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05-14-2010, 03:40 AM   #1
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Sigma Release 120mm-400mm 4.5-5.6 Lens for Penax & Sony

Sigma releases 120-400mm f/4.5-5.6 for Sony & Pentax: Digital Photography Review

05-14-2010, 05:21 AM   #2
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It is a pitty that it does not perform that well at the long end.
See this text from Slrgear.com:
++++++++++++++++++++++++++++++++++++++
Sharpness
The 120-400mm is a fairly sharp lens, but its performance is optimized for the wider range of its focal length spectrum. As you zoom in towards the 400mm range, image sharpness degrades significantly. Optimal image sharpness was achieved at either 120mm and ƒ/5.6, or 150mm and ƒ/8.

Wide open and wide-angle (120mm, ƒ/4.5) image sharpness is quite good, with test results showing 1.5 blur units across the frame. Stopping down to ƒ/5.6 improves central sharpness to 1 unit, but there is still some very slight corner softening. Diffraction limiting seems to set in at ƒ/11, but image quality never gets so bad, reaching 2.5 blur units at ƒ/22. Results at 150mm are almost the same, just a tad less sharp.

However, at 200mm and above, image sharpness starts to worsen. Our sample copy of the lens also showed some centering issues at this focal length. Sharpness showed results of between 1-2 blur units in a very small central region, while corner softness reached 4.5 blur units; as the lens is stopped down, quality improves dramatically at ƒ/8 and ƒ/11 (1 blur unit centrally, 2-3 units in the corners) and the image is generally soft at ƒ/25 (3 blur units).

Between 300 and 400mm, performance when used wide open (ƒ/5.6) is nothing to write home about - very uneven and soft (3-5 blur units at 300mm, and 5-8 units at 400mm). Stopping down to ƒ/8 or ƒ/11 is necessary to get any kind of sharpness out of the lens at this focal length. Interestingly, image sharpness is better at ƒ/22-29 than when used wide open at these focal lengths.
++++++++++++++++++++++++++++++++++++++

I think my DA*60-250mm + 1.7TC is still a good alternative.
As soon as Sigma delivers telezooms that are optimized for the long end, I'll get one.

- Bert
05-14-2010, 05:30 AM   #3
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QuoteOriginally posted by bymy141 Quote

I think my DA*60-250mm + 1.7TC is still a good alternative.
As soon as Sigma delivers telezooms that are optimized for the long end, I'll get one.

- Bert
I hate my DA* 60-250mm and 1.7x TC as a combo, gives very average results imo.
The Sigma 100-300mm f4 and 1.4x TC is so much better IQ wise (again imo).
05-14-2010, 05:32 AM   #4
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Its too bad that they didn't re-release the older 400mm apo macro and upgrade it with hsm. that lens had excellent optics. I don't get the logic in producing a long lens with poor long end performance.

05-14-2010, 06:02 AM   #5
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QuoteOriginally posted by Mike.P Quote
I hate my DA* 60-250mm and 1.7x TC as a combo, gives very average results imo.
The Sigma 100-300mm f4 and 1.4x TC is so much better IQ wise (again imo).
Would you be able to show some (photographic) results / tests to support that please?
Test results of the 100-300mm have been reasonable, but not very good.
The 60-250mm does a lot better. I also have a Kenko 1.5TC with which SDM AF works pretty much Ok.

We will be off to Africa again in 2 months, I need to decide what to take with me before then.

Thanks in advance.

- Bert
05-14-2010, 07:51 AM   #6
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The Slrgear review describes very closely the results I have had with my 70-300 Sigma, very sharp at the shorter lengths and soft at the long. I have my best results at f/11 also with that lens. The 70-300 has close up/macro mode between 200-300 which is very sharp. I think the lens is optimised for close up at the long end rather than infinity. This lens also focuses close, down to 150cm according to the specs at DP Review. The review above doesn't mention the close up IQ at the long end. I also question why they would make a long zoom that was obviously soft on performance at the long end. The 70-300 is so dirt cheap and the IQ good enough at f/11 that the lens is worth owning. This one has much steeper price tag.
05-14-2010, 08:43 AM   #7
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My Sigma 100-300 is amazing from wide open, throughout the entire zoom range, IMO. Granted I'm using it on a D700, but WOW.
05-14-2010, 12:27 PM   #8
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The lens that slrgear tested had some decentering issues, which may have affected the results. It seems to be pretty common with Sigma to have quite large sample variation, so if you're willing to go through a couple copies it should be possible to find one performing much better than what the slrgear review indicates. Other reviews I've read have had no complaints on sharpness.

That being said, I would probably rather choose the 150-500mm if I was in the market for a cheap super telephoto.

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