Performance?
    In terms of function/working, I am quite disappointed...the lens is noisy...very noisy. In my case as a 2nd hand lens, when pointing the lens down and focuses, there is a very distracting sound. I think the grease inside my lens is a bit dry out...and when the front become heavy, the sound comes. When holding horizontally or pointing upward (using auto focus...), no that sound...but the focusing is still noisy. The zoom ring is not ultra smooth, but not very hard to turn too. From 35-50mm, it is a little bit stiff, but from 28-35 and 50-70mm, smoother. From 70-28mm, smoother. Not very distracting...and I am just being particular. The lens is quite fast. Full focus from the minimum focusing distance of 0.4m to infinity is just about 63 degree turn. However, for manual focus, it is a bit too shallow...

    When using the lens, I find the zoom ring is a little bit too narrow...if wider, then better. In compare, the focusing ring is wider. In AF mode, it turns...(so can't rest fingers on it not a good design...). Manual focusing is not nice...too little torque, and the degree of turning is too little...but being an AF lens...it has to be like this. Maybe I am too addicted to my Nikkor AFD 60mm micro, even the 80-200mm f/2.8 that I tried is not nice in MF too. The aperture ring is nice, click stop perfectly. But again...I am not a fan of changing aperture using the aperture ring (F90X user?), thus for me, it is not important. I am using it on my F60D body, what I do is just turn and set it to the largest aperture and lock. One of the reason I don't like F90X is because I don't like changing aperture using the aperture ring...and for me, all lenses are having too narrow aperture ring, including Nikkor lenses (AFS is better...)!

    Did I mentioned the minimum distance is 0.4m? Oh yes...this is a big PLUS + ! It gives maximum magnification upto 1:4.2. Although this can't consider as macro...but if you compare it to Tokina ATX PRO and PRO II, you will start appreciate this...

    This lens is a D lens, which means it will give the distance info to the newly Nikon bodies (F50 onwards). When zooming the lens, my SB-26 that mounted to the F80D communicated with the lens, and the flash auto zoom accordingly. My F60D doesn't support this flash auto zooming feature...so it is useless to me at this moment...AT THIS MOMENT ONLY!

    This lens uses 77mm filter. This is normal for fast lens...but still, 77mm filters are very expensive.

    I am not sure if the glass performance is upto what I am expecting. I will shoot some films soon and will see then. From web reviews that I have read, Sigma EX 28-70mm is comparable to the Tokina ATX PRO II 28-70mm f/2.6-2.8 in terms of glass performance. There is a very good chinese website review of this lens at:
http://www.photosharp.com.tw/cameratest/sigma28-70ex_1.htm

and comparison of Sigma EX 28-70mm with Tokina ATX PRO II 28-70mm is at:

http://www.photosharp.com.tw/cameratest/tokina270pro_2.htm

From Photodo (http://www.photodo.com), MTF test of Sigma EX 28-70mm is higher or even better than Tokina ATX PRO, and PRO II 28-70mm. Need to bare in mind that this is just a rough guide line...there might be some samples variant... (I am not saying that Tokina ATX PRO or PRO II 28-70mm is no good. In fact, they are my original choice...but because of their high price tag...so I just have to compromise. I have tried Tokina PRO and PRO II before, their build quality is first class! Much much much...better than Sigma, at least this is what I can remember/feel...But since I am no big fan of third party lenses, so this Sigma just a 'temporary = might be a few years...' lens for me. Sooner or later I will still get Nikkor...)

Update: 5th April 2001
I just got the prints of some group photos that I shot using my Sigma EX 28-70mm lens. Hmm...is it sharp? On a 3R print...it is quite hard to check, so I blow one of the print into a 8R size. Before I comment, let me explain my setup first:

I mount the Sigma lens onto my Nikon F60D (which has no mirror lock up, no cable release, mirror damping vibration is quite significant...the most basic entry level Nikon camera in year 2000  and discontinue in year 2001), mount the camera onto a not so steady tripod (I put the tripod onto a table, as it is really too short to stand on itself. I only extend using 2 of the 3 sections, as the tripod feels really very unstable to me), I didn't take my filter off (Hoya MRC 77mm, sorry...I forgot...), didn't use self-timer (need 10 seconds to fire...so too long for the crowd to wait...I just steady my hand and press the shutter release), and finally I forgot to put the hood on. Ha...sorry for this lousy setup test...but I guess this should be the most frequent situation that many people are going to use this lens. The shutter speed was 1/125s, aperture at f/8, and I was using my Nikon SB-26 speedlight to give some fill-in flash. The film I was using is Fuji Superia 200 with 4th layer colour technology. The sun is shinning up on top with temperature at around 32 degree celcius (ha...just a guestimate, Malaysia is always HOT and HUMID!). The subject are brothers and sisters of my church, which consisted of around 220 people in the photos.

This is my first formal shooting experience, so there are many mistakes here and there. Before the shooting, I have actually done some homework by seeking some opinions from the very knowledgeable members of the NML (Nikon Mailing List). However, during the shooting, I tend to forget much of the 'standard precautious'...

The shooting was arranged after the Sunday service of my church. It is around 11 a.m. Ha...after the Sunday service, things were not arrange very properly. There were only another brother and me trying to organize the session...but the crowd was not giving much attention. So, finally my church Pastor became the MAIN INSTRUCTOR! Ha...he has strong and loud voice...so people started to move here and there faster, and I have time to do the my camera setup myself...

 

My original framing is not to include too much 'road = at the lower part, and building = at the upper part' in the photo, but there are too many people to be fitted in the frame, so I have to retreat another 2 to 3 meters...to wider up the frame, and as well have to include more upper and lower margins. Ha...before the shooting, I remember did ask a brother to close the upper right window...but when shooting...I forgot about it, and didn't notice that it was opened until I have my developed print in hand.

 

larger size available at 149 KB Focal Length: +-35mm at f/8, 1/125s, SB-26 flash on F60D

Ok, so now the results: when blowing upto 8R, I can still recognize every face of my brothers and sisters in Christ clearly. The image is sharper in the middle compare to both left and right corners, but their differences are not very significant. Overall, the photo is acceptable but I wouldn't consider it as very sharp. I am not sure if it can be blew into 10R or 12R size...and I will report it again if any of my church member require me to do so.

I also took a shot of my church in the morning with the sun shone directly into the lens. When shooting, I can see clearly flare appear from the viewfinder. The results...ha...the photo is underexposed. I should have dial in +1 or +1.5 compensation as the sun is too bright. I can see hardly any flare if it does exist in the photo. I used the provided 'PERFECT HOOD' in this shot and all I can say is that this lens gives VERY SATISFYING flare control! Even if you shoot directly into the SUN!

Distortion is not very much of my concern, and I can't give much comments from the photos I shot. All I can say is that the building does shows a bit curved on the upper and lower side of the photos, but I am not sure if it is due to the lens or the nature of the building itself. Anywhere...not very significant.

Conclusion
    Overall, the lens is ok...a fair buy at S$300 for me. The filter alone cost about S$50 new, so I am paying about S$250 for the lens. Anyhow, the filter is not mint (little paint peel off on the ring), but no scratch on the glass (might still be able to sell at S$20...OK...ok, so the lens cost me S$280?). From the receipt, the lens is near to two years old (20th May 1999)...priced at S$530 and filter at S$65 (+ another extra 3% government tax). There is  newer version available in April 2001, one with AF/MF changes capability on the lens itself + some other improvement. Ha...I do hope my Sigma EX 28-70mm value will not drop much then. I guess the owner very seldom used the lens...but keep it in drybox (which might be a little bit too dry) and dried out the grease. I am sure servicing will make the lens perfect/like new, but I doubt I will do so, as that will cost extra money...and the reason I bought this lens is because it is cheap. I can live with the noisy distracting sound...I hope so...

Update: 31st March 2001
I would like to add some more comment regarding the EX finishing of my Sigma lens. I find the finishing nice...but it is not so durable. After some (very little) usage, I can see the finishing peelable! If you scratch your lens, by rubbing it (the scratched part) against your finger nail, the EX finishing just get peel off...leaving ordinary plastic underneath. Ha...mine is not very obvious, just very hair line peel off at the edge of the focusing ring. However, this gives me little confident on how durable this lens is...it definitely going to look bad without the crinkle finishing...