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12-01-2011, 03:19 PM   #16
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I was shooting from approx 2-2.5m, yes - and perhaps you make a good point because I've noticed it before too, although never investigated it (and no, I wasn't closer than MFD ).

This is one of those wedding shots I was referring to - may have been some 5-7m away and got 12-13 OK photos, but AF was always too slow to get any shot when I really wanted to take one.




I was puzzled by the info to the left myself - there's things missing there all of the sudden.

I'm not too happy atm. about the service guys here. I just got the K-x back from repairs and I have a bit of a bad taste about the whole thing. I'll have to wait (hopefully not) next time I'm forced to send it in.


Last edited by Zafar Iqbal; 08-03-2013 at 06:19 AM.
12-03-2011, 02:54 AM   #17
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I decided to bring the Sigma with me to the party, but had to leave my home early so I missed the delivery. Oh well

Instead I brought my Pentax 21mm ltd, 35mm macro ltd and Vöigtlander 58mm along with me and one thing I realized, was that I had two too many lenses with me and not single one of these would have been sufficient enough IMO. It was OK to change them, but it would have been much better to just have one zoom lens. The cam was on my lap most of the time when I was seated, or left behind on the chair (vs table) because of limited space. This was the very reason I was interested in a flexible zoom in the first place.

I feel the need for such a lens is bigger than my worries about focusing - so I think I'll go ahead and keep it once I get my hands on it.
12-07-2011, 09:17 AM   #18
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Finally got the Sigma today - brought it with me to work, but didn't get proper chance to use it as it started to rain. It suffers from this soft glowish look when wide open, like my older sigmas, although the older ones are much worse.

I may not have used my 70-200 2.8 under similar conditions, but I do not have the impression it does the same thing, or to such a "severe" degree.

The lens renders amazingly sharp wide open. It's not a big surprise but it's easy to be let down once I expect something. The lens doesn't dissapoint on this part.

It's a shame with the AF switch (have to enable/disable both on cam and lens every time) on the lens and I wish the focusing ring would have been similar to the one on my 70-200 would.

OS is "fun". The viewfinder is sometimes a bit "wobly" because of this.

Have so far had quiet a few of focusing issues (indorr and outdoors - was very cloudy). Sometimes it doesn't lock where it should even though there was enough (IMO) contrast and light, and noting else nearby to focus on - but the lens is defo not suffering from FF/BF issues.

I brought my 35mm Macro ltd to the party and later noticed it missed focus points just like the Sigma - but not as much. My impression is still what I originally feared (slow focus) and I hope it's nothing else than a misplaced conviction.
12-07-2011, 11:29 AM   #19
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Did some non-scientific tests:

DA L 18-55 @ 55mm f5.6:

In focus: 14
Uncertain/ very close: 4
Missed focus: 2

Focus hunts: 1


DA L 18-55 @ 50mm f5.6:

In focus: 16
Uncertain/ very close: 1
Missed focus: 3

Focus hunts: 1


Sigma 17-50 @ 50mm f5.6:

In focus: 7
Uncertain/ very close: 0
Missed focus: 12

Focus hunt: 1, possibly 2

I apparently overlooked one shot in this test.

Sigma 17-50 @ 50mm f2.8:

In focus: 9
Uncertain/ very close: 0
Missed focus: 11

Focus hunts: 3, possibly 4


Sigma 17-50 @ 50mm f2.8:

In focus: 7
Uncertain/ very close: 5
Missed focus: 8

Focus hunt: 0


Lighting condition and testing method used:
Low light - close to but possibly brighter than a bar type of lighting.

I aimed at 20 random things located around in my room. Some tricky some easier subjects. I took the pictures from the same spot - my chair my the desk. I imported the first batch into my PC, and then used these pics as reference for the other shots - to make sure I aimed the proper places.

There's lots of margin for errors, but the results should be more random then. As I've been suspecting all along, the Sigma performed worse. This isn't a conclusion, but still worth chewing on.

Edit: Perhaps I should also mention that I had my Metz 58 AF-2 flash on, and it assisted for focusing.


Last edited by Zafar Iqbal; 12-07-2011 at 12:01 PM. Reason: typo
12-07-2011, 03:57 PM   #20
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DA L 50-200 4.0-5.6 vs Sigma 70-200 2.8

DA L 50-200 @ 200mm f5.6:

In focus: 16
Uncertain/ very close: 0
Missed focus: 0

Focus hunt: 3

Extreme focus hunt/couldn't lock: 6


Sigma 70-200 @ 200mm f2.8:

In focus: 14
Uncertain/ very close: 0
Missed focus: 1

Focus hunt: 6

Extreme focus hunt/couldn't lock: 10

(if you think the numbers for the Sigma don't add up (cant lock vs in focus), then it's because I kept trying and trying. Actually "can't lock" is true in some cases, while in most of them it's my verdict since I tried for so long that you might just give up and move to something else)

Same lighting as before - same subjects although 2 were within MFT and 2 were moved from previous positions, so I picked 4 new subjects to aim at.

Stats are still not in favor of Sigma - and still not random enough to put the Sigma ahead of Pentax.

Although the tests aren't scientific, I feel a pattern is emerging and it's very disappointing the Sigmas are lacking/not convincing considering the larger aperture.

Well, Also did one with the Sigma @ 70mm f2.8 but I didn't take notes about the focus. Lets just pretend its was super duper perfect (I really cant remember and now I'm too tired to continue):

In focus: 13
Uncertain/ very close: 1
Missed focus: 7

Still not topping any of the DA L results.

Last edited by Zafar Iqbal; 12-07-2011 at 04:03 PM.
12-07-2011, 05:10 PM   #21
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Do you have the camera set to use just the center AF point?
12-07-2011, 05:38 PM   #22
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Yes. Center point and contrast detection.
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