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01-13-2009, 03:02 PM   #1
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Tamron 17-50 f 2.8 vs Sigma 18-50 F2.8 macro

Any thoughts on which of the above lenses would be the best replacement for the kit lens? Both around the same price; sigma a little cheaper and has the "macro" function. The DA* is out of my price range and the Pentax 17-70 is more money and not as fast...
I apologize if this has been discussed--I couldn't find the thread.

Thanks!
Brad

01-13-2009, 03:38 PM   #2
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This have been discossed alot of times I think... just look around shots and see which one looks better for you. Although I'm probably being a hypocrite because I've been curious about this exact question but haven't spent the time to do just what i said

The 17-70 is just as fast as the 18-55, it's just a third (half)? stop faster at exatcly its widest angle. Starting from 19mm the 18-55 slows down to f/4 *edit* oh, I thought you meant not as fast as the kit lens. Apologies.
01-13-2009, 04:28 PM   #3
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QuoteOriginally posted by Andi Lo Quote
This have been discossed alot of times I think... just look around shots and see which one looks better for you. Although I'm probably being a hypocrite because I've been curious about this exact question but haven't spent the time to do just what i said

The 17-70 is just as fast as the 18-55, it's just a third (half)? stop faster at exatcly its widest angle. Starting from 19mm the 18-55 slows down to f/4 *edit* oh, I thought you meant not as fast as the kit lens. Apologies.
Sorry if I was confusing. I meant both the Sigma 18-50 2.8 macro and Tamron 17-50 2.8 are faster than the kit, and also the Pentax 17-70 (which seems to be $100 more anyway)...
01-13-2009, 07:17 PM   #4
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Go Sigma

I have the Sigma and its a great lens. Very confident when its on the camera.

From what I've read you can't go wrong with the Tamron but I think you will like the build quality of the Sigma more.

01-13-2009, 08:13 PM   #5
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Cameta Camera still (amazingly) shows the older version of the Sigma in stock for $279.99. I can get 5 keyboard keys in the shot with it - close enough for me.
01-13-2009, 08:36 PM   #6
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QuoteOriginally posted by bsimon Quote
The DA* is out of my price range and the Pentax 17-70 is more money and not as fast...
More money for SDM and a longer range. F2.8 is "just" one full stop lower than F4. If you don't shoot at low F numbers, then there's no point. With modern lenses, sharpness peaks at around F5.6-F8.
01-14-2009, 12:05 AM   #7
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It has been discussed and debated at length, sure. And it will likely be debated long after all of us here have lost the eyesight to continue shooting too.

I own the Tamron and wouldn't trade it for the DA*16-50. Now personally, I don't like Sigmas. That however is purely a matter of personal taste as optically I think they are fine lenses; they just don't feel right to me. Other people have exactly the opposite reaction comparing Tamron and Sigma.

In general, as far as speed and sharpness goes, the rule of thumb I go by is most modern lenses enter their sweet spots when stopped down 1 to 2 stops from full open. Max aperture has as much to do with depth of field control as it has for low light shooting, but when it comes to lower light situations an extra stop from f/4 to f/2.8 does mean you get two times as much light hitting the film/sensor at the same shutter speed. And in low light, I have more issues with color noise due to higher ISO than I do with any lack of optical sharpness at f/2.8 on the Tamron 17-50.

The real issue for me though when I'm shopping zooms is constant versus variable max aperture. Zooms allow me to frame my shot the way I want it when I either can not or do not desire to move my feet and the perspective I have of the scene from my location suits me. In these situations I'm not counting the millimeters of focal length but I am always concerned with my aperture and shutter speed. And for this reason I don't like variable aperture zooms. I find it very frustrating to zoom in a just tad tighter on a shot (it may only be a 10mm adjustment) and find I've dropped from 1/60s @ f/4 to 1/30 @ f/5.6. It's why I just consider my DA18-250 to be an f/6.7 lens and I put up with it until I find a better option or my little boy requires less gear of his own when we "go to the zoo".

So which one to buy? I'd advise putting your hands on each if possible and going with the one that feels the best to you. Optically they're not going to be very different but how they feel to you, in your hand, mounted on the camera, can make a world of difference in the photos you make.
01-14-2009, 12:21 AM   #8
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I feel the Tamron has the best reputation for wide open sharpness, but I forget where I read it when researching which of these three lenses to buy.
I own the Tamron, it works fine for me, but shooting alongside a 16-50mm recently it is noticeable that the Tamron is a little slower (let's through less light at matching apertures).
This is shown, amongst other things in the following test...

Pentax 16-50mm f/2.8 vs Sigma 18-50mm f/2.8 vs Tamron 17-50mm f/2.8

Note in this test the tester prefers the 16-50mm

Enjoy.

01-14-2009, 10:23 AM   #9
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QuoteOriginally posted by SpecialK Quote
Cameta Camera still (amazingly) shows the older version of the Sigma in stock for $279.99. I can get 5 keyboard keys in the shot with it - close enough for me.
Thanks--is the "macro" function worth the extra $100?
01-14-2009, 02:01 PM   #10
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The older version isn't as good as the newer. In my opinion the "Macro function" is a bonus, but not worth $100.
01-14-2009, 03:16 PM   #11
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Thanks! I ordered the Sigma with macro for $375. Arrives on Friday in time for the weekend!
01-14-2009, 08:11 PM   #12
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QuoteOriginally posted by bsimon Quote
Thanks! I ordered the Sigma with macro for $375. Arrives on Friday in time for the weekend!

I think you will like the Sigma. I have had one for a few months and it has been great - a huge improvement over the kit lens. The macro function is really handy, and it has great bokeh!



01-14-2009, 10:17 PM   #13
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I bought the Tamron 17-50mm and I am delighted with that decision. Best of luck on your decision.
01-18-2009, 10:42 PM   #14
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I received the lens and I'm liking it so far...
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