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Archive 2013 · Sigma 35mm f/1.4 DG HSM - AF
  
 
badlydrawnboy
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p.3 #1 · Sigma 35mm f/1.4 DG HSM - AF


Lars Johnsson wrote:
@badlydrawnboy

I'm not talking about others when I reply to you. So don't try to involve others here.

1. You have been posting at least 200 post lately that only involves AF and focus issues. So it's nearly impossible not to read a few of those. And I know for sure you don't test or try your new lenses in a proper way for AF issues. You have described how you do in many posts. Handholding the camera and shooting at subjects like children or dogs. And you also say that those are perfect for testing the AF on a new
...Show more

First of all, as I said earlier in this thread Canon has confirmed that my 5D3 has AF problems, which explains why I've had issues with several different lenses in recent months.

Prior to the 5D3, I had a 5D2 with Canon 35L, 85L, 50/1.4 and 100/2. I had no AF issues whatsoever. And yes, I was shooting my normal subjects at close distances and I never once had to "test" these lenses to make sure they focused properly. They just did.

With my 5D3, focus has been erratic and inconsistent with several lenses, which is why I suspected it had a problem in the first place. That said, the AF has been far worse with the two copies of the Sigma 35 I have than other Canon lenses like the 24-70, 50/1.4 and 40/2.8. It's probably not fair to judge the AF of a lens with a camera body that has AF problems; that's why I said I'll wait until getting the 5D3 back from Canon to make any judgments.

But the main point is this: I know how to shoot with wide aperture lenses, I have many fast lenses and previous camera bodies that I've never had any AF problems with. The same is true for other people in this thread. So why, then, if we notice problems with a new lens would it suddenly be an issue with our technique or the way we're testing a lens? That doesn't make any sense. There's a gap in your logic here.

This is a silly argument, especially in light of the fact that my 5D3 has AF problems. That is why I've had AF problems with several (3, not 7) lenses, not because of problems with my AF technique or the way I test lenses. I never had issues before with a different camera body, and I never found the need to "test" lenses on a tripod with focus charts. They just worked.



Jan 09, 2013 at 02:16 PM
goosemang
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p.3 #2 · Sigma 35mm f/1.4 DG HSM - AF


put about 150 clicks on this thing last night. after playing a bit i settled on +7 ma and it looks good. nailing focus at MFD and further away (15+ feet @ 1.4). outer cross type focus points on the 5d3 seem to perform just as well as the center.

AF is slower than canon L's i have... probably slightly slower than, for instance, the 135L, which isn't a rocket ship from MFD to infinity, but is good enough. it's a bit slower than that, but most of the travel is from 1-3 feet, so if you're constantly focusing on things that are a bit further away it's plenty quick.

i didn't have trouble locking focus in low light. it wasn't mind blowing but wasn't notably slower than my other lenses in these conditions. no idea about servo tracking yet. i'll have to get an event where i can test this out more. i usually use servo to track peoples eyes at f/1.4-2 with my 50mm when they're moving around a bit, so i'll be using this lens in the same way. i'll post how it is when i get a chance to really use it in that capacity.



Jan 09, 2013 at 02:27 PM
Gunzorro
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p.3 #3 · Sigma 35mm f/1.4 DG HSM - AF


macrobild wrote:
It is somewhat amusing to read all the comments.
First of all , you have to understand that Canon's AF has minor variations and AF accuracy is equivalent to f- 2.8 (3.4 to be exact) in cameras like 5dmk2 and therefore a AF test shall be made at F- 2.8 and with minor variations calculated in the results (and in the depth of field of 2,8). Depending on the lens and AF-motor the results can varies a lot.Take a series of 5 pictures and let the AF do a new measurement between every picture and you get maybe 2 of 5
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Good points. Yes, AF is sort of a crap shoot. The lens/camera don't have an infinite number of focusing steps. Choosing the "best" is something of a gamble even with calibrated lens/body.

I recommend whoever solves the AF conundrum and brings us reliable and repeatable AF to receive the Nobel Prize.



Jan 09, 2013 at 03:05 PM
Shield
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p.3 #4 · Sigma 35mm f/1.4 DG HSM - AF


goosemang wrote:
put about 150 clicks on this thing last night. after playing a bit i settled on +7 ma and it looks good. .


So which way did you vote in the poll?



Jan 09, 2013 at 03:09 PM
goosemang
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p.3 #5 · Sigma 35mm f/1.4 DG HSM - AF


Shield wrote:
So which way did you vote in the poll?


i actually didn't because i had clicked to view the results before i got the lens



Jan 09, 2013 at 03:16 PM
goosemang
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p.3 #6 · Sigma 35mm f/1.4 DG HSM - AF


but yes, the AF works as far as i am concerned so far. it's got a smaller MA than my 135L.

edit: here's how my lenses fall:

canon 17-40: no MA (duh)
sigma 35: +7
canon 40: no MA
canon 50: no MA
canon 135: +8



Jan 09, 2013 at 03:16 PM
RCicala
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p.3 #7 · Sigma 35mm f/1.4 DG HSM - AF


cputeq wrote:
Or conversely, it says very little about his testing methodology.

A lot of the apparent focus problems with this lens seem to be closer-in, which may be closer than what a test bench would direct you to use or that quick focus tests would show.

Point is - just because Roger tested 30x copies and found them good doesn't mean they're all good at all distances - only the distance(s) he tested.

I'm not arguing for or against the lens, no horse in this race, but until the details of Roger's testing is known (have a link? I only have the one Sigma
...Show more


Just to clear things up: the 30 copies tested are in a well lit lab and tested at 10 to 30 feet on stationary targets using center point AF. We do a back-frontfocus check using lens align, though, and all 30 copies were reasonably in spec, but again, well lit, 10-30 feet distance. In other words, no critical AF testing is done.

I leave critical AF testing to the reviewers.

My own copy shot in a variety of situations with a 5DIII was pretty good. I agree with what has been said -- maybe a tiny bit slower than the 35L but nothing significant.



Jan 09, 2013 at 06:50 PM
macrobild
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p.3 #8 · Sigma 35mm f/1.4 DG HSM - AF


None have done a critical AF testing, it should take several weeks to include all parameters.



Jan 09, 2013 at 10:24 PM
Shield
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p.3 #9 · Sigma 35mm f/1.4 DG HSM - AF


macrobild wrote:
None have done a critical AF testing, it should take several weeks to include all parameters.


How do you know what all of us have done? I've done "enough" testing to know that my first copy was off in real world use; enough that I'm getting a 2nd one. At some point you stop the testing as you have conclusive evidence to determine that something is severely wrong.



Jan 09, 2013 at 10:33 PM
curious80
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p.3 #10 · Sigma 35mm f/1.4 DG HSM - AF


cputeq wrote:
Or conversely, it says very little about his testing methodology....


Of course Roger was not doing AF testing, he was checking lens sharpness so his testing is not exhaustive by any means. The point however is that if this lens had any systematic AF issues as for example Sigma 50mm 1.4 had then there is a very good chance some issue would have turned up in his use of the 30 lenses. And we also have about 32 out of 38 users in this poll who report their copies work perfectly fine as well. So at this point there has been no evidence to suggest any specific AF issue with the lens other than the standard bad copy issue which happens with all lenses.

Edited on Jan 09, 2013 at 10:45 PM · View previous versions



Jan 09, 2013 at 10:39 PM
 

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snapsy
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p.3 #11 · Sigma 35mm f/1.4 DG HSM - AF


The 35mm looks like a winner and AF is good for me, but there's no question Sigma has a lot of history to live down and will need to prove itself to former customers who have been burned with flaky copies of the 50mm.


Jan 09, 2013 at 10:42 PM
macrobild
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p.3 #12 · Sigma 35mm f/1.4 DG HSM - AF


Shield wrote:
How do you know what all of us have done? I've done "enough" testing to know that my first copy was off in real world use; enough that I'm getting a 2nd one. At some point you stop the testing as you have conclusive evidence to determine that something is severely wrong.


what you have done I do not know, I replied that a proper evaluation of AF and put it in context would take weeks to do, for example, evaluate the 1DX vs D4 AF etc etc and I know none who have done that.


Edited on Jan 09, 2013 at 11:27 PM · View previous versions



Jan 09, 2013 at 11:21 PM
macrobild
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p.3 #13 · Sigma 35mm f/1.4 DG HSM - AF


curious80 wrote:
Of course Roger was not doing AF testing, he was checking lens sharpness so his testing is not exhaustive by any means. The point however is that if this lens had any systematic AF issues as for example Sigma 50mm 1.4 had then there is a very good chance some issue would have turned up in his use of the 30 lenses. And we also have about 32 out of 38 users in this poll who report their copies work perfectly fine as well. So at this point there has been no evidence to suggest any specific AF issue with
...Show more
so it is, and its a good start to know



Jan 09, 2013 at 11:26 PM
umihoshijima
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p.3 #14 · Sigma 35mm f/1.4 DG HSM - AF


Using the 5Dc without MA, might have to go with the 35 f/2 IS over the siggy :/


Jan 10, 2013 at 01:22 AM
snapsy
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p.3 #15 · Sigma 35mm f/1.4 DG HSM - AF


umihoshijima wrote:
Using the 5Dc without MA, might have to go with the 35 f/2 IS over the siggy :/


My Sigma 35mm requires +10 on the 5DM3 but focuses fine on my 5Dc.



Jan 10, 2013 at 01:24 AM
RobertLynn
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p.3 #16 · Sigma 35mm f/1.4 DG HSM - AF


I'm really hoping they get this one "right". I want a 1.4 wide angle prime, and I gave Canon two tries with the POS 24 1.4


Jan 10, 2013 at 01:38 AM
Sven Jeppesen
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p.3 #17 · Sigma 35mm f/1.4 DG HSM - AF


RobertLynn wrote:
I'm really hoping they get this one "right". I want a 1.4 wide angle prime, and I gave Canon two tries with the POS 24 1.4


They got this one "right". Both the image quality and AF is very good



Jan 10, 2013 at 01:42 AM
Sven Jeppesen
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p.3 #18 · Sigma 35mm f/1.4 DG HSM - AF


umihoshijima wrote:
Using the 5Dc without MA, might have to go with the 35 f/2 IS over the siggy :/


Why



Jan 10, 2013 at 01:43 AM
Sven Jeppesen
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p.3 #19 · Sigma 35mm f/1.4 DG HSM - AF


cputeq wrote:
Or conversely, it says very little about his testing methodology.

A lot of the apparent focus problems with this lens seem to be closer-in, which may be closer than what a test bench would direct you to use or that quick focus tests would show.

Point is - just because Roger tested 30x copies and found them good doesn't mean they're all good at all distances - only the distance(s) he tested.

I'm not arguing for or against the lens, no horse in this race, but until the details of Roger's testing is known (have a link? I only have the one Sigma
...Show more

I would guess Rogers testing is better than the average FM member in this thread. He is also more used to do lens testing than the average member here. And how many other people have even tested 30 copies of this lens. And he say more about his testing methodology than 99% of the other testers in this thread



Jan 10, 2013 at 01:47 AM
cputeq
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p.3 #20 · Sigma 35mm f/1.4 DG HSM - AF


Sven Jeppesen wrote:
I would guess Rogers testing is better than the average FM member in this thread. He is also more used to do lens testing than the average member here. And how many other people have even tested 30 copies of this lens. And he say more about his testing methodology than 99% of the other testers in this thread


Well we now know a bit more on how he tests and he states no critical AF testing, which is what I suspected, as it would be entirely too much work to test every single lens at every single focal distance possible.

Plus, a lot of you guys are really missing the nuances of my previous post.

My caution was to not take Roger's word that 30 copies tested fine at whatever his standard testing ranges are (apparently 10-30 ft) as equivalent that those same copies would perform fine at ALL focal distances, and then interpolating that data to mean most Sigma 35s would perform flawlessly-- it could very well be Sigma's AF routines are lacking in close-focus situations (as some problems indicated here at FM seem to happen at those close distances), or it could be user error, typical QA variances, etc and we will hopefully get a 90-95% "good" rate with the lens.

Again I dont have a horse in the race, not a Sigma basher (100% agnostic, trust me), but to cite a respectable but still small test sample (performed at standard test bench ranges) and proclaim Sigma has suddenly cured all their AF woes is statistical folly. More time and testing required, but I am hoping this lens is spot-on, as I plan to buy it eventually.



Jan 10, 2013 at 02:11 AM
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