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11-01-2011, 12:31 AM   #16
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But I have tried the Pentax 17-70 and found it great!

11-01-2011, 05:00 AM   #17
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QuoteOriginally posted by David&karen Quote
Karen had the Sigma 17-70 OS last spring and we found it was a bad copy(mis centered) and that it had an amazing amount of field curvature at 70mm and lots more lateral color than the 17-50 OS. I cna't believe that those 2 lenses are similar/same optical formula.

David
David,

did you try to do any micro adjustment on your camera using Sigma 17-70? Sigma also does calibration free of charge under warranty. I'm assuming you must have got a bad copy.

As Edgar said, on sigma's website it said they both specify 17 elements in 13 groups. The only difference is between FLD and ELD glass used in each one. The tech gentleman said "they have to use FLD in all their EX fixed aperture series based on their engineering design protocol to have highest light transmission to their lenses. With decent controlled lighting, the IQ should be pretty much the same. that's at least what we have experienced in our lab"

I think I'm going to order both and try them out with my K-5. I will post some photos.

these were taken with my old 17-70 before I sold it ( huge mistake ) see if any of these pictures look sharp to you compare to Karen's Sigma 17-70 or your 17-50.

Hell Burger, Arlington, VA. Obama's Favorite. | Flickr - Photo Sharing!

Tomatos | Flickr - Photo Sharing!

Fuchsia-PC | Flickr - Photo Sharing!

IMGP0854-PC | Flickr - Photo Sharing!

http://www.flickr.com/photos/42220695@N02/6024026172/in/photostream/

Derek

Last edited by dr_romix; 11-01-2011 at 05:21 AM.
11-01-2011, 05:13 AM   #18
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QuoteOriginally posted by dr_romix Quote
I just got off the phone with Sigma Technical support and they guy said if I have K-5 and not worried about low light high ISO, I should stick to 17-70. Both 17-70 and 17-50 use the same optics..The only difference is EX lenses have fixed 2.8 aperture and 4 year warranty vs DC lenses don't have fixed aperture and only 3 year warranty. He also said " As much as I would want to sell you 17-50 , if you have 17-70, I would hold on to that. I have the same lens and extra 20mm comes handy quite sometime. and in our lab test, I didn't notice a difference between the two".. now I'm even more confused..what do you guys think?
Interesting, because I do notice a difference in sharpness between my 17-70/2.8-4.5 and my 17-50/2.8. Maybe it's because my 17-70 is the older f/2.8-4.5 and not the f/2.8-4?
*shrugs*

QuoteOriginally posted by dr_romix Quote
He also highly praised 17-70's macro capability compare to 17-50 which is not macro.
Note that the "macro" capability in the 17-70 isn't real 1:1 macro as such, but it does magnify more than the 17-50, and the 17-70 has a minimum focusing distance that pretty much allows you to focus right on the front element

QuoteOriginally posted by dr_romix Quote
for general walk around, Landscape, street photo with K-5 what do you recommend my friend ?
In terms of pure versatility, I would say the 17-70. That extra range from 50-70mm will be useful, and my 17-70/2.8-4.5 served me well for about 3 years before I got my 17-50/2.8.
Having said that, ever since I got my 17-50/2.8, my 17-70/2.8-4.5 has been relegated to sitting at home, or in the bag as a backup lens.

Last edited by pop4; 11-01-2011 at 05:19 AM.
11-01-2011, 05:18 AM   #19
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QuoteOriginally posted by dr_romix Quote
this was taken with my old 17-70 before I sold it ( huge mistake ) see if that's sharp to you.

Hell Burger, Arlington, VA. Obama's Favorite. | Flickr - Photo Sharing!
The Dr. should have added that the picture is NSFHP (Not Safe For Hungry People).

The picture looks really good though.

11-01-2011, 05:27 AM   #20
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QuoteOriginally posted by Edgar_in_Indy Quote
The Dr. should have added that the picture is NSFHP (Not Safe For Hungry People).

The picture looks really good though.
Thanks.


or perhaps not safe for hungry foreign ( Russian ) president tho..

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