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07-14-2010, 12:25 PM   #1
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Sigma or Tamron, 70-300mm

This has probably been asked a million times, sorry. I need a new lens, all I have is my k-x's kit lens. I have like $160 to spend. Which one do I get?

I've seen the reviews on this site, and the Tamron looks sharper. The pictures in the review section of the Sigma don't impress me at all. But then I've seen pictures on flickr where the Sigma looks better. Are there any other problems these lenses have that I should know about?

I just don't know which one to get.

07-14-2010, 01:00 PM   #2
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It *has* been asked a million times :-). Note the forum ahs a searhc function (look to the top left of the screen), but it isn't always obvious what to search for. "Telephoto zoom" would be the best generic term here, I think.

Basically, you could flip a coin between these two for all the difference it would make, and save yourself a lot of aggravation. They're both fine lenses for the price. Looking at the reviews, you already know the standard list of differences. My impression is that more people settle on the Tamron, for whateve that's worth.

But as you'll find if you do search this forum for previous discussions, most oeople will suggest you kick a little extra and get the Pentax 55-300. The "DA L" version in particular should be available very lightly used for little more than your budget.
07-14-2010, 01:26 PM   #3
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I would recommend the Sigma for the 1:2 macro function (200-300mm only). My two cents
07-14-2010, 02:05 PM   #4
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The Tamron also has a similar 'macro' function. It should be noted that 1:2 magnification is only achieved at min. focus distance (0.95m) and 300mm, this goes for both the Tamron and Sigma.

From the Youtube clips linked below, I get the impression that the AF works faster on the Sigma. I know from experience that the AF with the Tamron is painfully slow at times. Other than that, the Tamron is sharper but the Sigma has less problems with 'purple fringing', which may be more of a pain in the back than lack of sharpness for some. I think the AF performance probably would decide if I was to buy another one (I've got the Tamron myself).

07-14-2010, 02:44 PM   #5
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QuoteOriginally posted by Marc Sabatella Quote
It *has* been asked a million times :-).
Old discussions probably won't include the new Sigma 70-300mm OS version in the discussion. They might include the DA 55-300mm. The DA 55-300mm and the Sigma 70-300mm OS are in the same price bracket, but I haven't read anything from a person that has had experience with both.

It would be interesting to hear whether the new lens correction software that is hitting the market this year makes the PF on the Tamron a non issue, or not. I don't think I've seen discussion about the software corrected output of a lens except in the discussions about the Sigma 10-20mm and the DA 12-24mm so I'm wonder if different lenses correct better than others?

I think things have changed enough that it really is worth reexamining things. Camera sensors seem to make a difference, is the PF of the Tamron as bad on a K-X, as the older Sony sensors? Is there any difference with the lens on the Samsung sensors?

Thank you
07-14-2010, 02:49 PM   #6
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From all accounts, the Tamron and Sigma (APO version) have about the same IQ. I had the Sigma, which was about the same as the Pentax 50-200. I put both of them away after getting the Pentax 55-300.

But if you have only $160, then get the Tamron and don't sweat it.

Last edited by SpecialK; 07-14-2010 at 05:28 PM.
07-14-2010, 03:50 PM   #7
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Well guys, the Sigma I'm looking at is the non-APO one. Sigma 70-300mm f/4-5.6 DG Macro Autofocus Lens 509109 - B&H

Yeah, I'm wondering about if the k-x can fix things like purple fringing or chromatic aberration. Then it would just be down to sharpness vs. AF speed.

Is the tamron really painfully slow? If all I'm used to is the kit lens, will I be disappointed or not notice a huge difference?
07-14-2010, 04:50 PM   #8
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QuoteOriginally posted by Cinders Quote
Yeah, I'm wondering about if the k-x can fix things like purple fringing or chromatic aberration. Then it would just be down to sharpness vs. AF speed.

Is the tamron really painfully slow? If all I'm used to is the kit lens, will I be disappointed or not notice a huge difference?
I used to have the Tamron but sold it; UGH that purple! Some people aren't that bothered by it, but I was, and I decided I'd rather have no autofocus tele at all than deal with the purple. At some point I'll invest in a nice tele lens.

Autofocus on the Tamron -- I wouldn't call it swift, but certainly not painfully slow. It gets the job done.

The K-x won't fix chromatic aberration or purple fringing on these lenses at all -- you'll need to post-process on the computer to do that. Generally, in-camera lens correction only works on genuine Pentax DA and DFA lenses, and perhaps the FA limiteds too, but I'm not sure about that. Definitely not a third party telezoom.

07-14-2010, 05:07 PM   #9

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Purple fringing/CA will be fixed by the K-x only for Pentax lenses. If you get a non-Pentax lens, you will have to fix that stuff up in post-processing.

As someone who has two cheapo Sigma zooms courtesy of eBay (the 100-300 f4.5-6.7 UC and the 100-300 f4.5-6.7 DL), AND the Tamron 70-300 f4-5.6 Di, AND now the Pentax DAL 55-300mm, permit me to offer you my messy journey through the world of cheapo zooms on the K-x.

I wanted a 300mm zoom mainly for casual birding. I started out with the Sigma 100-300 DL which I got as a kit with an old film body off eBay. It is a very soft lens at all focal lengths and nothing I could do could give me great, or even good, results. On top of that it has a plastic mount and the zoom mechanism was lumpy.

So I then picked up a Sigma two lens kit in good condition which included the Sigma 100-300 UC zoom with another Pentax film body off eBay for about $90AUD for the lot. Despite what some people say about this lens on these forums, I found this lens to be surprisingly sharp, even at 300mm, and with very few optical defects. And it has a metal mount and feels very solid.

Still, I wasn't happy. Surely I could do better, I thought, with a newer lens than the 10+ yo Sigma UC. So when a store nearby recently had a special on the Tamron 70-300, I got it for a good price. After using this lens for a while, and despite really wanting to like it, I am disappointed in it's optical performance. It has better contrast and colour than any of the Sigma's but unlike the Sigma UC, you can't expect sharpness out of it at all focal lengths - *especially* at 300mm, where I use it most. Up to 200mm the Tamron is great but beyond that, even stopped down, it disappoints. And yes, it lives up to it's reputation for lots of chromatic aberration. The macro feature is neat but not of much interest to me.

So I went back to using the Sigma 100-300 UC, and really liked it. I felt confident using it at all focal lengths without having to worry about softness and CA, and was getting good results.

After a while I noticed on eBay several sellers were selling new DAL 55-300's that had been seperated from the standard K-x kit, for about $300AUD. Hmm, that's about half the price of the standard DA 55-300. So I bought one of those a few weeks ago. Out of all these lenses, the Pentax 55-300mm is the best - contrast and colour redition is good and it is consistently sharp all across the zoom range, including at 300mm. You still need to stop it down a tad to obtain the best resolution, but it has all of the best features of the Tamron and Sigma's I've used, with few of the flaws. Have a look on eBay and see what the price of those DAL 55-300's may be in your currency. It's a good buy. (Even though it comes with no hood, I got a 58mm screw-on hood for $2 and it does the job).

Now I have to get around to selling the Tamron and the Sigma DL. The DAL 55-300 and the Sigma UC are keepers however.

AF on all of them is much the same, and can be slow, but AF speed depends very much on how you tell the camera to do AF. AF usually seems much faster in spot mode for example, than in any other mode.

Another point to note when using non-Pentax lenses with the K-x is that not only will the in-built CA removal feature not work, but the in-built lens distortion correction feature won't work either. Similarly, on all non-Pentax lenses the light metering defaults to centre-weighted average, rather than matrix, which isn't usually a problem but is worth noting. Use a Pentax lens and you get full support for all the features of the camera.

At the end of this cheapo zoom lens buying journey over the last year, I've probably spent as much as I would have if I'd just gone ahead and bought a brand new DA 55-300 straight up. I would also have spared myself a lot of hassle (and soft images) by doing so. While the DAL 55-300 is a great lens and I am very happy with it now that I have one, I've learnt my lesson and should have gone straight for the DA 55-300 to start with.
07-14-2010, 06:30 PM   #10
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Ok, well, I guess I'll just get the Tamron, I prefer sharpness over AF speed. The Pentax is $350, more than twice my budget. :<

Thanks for the help guys.
07-14-2010, 06:50 PM   #11
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QuoteOriginally posted by Cinders Quote
Ok, well, I guess I'll just get the Tamron, I prefer sharpness over AF speed. The Pentax is $350, more than twice my budget. :<

Thanks for the help guys.
It's worth saving a bit longer to get though.

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