Sigma 30 1.4 Backfocusing

G-day people,
Few days ago I've bought 30 1.4 and to my disapointment it FRONTFOCUSES. So I've got unlucky too, like many other users of this lens. I had yesterday session with model, I shot tethred and I've seen that focus is not 100% but continued using this lens thinking I would be able to pull extra focus in pp. I have about 200 images and silly to say, but 90% of the shots are made with 30 1.4. I don't really know what the hell I was thinking (probably - that doesn't happen to me). I was doubting my focus and recompose technique, then I've tried to choose the closest focusing point... Still no luck. I also had weird thoughts about extra shallow DOF at f9? Now, you all know how it goes when it doesn't go good, you start thinking silly (but still keep shooting with that prime, although you have all of your arsenal nearby - fight with a devil). Anyway, I'm calling shop tomorrow morning and hoping to bring the siggy in the afternoon there. In 5 weeks I'm going for vaccation, and I really need this lens for some portraits, otherwise it will proove to be wrong invesment in the wrong time. I still have nifty, and what I discovered to be stellar for head shots sigma 150 ex macro, plus all of the zooms. Whish me luck, and here are the proofs.

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I had to return this same lens 4 times for this problem and never got a good copy!!! Then I finally decided to go with a Canon 35L. After using it, I don't know why I didn't just buy the Canon to begin with.

I had a copy of this lens. Mine was even worse than that !

It had a focal plane that wasn't paralel to the sensor ! If I took a shot of a wall perfectly straight, the left hand side of the frame would be in focus and the right hand side would be slightly out. Every shot.

I thought that if Sigma could get it THIS wrong in the first place, there was no point sending it back to them to fix it. I sold it and now (eventually) own the 35L. Like Richard said, I can't believe I didn't just go for the best first.

Gary.

Trust me, I would have gone for L, but currently I am in need for that lens range with limited budget. I really like sigma, I own 3 of them and planing buying 24-70 also from them. I have no L fever, but if I had budget, I would certainly buy Canon in 95% of the cases.
Did anybody got this lens back fixed (recalibrated) from sigma with good results?

I had the Sigma for a week or so. Mine front focused far worse than that on subjects further than 6 feet. (like 2 feet misfocus).

I exchanged it for the 28 f/1.8 and have been very happy with it.

I don't want to sound like a chronic Sigma-basher, but I'd advise against the 24-70 EX. I've had one for a couple of months and I'm selling it as soon as possible. Horrible focusing. Slow, noisy, in-accurate (really hit-and-miss). Really bad resistance to flare. Very pronounced distortion at 24mm.

Erm . . . sorry.

Gary.

It's sharp, though . . .

So far no positives
I've checked invoice, I can return it in 8 days, so I'll give a try to another copy, otherwise...

Let me explain how horrible my 4 copies were... I would use center af to take a photo of the car across the street from me ( from where I was sitting, the mail box on my side of the street was about 1 foot to the left away from the car across the street). This was done to test the backfocus of this lens. Later when I looked at the photos, my mailbox on my side of the street was sure enough in focus and the car was completely out of focus! This test was done 5 times. *sigh*

a sigma lens with front focussin problems- surely not!!!!!!!!!!!!!!! lol!!
Only kidding- i guess the downside of sigma lenses is the poorer build quality and the higher number of faults- if you want the convenient price tag it looks as though you have to bounce them back to the factory until you are satisfied- something that is far easier than here in the uk.
There are alot of members here that are delighted with their re-calibrated sigma 30mm- the results are impressive, depends how much efforts you want to go through.

I'm kinda newby here--but I have this lens and I have not really experienced that unless I am extremely close to subject and on f/1.4. What is the best way to test for back or front focusing issues? I can see where the hat and the dress above are a bit sharper than the face, but with women, don't you want to soften the face focus a bit anyway? I think it could be sharper than it is though. It doesn't seem proper than so many would be bad, could it be camera communication with the lens?

vladnl wrote in post #3205023
Did anybody got this lens back fixed (recalibrated) from sigma with good results?

I sent mine in about 1.5 years ago for a quick AF adjustment and it's perfect now. Assuming the tech knows what he/she is doing, it should only take one service trip. Here is how a properly-focusing/normal-functioning 30EX compares to the 35L:

http://www.pbase.com/l​ightrules/30v35_1st
http://www.pbase.com/l​ightrules/30v35_2nd

and to the 28f1.8:

http://www.pbase.com/l​ightrules/28v30

No reason to get the 35L for a 1.6x body.

The focusing on this particular lens is so erratic it can't ever be relied upon.

jfb318 wrote in post #3206245
The focusing on this particular lens is so erratic it can't ever be relied upon.

And looking at your sig, I'm sure you're very objective FWIW, AF with mine is about as good as it gets for an f1.4.

I don't know if sigma send all the bad problem copy to US/UK. In Japan all of my friends or I know using 30mm f1.4 (canon, nikon and sigma mounts) got a good copy.
I agree with lightrules, no reason to get the 35L for crop cameras. Unless the cost doesn't matter to you.

I guess if you have a bad copy the smart thing to do is to get it calibrated instead of going through copies with this lens.