Sigma 18-35 mm F1.8 Art = Bad experience..

Got the sigma 18-35 two days ago.
The store has 3 copies that i played
around with..the first one, right off the bat needs
adjustment (soft/out of focus in the center) but
sharp on the corners.

The second one was front focusing. The third one
is also front focusing but not as bad as the
second one. So I got the third one.

Went home, set up an subject with good contrast, optimum
lighting and proceeded to to the calibration..
Adjusted the micro focus on the 7D2 and ended up
at +17 on wide and +15 on tele.
It was spot on perfect sharp on that setting.

Then I decided to move back 1 meter more from the
subject (I was about 2 meters away when I did the
calibration) and all hell breaks loose... The thing
went out of focus again! Moved back to my
original 2 meter distance and it was back to being
sharp.. I was like What the Heck?!!

So went back to the store and asked to change to
a different copy, went home, did the test
again..still problems..though not the same
problem as the first one but still very inconsistent.

Went back to the store, changed to the last copy,
went home and tested again...and still had some
problems! Finally the store told me that I may
have to buy the usb dock to calibrate it properly.
I said no thank you and got my money back. I will
never touch that thing with a 10 ft pole again!!!

Yes its sharp and sucks in light but VERY VERY INCONSISTENT!
I am thinking sigma may have intentionally did this
to give customers reason to buy the usb dock because
there will be no reason to buy the dock if the lens works
as it should right out of the box.
To be honest, I wont really mind paying for the dock,
the thing I dont like is spending more time to learn and
calibrate the lens via the dock.


And by the way, I have a 70-200L IS II, 85L, 50L and Zeiss 1.4/35
that I have been alternating during the test and are all spot sharp on the 7D2.

*rant mode off*

Cheers

tma-888 wrote in post #17408690
To be honest, I wont really mind paying for the dock,
the thing I dont like is spending more time to learn and
calibrate the lens via the dock.

What's there to learn? You calibrate the lens with the dock and same way you do in body mfa. Only difference is now you get several differnt adjustment (4) for several focal length (4).

Still, sucks that you had a bad experience with it. It's a truly amazing lens but bad copy's do happen.

Never owned a Sigma lens so far.

A question: will the dock work for all Sigma Art lenses? It'd better be. Nobody wants to buy one dock per lens.

l89kip wrote in post #17408716
Never owned a Sigma lens so far.

A question: will the dock work for all Sigma Art lenses? It'd better be. Nobody wants to buy one dock per lens.

Yes, the dock works with all of their new lenses. Art, sport, and contemperary.

Thanks. May try Sigma in the future. I am thinking of the 150-600 for reach. But Canon 100-400II is problem.

tma-888 wrote in post #17408690
Got the sigma 18-35 two days ago.
The store has 3 copies that i played
around with..the first one, right off the bat needs
adjustment (soft/out of focus in the center) but
sharp on the corners.

The second one was front focusing. The third one
is also front focusing but not as bad as the
second one. So I got the third one.

Went home, set up an subject with good contrast, optimum
lighting and proceeded to to the calibration..
Adjusted the micro focus on the 7D2 and ended up
at +17 on wide and +15 on tele.
It was spot on perfect sharp on that setting.

Then I decided to move back 1 meter more from the
subject (I was about 2 meters away when I did the
calibration) and all hell breaks loose... The thing
went out of focus again! Moved back to my
original 2 meter distance and it was back to being
sharp.. I was like What the Heck?!!

So went back to the store and asked to change to
a different copy, went home, did the test
again..still problems..though not the same
problem as the first one but still very inconsistent.

Went back to the store, changed to the last copy,
went home and tested again...and still had some
problems! Finally the store told me that I may
have to buy the usb dock to calibrate it properly.
I said no thank you and got my money back. I will
never touch that thing with a 10 ft pole again!!!

Yes its sharp and sucks in light but VERY VERY INCONSISTENT!
I am thinking sigma may have intentionally did this
to give customers reason to buy the usb dock because
there will be no reason to buy the dock if the lens works
as it should right out of the box.
To be honest, I wont really mind paying for the dock,
the thing I dont like is spending more time to learn and
calibrate the lens via the dock.


And by the way, I have a 70-200L IS II, 85L, 50L and Zeiss 1.4/35
that I have been alternating during the test and are all spot sharp on the 7D2.

*rant mode off*

Cheers

What aperture were you adjusting at? Wide open there are occasionally AF inconsistencies which are usually resolved by f/2.8. Your inconsistency problem seems much worse than the norm. Since Sigma's AF for Canon is reversed engineered I've found the same lens can have a varied performance from body to body. Adjustments to inconsistent AF performance, if it varies depending on the aperture, is usually not completely correctable either by the camera's MFA or the Sigma USB dock. I get very good but not perfect AF consistency with my copy on my 60D, but AF on my t2i and T3i is much more inconsistent. Of course AF is usually dead on with Liveview, and of course there is always Sigma's silky smooth manual focus ring. The end result is superb sharpness and color rendition with minimal distortion across the image even wide open. For me the results are well worth the the occasional frustration and extra effort. I really don't think it's a plot by Sigma to force you to buy a $50 dock.

I don't understand why people would bother attempting to fix a bad lens, let alone spending more $ on a dock to fix a lens that should've worked out of the box.

I've owned dozens of Canon glass and have never had an issue with accurate focus. Maybe I'm just lucky, but the handful of Sigmas I've owned all had focus issues. Tried MFA and it's just a crapshoot. Fix focus for one distance, all other distances goes wonky. It's awful.

I'll attribute my luck to only buying from reputable sellers with good return policies.

The only Sigma lens I have is the 120-300/2.8 Sport, and without the dock it would be un-usable. Calibrating it with the dock was a significant PITA, but as there is no alternate lens to the 120-300/2.8 in specification, I put up with it.

In general I buy only Canon lenses, and they work with less screwing around. That said, I have some level of MA dialed in on both bodies for just about every Canon EOS lens I own. But it is interesting to me that I've gotten nearly all of my Canon lenses working with the rudimentary MA available in the Canon bodies.

All but the 135L that is. That was one Canon lens I owned that could not be corrected with MA. It had to go to Canon for service to be accurate.

JeffreyG wrote in post #17410951
The only Sigma lens I have is the 120-300/2.8 Sport, and without the dock it would be un-usable. Calibrating it with the dock was a significant PITA, but as there is no alternate lens to the 120-300/2.8 in specification, I put up with it.

In general I buy only Canon lenses, and they work with less screwing around. That said, I have some level of MA dialed in on both bodies for just about every Canon EOS lens I own. But it is interesting to me that I've gotten nearly all of my Canon lenses working with the rudimentary MA available in the Canon bodies.

All but the 135L that is. That was one Canon lens I owned that could not be corrected with MA. It had to go to Canon for service to be accurate.

Since you put it that way; Who else has a 18-35mm, 1.8? Thats why I put up with it.

jmai86 wrote in post #17410637
I don't understand why people would bother attempting to fix a bad lens

There is a big difference between a "bad lens" and a lens that needs AF adjustment.

I've used canon L series lenses that have been out of focus (front or back focusing) with my body but dead on with the person's body that I was borrowing it from. Third party lenses will always run a larger risk of focus inaccuracies since the AF is reverse engineered. But AF issues can happen with any body/lens combo. That's just the nature of a body and lens being "with-in calibration limits". Lens rental has a couple very good articles on body and lens variation.

I'd say the 18-35's that tam-888 tried were bad. I didn't try them myself but if what he is saying about them is true then I'd say they were bad. My 18-35 was misfocusing on my camera. I adjusted it and it is now accurate and sharp with fast AF. So I would not consider that a bad lens. The 50L and 135L that I used that were misfocusing were also not "bad lenses". They needed adjustment but since my body doesn't offer mfa and canon doesn't have a usb dock I was sol. So yes the sigma usb dock is an extra $25, but I'm glad they offer it and I wish canon offered one was well (as you get multiple adjustment with the dock).

gremlin75 wrote in post #17411064
There is a big difference between a "bad lens" and a lens that needs AF adjustment.

I've used canon L series lenses that have been out of focus (front or back focusing) with my body but dead on with the person's body that I was borrowing it from. Third party lenses will always run a larger risk of focus inaccuracies since the AF is reverse engineered. But AF issues can happen with any body/lens combo. That's just the nature of a body and lens being "with-in calibration limits". Lens rental has a couple very good articles on body and lens variation.

I'd say the 18-35's that tam-888 tried were bad. I didn't try them myself but if what he is saying about them is true then I'd say they were bad. My 18-35 was misfocusing on my camera. I adjusted it and it is now accurate and sharp with fast AF. So I would not consider that a bad lens. The 50L and 135L that I used that were misfocusing were also not "bad lenses". They needed adjustment but since my body doesn't offer mfa and canon doesn't have a usb dock I was sol. So yes the sigma usb dock is an extra $25, but I'm glad they offer it and I wish canon offered one was well (as you get multiple adjustment with the dock).

Unfortunately sometimes the Sigma AF issues are dependent on which aperture you are using. At f/8 my 18-35 achieves sharp focus almost all the time. At f/1.8 to f/2.2 the percentage of hits varies with the size of the subject, the lighting and the contrast. Unfortunately the dock can't resolve those issues. Its 16 adjustments are for four focal lengths at four distances. You can't adjust anything to compensate for inconsistent AF at wide apertures.

Am I the only person with a good 18-35?

I shoot most of the time at f2 in various lighting situations and it only misses focus on a shot or two. Misses about the same as my canon lenses.

gremlin75 wrote in post #17411242
Am I the only person with a good 18-35?

No, but people with trouble make the most noise.

Sirrith wrote in post #17411310
No, but people with trouble make the most noise.

Well, isnt that the purpose of forums like this? To share experiences and knowledge about
products that SEEM to be good but are actually LEMONS?

So That The People Will Know!

Not really. The purpose of forums like this is to discuss photography. Only one of the minor aspects of photography (or even in the context of specific sub-forums such as this) is documenting problems with equipment.

Of course, it's useful to have this sort of discussion for later research but if we only talked about the negatives of any gear it'd be a really boring negative community.