If frogs had wings ...

Man.... acceptable but what did they do with the aperture? It's not providing an accurate reading (at least not with respect to the other lenses)

As far as sharpness goes, it looks a whole lot better!

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Originally Posted by dr4gon

Man.... acceptable but what did they do with the aperture? It's not providing an accurate reading (at least not with respect to the other lenses)

As far as sharpness goes, it looks a whole lot better!

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As I recall, it shot "dark" when I first got it. I would like to see some other people's comparisons of the lens to their TAMRONs.

EDIT: Okay ... after several other test shots ... between the 18-250 "all-in-one" and the 10-20 "UWA", it is more like a third of an f-stop "darker" ... when the TAMRON is set to f/6.3 ... I get the same illumination of the image at f/5.6 on the SIGMA. But, I already knew the 18-250 shot a little darker than the f/2.8 lenses. It's not of the same caliber. It's a longer, darker lens.

I will post the aperture comparisons later on, to gauge this a bit more accurately ... but, it is hard to believe. I don't even know how to complain about it to the factory guys ... because this is a design error ... not a repair. Whoa. I know the TAMRON (or KM) f/2.8s do shoot brighter ... the question is ... which is correct? What should I use as a standard? The closest PRIME I have is the Minolta AF 24mm f/2.8. Lighting is lighting, but distance does factor into the equation. There is quite a gap between 20mm and 24mm, although it may not seem like it. I suppose I could run out and just buy a SONY 20mm f/2.8 PRIME. Although, I don't think the SONY Style store has them in stock. It is not a high-demand lens, unlike the 28mm or the 50mm.

As I thought about this ... I decided to compare the TAMRON (& KM) at the equivalent 24mm with the Minolta PRIME. That will provide a direct correlation with the calibration of those lenses and the SIGMA. (BTW: The Minolta AF 24mm f/2.8 was recently cleaned and calibrated) If the TAMRON (& KM) are spot on ... SIGMA has some 'splaining to do.

Man oh man ... this definitely qualifies as "weird."

Okay ... after conducting the snaps ... the Minolta 24mm f/2.8 set @ f/5.6 confirms the f/5.6 exposure setting of both the TAMRON & KM f/2.8 lens is correct.

Minolta PRIME 24mm f/2.8 @ f/5.6
Attachment 43484

TAMRON SP AF 17~50mm f/2.8 @ f/5.6
Attachment 43485

Konica-Minolta AF 17~35mm f/2.8~4 "D" @ f/5.6
Attachment 43486

So ... concluding the KM has the EV right ... a side-by-side against the SIGMA 10-20 @ 20mm - f/5.6

A: KM @ f/5.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIGMA @ f/5.6
Attachment 43487Attachment 43490

B: KM @ f/6.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIGMA @ f/5.6
Attachment 43488Attachment 43490

C: KM @ f/7.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIGMA @ f/5.6
Attachment 43489Attachment 43490

So the question is ... which of these exposures looks like the SIGMA's f/5.6? A, B, or C?

It's not the full stop that I seemed to have had experienced earlier ... but, it still is not as accurate as I had hoped. It's more like a f/4.5-6.3 lens, than a f/4-5.6 lens. So much for my results ... you can try this when you get yours.

With the PRIME up against it ... LOL

Minolta AF 24 @ f/5.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIGMA 10-20 @ f/5.6 (20mm)
Attachment 43493Attachment 43492

f/5.6 just ain't what it used to be ... :rolleyes:

Well from what I can tell, the sigma is certainly sharper!

I'd say F/6.3 is about right. 5.6 is pretty close, but not quite.

I hope that last edit put it together ... it is dark. Sharp, but dark.

Yeah I'm sure the contrast helps make it sharper too.

In Pop Photo's Feb. 2008 issue, they rate Tamron's 10-24mm very favorably.

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"With excellent-range SQF scores at the three tested focal lengths, the lens promises faultless contrast and resolving powers" ....

"slight barrel distortion...noticeable improvments over the 11-18mm

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light falloff left the Tamron's corners by f/5.6 at 10mm, and there was no discernaible vignetting at the other tested focal lengths. WOW!

close-up performance was also stellar....

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They seem to really like the lens!

The SQF table was about 1 point or less all around over the Sony (Tamron) 11-18mm tested here:

http://www.popphoto.com/cameralenses...ons-page2.html

The "size" is that megapixels?

Quote:

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Originally Posted by dr4gon

In Pop Photo's Feb. 2008 issue, they rate Tamron's 10-24mm very favorably.



They seem to really like the lens!

The SQF table was about 1 point or less all around over the Sony (Tamron) 11-18mm tested here:

http://www.popphoto.com/cameralenses...ons-page2.html

The "size" is that megapixels?

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No, the "size" is the aperture setting on the lens. You can see that the minimum size goes up as the focal length gets longer. The chart indicates quality of image in an inch-by-inch format.