Cheap and best lens for canon eos 500d
Monday, July 27, 2009
250mm
131mm
65mm
55mm
The Canon 55-250 lens does not have a USM focus system, so the front of the barrel rotates & extends, plus it's not super fast. However, at least on my Canon 40D, it's darn accurate, especially as you zoom in. To test this, I used Moire' Interference Patterns at various focal lengths and here are full-size center crops using the auto-focus, and then doing "best" possible with Live View. The 40D was tripod mounted about eight feet away for the 250 and 200 shots - about six feet away for the 55 and 90 pictures. Timed shooting was used to minimize any camera shake and aperture was maximum possible with ISO 800 - shutter speeds were 1/60 to 1/160.
Note the fuzziness at full wide at 55mm - this was repeatable and is slightly back-focused, although it may be due to the fact that the test image isn't large for super-precise focus since if I moved to the minimum focusing distance, it was then dead on. I'll do some real-world testing when I have a chance, especially since this just tests close-in focusing.
Note the fuzziness at full wide at 55mm - this was repeatable and is slightly back-focused, although it may be due to the fact that the test image isn't large for super-precise focus since if I moved to the minimum focusing distance, it was then dead on. I'll do some real-world testing when I have a chance, especially since this just tests close-in focusing.
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