the hard drive, which means re-installing all my software - major sigh!).

Here's the first application, concentrating on a distant scene. In this case, the object is the top of the far stairs (theone between buildings in the distance)- about 2,000 feet away. I used the same 18mm shot originally posted to start the series, since I was sitting in the same place, and it shows the relationship of the two series.

K10, kit lens, 23mm.
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Old Mar 5, 2007, 10:48 PM   #4
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Kit lens at 43mm - this seemed to be close to "normal" magnification for my eye.
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Old Mar 5, 2007, 10:49 PM   #5
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K10, Kit lens 55mm - longest focal length of the kit lens.
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Old Mar 5, 2007, 10:51 PM   #6
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K10, 50mm - shortestfocal length (widest fieldof view)for the DA 50-200. It's slightly out of order by focal length, but thought I would keep it within the lens capability.
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Old Mar 5, 2007, 10:52 PM   #7
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K10, 80mm (DA 50-200). I tried to cover common focal lengths of various lenses, but not always good at getting the exact number.
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Old Mar 5, 2007, 10:53 PM   #8
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K10, 95mm (DA 50-200)
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Old Mar 5, 2007, 10:55 PM   #9
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K10, 138mm (DA 50-200)
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Old Mar 5, 2007, 10:58 PM   #10
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K10 160mm (DA 50-200)
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