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Old May 30, 2007, 1:05 PM   #11
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Keith

I am not quite sureI understand when you say that your Sigma can not be chipped. Why does it need a new chip? Did a function of the lens quit working on you or you you trying to rechip to achieve compatibility with your Samsung? If it is a Pentax mount lens, it will work with your GX-10. Most of the time, company reps are the most unreliable sources of information. If it's not printed in the documentation, it must not be compatible or so they say! We know better.

Regardless it sounds you have decided on a new zoom lens. Sounds like the Sigma marketing and advertising is working to persuade you to buy another one of their lenses. The truth is both Sigma and Tamron 70-300 are great budget zooms for the price. You won't go wrong with either. But the Sigma has three letters that the Tamron doesn't... APO. We want to get the Sigma because it has something the Tamron doesn't and that is what the folks at Sigma want you to believe. It's pure marketing.

Honestly, for every great reference you read about the Sigma, I can show you just as many more about the Tamron. Tests have shown that the APO version of the Sigma lens boosts contrast by less than 5 percent at 300mm compared to their non-APO version of the 70-300. The difference is even lower at the 70mm side of things. It does this by changingtwo SLD glass elements in the lens. The Sigma has a 1 year warranty, the Tamron has a 6 year warranty.

Here is my view between the two. Yes the Sigma w/APO doesgive memore contrastcompared to the Tamron, but the difference is so small that I can only see the difference if both images are side by side and that is afterI compare thema coupletimes. The Tamron is sharper at 300mm that the Sigma, this was more noticeable than the difference in contrast. Both were about the same at 200mm. At 70mm, I'd have to say the Sigma was slightly sharper at the widest aperture, but stopped down I couldn't see any difference. To me the length of thewarranty doesn't matter, but for some it is.

Brand loyalty is one thing, but that doesn't mean that they have the best product available. Side by side, I believe the edge is to the Tamron in the 70-300 budget telephoto zoom market. If you want to plunk down even some more change, go for the Sigma 50-500, akathe Bigma.

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Old May 30, 2007, 2:03 PM   #12
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Keithw wrote:
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Thanks guys. I sort of knew that the 28-300mm would be a "no-no" but I thought I'd better check.

Having seen more references to the Sigma than the Tamron, I think that's the way I'll go.

Hayward - I just love those photos. I can't see a setting sun without pointing a camera in its direction. OK so they don't always come out. But when they do ...

TC3 - thanks for the link; that is quite a saving. However, I suspect that the Tamron is the equivalent of the non-APO version of the Sigma which is avaiable for less than the APO albeit not as cheap as the Tamron. But as I said above I think I'll go for the Sigma

Rudy - The lens is already set to "A" although I thought that related to the aperture and not the focussing. In any case Sigma have told me that the lens isn't compatible and cannot be re-chipped, hence my need for a new lens (or as it could be referred to - yet more bl**dy expense!)

errno_gmm - I have the Samsung GX-10
Actually thats the latest edition of the lens and has been purchased by a few on the DPreview pentax forum with examples that show it is good for the money
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Old May 30, 2007, 4:40 PM   #13
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ishino wrote:
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I am not quite sureI understand when you say that your Sigma can not be chipped. Why does it need a new chip? Did a function of the lens quit working on you or you you trying to rechip to achieve compatibility with your Samsung? If it is a Pentax mount lens, it will work with your GX-10. Most of the time, company reps are the most unreliable sources of information. If it's not printed in the documentation, it must not be compatible or so they say! We know better.
Hi Ishino

The Sigma is from my 10 yr old Pentax film camera. On the GX-10 it quite happily focusses at 200mm but at anything less it positively refuses to focus properly. So I end up having to focus at maximum zoom then zoom out to frame the shot as I want it. As you can imagine, that's not very convenient. Someone, can't remember who, suggested that Sigma might be able to re-chip the lens. So I contacted their tech support but was told that the lens is incompatible with the new circuitry in the camera. What's more it cannot be re-chipped/upgraded.

As tech support aren't trying to sell me a new lens I assume that they are telling the truth. in any case re-chipping could easily have been too expensive, especially with the current cost of consumer zoom lenses.

As for the Sigma vTamron decision, it really isn't to do with advertising or marketing or even brand loyalty. It's more to do with reading this and other Pentax forums and seeing that there are just more reviews of the Sigma than the Tamron. Better still, the reviews and examples are generally very good. Now the fact that the Tamron is significantly cheaper is quite appealing. I originally intended to but a 9 or 10MP bridge camera so even buying a "cheap" (or, bearing in mind my current avatar, should that be cheep?) dSLR I've already shelled out a lot more than originally intended. However, if I'm going to spend money I want to make sure I don't go for quantity over quality. Hence relying on real-life reviews on forums.

Still I will check out the Tamron just in case. But I mustn't prevaricate for too long as I'm off to the north-west of Scotland in a couple of weeks so will need the lens by then.

Cheers

Keith
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