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08-28-2008, 05:23 PM   #16
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Thanks, Daniel.......I actually saw those threads when I was doing my research. The pics posted in the first link from DPR is what really made me want it.

08-28-2008, 06:04 PM   #17
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as I am testing it now to decide whether to buy it or not - I found one small negative (at least inconvenient) factor (for now at least) - Sigma DG 20-60/2.8 is not supported by PTLens ... do you gus have a good building nearby to right the wrongs ?

http://epaperpress.com/ptlens/calTargets.html
08-28-2008, 06:24 PM   #18
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Wow! That is a great lens, considering that you can get it for super cheap from Cameta via Amazon.com:
Amazon.com: Sigma 24-60mm f/2.8 EX DG IF Aspherical Wide Angle Zoom Lens for Pentax and Samsung SLR Cameras: Electronics

Heather
08-28-2008, 06:33 PM   #19
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Shut up all of you. I'm not buying a new lens until my birthday in October. They better have that price still.

08-28-2008, 07:58 PM   #20
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QuoteOriginally posted by deejjjaaaa Quote
as I am testing it now to decide whether to buy it or not - I found one small negative (at least inconvenient) factor (for now at least) - Sigma DG 20-60/2.8 is not supported by PTLens ... do you gus have a good building nearby to right the wrongs ?

http://epaperpress.com/ptlens/calTargets.html
PTlens is for lens correction I believe (like defishing).
But even at 24mm, it is hardly wide at all.


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08-28-2008, 08:46 PM   #21
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QuoteOriginally posted by danielchtong Quote
PTlens is for lens correction I believe (like defishing).
But even at 24mm, it is hardly wide at all.


Daniel
come on - you can clearly see that it has barrel distortion, even if it is 1.x% something it still worth to get it corrected...
08-29-2008, 08:56 AM   #22
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I purchased this lens a few months ago. I am impressed by the sharpness for a zoom lens. I compared some images taken with my Pentax FA50 at same F settings with great results. Mine tested perfectly for BF/FF at 24 and 60mm with F2.8 settings. If you have a good copy, you will be happy for the price. Fewer of these will be available as I believe Sigma is not producing any more. Special prices have appeared everywhere indicating a move of old stock. Competition with 24-70mm F2.8 and 28-70mm F2.8 has caused this lens to fail being notice.
08-29-2008, 08:58 AM   #23
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is it FF compatable? ( i still havent a clue how to figure that out with sigma lenses)

08-29-2008, 09:14 AM   #24
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QuoteOriginally posted by Gooshin Quote
is it FF compatable? ( i still havent a clue how to figure that out with sigma lenses)
yes, it is... Sigma marks cropped lenses with "DC", no "DC" = FF lens.
08-29-2008, 10:36 AM   #25
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QuoteOriginally posted by Denis Quote
Mine tested perfectly for BF/FF at 24 and 60mm with F2.8 settings.
through 4 Sigma zooms and 3 Pentax bodies (*istDL, K10D, K20D) I am yet to see the combination
that does it precisely and w/o AF adjustment for both daylight and genuine ("yellow") tungsten through all focus length'...

well, here is a quick daylight testing under the daylight (K20D, tripod, SR off, remote control, etc), PP'ed in attempt to make it more visible (in focus/BF/FF).

warning - the image is WIDE.

24mm->28mm->35mm->40mm->50mm->55mm->60mm

note that 24, 40, 50, 55, 60 looks more or less OK, but 28, 35 are not... I will retest these 2.

click below and then click it again there to see the full size

08-29-2008, 10:52 AM   #26
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ok, now the same setup (daylight, K20D, tripod, etc) - just different angle and 28mm (left) + 35mm (right)

note that images were PP'ed (contrast, etc) to make it more visible:



08-29-2008, 11:52 AM   #27
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is it exactly 45 degrees? makes a difference
try this neat focus chart
https://www.pentaxforums.com/forums/pentax-dslr-discussion/33853-charts-auto-...ed-pentax.html
08-29-2008, 12:58 PM   #28
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QuoteOriginally posted by k100d Quote
is it exactly 45 degrees? makes a difference
try this neat focus chart
https://www.pentaxforums.com/forums/pentax-dslr-discussion/33853-charts-auto-...ed-pentax.html
it does not make a big difference - if you have FF or BF it will be there
regardless whether it is 45 or 30 or 60 degrees...

PS: charts must have the same scale on both sides, so those from Yvon Bourque are not very good... it is a very stupid idea to have one side marked in mm' and another one in inch'... the lines on the left must be corresponding w/ the lines on the right - that way it is much easier to see if you have not only a BF/FF, but decentering/tilted element inside the lens... not that different scales are not usable -they are just not convenient, I'd rather make 2 .PDFs
08-29-2008, 02:29 PM   #29
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I quickly scrolled through the contents of this thread and couldn't believe the number of focus charts and graphs I saw.

PEOPLE! Stop measurebating!
08-29-2008, 02:34 PM   #30
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QuoteOriginally posted by ftpaddict Quote
I quickly scrolled through the contents of this thread and couldn't believe the number of focus charts and graphs I saw.

PEOPLE! Stop measurebating!
Sorry, we just can't entrust our IQ (photos) to pentax AF and sigma QC (and pentax QC either... 16-50/2.8)... all that 14.x CMOS is useless if you can't get it focused.
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