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12-09-2007, 11:03 PM   #1
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SDM vs USM/SWM

Hi,

I would like to know how is the AF speed issue esp. in low light performance with the SDM as compared to the USM/SWM?

I am frustrated with my k100d AF performance (the only thing i didnt like about it).

Thanks.

12-10-2007, 02:29 PM   #2
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QuoteOriginally posted by darthkir Quote
Hi,

I would like to know how is the AF speed issue esp. in low light performance with the SDM as compared to the USM/SWM?

I am frustrated with my k100d AF performance (the only thing i didnt like about it).

Thanks.
I had a K10D and a DA* 50-135mm f2.8 SDM lens. The SDM lens does improve AF performance as compared to the screw drive AF. It is much quieter and smoother, and was definitely faster in good light. But in dim light the AF was still unreliable. Sometimes the AF would confirm focus when it clearly was not properly focused. And sometimes it would simply go from the close stop to the infinity stop and then give up with the green dot flashing. Using a hot shoe flash in focus-assist mode (a Pentax AF-360FGZ) didn't help, as the focus assist would hardly ever activate.

I ended up selling my Pentax AF gear and replaced it with a Nikon D80 and various lenses. The two SWM lenses that I have used in low light are the Nikkor AF-S 17-55mm f2.8 DX and the Nikkor AF-S 70-200mm f2.8 VR. This set-up will focus reliably in near total darkness. Low light AF is much faster and much more reliable as compared to the Pentax gear. It isn't perfect and sometimes it won't focus, but it is a huge improvement. With the Pentax, I was forced to use manual focus in most dimly lit interiors, whereas the Nikon will correctly AF in these situations. And the focus-assist light on the hot shoes flash (Nikon SB-800) actually comes on when needed.

I have never owned any Canon gear (except for my wife's point and shoot) so I can't offer any personal experience on how Canon SLR gear will focus in dim light.
12-12-2007, 02:01 AM   #3
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QuoteOriginally posted by GaryML Quote
I had a K10D and a DA* 50-135mm f2.8 SDM lens. The SDM lens does improve AF performance as compared to the screw drive AF. It is much quieter and smoother, and was definitely faster in good light. But in dim light the AF was still unreliable. Sometimes the AF would confirm focus when it clearly was not properly focused. And sometimes it would simply go from the close stop to the infinity stop and then give up with the green dot flashing. Using a hot shoe flash in focus-assist mode (a Pentax AF-360FGZ) didn't help, as the focus assist would hardly ever activate.

I ended up selling my Pentax AF gear and replaced it with a Nikon D80 and various lenses. The two SWM lenses that I have used in low light are the Nikkor AF-S 17-55mm f2.8 DX and the Nikkor AF-S 70-200mm f2.8 VR. This set-up will focus reliably in near total darkness. Low light AF is much faster and much more reliable as compared to the Pentax gear. It isn't perfect and sometimes it won't focus, but it is a huge improvement. With the Pentax, I was forced to use manual focus in most dimly lit interiors, whereas the Nikon will correctly AF in these situations. And the focus-assist light on the hot shoes flash (Nikon SB-800) actually comes on when needed.

I have never owned any Canon gear (except for my wife's point and shoot) so I can't offer any personal experience on how Canon SLR gear will focus in dim light.
Thanks. At least your opinion confirms to my findings as well.

I hope the new bodies will match the Nikon/Canon AF performance and metering.
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