f 1.4 Driving me nuts!

ive tried various large aperture lenses: 3 copies of canon 50 1.4, my current 50 1.2, and a sigma art 35 1.4 and have many other lenses. I have the most problems with autofocus with the large aperture primes. All my other lenses focus far more accurately. And for me it's not a dof problem. Sometimes it will focus consistently one way. Then in other conditions focus a different direction consistently.

I think such lenses seem to be prone to af problems. Especially when dark. And of course ironically that's what I need them for.

My normal procedure now is to do a test shot wherever I go with one of those lenses and do some quick micro adjustments before using the lens.

Thanks for all the advises guys, I have found a way of getting around this lens. But I worry it might damage its focusing system. After attaining focus, I will turn the ring slightly (shutter button still half pressed) to make the lens motor make a little adjustment in focusing. If Im doing this, it gives me very good results even at 1.4. Can I ask you guys if this is friendly to the lens af system? Manual focusing with half pressed shutter button is also great but is only good (at least for me) for non moving subjects.

The lens has improved its consistency a little. I'm starting to think that it gets better as it gets used frequently, lubricating perhaps? Just like a car wherein you have to do a break-in for a period of time before using it for a fast speed and long drive? Just my speculation.

Jiggo0109 wrote in post #17215503
Thanks for all the advises guys, I have found a way of getting around this lens. But I worry it might damage its focusing system. After attaining focus, I will turn the ring slightly (shutter button still half pressed) to make the lens motor make a little adjustment in focusing. If Im doing this, it gives me very good results even at 1.4. Can I ask you guys if this is friendly to the lens af system? Manual focusing with half pressed shutter button is also great but is only good (at least for me) for non moving subjects.

The lens has improved its consistency a little. I'm starting to think that it gets better as it gets used frequently, lubricating perhaps? Just like a car wherein you have to do a break-in for a period of time before using it for a fast speed and long drive? Just my speculation.

is this the new art version or the old one? if it's the old one, I say you either send it to sigma to be fixed or just return it. if it's the art, you should try the dock first.

as for whether what you're doing would damage it... I dunno... but it sounds like the weirdest "fix" I've ever heard. no need to do so much to get it to work right. just get it fixed.

turning the ring will not damage the lens after focus is done. it has the HSM focus motor with full time manual focus so its built to be able to do that.

Jiggo0109 wrote in post #17212109
oops... Im sorry, its the non art version I purchased. Brand new.

Xyclopx wrote in post #17215533
... but it sounds like the weirdest "fix" I've ever heard. no need to do so much to get it to work right. just get it fixed.

^^^ This. You bought it brand new, so if at all possible get it returned. Life with a new lens shouldn't be this hard.

I bought an ND8 filter for my 50L so I would walk around shooting at f1.2 in the afternoon sun.
It is a great setup, and I use both AF and MF.
The razor thin DOF is often to blame, when adding in tiny movements like breathing.
I get just as many OOF images using MF as I do with AF. I trust my AF, I use center only, one shot AF.

If using live view consistently gives you sharper photos than your viewfinder's AF, then MFA is needed.

pridash wrote in post #17216373
^^^ This. You bought it brand new, so if at all possible get it returned. Life with a new lens shouldn't be this hard.

I've decided to return the lens, Ill be shipping i tomorrow or perhaps travel to Manila so I can choose a good copy at the shop. The store owner said they will attempt a calibration first and my worry is how it will perform on other bodies. But they are willing to replace it if I'll insist.

Jiggo0109 wrote in post #17219234
I've decided to return the lens, Ill be shipping i tomorrow or perhaps travel to Manila so I can choose a good copy at the shop. The store owner said they will attempt a calibration first and my worry is how it will perform on other bodies. But they are willing to replace it if I'll insist.

I assume u mean they are calibrating the lens and not your body. And yeah, that's the nature of calibrating a lens--each body is different and require different adjustments. That's why I would never buy a body without micro adjustment capability.

Anyway i would only let sigma touch my lens if I were u. Otherwise have them replace it.

but be prepared that I might have the same problems. The art version would be user adjustable if u can swing it.

Xyclopx wrote in post #17219238
I assume u mean they are calibrating the lens and not your body. And yeah, that's the nature of calibrating a lens--each body is different and require different adjustments. That's why I would never buy a body without micro adjustment capability.

Anyway i would only let sigma touch my lens if I were u. Otherwise have them replace it.

but be prepared that I might have the same problems. The art version would be user adjustable if u can swing it.

According to them, they will only work with the lens. I guess I should just go along with my camera to have an eye on it.

LeeRatters wrote in post #17211739
I find at f/1.4 [Canon] it's more a DOF issue than a lens issue.

What's it like on a tripod shooing a static object?

I wish this forum had a 'like' button.

Hi again... Just got home with my 50. Sigma immediately replaced the unit after some tests... My 1st copy had a severe issue according to them. They let me chose until I found a good one. Now, my 2nd copy focuses accurately and fast beyond my expectations. MFA'd +5. Thanks for all the advises.

Jiggo0109 wrote in post #17212087
@1Tanker: Nope, I do not recompose on test shots actually.

Actually, it's quite probable that you do recompose if you're shooting handheld.

A friend of mine had big problems shooting butterflies (perched) with her 300 f2.8. I watched her and saw that she was half-pressing the shutter button, then moving forward or backward to get the framing spot-on. It was only a tiny movement (about 1cm), but enough to move the subject out of the (very thin) focal plane.

She switched to AI servo and the problem disappeared.

hollis_f wrote in post #17239411
Actually, it's quite probable that you do recompose if you're shooting handheld.

A friend of mine had big problems shooting butterflies (perched) with her 300 f2.8. I watched her and saw that she was half-pressing the shutter button, then moving forward or backward to get the framing spot-on. It was only a tiny movement (about 1cm), but enough to move the subject out of the (very thin) focal plane.

She switched to AI servo and the problem disappeared.

Tested it on a tripod too... Sigma had replaced it with a new one. They confirmed the lens has a severe issue. It does not lock focus in live view mode and fails at wide open apertures.