AF problem with D200 + Sigma 30/1.4

I have had my D200 and the Sigma 30/1.4 for a while now. It's my favourite lens

but there is a curios problem I never read or heard about elsewhere. Focussing

is only accurate when I use the AF sensor in the center. Switching to any of the

other AF sensors results in front focus. Nikon checked the D200's AF and today I

received the lens back from Sigma Japan but the problem persists. Now that I

have a Katz Eye focusing screen installed I can correct focus manually thanks to

the Sigma's HSM drive but I find it quite peculiar. Has anyone had a similar

problems and was there a solution or at least an explanation? The Swiss Sigma

distributor wont exchange the lens since it passes their test procedure (which

involves only the central AF sensor).

Sigma have a history of there lenses not being totally compatible with Nikon camera's. I bet Nikon are not so upset about this situation.

From what Ive read, Sigma reverse engineers Nikons technology rather then buying the rights to it. Because of this some of sigmas lenses arent always 100% compatable especially when Nikon comes out with a new body.

 

Sigmas flashes also have problems with the D200. And many of thier HSM lenses wont autofocus with the D200 when you use the AF button on the grip or body, but work fine when you push the shutter release to focus.

I've now gone through 3 different D200's and I've had problems with AF on each of them. I've had my recent camera into Nikon 4 times, and they say there isn't a problem, but it's obviously back focusing. They suggested that I shoot at f9, and that would solve the problem. Well of course it will... I've also had it into 3 different stores and had them do test shots and they came up with the same results as me. They offered to trade it on a new one but after going over 3 different bodies we couldn't find 1 good one.

I know there are a lot of people out there that love this camera, myself... I'm not too impressed!

 

FFHamilton<div></div>

sorry I should have given more info... that's the tech taking a picture of me at nikon... 100% crop, he says it's sharp... but like all of my shots taken under 24mm it's both out of focus and soft!

Ryan

When I first got the Sigma 30mm (used) I was getting severe backfocus with all sensors on

my D200. I sent the lens in for service and when I got it back I was getting much more

reliable autofocus performance, although I do sometimes have slightly different results

between the centre and other sensors. I do use the centre one about 75% of the time anyway

and as a cross type sensor it's more sensitive as well, so the fact that the other sensors can

sometimes backfocus very slightly doesn't really bother me too much. If i'm using a sensor

other than the centre one and the focus indicator says I'm in focus, usually a second half-tap

of the shutter will settle the lens into proper focus.

This is an interesting issue. I shot

<a href="http://www.photo.net/photo/5687870">this</a> with the exact same combo. In fact, I've used the 30 f1.4 & D200 very often in

<a href="http://www.sportsshooter.com/tsoi/uwvsucla2007/">past couple months</a> as a second body and had been happy with it. It's best to select center AF point with group dynamic (passing off focus point to neighboring AF points.) The only issue I know of is that the lens will not allow AF-ON focus (focusing with AF-ON button and fire shutter separately) in which Sigma made announcement (search dpreview.com for detail) and offer fix.

You might try my fix for a Sigma 500 mm lens that works on every Nikon body except the D200. On the D200 I have to move the aperture ring as far past the smallest setting (f22) as possible and tape it into that position --- that being done, the lens works fine.

forgive my ignorance (again), but what is backfocus?

I have the 70 200 F2.8 HSM Sigma lens and it is in for service right now for back focusing. The head technicion told me that they sometimes need to reprogram the lens to get it to work in sync with the cameras AF sensor because there is a .5 mm tolerance(I have no idea what that really means). They wanted me to send my D200 in with it, but I did not want to because every other lens works fine on the camera, and the Sigma lens didn't focus right on any of the 3 cameras I tried it on. To me, the entire point of having a heavier, fast aperture lens, is that you plan to use it aty the wider aperture settings. If focus can not "fall within the tolerence" unles you stop way down, I might as well have some compact 4.5-5.6 lens.

 

I just bought a used 80 200 Nikkor f2.8 two touch lens, and it focuses spot on even at 200mm and f2.8. Its noticeably sharper than the Sigma at the long end and wider apertures, and has better color, and I also noticed the exposures were more accurate and more consistent. I have had some good Sigma lenses in the past, but am hesitant to try another at this point on these new "computer/cameras". I have a feeling that as some have said, compatibility problems are due to reverse engineering the interface with the Nikon cameras. They get in 90% right-and it shows up on the fast lenses. I'll report back if they actually fix the lens.

FYI, the latest firmware for the d200 fixes the focus with AF-ON issue. At least for the 30/1.4 anyway. That's the only sigma lens I have.

 

Prior to that, you could send it in to sigma and have it chipped for free. Not a bad deal, in my opinion, and maybe not worth complaining about the manufacturer in public forums over. Recall that this lens was designed before the d200 existed. It's even better that nikon essentially produced a fix for third-party lenses.

 

As far as the af sensor issue, I don't think the center and sides can be independently adjusted, can they? Are you sure it's not an issue of cross vs. single-line sensors, i.e. does this happen in a tripod shot of a test chart in decent light?

Thanks for all answers. The 30/1.4 is a "G" lens, no aperture ring. The lens has the latest firmware & the D200 has firmware version 2.00. The Swiss Sigma distributor had both, lens & camera but couldn't find a problem (of course they're only testing the central sensor...). I have no AF problems whatsoever with my other lenses. I can even focus the 50/1.2 accurately wide open.

 

Yes, the problem is very peculiar. Most of the time I use focus-recompose anyway & now that I have the KatzEye screen it's even less of a problem but still... sligthly annoying...

andy: yes, it does happen on a tripod with a focus test chart, unfortunately. otherwise it might just have been my technique, but it isn't.