[hopesfallb]

שלום
אני מתכוון להחליף את עדשת הקיט שלי
ואני מתחבט בין סיגמא לפנטקס שניהם עולים אותו מחיר בחו"ל
וקראתי המון מאמרים וזה עשה לי כאב ראש
אתם בבקשה יכולים לעשות לי קצת סדר ולכוון אותי מה יותר עדיף
תודה

[hramat]

what kit lens you are referring to?
I own Sigma 17-70 and it is a great lens. good optically, good mechanically, just bit too big in size and heavy.

Since I also own Pentax DA 55-300 (focal length overlap), I would rather consider Tamron 17-50 f/2.8 now which seems bit superior in image sharpness.

I am not able compare to Pentax DA 18-55, 17-70, 16-45

[bdery]

The Sigma 17-70 is regarded as one of the best options when one wants to upgrade from the kit lens. It is a lens that comes close to professionnal quality, it is versatile and reliable. I love mine and will keep it as long as possible.

The Pentax 17-70 is a good lens too, but it has three flaws when compared to the Sigma:

1-slower at wide angle
2-no real close focusing capabilities
3-more expensive

So I would personally recommend the Sigma.

[hopesfallb]

אני מחפש לשדרג מעדשת 18-55 הסטנדרטית
יש לי את da 55-300
לפי פוטוזון טאמרון 17-50 זאת עדשה ממש טובה
אבל אני מחפש עם קצת יותר מרחק

[JHD]

Another point to consider is you'll have to decide where you stand on the SDM issue. This is important because Pentax doesn't stand behind / warranty their lenses like Sigma does. Whereas SDM has a shaky reputation, reports of HSM problems are few and far between. This is even more significant when you consider Sigma sells far more lenses with HSM than Pentax does with SDM.

[hopesfallb]

כנראה אני ילך על טמרון 17-50 היא פשוט מאוד חדה וזה עדיף על אקסטרה 20 מ"מ למרות שהיא קצת מרעישה
תודה רבה

[JHD]

The Tammy 17-50 is a very good lens and it is a stop faster than the Sigma. I like having the extra 20mm and the extreme close-up capability of the Sigma. Either way, you can't go wrong. IMO they are both clearly better options than the Pentax.

[GeneV]

I use those extra 20mm a lot. I can't see giving them up.

[mokey]

As much as I love the Pentax brand, I would now stay wholeheartedly clear of any SDM lens. My 16-50 was repaired twice, and now my 50-135 needs to go back for it's 2nd replacement. ARGH!

[arv]

On slrgear.com you can find the same images made with both sigma 17-70 and Pentax 17 - 70 (and kit II version). IMO Sigma is better at long end, Pentax - at wide end.

A.

[hopesfallb]

שלום שוב אחרי התלבטות ירדתי לשני אופציות סיגמא 17-70 החדש והישן ואני שואל אם אני באמת צריך מונע רעידות שיש לי בגוף עצמו או/ו הישן יספק אותי הסכום לא פקטור
תודה

[demuire]

I just replaced my kit lens with the Sigma 17-70 f2.8-4.5 (non OS, non HSM). It's pretty big compared to the kit lens, but smaller than the HSM version. I tried both the HSM and non-HSM version back to back, and couldn't tell any focusing speed difference between the two. The HSM version is obviously a lot quieter, I almost couldn't hear it focusing at all. At the shop I was shopping at, there was a $220 difference between the two, I couldn't justify that just to get a quieter focus and half a stop faster on the long end. Plus, the OS also uses battery even when it's off...

Brought it home and tested the new lens. In good light, focusing is as quick as the kit lens. It's faster (aperture) and has longer reach (70mm vs 55mm), and is optically excellent. In low light and with a dark subject (black cat, in my case), autofocus isn't as good as the kit lens though. My previous photos of my black cat with the kit lens have all been done using autofocus (auto-5 point), with the new Sigma it struggled even with center point focus, so I ended up taking most of the photos with manual focus. Admittedly it can't be easy focusing on a black cat in poor light, but seeing as the slower kit lens can do it, it's disappointing that my faster more expensive lens can't

In any case, that's the only downside I've found to it so far, but then again I haven't taken many other photos with it either!

[bdery]

the new Sigma it struggled even with center point focus, so I ended up taking most of the photos with manual focus.

Are you sure you were in the same conditions? AF efficiency is mainly related to the max aperture of the lens, and the Sigma is faster than the kit at all wavelengths..

AF SPEED can be related to the gears and weigth of the lens, but its efficiency shouldn't. I suggest you tyry AF in more controlled conditions, there might be a problem with your Sigma.

[bobmaxja]

I have the old Sigma and very happy. You
On Flickr, many groups on Sigma 17-70, tons of photo

Flickr: Search for a group

[demuire]

Are you sure you were in the same conditions? AF efficiency is mainly related to the max aperture of the lens, and the Sigma is faster than the kit at all wavelengths..

AF SPEED can be related to the gears and weigth of the lens, but its efficiency shouldn't. I suggest you tyry AF in more controlled conditions, there might be a problem with your Sigma.

Yes, exact same conditions - in the same room, with the same light, with the cat in the same spot, in more or less the same pose. AF speed seems pretty much identical to the kit lens as far as I can tell, but for some reason the kit lens would get a focus lock, where the Sigma would hunt back and forth and eventually give up. Given better light, the Sigma is perfect.

I spoke to a workmate who has a few lenses (Nikon), and he too said that his faster lenses tended to not get a focus lock as easily as his slower lenses. I have no idea why this would be the case...