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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses
Thread started 05 Sep 2008 (Friday) 10:30
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Sigma 30mm front focus (posted to death)

 
AlanU
Cream of the Crop
Joined Feb 2008
Vancouver, BC
Sep 05, 2008 10:30 |  #1

Hello all,

Well I just purchased the famous love/hated lens. Well I've taken a good hundred shots so far (most indoors) and its been flawless and phenominal wide open. Some of the photos outdoors I did see some front focus but the subject was a good 30+ feet away with the lens wide open.

I'd say a decent 95% of my shots worked out from excellent to very useable.

I'm thinking user error and lens is in question.

So many fellow POTN members I've PM'ed have said its very good "realistic" keepers ratio.

Is there Sigma 30mm users with 100% full proof AF???? I'm NOT the sort to tell un truths so this is why I'm asking. I wonder if certain focus issues are just a part of "nature of the product"

I can see bad copies but in my eyes I think I have a very good copy.

Do I sound like I'm off the rocker??

any input would be much appreciated


5Dmkiv |5Dmkiii | 80D | 24LmkII | 35mm f/2 IS | 85 mkII L | 100L | EF-S 10-22 | 16-35L mkII | 24-70 f/2.8L mkii| 70-200 f/2.8 ISL mkII| 600EX-RT x2 | 580 EX II x2 | Einstein's
Fuji X-T2 w/battery booster | 16mm f/1.4 | 56 f/1.2 | 10-24 f/4.0 | 55-200 | EF-X500

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Qwest905
Member
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242 posts
Joined Aug 2008
Canada (Mississauga)
Sep 05, 2008 10:33 |  #2

i find my copy is excellent


Canon g10

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lukeap69
Goldmember
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1,206 posts
Joined May 2008
Near the desert
Sep 05, 2008 10:59 |  #3

Mine is excellent too and I am very happy with it.


Arnold
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Jman13
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Joined Dec 2005
Columbus, OH
Sep 05, 2008 11:03 |  #4

My third one will be here Monday. I hope mine is spot on this time. The first two had terrible AF problems. I'd focus on a house 80 feet away, and the camera would focus 15-20 feet out.


Jordan Steele - http://www.jordansteel​e.comexternal link
Admiring Light - http://www.admiringlig​ht.comexternal link

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AlanU
THREAD ­ STARTER
Cream of the Crop
Joined Feb 2008
Vancouver, BC
Sep 05, 2008 11:42 |  #5

Qwest905 wrote in post #6246693external link
i find my copy is excellent

Have you done extensive exhausting tests?

Realistically I wouldn't have been looking for problems but the internet is giving the idea that I should.

If you do pics 20+ feet I'm thinking you may find front focussing. I just want to see if theres a certain threshold of tolerance for front focus (extremely minor in my case)

My realistic view is I wont see the problems since I'm very close to the subjects so the front focus will never really reveal its ugly head. As I said indoors I've seen NO issues. I'd say majority of my pics will be indoors with this lens.

All in all this lens is freakishly impressive with amazing sharpness wide open. When stopped down its in the same league if not better as my 24-70L stopped down. Infact I think I'll send the "brick" out for inspection to see if IQ can be increased.


5Dmkiv |5Dmkiii | 80D | 24LmkII | 35mm f/2 IS | 85 mkII L | 100L | EF-S 10-22 | 16-35L mkII | 24-70 f/2.8L mkii| 70-200 f/2.8 ISL mkII| 600EX-RT x2 | 580 EX II x2 | Einstein's
Fuji X-T2 w/battery booster | 16mm f/1.4 | 56 f/1.2 | 10-24 f/4.0 | 55-200 | EF-X500

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egordon99
Cream of the Crop
10,247 posts
Joined Feb 2008
Philly 'burbs
Sep 05, 2008 12:24 as a reply to AlanU's post |  #6

Mine is excellent. I haven't done ANY testing because I've been happy with the pictures I get and have seen no need to run exhaustive tests with AA batteries lined up in a row, or some focus chart at a 45 degree angle........

Folks need to realize that (1)DOF is very shallow at wide apertures, and (2)The focus "point" is actually more than just the dot in the viewfinder, so it is very possible that the AF system will find an area of more contrast (still within the selected AF area) on something other than what you intended.




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egordon99
Cream of the Crop
10,247 posts
Joined Feb 2008
Philly 'burbs
Sep 05, 2008 12:25 as a reply to egordon99's post |  #7

I tend to shoot mine at f/1.4-f/2, but the few times I've stopped down even further I have been aghast at the sharpness of the images when viewed 100% in the ACR window.

It really is a gem of a lens, and I do feel bad if folks really did get a bad copy, but based on my post above, I think most (some?) folks screaming "bad copy" just have never experienced a fast lens before.




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Jman13
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Columbus, OH
Sep 05, 2008 12:40 |  #8

Considering I can hit focus manaully with my Rokkor 58 f/1.2, an autofocus lens at 30mm f/1.4 should be able to get within 60 feet of the focus point on a HOUSE. If you get a bad copy (and I've had two), the focus problems at a distance are HORRIBLE. And yes, I can manually focus the misfocused shot and have it look beautiful.

These front focus errors are more pronounced on further subjects, which is when it should be the least pronounced (DOF at 20 feet f/1.4 is a few feet, while at 4 feet, when it DOES hit focus, it's only a few inches.)

It is the only lens I've owned where the focusing is this far off. Bad copies of this lens do exist, and are quite prevalent. The fact that I am willing to try for a 3rd copy (and if this one stinks I'll go the calibration route) is a testament to the optics, because I wouldn't go through this if the thing weren't deadly sharp even at f/1.4 (when it's in focus, of course).


Jordan Steele - http://www.jordansteel​e.comexternal link
Admiring Light - http://www.admiringlig​ht.comexternal link

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bakatari
Senior Member
459 posts
Joined Aug 2008
Seattle
Sep 05, 2008 13:06 |  #9

I bought mine used off the forum, it works so great I had to ask the original seller if he had it sent in for calibration. Needless to say it hadn't been sent in. I love the lens.


5d2

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egordon99
Cream of the Crop
10,247 posts
Joined Feb 2008
Philly 'burbs
Sep 05, 2008 13:07 |  #10

Fair point Jman....I tend to only use my 30mm for up close (and personal!) subjects. I should go out and try some distance shots (or maybe not?)




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AlanU
THREAD ­ STARTER
Cream of the Crop
Joined Feb 2008
Vancouver, BC
Sep 05, 2008 14:24 |  #11

I hear ya. I did the battery test and other tests and my lens is perfect. Take it out and shoot long distances and its a different story. Many will say the same.

I still love this lens though.

egordon99 wrote in post #6247370external link
Mine is excellent. I haven't done ANY testing because I've been happy with the pictures I get and have seen no need to run exhaustive tests with AA batteries lined up in a row, or some focus chart at a 45 degree angle........

Folks need to realize that (1)DOF is very shallow at wide apertures, and (2)The focus "point" is actually more than just the dot in the viewfinder, so it is very possible that the AF system will find an area of more contrast (still within the selected AF area) on something other than what you intended.


5Dmkiv |5Dmkiii | 80D | 24LmkII | 35mm f/2 IS | 85 mkII L | 100L | EF-S 10-22 | 16-35L mkII | 24-70 f/2.8L mkii| 70-200 f/2.8 ISL mkII| 600EX-RT x2 | 580 EX II x2 | Einstein's
Fuji X-T2 w/battery booster | 16mm f/1.4 | 56 f/1.2 | 10-24 f/4.0 | 55-200 | EF-X500

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jasonlitka
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900 posts
Joined Mar 2008
Exton, PA
Sep 05, 2008 14:32 |  #12

Jman13 wrote in post #6246865external link
My third one will be here Monday. I hope mine is spot on this time. The first two had terrible AF problems. I'd focus on a house 80 feet away, and the camera would focus 15-20 feet out.

Mine did something similar to that, although it wasn't that dramatic. A quick calibration by Sigma in NY cleared the problem right up.


Jason Litka | Utter Ramblingsexternal link
7D, Rebel T2i, 24-105mm f/4L IS USM, 70-300mm f/4-5.6L, 100mm f/2.8L Macro IS USM, 24mm f/1.4L II USM, 10-22mm USM, 17-85mm IS USM, Sigma 30mm f/1.4, Speedlite 270EX, Panasonic Lumix DMC-LX5, Fuji X100s on order.

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Jman13
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Joined Dec 2005
Columbus, OH
Sep 05, 2008 14:34 |  #13

Here's an example from my 2nd Sigma 30. Shot with the center focus point active, focus was on the Nissan Rogue. This shot was taken at f/1.8, where the Sigma 30 is VERY sharp. You'll notice there's nothing up close anywhere near to the center that could have been caught and been the reason for the misfocus.

IMAGE: http://www.jordansteele.com/forumlinks/30test_full.jpg

Here is a 100% crop of the area I focused on (center part of the image).
IMAGE: http://www.jordansteele.com/forumlinks/30test_focus.jpg

And here's a 100% crop of the part of the image that was actually in focus:
IMAGE: http://www.jordansteele.com/forumlinks/30test_actual.jpg

Jordan Steele - http://www.jordansteel​e.comexternal link
Admiring Light - http://www.admiringlig​ht.comexternal link

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Grimes
Goldmember
1,323 posts
Joined Mar 2006
Sep 05, 2008 14:39 |  #14

My copy was bad before and after calibration at their service center :(


Alex
5DMKII | 85 f/1.8 | 17-40L f/4 | 24-105 f/4 IS | 40 f/2.8

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Sigma 30mm front focus (posted to death)
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