[chanpcw]

小弟用的是 Pentax *ist DS，跟機的 18-55mm 實在太短，現在想買一枝鐘頭取代，經過一輪 research 後，目標如下:

1. Sigma 18-125mm F3.5-5.6 DC
2. Sigma 55-200mm F4-5.6 DC (留 18-55mm 跟機鐘作短距用)

買 18-125mm 的話，可以避免換鏡的麻煩，對我這樣的新手來說是一個優點！

我用機是在戶外影人像居多的，心想 55-200mm 既影像質素可能較好，是嗎？

想問資深的的攝友，55-200mm 作為 "carry around" 鏡頭是不是有點牽強？

[chanpcw]

By the way, Sigma 18-200mm isn't an option for me, cos' they aren't available for Pentax mount.

[Rol]

To : Chanpcw

I have DS and faced the same options like you three months ago.

- Sigma 55-200mm is around $12xx, DCfever offered a set of two Sigma lens 18-55 and 55-200mm, just around $16xx, but this lens kit will duplicate the Pentax kit len you already have.

- Tarrmon 28-200 has Pentax mount in WIng Shing , the old version is $18xx and new version (they claim faster AF) is around 23xx

- Another option is 70-300 mm from Sigma or Tarmon, Sigma 70-300 APO is popularly used by many Canon, Nikon user. It is cheap (around $15xx) and good for budget DSLR use. But most shops do not keep Sigma lens with Pentax mount, you may need to order the lens. Tarmon 70-300 is just $1280 and general comment on this lens quality is quite same as Sigma 70-300.

- Pentax has FA 70-300 ($1200) but its F4.5 is smaller than F4.0 from Tarmon & Sigma

For me if i paid $12xx just for 55-200mm from Sigma, i prefer Tarmon 70-300, or paid more for Sigma 70-300. The loss of 55-70mm is smaller than the gain of 200-300mm. So Finally I bought Tarmon 70-300, the quality is as good as the kit len and i am happy with it.

In theory 55-200 (with less zoom) should have better quality than 70-300mm, but you should not expect much difference from just cheap $1xxx lens.

Pentax will launch the new DA lens 55-200mm soon and would be another option.

Hope that it can help you

[happylu]

新手, 想請教Rol 師兄. Some people say Sigma 鏡偏黃, Tamron AF is slow. What do you think ? 70-300 Sigma is metal alloy or plastic? What 'APO' means? More often 影夜景 & concert.
I'm still thinking which one to buy.

Thanks for help.

[Rol]

To : happylu

I am also beginner in DSLR.

Not sure what body you are using, as DS is slow in AF among DSLR, but Tamron 70-300 is not running too slow in my DS compare the kit lens.

Sigma 70-300mm with "APO" (lens which reduce color and spherical abberration), but Tamron 70-300mm has "ED" with similar feature. Before buying Tarmon I searched forums and found the comment on both lens is similar, I did not hear that Sigma lens incline to yellow. For Tarmon 70-300, you can see the photo in my Dcfever account.

[chanpcw]

Rol,

Your advise came in a little too late as I already went out to purchase the Sigma 18-125mm during lunch time today. I'm wanting a "walk-around" lens that is more capable than the kit len and my decision was very much based on my research in the Internet where the Sigma 18-125mm lens is generally praised by most of the owners. I considered the Sigma 18-200mm too but not sure whether it can produce the same image quality as the 18-125mm so I decided not to wait for the former (pentax mount not available yet, might have to wait until July).

You mentioned the Tamron 28-200mm, that is an interesting one I overlooked during my research. Not sure whether I would pick this one instead of the Sigma 18-125 if I knew about it earlier. Frankly speaking, I've been trying to avoid the Tamron lens (low grade ones of course) due to the plastic mount.

If I needed a long reach later, I'll get the Sigma 70-300mm as you suggested.

Thanks a lot for your input.

Regards,
Chanpcw.