pentax 16-45 vs. Sigma 17-70

Has anyone used the Sigma 17-70 which could be a alternative to the Pentax 16-45?
I seems quite good as well:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=20842152

The sigma goes for Euro. 325,00
The Pentax goes for Euro. 389,00

I've had a look at the pictures, but they don't prove anything unfortunately. It isn't a very scientific test, more a couple of casual shots.

If a lens test is being undertaken at least start with using a tripod!

thanks for the link, I have been thinking about replacing my 18-55 for a while (though not too desparatly as Pentax saw fit to give us the best of the "kit" zooms) and these two are both on the list of possibles

Agree with John... you can tell almost nothing from a casual shot like that. Areas where differences are likely include:

* Flare control. What about shots into the sun, with strong point sources of light etc?
* Chromatic aberration
* Bokeh
* Distortions (barrel/pincushion)
* MTF across the diameter of the lens (ie exactly how sharp, and is it only in the centre?)

At the very least it's good to see a variety of subjects and lighting conditions compared between lenses. The shots shown were very "tame"

Matt

Because the price difference is not huge my feelings stay with the Pentax units.
In this review they talk about CA being "worse" in the 16-45. I was allways under the impression that the 16-45 performed very well in this area.

anyway, I'm just about ready to place an order for a 16-45.

How come Pentax is more expensive? Is`t opposite here in N. America......

In this case, I would go for Sigma, you get 45-70 range + Macro mode for less money.....

Err, "45-70 range".........have I missed something here?

Ah, yes I see, the Sigma is a wider range but I very much doubt that it's a better performer but it's certainly good value.
I think you really have to handle a lens and preferably fire a few test shots before you can decide whether or not it is for you

Well, I am not saying there`s something wrong with 16-45 , I am in a similar situation which one to pick for myself. I am opting towards Pentax just because it`s about US$ 100 cheaper than Sigma here in Canada and I don`t need macro. Also, Sigma is known for quality inconsistency so I agree with you, the best way to make a choice is to try both of them.

I just took a look at the lens roadmap, there is a new 16-50 lens coming up scheduled for march 2007.
It will be a constant aperture zoom at f2.8
Anybody care to take a guess on what the pricerange will be? The 16-45 is at 389 Euro's now.
Looking at Tamron and Sigma lenses in the same focal length range and with a 2.8 constat aperture they are around 400 Euro's.
Tokina is allso scheduling a [email protected] for march 2007, but I don't know if it will be available for Pentax.
Perhaps I'll wait and see what the price on the 16-50 will be before shelling out cash for the 16-45...

[edit] I just found another site that the 16-50 will be a new DA* lens with USM motor, it looks the same as the Tokina lens... Will these USM lenses work on the older bodies? Or are they exclusively for the K10D and upwards?
[/edit]

That would probably be a good idea waiting for that 16-50mm, but I am not sure about the price, IMO it will be much more expensive than 16-45........

I'm guessing its another Pentax/Tokina joint project. I am also interested if these lenses will work with the older bodies. I suspect the reason Power Zoom has been resurected on the K10D is to provide power for the SSM, so nothing in the consumer MZ or *ist series will be able to power the new motors (though perhaps the Z series will??), but will there be some sort of pass through to allow focus drive by the old method?

The Nikon USM lenses don't work with old Nikon AF bodys, but Pentax backward compatibility has always been a cut above Nikon so who knows.

But, Pentax backwards compatibility allways focussed on the bodies, not on the lenses.
People with a camera with a M42 thread couldn't use the K-mount lenses when they came out. The newer K-mount bodies could use M42 lenses through an adapter (has Pentax ever had a adapter by themselves?).
It could very well be a new step in the development, just like with the move from M42 to K-mount. I will not be surprised if the pre K10D bodies can't use the new lenses.

Making a lens with a USM motor and puting in the gears to make it work on an older body seems like a big effort and it will cost a great deal more I guess.

thats basically my line of thinking too. Still at least it will keep me from being tempted by the new lenses!

Oh and Pentax do (or did, I guess probably not anymore) make both M42-K adaptors and 645-K adaptors. My M42-K ring is a genuine Asahi Pentax item.

The thinking might well be that those who want DA* lenses probably have a K10D anyway, and they are probably right.

First, power zoom has not been fully resurrected. The power contacts are there for the new lenses, and the old PZ lenses can tap the power for the zoom motor, but the K10D body provides no functionality.

Second, it will be very interesting to see what Pentax do about backwards compatibility for the new lenses. There is an argument that says that the K10D is so cheap that anybody who can afford to buy the lens, will have no trouble paying for a K10D body. Therefore, there is no need to make it focus with older bodies.

We shall just have to see.

G

At some point, continually providing backwards compatability will become uneconomic and Pentax will be forced to draw a line in the sand somewhere. Sad but true I'm afraid.