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03-20-2011, 06:15 PM   #1
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Comparison of K-5 low light focus accuracy with v1.01 and v1.03 of firmware

Interested in what others have found

Got my k-5 this week from B&H, serial 400XXXX. Came with v1.01 firmware. Using a 35mm 2.8 macro limited and shooting a test chart from about 1.5 feet at a 45 degree angle I tested the focus accuracy with v1.01 firmware, then upgraded to v1.03 and repeated the tests. The focus adjust was fine tuned for this lens in v1.01 during daylight (EV>12) prior to the after dark testing. With the camera set to manual mode, iso at 800, apeture at 2.8, I varied the exposure time from 1 s (=EV0) up to 1/60 of a second (=EV6), halving the exposure time with each pair of shots; i adjusted the room light using a tungsten lightbulb chandelier on a reostat and adjusted the light so the camera meter showed correct exposure with each of the manually assigned shutter speeds. Based on a wiki EV chart 1s=EV0, 0.5s=EV1, 1/4s=EV2, 1/8s=EV3, 1/15s=EV4, 1/30s=EV5, 1/60s=EV6. The assist light was set to off. This is what I found:

With v1.01 the camera would not lock focus at EV0. The camera front focused about 2-3 cm on the chart until light was adjusted up for correct exposure at 1/30th of a second (=EV5). At this light level, focus was suddenly spot on. At all lower levels, exposure was front focused 2-3 cm.

With v1.03 the camera still wouldn't lock at EV0 (I couldn't see the chart either).
At 0.5 s and 1/4s exposures there was FF of about 10-12 mm (half of what I saw with v1.01) corresponding with EV 1 and EV 2 light levels, respectively. By the time light was increased for correct exposure at 1/8s shutter speed (light level of EV3), focus was spot on and stayed so. Thus the new firmware has given me accurate focus at 2 stops lower light than v1.01 which seems to be significant.

EV 0, 1, and 2 are really quite low light. I'm very pleased with this performance, and can recommend the firmware upgrade.

03-20-2011, 07:27 PM   #2
Brooke Meyer
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Ev 14

The Moon was EV14, the Longleaf Pine a lot less. Could be Front or Rear focused. Seems to work okay.

Last edited by Brooke Meyer; 06-06-2011 at 07:40 PM.
03-20-2011, 08:12 PM   #3
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Ev14?
03-20-2011, 08:13 PM   #4
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QuoteOriginally posted by tram57 Quote
Interested in what others have found

Got my k-5 this week from B&H, serial 400XXXX. Came with v1.01 firmware. Using a 35mm 2.8 macro limited and shooting a test chart from about 1.5 feet at a 45 degree angle I tested the focus accuracy with v1.01 firmware, then upgraded to v1.03 and repeated the tests. The focus adjust was fine tuned for this lens in v1.01 during daylight (EV>12) prior to the after dark testing. With the camera set to manual mode, iso at 800, apeture at 2.8, I varied the exposure time from 1 s (=EV0) up to 1/60 of a second (=EV6), halving the exposure time with each pair of shots; i adjusted the room light using a tungsten lightbulb chandelier on a reostat and adjusted the light so the camera meter showed correct exposure with each of the manually assigned shutter speeds. Based on a wiki EV chart 1s=EV0, 0.5s=EV1, 1/4s=EV2, 1/8s=EV3, 1/15s=EV4, 1/30s=EV5, 1/60s=EV6. The assist light was set to off. This is what I found:

With v1.01 the camera would not lock focus at EV0. The camera front focused about 2-3 cm on the chart until light was adjusted up for correct exposure at 1/30th of a second (=EV5). At this light level, focus was suddenly spot on. At all lower levels, exposure was front focused 2-3 cm.

With v1.03 the camera still wouldn't lock at EV0 (I couldn't see the chart either).
At 0.5 s and 1/4s exposures there was FF of about 10-12 mm (half of what I saw with v1.01) corresponding with EV 1 and EV 2 light levels, respectively. By the time light was increased for correct exposure at 1/8s shutter speed (light level of EV3), focus was spot on and stayed so. Thus the new firmware has given me accurate focus at 2 stops lower light than v1.01 which seems to be significant.

EV 0, 1, and 2 are really quite low light. I'm very pleased with this performance, and can recommend the firmware upgrade.
The K-5's AF is specified to work down to EV-1

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