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Old Jun 23, 2006, 9:12 AM   #1
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I'm considering to buy a used Sigma 120-300 2.8 (non-DG).
Since quite a few members of this forum have this lens I'd like to ask you:

- is there any particular problem such as quality issues,high variation of performance etc. for this lens?

- is there a significant difference in image quality in between the non-DG and the DG version?

- how is the compatibility with present Canon DSLRs (I'm using a Rebel XT, occasionally 20D)regarding focus accuracy?

- is this lens firmware upgradeble in case Canon introduces some further annoyances in future bodies?

- which kind of extender (Canon, Sigma, Kenko...) is preferable for this lens?
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Old Jun 23, 2006, 11:00 AM   #2
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Guess I'll go first.

I bought a non-DG version of this lens this spring and used it extensively all spring shooting sports - probably about 8000 images or so.

Overall, it's an exceptional lens. It's very sharp, has good color and contrast and focuses reasonably fast. It only suffers when you compare it to the Canon 300mm 2.8. But that lens is twice the cost so it has to be better. But, one benefit for most of us that the Sigma has is that it's a zoom. That's huge for me. If I was shooting with the prime I would need to invest more money in a 2nd body. This way I can shoot with just the 120-300 and don't need a 2nd body.

Now, it's a heavy lens (since it's 2.8) so be prepared for that. That's not a knock it's just a fact that any lens of 300mm 2.8 is going to be heavy.

The only 'problem' I've had with my lens is I see a lot of purple fringing in bright daylight. The 'fringe' is narrow so it's not pronounced but it occurs more frequently than with, say, my Canon 100-400 in similar lighting conditions. Again, because it's usually a narrow band you don't notice it in small prints or when looking at regular web images. I would, however notice it when editing my photos.

Overall, it's a great lens and I highly recommend it. I am also a fan of getting the non-DG version. Personally I don't like the fact that Sigma is messing with their optics. IMHO it is simply a marketing ploy that is an excuse to raise the price by $300. In reality I think they risk doing more harm to the lens than good. So, if you are buying from a trusted source, I say absolutely - get the lens.

I've had no issues with my 20d and this lens. For future compatibility I'm confident Sigma would re-chip it. They're not going to rechip their cheap lenses but I'm confident they'll want to keep the business of people who are buying $2000 lenses so if the successor to the 30d requires a re-chip I'm betting they'll do it.


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Old Jun 23, 2006, 1:02 PM   #3
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I can add to JohnG excellent comments...

Quote:
- how is the compatibility with present Canon DSLRs (I'm using a Rebel XT, occasionally 20D)regarding focus accuracy?
A lens does not focus by itself...
The body tells the lens to focus so if anyone has a focusing issue it's most likely the body - If you don't believe this then put a diopter in front of a lens to change its myopia (i.e. mess the lens up), what happen? The body 'see' through the lens and still focus correctly within its range right?

-> A lens is dumb, it just responds to what its being told by the bodies:
http://forums.dpreview.com/forums/re...ssage=16597876



Quote:
- is this lens firmware upgradeble in case Canon introduces some further annoyances in future bodies
While I agree that Sigma was the only manufacturer who made a booboo in the past on their non-HSM lens (the 120-300 is HSM BTW), and should learn from this experience; However, if I was a Sigma designer all I have to do is to emulate any of Canon 20 years old lenses such as the 50mm f/1.4 or the 85mm f/1.2L (which I have BTW)... Unless future bodies would not work with theses lenses either :-)
Come on! Companies can reverse engineer a 32-bit Pentium what's so difficult about an old serial protocol? :idea:



Quote:
- which kind of extender (Canon, Sigma, Kenko...) is preferable for this lens?
It's best to 'match' it to a Sigma teleconverter - beside why would you mix black and white color :-)
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Old Jun 24, 2006, 12:54 AM   #4
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I was just wondering... photozone doesn't have a favourable review for the sigma 120-300 . Was the tested sample defected or does the lens really suffer from field curvature? If so, I can imagine f/2.8 at 300mm being a problem (sometimes) with its thin DOF... :shock:
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Old Jun 24, 2006, 6:21 AM   #5
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Thank you very much for all the information!

@ NHL: I don't have any doubt that Sigma produces some outstanding lenses. However, I've bought a new 30 1.4 about a month ago which suffers of heavy purple fringing (ca. 5 pixels)as visible in the enclosed crop. Do you consider such fringing to be normal? This lens also suffers a bit of back-focussing, whereas my old 80-200 2,8 focusses right on the spot. Thus, I'm considering to send the 30 1.4 back to Sigma for verification.
Obviously, the body controls the focussing, but the protocol for the communication with the lens' AF steering surely has an influence on the result too. Thanks for the link to the great article for adjusting the Rebel XT's focal plane.

@ BoYFrMSpC: That photozone review was one of the reasons for this topic. Since a few members of this board might have tried this lens, or know people who did it might be interesting to see if only the guys from photozone got a bad sample.
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Old Jun 24, 2006, 7:07 AM   #6
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www wrote:
Quote:
...However, I've bought a new 30 1.4 about a month ago which suffers of heavy purple fringing (ca. 5 pixels)as visible in the enclosed crop. Do you consider such fringing to be normal?
I don't know if it's normal, but I do have an EF 50mm f/1.4 which exposed similar problem in high contrast area when wide open:


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Old Jun 24, 2006, 7:10 AM   #7
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www wrote:
Quote:
That photozone review was one of the reasons for this topic. Since a few members of this board might have tried this lens, or know people who did it might be interesting to see if only the guys from photozone got a bad sample.
The Photozone folks did say they are not sure; However the older Photozone tests (which are now removed) did rate it quite excellent or this review: http://www.popphoto.com/assets/downl...2003163559.pdf

www: I don't know how old the lens you're getting is, but if it's a USA one - You do have 4 years to send it back in for adjustment depending on when it's bought



BTW I can't help to notice how excellent the 100-300 f/4 EX is if you can't afford the f/2.8: :idea:
http://www.photozone.de/8Reviews/len...00_4/index.htm

-> It's MTF is just plain amazing for the lost of just 1-stop (even compared to the L)


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Old Jun 24, 2006, 8:39 AM   #8
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@ NHL: It's indeed interesting to see that the purple fringing also is observed with some Canon lenses. I guess the only hope is to send it back and find out how good Sigma's customer service is in Japan.
The 100-300 is lighter, sharper and more compact - but after combining it with a TC might be too slow and I'm not sure how fast the AF works then.
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Old Jun 24, 2006, 10:35 AM   #9
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my sigma 30 also fringes pretty badly in some situations. Your night shot looks like a typical sigma 30 fringing moment.
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Old Jun 24, 2006, 10:44 AM   #10
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BoYFrMSpC wrote:
Quote:
I was just wondering... photozone doesn't have a favourable review for the sigma 120-300 . Was the tested sample defected or does the lens really suffer from field curvature? If so, I can imagine f/2.8 at 300mm being a problem (sometimes) with its thin DOF... :shock:
Actually if you trust the # at the Photozone they are not really bad if you ignore their comments:
Center Canon @ 300mm f/2.8: 1641 f/4: 1839 f/5.6: 1954 f/8: 1877
Center Sigma @ 300mm f/2.8: 1661 f/4: 1709 f/5.6: 1842 f/8: 1801
-> The Sigma is actually better @ 300mm f/2.8 than the Canon

Also one would expect to take a hit in a zoom, and @ 50% of the cost of the EF-300 f/2.8L some compromises are to be expected right?
Let's now take the worst number for the border with Sigma which is 1458 and compare to the 1608 for Canon: This is only about a 10% degradation worst case for about 1/2 the $ saving: I'll take that any day especially in a long zoom where the center is the most critical
-> the border will be part of the Bokeh anyway! :idea:


As to the focus accuracy: :-)


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