Push Pull Zoom Dust

So I have been debateing between the 400 5.6 and the 100-400. I have read a fair amount of reviews on here as well as asked for advice, but today I read something that I havent heard of up until now and never really thought of it.


With the Push-Pull Zoom mechanism the air has to come in and outfrom inside the lens, with that there would have to be dust. Has anyone experienced this? I had and still have a pentax lens that was used on a k1000 that was push pull, but havent used any others. Is there some type of "seal" that helps keep the dust out?


If there isnt a seal, it would seem to me that the push pull zoom would be a dustpump of sorts.


thanks


joel

I haven't owned either lens, but I can tell you this:


Buy the lens you need. Don't buy the 400 5.6 L just beceause there are reports of dust problems with the 100-400 L.


Now, say CA and vignetting were bad on a certain lens, that should move your attention elsewhere. But IMHO, don't look at the dust problem as something that would cause you not to buy the 100-400 L.





PS. I would assume some sort of sealing since the 100-400 L is indeed an L lens.

Im not looking at it as a problem because if it was a major problem then more poeple would be voicing it, I would like to know if anyone has had experience with this question. But if it does have some suction that is bringingdust into the inner workings that isnt good, even being an "L" lens if air is entering and leaving because you are expanding the chamber inside then dust as well could get in....and out....


Thanks


Joel


p.s. There's enough posts of information on the advantages and disadvantages of certain lenses, but this topic hasnt come up as far as I know so lets try to keep it at that...no hard feelings just dont want this topic to become a debate between lens choices.

Quote:

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Originally Posted by Joel Bookhammer

I would like to know if anyone has had experience with this question
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First off sorry because I have not hadany problems with dust. I do own this lens however andwill also be interested to hear from other members. Hopefully my experience will make you feel slightly better about your pending purchase though :)

I hit "Post" twice by accident. Sorry!

Any lens that extends when zooming or focusing is going to require air to enter and leave the lens. I am not aware of any lenses that completely seals requiring a pressure different between the inside and outsize of the lens. The 100-400 may be more susceptible to dust since a larger volume of air is exchanged when zooming (which is why it is designed as a push-pull in the first place) and there may be a more direct route for dust to get in since rotational zoom mechanisms may trap dust, depending on how they are constructed.

<span style="font-size: 6pt; color: black; font-family: Verdana;"]<o:p>


<span style="font-size: 10pt; color: black; font-family: Verdana;"]I bought mine used of FM, it's a '06 model, no dust present thus far.<o:p></o:p>


<span style="font-size: 10pt; color: black; font-family: Verdana;"]This lens has been out for over 6 years, if there was a problem with dust, it would have been discovered and addressed long time ago. <o:p></o:p>


<span style="font-size: 10pt; color: black; font-family: Verdana;"]It's a great lens, super sharp,super useful, I would definitely recommend it.<o:p></o:p>



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Joel;


I've had the 100-400L for nearly 2 years, it's on the camera 95% of the time.....no dust yet.


I wouldn't allow this (non) issue to be a factor in your decision making.


Regards


Bill

I have this lens since 3 years. I used it a lot. I do not have problem with dust in the lens, my lens is very clean. I occasionally had dust on my sensor on my 5d, but I think this is due to changing lens rather than from my 100-400.

I have my 100-400 for more than 2 years, use it quite a bit, and no dust so far. Take care

Well, I'd say that's a fairly unanimous response--no dust problem. Buy the lens and enjoy it!

Thanks everyone deffinitly doesnt make my decision any easier now, Still decideing which one I want to get but im sure in theend whichever I choose I will enjoy.


thanks


joel

Quote:

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Originally Posted by Joel Bookhammer

So I have been debateing between the 400 5.6 and the 100-400.

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I'd go with the 100-400 for IS and versatility. IQ is a little better with the 400/5.6, though.

Quote:

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Originally Posted by Joel Bookhammer

With the Push-Pull Zoom mechanism the air has to come in and outfrom inside the lens, with that there would have to be dust. (...) Is there some type of "seal" that helps keep the dust out? If there isnt a seal, it would seem to me that the push pull zoom would be a dustpump of sorts.

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The push-pull is a "dust pump of sorts"; any lens that changes length is. The only lenses that are "sealed" against dust are the weathersealed lenses. Of course, a lens that zooms internally (like the 16-35L and 70-200L), also keeps dust out well. For some reason, the EF-S 17-55/2.8 IS seems to be the only lens that is known for collecting dust.