Jefferson Offline Upload & Sell: Off
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Roland W wrote:
So, your primary point mentioning the new version II not being a "dust pump" is basically wrong. And your mention of the look of the lens when zoomed to the telephoto end is also wrong. The new 100-400 L IS II lens has a front that extends dramatically as you zoom, and has the same or a very similar overall volume change as the old version I lens. It also needs seals around the extending front for some moisture resistance. And, the description has no mention of it being any different in the location and type of those seals that help keep moisture out. The net result of that is that the new version II lens likely is exactly the same as the old version I lens in terms of any tendency to suck in more dust than other lenses. So no more or less a "dust pump".
In general, the old version I lens did not really have much if any different tendency for collecting internal dust than other extending zoom lenses. There is no question that in theory, a non extending lens that has no front opening gap for dust ingress, or has a front protective filter covering the front opening gap, will likely have less tendency to get dust in side than an extending lens. But, there are plenty of extending zooms other than the 100-400 that change overall volume, and so should all of those be called "dust pumps"? Is my very nice 70-300 L IS zoom with a rotary zoom and an extending front a dust pump?
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Thats a horrible revelation requiring new evaluation
Just saw a photo in the extended
Zoomed
position.
Seems Canon has attempted to solve the dust pump phenomenon by slowing the ability of the newly designed lens to suck dust
and I would assume the rotational zoom design, in addition to slowing the zoom rate, works like some vacuum cleaner designs Ive seen
using the Tornado air flow (Rotational Zoom), to centrifugally remove dust from the inrush of particulate laden atmosphere, albeit a slower rate
Jefferson
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