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ghaleon109
6th of September 2005 (Tue), 14:55
I recently got back from a shoot at the BMX track and was just wondering a few things before I go back...

I only use my Tamron 28-75mm f2.8 but it's very VERY dusty out there. Can any of that dust harm my camera or lens? I don't change lenses out there so the body is never left open and exposed, but when my Tamron zooms the front part of the lens extends and there is about 2 cm gap between the exterior of the lens and the piece that extends. Can dust get in there and ruin my lens?? Or is it sealed?

Thanks :)
tim
6th of September 2005 (Tue), 16:20
Yes, dust can get in, and no it's not sealed. Because the lens size changes the volume of air inside changes, it has to get it from somewhere, so it uses whatever's around the lens. You'd probably be better off with an L series lens, AFAIK most of them don't change size when you zoom (my 70-200 F2.8 IS doesn't).
ghaleon109
6th of September 2005 (Tue), 16:40
*sigh* Well, my 70-200 is a bit too long... and I need to be pretty close if I want a fill flash right? I'll try shooting it again friday with my "L" and see how it goes. But would you reccomend selling the Tamron and getting the 17-40?
tim
6th of September 2005 (Tue), 23:35
Your external flash should auto-zoom to 105mm or so, and should be effective even with a slightly longer length lens. 200mm might be pushing it a bit far though, without a beamer attachment or something.
ghaleon109
7th of September 2005 (Wed), 00:03
Damn, and I thought I had an excuse to by the 17-40 L. :lol: But I'm going to go with the 420, If I need more later on I'll get the 580 and just use the 420 as a slave. I'll try to back up some and use my L at 70mm, Hopefully the 420 will work out well.

Thanks again Tim :)
tim
7th of September 2005 (Wed), 00:18
You're welcome, good luck :)
condyk
7th of September 2005 (Wed), 04:00
I guess (can anyone really be totally sure?) that the dust problem is overstated. Never happened with me travelling in dusty areas. If you find you have fine dust settling on the area of the lens that moves in and out then you may have a problem at some point. If there is dust around then you'll get it on your glass too. You could stand somewhere less dusty and save the worry.