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11-11-2008, 01:11 PM   #16
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QuoteOriginally posted by SpecialK Quote
And the mounts will match his filters.
filter GLASS

my filter rings are perfectly fine thank you very much

11-11-2008, 01:50 PM   #17
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Meh...I've never had a problem with any of my lenses.

I don't pixel peep either though...just shoot and enjoy.

c[_]
11-11-2008, 07:56 PM   #18
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QuoteOriginally posted by gkopeliadis Quote
Now I’m going through the same with a brand new Pentax DA 12-24/4.0 I bought a week ago with major decentering problem on the left side.
The Pentax 12-24 is on my "want to buy" list -- now I'm scared!

(I must admit, I've always been a bit wary of zooms )

Would you be willing to post a few test images to demonstrate what a bad copy produces?

Thanks
11-12-2008, 03:38 AM   #19
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QuoteOriginally posted by troyz Quote
...Would you be willing to post a few test images to demonstrate what a bad copy produces?...
17mm, f8, 1/125sec

Notice the softness at the bottom (down is right )
@f8, 17mm it's NOT depth of field, FF or BF issue. Other Photograph areas are sharp and away or sharp and near.




Last edited by gkopeliadis; 11-12-2008 at 03:45 AM.
11-12-2008, 03:57 AM   #20
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Testing lens decentering

QuoteOriginally posted by troyz Quote
Would you be willing to post a few test images to demonstrate what a bad copy produces?
A good method is described here. It is in German but just look at the pictures and you get the idea.

In a nutshell:
  • select an object at least 20m away.
  • use a tripod and mirror lock-up
  • focus (e.g., using AF with the centre focus sensor) and then switch to MF and do not change the focus anymore
  • use an aperture that gives acceptable sharpness in the corners
  • preferably use manual metering to keep it constant for the following shots
  • take four pictures, placing the subject in all four corners respectively
  • compare the images
If the four images deviate considerably in sharpness, your lens is not centred correctly.
11-12-2008, 04:18 AM   #21
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QuoteOriginally posted by Class A Quote
A good method is described here. It is in German but just look at the pictures and you get the idea.

In a nutshell:
  • select an object at least 20m away.
  • use a tripod and mirror lock-up
  • focus (e.g., using AF with the centre focus sensor) and then switch to MF and do not change the focus anymore
  • use an aperture that gives acceptable sharpness in the corners
  • preferably use manual metering to keep it constant for the following shots
  • take four pictures, placing the subject in all four corners respectively
  • compare the images
If the four images deviate considerably in sharpness, your lens is not centred correctly.
When the new copy arrive ....
11-12-2008, 11:02 AM   #22
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QuoteOriginally posted by gkopeliadis Quote
17mm, f8, 1/125sec

Notice the softness at the bottom (down is right )
@f8, 17mm it's NOT depth of field, FF or BF issue. Other Photograph areas are sharp and away or sharp and near.
That's shockingly bad!

Thanks for the info. I hope your next copy is better.
11-12-2008, 08:26 PM   #23
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QuoteQuote:
Notice the softness at the bottom (down is right )
@f8, 17mm it's NOT depth of field, FF or BF issue. Other Photograph areas are sharp and away or sharp and near.
That does not look good, however, this is the only bad example I've ever seen. The lens is highly praised by nearly every owner. Hopefully your replacement will be a good one. It was the last lens I got, but I use it the most, perhaps (though the fisheye is my favorite and most fun).

11-13-2008, 03:02 AM   #24
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QuoteOriginally posted by Gooshin Quote
dont know

but it seems the majority of lens defects are reported by people with K10D's , why, i dont know.
maybe they are more than K20D owners
I don't know.
Film lovers on the other hand don't pixel peep
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