SD15 autofocus poll

Started Jun 6, 2011 | Discussions thread
Tom Schum
OP Tom Schum Veteran Member • Posts: 6,481
Re: SD15 autofocus poll

Chuck Lantz wrote:

Since you and others mentioned having Sigma calibrate the body and lenses, I was wondering if part of the adjustment process involves adjusting the body itself. If that is the case, wouldn't those adjustments to the camera body throw it off for any other lenses that you didn't send to Sigma? In other words, is it best to send all your lenses for matching?

When I sent in my SD15 + 17-50 lens, Sigma USA evaluated my camera body separately (camera was also under warranty) and found nothing wrong. They then proceeded to set up the 17-50 lens to work better with the camera. This probably involved changing some flash settings in the lens itself (but I really have no idea of course). When I received lens and camera back, I checked operation with my 50-200 lens (never sent into Sigma) and all was the same (perfect). And, the 17-50 autofocused much much better than before, too. I am fully satisfied with the results, but it is still a hassle to box up the camera and lens, take it to the post office, pay insurance and fill out the shipping forms etc. Next time, they will have it in their records that there was nothing wrong with the body, and then they can adjust the lens as needed.

You also asked about sharpness with the SD15 being effected by light situations. I just finished shooting a vintage car racing event, and it was overcast all day. Since I have the bad habit of carrying-over the basic SD14 settings I usually use in those situations, a few of the shots were softer than expected until I bumped up the ISO on the SD15, which I only rarely did with the earlier models.

That's very interesting. I never knew that since I don't have a SD14. I can't compare them in similar situations like you can.

What I was talking about in the original post for this thread was that I notice that there seems to be some dependency between autofocus consistency and light level: with more light the the autofocus seems to be consistently better. This might apply more stringently to large aperture lenses such as the 85mm F1.4, or my copy of the lens might simply need adjustment. However, I am not really sure about any of this since my 50-200 lens focuses well in low light even though it has a maximum aperture of only F5.6 at 200mm! I will have to investigate this further with my 85mm F1.4 by increasing SD15 ISO in low light!

I guess what I'm trying to say is that the SD15 is, in some ways, a completely different camera than the SD14, rather than simply an improved version of the SD14. Using the same settings on both will not give the same results. Old dog; new tricks, etc.

From what I have seen on the forum so far, the SD15 has a better reputation for consistency and reliability than the SD14. Carl Rytterfalk said he finds the color in the SD14 subtly different and in some cases better than that in the SD15. He is very very good with both cameras though. I'll never find out for sure, since I have only a SD15.

With all this "adjustment" discussion going on, it gets me wondering if Sigma makes the lenses optimized for something else (such as Canon) then somebody in Sigma USA changes the mount to SA mount whenever such a lens is ordered, because quantities of SA lenses sold are so very small. Then, I get a SA mount lens optimized for Canon, and of course it is out of adjustment on my SD15. This theory does not hold a lot of water however, since many others have no trouble with their new SA lenses...
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Tom Schum

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