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07-15-2009, 05:44 PM   #1
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Sigma 17-70mm f/2.8-4.5 not as good....

...... as my 21 year old manual KA Ozunon 35-70mm lens. The Sigma 17-70mm lens I bought a few weeks ago isn't sharp as I'd like. I've done a few comparison pics and found the old Ozunon to be sharper. Is this common for the Sigma, do I have a bad copy, or is it just not as good as old glass?


Ozunon lens



Sigma 17-70mm



Ozunon lens


Sigma 17-70mm

07-15-2009, 10:53 PM   #2
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very hard to tell the difference. In fact I don't notice a difference in sharpness at all with the pictures of the soup can. What I do notice is the second shot of the soup can appears to be more contrasty.
07-16-2009, 12:17 AM   #3
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The Sigma is a very good lens- I owned one for 18months and got some very good results (most of the shots on my website).

What aperture etc were these taken at as it isn't the sharpest wide open, stopped down a little and its very good

Like all lenses it's prone to sample variation also so it is possible you haven't got the sharpest copy, although as already mentioned it's difficult to tell from these shots

simon
07-16-2009, 12:27 AM   #4
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I've found the Sigma to be a fine lens but like everything else, there could be sample variations. Now I think you also need to consider if the issue isn't really the lens but your K10D body. With your old Ozunon you have to focus manually, whereas the Sigma is an AF lens. You haven't indicated if you focused manually or used the camera's AF when using the Sigma. Given the oft mentioned focusing accuracy issues of the K10D, I'd suggest you test the Sigma by focusing manually. Also the exposure and ISO for the different lenses are also different...

07-16-2009, 02:51 AM   #5
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QuoteOriginally posted by kthung Quote
very hard to tell the difference. In fact I don't notice a difference in sharpness at all with the pictures of the soup can. What I do notice is the second shot of the soup can appears to be more contrasty.
Hmm. I can personally see a significant and very real difference in sharpness all over the soup shot. Contrast appears to be similar. Sigma is warmer in tone, though.

OP: you need to specify what apertures you used in order for this test to be meaningful.
07-16-2009, 03:14 AM   #6
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Without looking at the EXIF data, and not comparing tones, the ozunon lens stands out from the sigma in terms of the crispness of the image - which as Denis points out may be a focusing issue and I agree. One other factor may be lens contrast - to me it seems that the ozunon lens is more contrasty, with more differentiation between the darker and lighter colours, and hence look sharper.
07-16-2009, 08:35 AM   #7
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I did a google search and found a post on a Nikon site where someone was having the same sharpness issue. Turns out it was due to the Hoya Pro1 UV filter I was using. I removed it this morning and took a few shots. The sharpness problem is gone.
07-16-2009, 08:37 AM   #8
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Another point for lenshood-only club

07-16-2009, 10:38 AM   #9
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QuoteOriginally posted by Andi Lo Quote
Another point for lenshood-only club
I had that revelation taking a photo of a city scene after dark...my reaction was, why is there two of everything?!
07-16-2009, 12:21 PM   #10
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this is my believe, don't have facts to prove it:
The Sigma is a quite good lens, better than most / pretty much any modern 'standard' zoom
but: many old lenses, specially prime lenses are way better.
it is somewhat surprising that an old zoom also is outperforming it, above all one not many ever will have heard of ( Ozunon?? ) but nevertheless it is believable.
07-16-2009, 05:36 PM   #11
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QuoteOriginally posted by kuuan Quote
this is my believe, don't have facts to prove it:
The Sigma is a quite good lens, better than most / pretty much any modern 'standard' zoom
but: many old lenses, specially prime lenses are way better.
it is somewhat surprising that an old zoom also is outperforming it, above all one not many ever will have heard of ( Ozunon?? ) but nevertheless it is believable.
THe ozunon might be a rebrand of a good lens though, so being a no-name is not always a handicap
07-16-2009, 06:57 PM   #12
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QuoteOriginally posted by Andi Lo Quote
THe ozunon might be a rebrand of a good lens though, so being a no-name is not always a handicap
Photome says it's either a Tokina SD 28-70mm or an SMC Pentax-A SMC 35-105mm. I'm guessing its a Tokina. It was the kit lens that came with my first slr, a Chinon CM-7 that my parents bought for me when I was 15, 21 years ago.
07-17-2009, 01:05 AM   #13
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QuoteOriginally posted by HeavyD Quote
Photome says it's either a Tokina SD 28-70mm or an SMC Pentax-A SMC 35-105mm. I'm guessing its a Tokina. It was the kit lens that came with my first slr, a Chinon CM-7 that my parents bought for me when I was 15, 21 years ago.
No offense, but how could it be either a 28-70 or a 35-105 when the focal length range of your lens is 35-70?
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