Any comparisons/experiences please: (a) Sigma 28-105 F/2.8-4.0 Aspherical Canon AF (b) Cosina 28-105 F/2.8-3.8 Canon AF and (c) Canon 28-105 F/3.5-4.5 EF. Thanks...

-- Mohan Iyengar (vmohani@vsnl.net), March 20, 2002

Answers

www.photodo.com MTF:

Canon 28-105/3.5-4.5: MTF 3,3 Cosina 28-105/2.8-3.8: MTF 2,0 Sigma 28-105/2.8-4: MTF 2,4

I own the Canon 28-105 and it's a very good consumer-grade zoom (www.photo.net/canon/28-105). But I prefer my fixed lenses, Canon 50/1.8 and Tamron 90/2.8...

-- Fredrik K (miffe_@hotmail.com), March 20, 2002.

The Canon lens is very good for a lower priced consumer zoom. It's not a lens I use much but it gives good results every time I do use it.

-- Lee (Leemarthakiri@sport.rr.com), March 20, 2002.

I can tell you from owning the sigma and having used the canon that in terms of contrast and resolution, they are about equal. With that being said the canon is superior in every other way. In terms of built quality the sigma is not even close, my slow auto-focus has already required factory repair because its cheepo belt wore out. also in terms of distortion the sigma is inferior, although the images are sharp the pincusion distortion is extreem. do yourself a favor only buy canon you will never regret it.

-- joe cap (joemocap@yahoo.com), March 20, 2002.

I can tell you from owning two of these same Sigmas and two more of these same Canons that in terms of resolution, they are not even close to being equal. The Canon 28-10 USM is fine. The Sigma 28-105 f/2.8-4 is very soft wide open and never gets really sharp when stopped down.

Sigma makes some good lenses. This is not one of them. It's crap!

-- Jim Strutz (j.strutz@gci.net), March 23, 2002.

Jim if you look at resolution tests with the sigma 28-105 and the canon 28-105 the sigma exceeds 71 lines of resolution at 5.6 at all focal legnths while the canon peaks out at 64 lines. It is true that wide open it is not as sharp, but the canon dosent even go to f2.8. there is a chance that with sigmas shoddy quality control that you got a bad sample(with sigma that is usually the case) but I would still suggest the canon for the other reasons that I stated.

-- joe cap (joemocap@yahoo.com), March 23, 2002.

Possible, but I have had two of each. Both Sigmas were bad.

-- Jim Strutz (j.strutz@gci.net), March 23, 2002.

And Joe, you may be right. I have seen others praise this lens sharpness too. But I've heard more people complain about it's lack of sharpness.

-- Jim Strutz (j.strutz@gci.net), March 23, 2002.

Jim after looking around the internet I got confirmation of what you saw, I can say that I got one of the first 28-105f2.8-4 availible in my area. I don't know if the plant or process was any different then. I have noticed that many of the complaints are from recent purchases I am curious as to when you bought yours. thanks

-- joe cap (joemocap@yahoo.com), March 26, 2002.