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03-18-2011, 09:53 PM - 1 Like   #121
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K7 Sequence



Observations (leaving aside test imperfections ):

EDITED TO ADD: A single digit adjustment to the AF in the first shot will not perfectly center the DOF. The result is a very similar amount of focus miss, but towards FF.

The K7 will only lock 1 out of 4 tries at EV 2.2 in tungsten lighting with this lens, and is not always in focus when it does lock. I was surprised about this as the K20 hunts a bit but usually locks at this light level, and is consistent when it does. I gradually increased the light until the focus locked every time and was even more shocked to see that the K7 would not lock consistently until I hit EV4.5!

The K7 focus shift performs in a very similar manner to the K20 in this test.

I ran another set of shots at f4.0, where I set BF in the 5500K light, and the camera will barely hold DOF (FF) at the lowest light level of EV 2.2 (assuming it locks and is in focus when it does). This is very similar to the K20, in my experience.

The K5 is clearly better than this, at least in these test conditions as it holds f1.4 DOF pretty well in the same lighting.

I will post a K20 sequence soon.

Ray

03-19-2011, 01:11 AM   #122
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crikey Ray..so the K7 isn't as good as the K5..thats good to hear for us K5 owners.

Rep added for your trouble old son
03-19-2011, 02:13 AM   #123
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On j鳵nyt p鳵lle himo testaus.
03-19-2011, 08:40 AM   #124
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QuoteOriginally posted by 30v iPentax Quote
On j鳵nyt p鳵lle himo testaus.
I must say that I look forward to trying to figure out your obtuse posts.

Kiitos

Ray

03-19-2011, 09:07 AM   #125
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QuoteOriginally posted by Ray Pulley Quote
I must say that I look forward to trying to figure out your obtuse posts.

Kiitos

Ray
I think it's the translation software, not the poster.
03-19-2011, 09:28 AM   #126
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QuoteOriginally posted by Ray Pulley Quote
I must say that I look forward to trying to figure out your obtuse posts.

Kiitos

Ray
I think what our Finnish friend said, and the software bollixed up nicely was that the K-7 had been at the top of his list of cameras yet to be tested.

NaCl(of course it could mean "boston is full of small fried turkeys" too)H2O

explanation: My sister used to teach English to Japanese business men. She once asked for a sentence using a prepositional phrase and the above is what she got.
03-19-2011, 10:00 AM   #127
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Finnish is hard to translate automatically

QuoteOriginally posted by Parallax Quote
I think it's the translation software, not the poster.
I spent some time in Finland and it is a hard language to learn and very hard to translate automatically, so I am sure you are correct.

The point being it is like a puzzle reading these posts.

Kiitos = Thank You, BTW.

Ray
03-19-2011, 10:30 AM   #128
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Thanks

QuoteOriginally posted by Tommot1965 Quote
crikey Ray..so the K7 isn't as good as the K5..thats good to hear for us K5 owners.

Rep added for your trouble old son
You are too kind.

A couple of notes that everyone should keep in mind:

This is f1.4. I almost never shoot wide open on any lens I own, because as good as the Pentax glass is, the difference between wide open and a bit stopped down is almost always significant.

We have not heard much about K7 focus issues. There is a poster on the other forums who reports FF in Tungsten with his K7 in the threads about the K5 FF issue. For the most part it seems as though we were all used to the K10/K20 AF performance, which the K7 at least seems to match, and by most reports exceeds in terms of speed.

Cameras and lenses all have certain tolerances and a given combination could be worse than another combination, or better for that matter. It can even be that a given lens or camera is out of specification and needs repair.

That being said, I have been using the K20 since it was introduced and while I thought the K7 might be better in low tungsten (after all it has the magic + sign in the SAFOX model name ) it looks like it is more or less just like the K20, at least in this test.

What does this mean? Well, while I know that others might well use the camera in ways where this will be a problem, clearly the K20 level of performance has worked for me for some time now, and I assume that the K7 has done so for others as well.

Since I do not shoot like this much (if ever) my next step is to check the camera at various f stops, and if it can be calibrated to hold DOF (even barely) in a test like this at even f4.0, it will do the job.

For critical macro shots, I presume LV is a better alternative anyway.

So, while it seems as though some are still seeing issues with the K5, and I may also after more real life shooting, I am still encouraged and think that the last upgrade has improved the K5 to the point that for me it will be ok.

Ray

03-19-2011, 05:32 PM   #129
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I returned my first K-5 as my older K-7 was able to focus under low light and the K-5 couldn't.

Bought my second K-5 after the firmware release and I am happy with it's performance and I am sure it is at least as good as the K-7 (didn't bother to compare them).

P.S: Surprised to see this thread remain open for so long, that's not the norm here any more is it ?
03-20-2011, 06:05 PM   #130
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comparison of low light focus with v1.01 and v1.03 of firmware

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 during daylight (EV>12). 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 tungten lightbulb chandelier on a reostat and adjusted the light so the camera meter showed correct exposure with each of the manually assigned shutter speeds. 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, 09:30 PM   #131
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QuoteOriginally posted by tram57 Quote
With v1.03 the camera still wouldn't lock at EV0 (I couldn't see the chart either).
Moonlight is supposed to be EV −3 to EV −2 so one should be able to see a chart at EV 0?

Sounds like a good test, though. Thanks a lot for sharing the results.

Do you happen to have a faster lens and shot it with V1.01? Falconeye didn't see an improvement with the 31/1.8 and the faster lens speed (compared to your f/2.8) could be a potential explanation.
03-26-2011, 09:42 PM   #132
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Falk Lumo: LumoLabs: Pentax K-5 low light focus with firmware upgrade 1.03

Looks like Falk's scientific tests has corroborated my findings with 1.03
03-26-2011, 10:19 PM   #133
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yep read that smeggy...trouble is it dont hold true for my K5 now...not sure what to make of it really...
03-27-2011, 12:16 AM   #134
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I have never turned on my K-5 at night or in tungston light. I may never attempt it now..
What a crock for the people that shoot in these conditions. I love mine but never shoot in those conditions. Hmmmmmmm. 1.03 a crock...
03-27-2011, 01:56 PM   #135
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QuoteOriginally posted by Tommot1965 Quote
yep read that smeggy...trouble is it dont hold true for my K5 now...not sure what to make of it really...
Well I'm still replacing mine. it's supposed to be picked up by the courier tomorrow and being replaced with a 4xxxxxx serial number model the same day. Although I haven't heard final confirmation from the retailer so I better pack the camera up just in case.
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