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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 28 Jan 2012 (Saturday) 10:06
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Help me interpret these results...Sigma 30mm test

 
bowenbee
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Jan 28, 2012 10:06 |  #1

So, I've been playing around with the Sigma 30mm f1.4 that I got a few weeks ago, and I decided today to the notorious "battery test" I shot in 1 stop increments from 1.4 to 4. Center focus in live view 10x used tripod, well lit room, shutter cable, etc etc, blah blah blah...

Here's the results at shooting 2 feet away first. 100% crop:

F/1.4:

IMAGE: http://i42.tinypic.com/szh442.jpg

F/2:

IMAGE: http://i43.tinypic.com/2eygt9d.jpg

F/2.8:

IMAGE: http://i44.tinypic.com/20ayvzc.jpg


F/4:

IMAGE: http://i39.tinypic.com/52jnmq.jpg

I shot at about five away too. But I'll wait before or if I should even post those. I focused from infinity each time and it didn't always get it right, but there was a slighting distracting background and at a narrow DoF I figured was the cause. It looks like the right battery is slightly sharper than the center? (at least at the wide apertures) Any thoughts? Suggestions?

Eos 7D | 15-85mm | 50mm f/1.8 | 70-200 F/4 IS L | 430EX |

  
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bobbyz
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Jan 28, 2012 10:20 |  #2

which battery front and which one back. If focus off why not do MA and repeat the test?

my copy is as sharp @f1.4 as your showing at f2.8/f4.


5dmk3, 35L, 85L II, 300mm f2.8 IS I, 400mm f5.6
Fuji XT-1, 14mm f2.8, 23mm f1.4, 35mm f1.4, 56mm f1.2, 90mm f2, 50-140mm f2.8

  
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bowenbee
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Jan 28, 2012 10:29 |  #3

bobbyz wrote in post #13783190 (external link)
which battery front and which one back. If focus off why not do MA and repeat the test?


Right one is in front and left is back. I've tried MA but honestly it's hard to tell much difference.

my copy is as sharp @f1.4 as your showing at f2.8/f4.

Well, that's worrying for me..


Eos 7D | 15-85mm | 50mm f/1.8 | 70-200 F/4 IS L | 430EX |

  
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DreDaze
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Jan 28, 2012 11:22 |  #4

put the batteries more in front, and more in back, they look like they're nearly on the same plane......also why are you using live view to test the focus accuracy...


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bowenbee
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Jan 28, 2012 12:07 |  #5

DreDaze wrote in post #13783505 (external link)
put the batteries more in front, and more in back, they look like they're nearly on the same plane......also why are you using live view to test the focus accuracy...

Ok, well I spaced them approx. 3 inches apart right in foreground, left in background and used single point af center point. I also tried MA on my 7D. I got even more confounding results...

Here's with 0MA. Again center point on the center battery...:

F/1.4:

IMAGE: http://i44.tinypic.com/soty0j.jpg

F/2

IMAGE: http://i43.tinypic.com/ny9xl2.jpg

I don't I need to post the rest because to result is the same: they all look severely back focused and not acceptably sharp. I am doing something wrong, or do I truly have a problem with the lens?

Eos 7D | 15-85mm | 50mm f/1.8 | 70-200 F/4 IS L | 430EX |

  
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DreDaze
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Jan 28, 2012 12:13 |  #6

and you're manually focusing these?


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bowenbee
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Jan 28, 2012 12:16 |  #7

No, using AF. Should I be for testing purposes?


Eos 7D | 15-85mm | 50mm f/1.8 | 70-200 F/4 IS L | 430EX |

  
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starkyrulz
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Jan 28, 2012 12:27 |  #8

are you crazy - use a focus chart - even using that handheld with lens wide open there are problems. use a tripod and use a focus chart and still under the prescribed conditions you have problems - send it back.


| 5D Mark III | T3i | 24-70 f2.8 MK II L | 70-200 f2.8 IS mk II L | 18-200 f3.5-5.6 | Σ 30mm f1.4 | 50 f1.8 | 430exII | YongnouYN560 | YongnouRF603 | Vangaurd 263AT |

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DreDaze
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Jan 28, 2012 12:31 |  #9

bowenbee wrote in post #13783733 (external link)
No, using AF. Should I be for testing purposes?

no, i'd use AF...this line had me thinking you MF it...

bowenbee wrote in post #13783119 (external link)
Center focus in live view 10x used tripod,

i don't see how using a focus chart would show you that the lens performs any differently...have you tried MA(i don't have a camera capable of that, so will let others help you there)


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jfueng
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Jan 28, 2012 12:32 |  #10

Have you used it on anything else besides batteries?




  
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Dreamt
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Jan 28, 2012 14:03 |  #11

I gave up on my Sigma 30mm with my 7d, it was fine on a 600d, but on the 7D the results were the same as yours.
I tried everything, all i got was random focusing with it, front, back, spot on and nowhere near.
I spoke to Sigma and they want me to send it for a service (£86 +post), i am still deciding.

Good luck with yours, mine drove me mad for weeks.


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Stone ­ 13
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Jan 28, 2012 14:14 |  #12

I have to admit that my Sigma 30 is brilliant on my Rebel, less so on my 7D. I plan on doing some MFA this weekend to see if I can get it to be a bit more consistent.

Honestly, I love the IQ from the sigma but I'm seriously thinking of replacing it with the 35L pretty soon....


Ken
Fujifilm X100T | 5D III gripped |35L | 24-70 2.8L II | 70-200 2.8L IS II | 85 1.8 | 430 EX II | Yongnuo YN-568EX | Billingham 445 | Think Tank UD 60 |

  
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bowenbee
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Jan 28, 2012 14:32 |  #13

Stone 13 wrote in post #13784240 (external link)
I have to admit that my Sigma 30 is brilliant on my Rebel, less so on my 7D. I plan on doing some MFA this weekend to see if I can get it to be a bit more consistent.

Honestly, I love the IQ from the sigma but I'm seriously thinking of replacing it with the 35L pretty soon....

Funny you should mention that because I just tried this test again; this time with my a t3i and the sigma. It was able to accurately focus on the center battery and render it sharper...with the 7D it still misses every time..

I'm beyond frustrated with this thing.


Eos 7D | 15-85mm | 50mm f/1.8 | 70-200 F/4 IS L | 430EX |

  
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Stone ­ 13
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Jan 28, 2012 14:36 |  #14

bowenbee wrote in post #13784330 (external link)
Funny you should mention that because I just tried this test again; this time with my a t3i and the sigma. It was able to accurately focus on the center battery and render it sharper...with the 7D it still misses every time..

I'm beyond frustrated with this thing.

I feel your pain, my siggy has served me well for a long time and I hate to give it up over this. I might just send it in and see what happens, but if it's still inconsistent then I'll bite the bullet and get the 35L. I use this fl quite a bit and I didn't buy an f1.4 lens to shoot at f2.8


Ken
Fujifilm X100T | 5D III gripped |35L | 24-70 2.8L II | 70-200 2.8L IS II | 85 1.8 | 430 EX II | Yongnuo YN-568EX | Billingham 445 | Think Tank UD 60 |

  
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Unregistered.Coward
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Jan 28, 2012 14:43 |  #15

bowenbee wrote in post #13783687 (external link)
Ok, well I spaced them approx. 3 inches apart right in foreground, left in background and used single point af center point. I also tried MA on my 7D. I got even more confounding results...


This is a perfect example of a very poorly constructed focusing test.


....the best camera is the one you have on you at the time.

  
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Help me interpret these results...Sigma 30mm test
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