[Guest]

Review just posted in DP Review

 

"diffraction-limited in lower half of range..."

 

Some autofocus difficulties however.  (not that surprising)

 

Tested in Canon mount

 

 

Pretty remarkable lens

[Guest]

Pretty useless, too. A sharp f/1.8  zoom lens that doesnt AF properly is a fascinating toy for tech-geeks but not really something for working photographers.  When I first heard about this lens I was excited. Now I  just shake my head. The fast aperture and the zoom range makes this lens suitable for documentory work, street and event shooting. Its just that I wont get any picture that isnt precisely focued through my agency and if  I cant make large prints  because the images are misfocussed its all a waste anyway.  For me a lens needs to be reliable to get The Shot. Time after time. Very often I dont get a second chance.

 

For landscape and travel I'd prefer a slower, smaller and lighter lens with image stabilization.

 

 Apart from lens collectors most photographers are probably better served with a 15-85 or 17-55 zoom plus a fast prime from the original manufacturers. More expensive but certainly more practical. (Unless you have very  special needs, of course. (Wide angle shallow dof photography, which requires zoom but no precise AF????)).

[popo]

I wonder how bad it really is in practice. I mean, compared to other fast primes. I've always had a bit of variation when working at particularly shallow depth of field, and if it is critical then it's out with a tripod and magnified live view.

[stevenb]

If someone is not satisfied with the AF he may try to improve the setups by using the USB-Dock.

Lenstip says: "When it comes to the accuracy of the autofocus, our assessment is very positive. The number of misses in studio conditions reached less than 4% which is a very good result. What’s interesting, most of these misses were registered at 18 mm."

 

Imho this lens is worth a try. Try means using it on your own camera not only reading about the lens.

 

Jenbenn, are you using APS-C cameras? I took a look at your fascinating pictures but didn`t manage to find some taken with the APS-C Sensor. If not the lens is indeed useless for you.

[Guest]

If someone is not satisfied with the AF he may try to improve the setups by using the USB-Dock.

Lenstip says: "When it comes to the accuracy of the autofocus, our assessment is very positive. The number of misses in studio conditions reached less than 4% which is a very good result. What’s interesting, most of these misses were registered at 18 mm."

 

Imho this lens is worth a try. Try means using it on your own camera not only reading about the lens.

 

Jenbenn, are you using APS-C cameras? I took a look at your fascinating pictures but didn`t manage to find some taken with the APS-C Sensor. If not the lens is indeed useless for you.

Hm, dpreview writes that the USB dock fixes the problem only partly. The lens still misfocusses  at distances between 0.5m and infinity because the USB dock software does not offer any calibration steps for distances in between.

 

 From experience I can tell you that AF misfires are the biggest detriment to good photos.  I once shot a Sigma 70-200 2.8. In the end I used it  only at f/5.6 or smaller because it was impossible to know if and when the lens would focus accuratly wide open. Your only chance was to shoot 5-6 photos and hope that one of those would be focussed correctly. Micro adjustment or Sigma-Service did not help as the degree of misfoucs greatly varied between focus distances and focal length.

 

This is why I recommend to people who shoot ouside a controlled studio environment to better go for the less stellar but more accurate lens rather than buy the "sharpest" one,  only to end up with unsharp photos because the lens does not focus properly in real life.

 

 Since I shoot only canon lenses I never had a misfocussed image that I couldnt blame on my own improper technique (one shot AF-mode only, of course). I am not a a brand loyal but this is just a fact.

 

 And yes, I still have an Aps-C Eos 50D (all of my Burma images have been shot on this camera). Nowadays I mostly use a 5D3, however.

[netrex]

I've read quite a lot good about it, and according to some Norwegian shops, it will come for Pentax (and Sony), even though it says only Nikon and Canon on the Sigma website. I will get it if it comes for Pentax, looks very promising, and will be very usefull I believe.

[JJ_SO]

The dock offers calibration at 0.3, 0.4, 0.6 and 4 meters for the 35mm prime. Can't imagine the software not offering the same for this zoom. And even if - what,s the problem? I'd use AF fine tuning of the camera, if that distance is critical, and do the rest via dock.


Haven't seen the 18-35 on my dock yet. I don't talk in terms of "pretty useless" before I had the lens in my hand, because I do find comments like that one pretty useless, to use a polite expression. Especially if the person in question doesn't even have a new Sigma lens with a dock, but is referring on old conventional stuff.

[stevenb]

Hm, dpreview writes that the USB dock fixes the problem only partly. The lens still misfocusses  at distances between 0.5m and infinity because the USB dock software does not offer any calibration steps for distances in between.

 

 From experience I can tell you that AF misfires are the biggest detriment to good photos.  I once shot a Sigma 70-200 2.8. In the end I used it  only at f/5.6 or smaller because it was impossible to know if and when the lens would focus accuratly wide open. Your only chance was to shoot 5-6 photos and hope that one of those would be focussed correctly. Micro adjustment or Sigma-Service did not help as the degree of misfoucs greatly varied between focus distances and focal length.

 

This is why I recommend to people who shoot ouside a controlled studio environment to better go for the less stellar but more accurate lens rather than buy the "sharpest" one,  only to end up with unsharp photos because the lens does not focus properly in real life.

 

 Since I shoot only canon lenses I never had a misfocussed image that I couldnt blame on my own improper technique (one shot AF-mode only, of course). I am not a a brand loyal but this is just a fact.

 

 And yes, I still have an Aps-C Eos 50D (all of my Burma images have been shot on this camera). Nowadays I mostly use a 5D3, however.

Well, i am not a professional photographer but try to improve my hobby. (Btw: Imho all the companies like Nikon, Canon, Sigma,... make most of their money with photographers like me and not with the professionals). For me the package sounds very good and i can live with 4% misfocusses at 18mm since i focus manualy most times and indeed shoot 5-6 fotos a time.  And what it makes easier for me: I don`t face any problems with any agency. 1.8 will give me a bright picture in the viewfinder of my D7000. We will see what Photozone will say to this lens while dpreview is for now the only source complaining about the AF of this lens.

[stevenb]

Hm, dpreview writes that the USB dock fixes the problem only partly. The lens still misfocusses  at distances between 0.5m and infinity because the USB dock software does not offer any calibration steps for distances in between.

The USB-Dock offers the opportunity to customize the speed of the AF to your needs: Faster AF more insecure and slower AF with less misfocusses. Choose what you need!

[dave9t5]

dpreview's "typical example" is a low contrast target (a white eye on a white statue) which is also tiny relative to the scene.  I don't think that this is a good example.  

 

On the other hand, like a lot of wide-angle autofocus lenses the focus throw on this lens is uselessly short.  From 2m to Infinity is only a degree or so of focus-throw: http://www.dpreview.com/lensreviews/sigm...ndview.jpg.  The dock or calibration won't help autofocus much in this range if the focus throw is so short!  



It's an inherent flaw in the Sigma and a lot of lenses and has little to do with AF accuracy.  Anything in this range is basically an autofocus crap-shoot or just defaults to infinity.


 

My Pentax DA14mm, DA15mm both had/have a frustrating short throw close to infinity, as did my Sigma 28/1.8.  I have had trouble focusing them accurately even manually sometimes in that rather large range from ~2m to Infinity.  My Pentax 18-135 also does not autofocus accurately at wide-angle.  With all these lenses, it's noticeable at f/2.8~f/4 and only gets worse at f/1.8.

 

(Weirdly, my Zeiss 25mm Distagon also has a stupid AF-like short throw from 2m to Infinity, despite having 360° of focus throw in it's range but never being available with AF).