Sigma 30mm f/1.4 HSM Art and Sigma dock

I just received my Sigma 30mm f/1.4 HSM Art lens, and I have never seen such flaky AF performance. WIth my 7D, on a tripod, with a cable release, shooting a high-contrast focus target, its AF is all over the place, hitting focus one time and front focusing by inches the next. I tried to use standard methods to adjust AF, but it is so inconsistent that it is impossible to determine performance at any MA setting. I also tried the Dot-Focus method, which usually works great, but it failed to achieve solid focus over the entire range of -20 to +20.

There are reviews of this lens where the reviewers reported similar behavior, and had to use Live View to focus for their tests. They indicated that the Sigma USB Dock solved the problems and ended up giving the lens a great review. If the lens is as good as many say, I don't want to give up on it. On the the other hand, I don't want to spend another $60 for the dock if I should be returning the lens instead. I am wondering if anyone here has had similar issues with this lens, and if they tried the USB Dock. Thanks.

EF 35mm f/2 IS USM. Same price as the Σ30 1.4 with dock. Major difference: it works.

if you just bought it, you can ask the retailer to fix it under warranty or something. They might be able to fix it without forcing you to buy the dock.

Don't hesitate, Return it for another.

Heya,

I bought that lens and dock. I sent it back too. I tried to fix the focus with the dock. You certainly can. It's an amazingly sharp and well built lens. But the focus issues from Sigma are a pain--which is why the dock was even made, they recognize it obviously and it's a nice tool to have regardless as not all cameras have built-in MFA. But, that said, I tried to fix mine's focus issues and I could never get it 100%, not even 90% there. I'd get 2 out of 4 of the focus ranges focusing right, then when I tried to get that 3rd and 4th, I just couldn't get it and the other 2 would start to not focus well anymore either. It's just a pain.

So I sent it back and got the Canon EF 35mm F2 IS.

I'm completely happy with the 35mm F2 IS.

Very best,

Before you return it, do an experiment please, I'm curious to see something...

Use an off-center AF point on your 7D and test it that way. Also, test it with your XT too.
I'm curious about the results. There may be a slim chance that your 7D, similarly to many other 7Ds in the past, gives very inconsistent results with certain fast primes AND center single AF point.

Of course, that doesn't mean that if the off-center points perform better, you can keep the lens, since obviously the combo isn't capable of good AF results. But just the heck of it, try those off-center points.

gabebalazs wrote in post #16738379
Before you return it, do an experiment please, I'm curious to see something...

Use an off-center AF point on your 7D and test it that way. Also, test it with your XT too.
I'm curious about the results. There may be a slim chance that your 7D, similarly to many other 7Ds in the past, gives very inconsistent results with certain fast primes AND center single AF point.

Of course, that doesn't mean that if the off-center points perform better, you can keep the lens, since obviously the combo isn't capable of good AF results. But just the heck of it, try those off-center points.

Thanks, Gabe. I will give that a try before sending it back and post the results It won't be until tomorrow, though. The EF 35mm f/2 might be where I end up.

Are you testing it under fluorescent/artificial light?

With my Sigma 30 (non-ART) on the 7D I had trouble under fluro lights. I think it was inconsistent because it depended on where in the 50/60Hz AC cycle the fluro light was, probably a different wavelength or something, and the AF would shift all over the place (you'll notice focusing scales on lenses different for IR versus visible light etc).

I think it happens with all lenses but is particularly noticeable with fast lenses, which is not unusual.

Using AF-assist (speedlight) or shooting in natural light I had consistent AF.

phreeky wrote in post #16738474
Are you testing it under fluorescent/artificial light?

With my Sigma 30 (non-ART) on the 7D I had trouble under fluro lights. I think it was inconsistent because it depended on where in the 50/60Hz AC cycle the fluro light was, probably a different wavelength or something, and the AF would shift all over the place (you'll notice focusing scales on lenses different for IR versus visible light etc).

I think it happens with all lenses but is particularly noticeable with fast lenses, which is not unusual.

Using AF-assist (speedlight) or shooting in natural light I had consistent AF.

Interesting thought. All of the lights in both rooms that I tested this in have fluorescent lights. I don't know if I have any incandescent lights anywhere. When the weather clears I will try it outside in natural light, and I will see what happens with AF assist as well. With so few incandescent lights these days, it would be a shame if a 1.4 lens needs flash for interior shots.

I recently was focus testing that combination also, Sigma 30mm Art with 7D. I didn't have any of those focusing issues you're experiencing. I did it in my kitchen when there was lots of natural light coming in the windows though. I also got the dock, mainly for the T2i since it doesn't have MF capabilities. I put a white box behind the focus target so the background wouldn't have any contrasty subjects to focus on other than the target.

MalVeauX wrote in post #16738369
Heya,

I bought that lens and dock. I sent it back too. I tried to fix the focus with the dock. You certainly can. It's an amazingly sharp and well built lens. But the focus issues from Sigma are a pain--which is why the dock was even made, they recognize it obviously and it's a nice tool to have regardless as not all cameras have built-in MFA. But, that said, I tried to fix mine's focus issues and I could never get it 100%, not even 90% there. I'd get 2 out of 4 of the focus ranges focusing right, then when I tried to get that 3rd and 4th, I just couldn't get it and the other 2 would start to not focus well anymore either. It's just a pain.

So I sent it back and got the Canon EF 35mm F2 IS.

I'm completely happy with the 35mm F2 IS.

Very best,

I'm also looking for another prime (Sigma 30mm 1.4 Art or Canon 35 F2 IS) but not sure which one. How does 35 f2 performs in low light? Is it good for group shot i.e 4-5 people? Would it be fast like the 85 f1.8? Would there be big difference between 40 and 35mm? Planning to buy in a month or 2 for coming vacation..

robienyshe wrote in post #16739000
I'm also looking for another prime (Sigma 30mm 1.4 Art or Canon 35 F2 IS) but not sure which one. How does 35 f2 performs in low light? Is it good for group shot i.e 4-5 people? Would it be fast like the 85 f1.8? Would there be big difference between 40 and 35mm? Planning to buy in a month or 2 for coming vacation..

Heya,

I use my 35 F2 IS for everything, it's my go to primary lens. Does very well in low light. Nails focus every time for me. I can do handheld shots at 2 seconds with it even, with it's generation of IS. It's just a phenomenal lens. Very sharp. Great contrast. Great color. It's wide enough to do group shots, we did it at Christmas. It's fast like the 85 F1.8. I use the 35mm F2 IS and 85mm F1.8 the most, they are my two main primes. There's not a massive difference between the 35mm and 40mm in terms of field of view, it's minor. But there is a difference in depth of field control, sharpness, IS performance, etc. The 40mm is a great travel lens. But it's a whole stop slower, and it doesn't have the same image quality as the 35mm. Comes down to budget. I still pick the 35mm even at more than twice the cost, it just performs so well, without the `L price tag (and frankly is as good, if not possibly a bit better, than the 35L... bring the flames).

Very best,

mnphotos wrote in post #16738973
I recently was focus testing that combination also, Sigma 30mm Art with 7D. I didn't have any of those focusing issues you're experiencing. I did it in my kitchen when there was lots of natural light coming in the windows though. I also got the dock, mainly for the T2i since it doesn't have MF capabilities. I put a white box behind the focus target so the background wouldn't have any contrasty subjects to focus on other than the target.

My target was pinned to a totally blank wall. Nothing there but the target.

gabebalazs wrote in post #16738379
Before you return it, do an experiment please, I'm curious to see something...

Use an off-center AF point on your 7D and test it that way. Also, test it with your XT too.
I'm curious about the results. There may be a slim chance that your 7D, similarly to many other 7Ds in the past, gives very inconsistent results with certain fast primes AND center single AF point.

Of course, that doesn't mean that if the off-center points perform better, you can keep the lens, since obviously the combo isn't capable of good AF results. But just the heck of it, try those off-center points.

Gabe,

I did have a chance to try it again, using the Dot-Tune method (http://www.youtube.com​/watch?v=7zE50jCUPhM). I got flaky results with the center point again (although different flakes than yesterday), so I tried an off-center AF point. I thought that might be it, as the behavior of the AF was much more systematic at first. However, upon rechecking the results it started to indicate that the settings that had achieved focus a few minutes earlier were no longer achieving focus. So much for that. I just don't have any way to check the focus accuracy or make logical adjustments to the focus at this time.

I haven't had time to try the XT yet, but I have no intention of using it on the XT, so I just may not.

We will be visiting the grandkids this weekend, so I might take a slew of indoor shots to see how it behaves. If it can't work consistently indoors, there isn't much point to having it.

I don't seem to be able to do AF alignment operations on mine, even :/ must be a compatibility issue with Windows 8.1 as it wasn't even detecting the connected lens until I ran it as an administrator.