brainiac wrote:
I don't even know what you mean. It does have a distance slider if that's what you mean, but I don't think that means it can correct for colour shifts off the focal plane.
LoCA is (uncommonly?) accepted to mean "longitudinal CA" which is as you say; longitudinal "colour shifts [in front and behind] the focal plane."
Something tells me that this aberration would be more difficult to correct than standard (lateral) CA. Correct me if I am wrong here.
Yes, these are difficult if not impossible to correct. This is a big problem with almost every wide-aperture lens.
I've noticed the Sigma 30/1.4 shows FAR less (almost 0) LoCA than the 35L.
I recently got a Sigma 50/1.4 and it still has a decent amount of LoCAs, but still a bit less than the Canon 50/1.4. The way the Sigma's bokeh works makes the LoCAs look a lot less harsh, but unfortunately the color shifts are still there.
m_appeal wrote:
Aren't the focus problems with the Canon mount only?
Probably, I havent heard of any problems with the Nikon mount. Is the SA mount version out now as well?
After weeks of vigorous reporting the very real AF issue here, people seem to have stopped buying the lens - at least for Canon... Or maybe people are getting good copies now? In that case, please let us know. Especially a serial number....
Sam N wrote:
I recently got a Sigma 50/1.4 and it still has a decent amount of LoCAs, but still a bit less than the Canon 50/1.4.
Rubber Soul wrote:
What is the rationale behind this statement?
I'll be the first to say that DPReview's camera reviews leave much to be desired. Too many misleading charts, too much reliance on in-camera JPEGs, and a ridiculous amount of importance placed on default settings. They would test a $7000 digital SLR as though it was going to be operated by a moron with a $99 point & shoot. Their reviews read like a bunch of nonsense dressed up with many, many pages of colorful graphs.
So we agree then. What bothers me is the way they compare noise between cameras at differing magnifications. Really dumb.
> But that's for their camera reviews.
I thought that their lens reviews are actually quite good. As good as any I've seen on the net. I don't see one single thing wrong with the way they conduct and present their lens tests. It's one of the few good things to come out of DPReview in the last few years.
I don't use their lens reviews much. I prefer to read what folks here say.
Okay, I gambled and just pulled the trigger on one mail-order from NYC via eBay.
The guy said it has a US warranty; it better in case it needs to go back. Shop has good feedback though, and he said he's sold a ton and hasn't had any come back. And he just received a new shipment, so hopefully Sig has fixed the focus problem.
Ravon, thanks for posting. What is the first 4 digits in your serial number?
Your copy or possibly the combo 400D + Sig50 seems to work. Maybe there is no issue with crop sensors? Could it be a specific problem with 5D plus this lens?
I have now tested 4 different copies on my 5D and all of them are severly out of whack.
Drew_Persson wrote:
Okay, I gambled and just pulled the trigger on one mail-order from NYC via eBay.
The guy said it has a US warranty; it better in case it needs to go back. Shop has good feedback though, and he said he's sold a ton and hasn't had any come back. And he just received a new shipment, so hopefully Sig has fixed the focus problem.
Drew, good luck, please post results here when you find out something. Also your serial number. I am getting quite obsessed with this lens not working properly... .
Sounds like a Canon issue. Maybe Canon don't bother calibrating bodies and lenses, instead they want the user to do it for them (send it in). Makes a nice case for Canon users sticking to Canon lenses
ugh I guess cos this thread is really long no one bothers to read the earlier posts but this much has been established:
1. The issue is back focusing when focusing beyond 10' on full frame bodies
2. Many copies focus perfectly on crop frame bodies
3. The more common issue (if there is one) on crop bodies is front focusing
4. Calibration is NOT the issue - calibrated full frame bodies matched to calibrated sigma 50/1.4's get the same issue. It is not correctable with lens profiles in mark III bodies.
Thrice, thanks for recapping - If you dont mind I will use your recap to start a new thread as your point about this thread becoming hard to keep track of is very valid.
And Ulrik - I believe the Nikons are fine, but only from reading Nikon forum threads talking about the lens in general, not mentioning any problems....
ovredal73 wrote:
Ravon, thanks for posting. What is the first 4 digits in your serial number?
Your copy or possibly the combo 400D + Sig50 seems to work. Maybe there is no issue with crop sensors? Could it be a specific problem with 5D plus this lens?
I have now tested 4 different copies on my 5D and all of them are severly out of whack.
You're welcome. The serial number of my Sigma 50 mm is 1006###.
My combo works really great, I have tested the Canon f/1.8 mk1 and I took a brief look at the f/1.4 and my experience sofar is that the Sigma outperforms both Canon lenses.
Simply assuming that Canon does a flawless job in camera's or lenses does not make much sense to me. Have you ever tested your Sigma 50 mm on a crop sensor camera or on another 5D?
ravon wrote:
Have you ever tested your Sigma 50 mm on a crop sensor camera or on another 5D?
Neither unfortunately. I dont have access to another 5D, but I will try it on a 350D tomorrow, before returning it. I guess the problem is with FF only, so I expect it to work nicely on the 350. But I use FF...
It's a shame this Sigma has focus problems similar to the Canon EF 50/1.2L (a real letdown). I continue to limp along with the EF 50/1.4 - lumpy construction, lousy bokeh, lifeless @ f/1.4. Next up for us fans of the fast 50 is Nikon's AF-S redesign. My fingers are crossed...
Odd that a lens can have AF issues, I've used a DSLR with an AF-confirm chip adapter on a view camera with a large format lens and the focus is spot-on. No connection between the camera and the lens whatsoever, just adjust the standard until the AF light flashes and the body beeps.
Seems like the lens should be irrelevant, the camera knows when to stop the lens focus drive. Maybe the lens coasts past the optimum point.
Seems like the lens should be irrelevant, the camera knows when to stop the lens focus drive. Maybe the lens coasts past the optimum point.
That may be part of the problem. The Sigma 50/1.4 has relatively heavy
glass to move, and it moves it pretty quickly.
But.....
I've tried pumping the * button to repeatedly AF the thing, and once it has locked
onto the misfocused range, it stays there, so I expect there is still a control
algorithm problem.
.