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Old Sep 19, 2011, 6:02 PM   #1
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Default Narrowed it down to two.

Ok, I've got it down to two lenses for my walkabout lens. Either the Pentax 18-135 because of it's quick shift, and weather sealing primarily for dust, and the Sigma 18-250 because of it's reach. I'm kind of concerned about not having a sealed lens on the camera for two weeks because of dust. I'm pretty sure the image quality is pretty close. So, what do you guys think? Is the dust thing a non issue?
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Old Sep 19, 2011, 9:45 PM   #2
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99.9% of lenses out there are not weather sealed so dust really isn't a major issue. Look at lenses 50 years old, there may be a little dust inside them (certainly in zooms, because of the suction effect of zooming they are usually far more prone to dust than primes) but in the vast majority of cases it has zero effect on your images.

Don't know the 18-250 but with that sort of multiplier you could have stuck with a P&S ! Maybe you can get good shots from it and it'll be OK as a walkabout lens but you are not going to get top quality and it's going to be slow.
The Pentax also has a high multiplier, though obviously not as high as the Sigma (the better/best zooms have no more than a x3 or x4). Reports have been varied and it is over-priced but I have seen excellent shots from it and it does have WR if that is important to you (for most people it's really not - for the very very few times I'm out shooting in the rain then plastic bags and rubber bands are more than enough).

EDIT. If you just want a decent zoom to cover a useful range then the Sigma 18-125 is worth considering used and then sell it again when you get back. Shouldn't cost you more than US$150 and it's a very decent lens. IMHO I'd save your bigger bucks for better lenses.
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Pentax : 15 Ltd, 77 Ltd, 43/1.9 Ltd, Cosina 55/1.2, DA*300/4, Contax Zeiss Distagon 28/2.8, Raynox 150/250, AFA x1.7, Metz 50 af1.

Nikon : D800, D600, Sigma 500/4.5, Sigma 120-300/2.8, Zeiss Distagon ZF2 - 21/2.8, Zeiss Distagon ZF2 - 35/2.0, Nikkor 85/1.8G, Sigma 50/1.4. Nikon x1.4 TC, Sigma x2.0 TC

Last edited by Frogfish; Sep 19, 2011 at 10:37 PM.
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Old Sep 19, 2011, 10:20 PM   #3
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For the most part I don't worry much about dust getting in through the lens opening while the lens is mounted, unless it's windy and I'm in the Mojave Desert or Las Vegas (not an uncommon occurrence) or another dusty/sandy location. As far as your upcoming trip goes I wouldn't use dust to rule in or out either lens as I don't see you in that many situations where blowing dust is going to be a problem. I would be more concerned about rain (advantage Pentax), though I'd be more likely to make my decision based on size, weight, and focal length needs.
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Old Sep 20, 2011, 4:19 PM   #4
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Never had a problem with dust using non weathersealed lenses. On the other hand, I've had dust using weather/dust sealed lenses...especially zooms which can suck in air and dust each time you zoom. And each time you switch lenses, there is the opportunity for dust to get into the sensor chamber. Nothing that a blast of air or a wet clean can't handle. If it were up to me, I'd take the zoom so long (as Mtgal has also said) the size and weight are not unreasonable. FYI, I have the Tamron 18-270 and it is a great walk about lens for travel...very compact and excellent IQ.

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Old Sep 20, 2011, 7:36 PM   #5
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Quote:
Originally Posted by Wingman View Post
Never had a problem with dust using non weathersealed lenses. On the other hand, I've had dust using weather/dust sealed lenses...especially zooms which can suck in air and dust each time you zoom. And each time you switch lenses, there is the opportunity for dust to get into the sensor chamber. Nothing that a blast of air or a wet clean can't handle. If it were up to me, I'd take the zoom so long (as Mtgal has also said) the size and weight are not unreasonable. FYI, I have the Tamron 18-270 and it is a great walk about lens for travel...very compact and excellent IQ.

Jehan
I though the Tamron 270 wasn't available on the Pentax??
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Old Sep 20, 2011, 8:01 PM   #6
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Quote:
Originally Posted by tony3dd View Post
I though the Tamron 270 wasn't available on the Pentax??
Sorry, I should have clarified the context of my comment which was that the non OE brands are good value for money. Performance ought to be comparable to the Sigma 18-250. You are corrent in that the Tamron 18-270 is not available in the Pentax mount. I use mine on a Non-Pentax body.
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