Grr... Sigma 30mm

I just switched from an XSi to a T2i and now my Sigma 30 is front focusing again... It's off by about 1cm @ MFD. At 1m it's off by more like 2cm.

This lens has already been in once (right after I bought it). I know that this is an argument towards getting the 7D (or any body with micro-adjustment), but seriously Sigma, what is wrong with you? Micro-adjustment shouldn't be needed on a brand new lens and certainly shouldn't be needed on a lens that has already been serviced and has spent most of the time since that service sitting on the shelf.

Now I'm going to have to be without my new T2i for a week while Sigma tinkers with it...

Did you send the XSi in with the 30mm when you had it calibrated originally? If so, it's possible the XSi was slightly off and they calibrated the lens to match the body. If not, then the T2i is probably slightly off.

Sounds like its a body-problem..

Yes, the XSi went in with the 30mm the first time.

I've got a friend with a Sigma 30mm and his was never calibrated. His is dead on with his XSi, my XSi, and my new T2i, so I'm fairly certain that it's not either of my bodies. It's just Sigma's crappy quality control.

You should be saying " DANG CANON" not grr Sigma

jasonlitka wrote in post #9714621
Yes, the XSi went in with the 30mm the first time.

I've got a friend with a Sigma 30mm and his was never calibrated. His is dead on with his XSi, my XSi, and my new T2i, so I'm fairly certain that it's not either of my bodies. It's just Sigma's crappy quality control.

DO you still own both camera bodies?

I think there is still a tolerable margin there with your cameras and that is normal. The fact that it is calibrated for the XSi, that means there is a difference between the said XSi with your T2i otherwise the lens would be in focus. So there is a slight difference between your cameras unless the lens calibrated it back to front focusing on the shelf.

midnight_rider wrote in post #9714642
DO you still own both camera bodies?

Yes, both are sitting here in front of me. The 30 is still reasonably accurate at MFD on the XSi (looks to be off by a couple mm on the focustestchart.com test, vs. 10mm for the T2i). As I said though, I also just tested a friend's 30 and his is dead on for both my XSi and T2i.

That says to me that there's something off with mine.

Just got a response from Sigma. Sending the lens & T2i out today. They're in NY and I'm in PA, so hopefully we can get this wrapped up by the middle of next week.

focusing on the nose will lead to the eyes being in focus...

Sorry to hear about your siggy. Have fun with the super-rebel!

jasonlitka wrote in post #9721159
Just got a response from Sigma. Sending the lens & T2i out today. They're in NY and I'm in PA, so hopefully we can get this wrapped up by the middle of next week.

Are you Keeping both cameras? If so I hope that they do not throw of the calibration of the first one by tuning the lens to the second one.
I hope everything comes back as sharp as a tack for you

I am thinking of sending my Sigma 30 off at the end of the month to get calibrated, its soft at 2.0 and wider. If I send my body with the lens, is there a chance my other lenses might not focus as well as they do currently?

Makes me appreciate my MA feature all that much more.

slm95 wrote in post #9722135
I am thinking of sending my Sigma 30 off at the end of the month to get calibrated, its soft at 2.0 and wider. If I send my body with the lens, is there a chance my other lenses might not focus as well as they do currently?

If you're pixel peeping you'll always notice that the 30 is slightly softer at 1.4 than 2.0; in relative (to other lenses) terms, yes, this lens is sharp wide open, but all lenses sharpen up a bit stopped down from their widest aperture setting.

ImRaptor wrote in post #9722169
Makes me appreciate my MA feature all that much more.

Exactly.. All my lenses are sharp on my 20D but some were so-so on my 50D.. AF Micro adjustment saved the day..

Usually it's not the lens or camera alone but the combination of the two..