Originally posted by biz-engineer Whether the front element moves or not probably has an impact on optical properties of the lens. All macros lenses that I'm aware of focus with moving front group, there must be a good reason.
Of course, anything a designer does to his/her design impacts the performances one way or another.
Many macro lenses move the whole apparatus when focusing, essentially changing the distance between the lenses and the sensor. In other words, applying the thin lens equation, simply using 1/f = 1/o + 1/i .
Originally posted by reh321 Isn't weather-sealing more reliable on internally zooming lenses, because there are fewer places where water could get in??
In theory, yes. In practice, the difference might be difficult to notice.