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05-22-2010, 08:21 PM   #16
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Good thought, Rondec - but I don't have a Sigma 70-200. I do, however, have a 100-300, but I don't have any focus corrections on either of my K20D bodies at all.

I'm wondering if the firmware on the Siggie is faulty? It was purchased from a reputable dealer in London, so I doubt that it is grey market goods - and it works just fine anyway. I'll have to find out who to contact re Sigma here in Australia.

I have the latest Aperture updates, but I'm wondering if the lens itself needs to have its firmware updated?

Not sure who to contact in Australia re firmware etc for Siggies....

EDIT: PS - for Aussies, it is C R Kennedy who distribute Sigma here. Also, after some Googling, I found that several people on Canon, Nikon, and other forums, were getting similar problems, and not just from this lens either. However, all were from third party lenses, usually Sigma or Tamron, and it is generally thought to be some problem with the built-in databases not recognising the lens accurately. Apparently there is a program called "EXIF Tool" by Phil Harvey that will check the real EXIF data from the lens/photo combination, but it is a command line program that runs in Terminal on the Mac, and although I've downloaded it, it appears to be very complex for non-programming types like moi.


Last edited by Derridale; 05-22-2010 at 09:23 PM.
05-22-2010, 08:50 PM   #17
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QuoteOriginally posted by Marc Sabatella Quote
*Meters* ahead? That's flat out impossible. If it's focusing meters away from where you intended, that's not front focus - that's simply the camera choosing a different target than you intended. Focus problems are measured in millimeters, not meters.

I agree with Marc...........that's insane!
05-22-2010, 11:18 PM   #18
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Okay here are my test chart images: I took several and the results were pretty consistent:

First is with my camera's starting adjustment of -20um from my DA 70mm and you can see its very front focused.



2nd is -150um and slightly closer to the target. And its focusing pretty spot on now.



White balance is different because i tried natural and artificial light and neither affected results.
Always use center point focus and it was dead on the border and center of target, tripod looks slightly angled but should not affect it.

Last edited by WerTicus; 05-22-2010 at 11:24 PM.
05-23-2010, 12:28 AM   #19
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*Those* results are certainly believable.

05-23-2010, 08:18 PM   #20
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can a focus screen affect the auto focus in point focus mode?
05-24-2010, 03:36 AM   #21
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Friends of mine who are Canon and Nikon users have experienced focus issues with this lens. All sent their lenses back to the local Sigma agent for recalibration.
05-24-2010, 03:48 AM   #22
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QuoteOriginally posted by WerTicus Quote
can a focus screen affect the auto focus in point focus mode?
the focusing screen has nothing to do with autofocus, i've the stock one, a chinese brand and a nikon fitted to pentax and autofocus behaves the same with every screen i've used.
05-24-2010, 08:05 AM   #23
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Yeah im sending mine in to be calibrated, but it will have to wait a couple weeks. You need to send your body with it?


Last edited by WerTicus; 05-24-2010 at 08:47 AM.
05-24-2010, 09:39 AM   #24
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QuoteOriginally posted by WerTicus Quote
Yeah im sending mine in to be calibrated, but it will have to wait a couple weeks. You need to send your body with it?

I had one for my D700 and I fixed it at home. Sigma uses metal shims under the rear metal mount. I just unscrewed the rear mount and took both shims out, that was too much, so I put one back in and presto, perfect focus on the D700 with no correction.
05-24-2010, 10:48 AM   #25
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okay if mine is front focusing do i need to add or remove shims? I would think id need to add an extra shim i don't have?
05-24-2010, 11:17 AM   #26
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okay i removed one shim and its improved somewhat, but the 2nd shim is thinner and i dont think it will be enough change even with both removed but ill try it.
05-24-2010, 11:45 AM   #27
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QuoteOriginally posted by JMI Quote
I had one for my D700 and I fixed it at home. Sigma uses metal shims under the rear metal mount. I just unscrewed the rear mount and took both shims out, that was too much, so I put one back in and presto, perfect focus on the D700 with no correction.
Interesting! I have one in Canon mount and it front focused something fierce at closer distances when I got it, then sent it to Sigma which fixed that, except now it back focuses at longer distances. Not sure if dinking around with shims will do anything about that.
05-27-2010, 08:19 AM   #28
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Any updates on this issue?
05-27-2010, 05:45 PM   #29
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I just sent in my Sigma lens to have calibrated with my camera. Now i have no camera. At 2.8 it was front focusing so bad the images could not be used. You could look at the pics and see the focus point. And i use only center spot focus.
What a pain. I will get it back in 3 weeks i hope. I had to send mine to Japan. 150 dollars one way. What a rip.
05-27-2010, 06:06 PM   #30
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QuoteOriginally posted by Derridale Quote
Don't know if it makes any difference, but I virtually always use the single point spot focus on my K20D. I never use the multi-focus points or the "Select the point" type.

But I don't know if that has anything to do with this....

Here is a pic of my Dad on his 96th birthday taken with the Siggy 50mm f/1.4:



No tweaking or sharpening - shot in RAW on the K20D

Can't see too much problem with the focus point, which was his eyes.

And another - again using single-point autofocus:

God bless you both, man:

My dad passed away at 56.

And I'm 53.
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