Cosina 19-35 vs. Sigma 18-50

[mikekiwi]

Currently I'm owning a Sigma 18-50 DC lens to go with my D60. Today I was offered to buy a used Cosina 19-35 lens (don't know the price yet). Does anybody has experience with both lenses? Will the Cosina be an upgrade to the Sigma (wich is not that bad, but does show some CA and barrel distortion). I know it is still not a 17-40L, but still saving money for that one

Is it wise to go for this lens or should I stay with the Sigma?

Thanks,
Michael

[RichardtheSane]

Never had the Sigma, but I did have the cosina.
I hated the amount of post-processing I needed to get a sharp image.
I NEVER shot wide open. Below is a typical sample from this lens (sorry about filesize, didn't want to compress too much) shot with 10D at 1/100th sec @ f5.6 on a tripod.

First image is a 100% crop, second image is there to give an idea of distortion,

Finally at the bottom is a link to the image as it came out of the camera, but that is a full size large/fine jpeg at about 3Mb





http://www.richardlindley.co.uk/imag...fftop_0026.JPG

Hope this helps

[Mark Kemp]

I have the Cosina too, mine is not as bad as Richard's samples, but it is not brillaint either.

I just bought the Canon 17-40 and that is much better, but of course it is 3 times the price!

Never tried the Sigma 18-50. The 15-30 has pretty good image quality, somewhere between the Canon and the Cosina, but it is large and I find the handling a bit awkward. Some Sigmas require you to pull the focus ring and switch the switch to go from manual to auto, which can be a pain. I am not sure if the 18-50 is like this or not.

I guess lenses are like a lot of things - you get what you pay for, but of course the last 10 percent of the quality costs most of the money.

The Cosina is a reasonable budget lens, I would expect the Sigma to be better but cost more and the Canon to be better still and even more expensive.

I guess it depends on how much you have to spend, how much you will use the lens and what kind of quality you are prepared to accept.

[mikekiwi]

Thanks for the info and the sample picture (great Richard, just what I wanted to see). I've decided not to take the lens and continue using the Sigma until I find a lens which is really an upgrade...

Cheers,

Michael

[RichardtheSane]

No problem. I think you have made a good choice.
Out of interest, how does your sigma compare?

[mikekiwi]

Well Richard,

the Sigma lens performed at least as good as the Cosina for what I could see. The Cosina looked very soft to me on almost every picture I saw, while my Sigma sure is very soft wide-open at 50mm, but overall it's a pleasure to use. There is some barrel-distortion at 18mm which maybe more that at the Cosina (hard to compare as pictures did differ a lot).
The barrel distortion is relatively easy to decrease with Panotools in PS, after editing in PS, it's very acceptable.
Please note that I made a city-trip and shot a lot of pictures of buildings at 18mm, and those are the situations, the distortion is most visible.
In everyday snapshots etc. you can hardly notice it.

There were some complaints of heavy CA with the Sigma, but I can't find it, while my Oly C40 did show some CA on the same trip....

I think the Sigma is well worth it's money, in the future I'll certainly do an upgrade, but for now it's o.k. to use it...

Cheers,
Michael

[RichardtheSane]

It certainly seems to me that you have the better lens.
I would definitly place the quality of any sigma I have owned over this.
Strangly though the cosina looked fine on slide film

I now use the 17-40L and that is a very good lens, and also a lot of lens for the money. When you are ready to upgrade that lens is well worth considering