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11-03-2010, 08:29 PM   #1
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AF Assist Lamp and Tungsten Focus Inaccuracy

Does the assist lamp somewhat offset/improve the tungsten focus inaccuracy? I understand it might not help depending on the distance to subject though .

My problem is that I'm deciding on between K-7 and K-r (assuming they will almost be the same price). I have shot in tungsten light and the focus inaccuracy is prevalent.

So the trade off probably is a newer faster(?) Safox 9 vs a more (tungsten) accurate Safox 8+.

Now if Safox 9 handles tungsten without the secondary light sensor better (with or without the assist lamp), it would tip the scales in K-r's favor.

Ok. I also understand the other differences between the two. But this is one of my primary criteria for choosing.

Thanks in advance .

11-03-2010, 10:44 PM   #2
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I have both the K-r and K-7 cameras. Indoors in tungsten light the K-r will front focus. This will only really be a problem with a narrow DOF shot (ie fast lens wide open).
When the assist lamp comes on, the front focus problem goes away.
The K-7 doesn't have any focus problems in Tungsten based lighting.
11-03-2010, 11:29 PM   #3
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Hey thanks! So with the AF lamp on, this helps negate (or minimize) tungsten focusing inaccuracies .

So the K-r does not really need the 2nd light sensor, unless of course the subject is too far away to illuminate.
11-04-2010, 12:02 AM   #4
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QuoteOriginally posted by GrinMode Quote
Hey thanks! So with the AF lamp on, this helps negate (or minimize) tungsten focusing inaccuracies .

So the K-r does not really need the 2nd light sensor, unless of course the subject is too far away to illuminate.
1. Your first point is correct.

2. The k-r doesn't have the (second sensor)light wavelength sensor (only the "+" version of Safox 8, or 9 does i.e. K-7 or K-5 or 645D cameras) - presumably to keep the cost down. The low light focusing and tungsten light focusing performance is mostly OK, it isn't a camera killer!

11-04-2010, 12:51 AM   #5
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I was aware of the '+' designation of the Safox 8 & 9. It was one advantage the 8+ had over 9, meaning a plus for the K-7.

But that advantage has been lessened somewhat with the AF lamp on the K-r, so it affects my decision making .

Btw, how is the AF-S comparison in good light? Thanks again
11-04-2010, 01:12 AM   #6
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QuoteOriginally posted by GrinMode Quote
I was aware of the '+' designation of the Safox 8 & 9. It was one advantage the 8+ had over 9, meaning a plus for the K-7.

But that advantage has been lessened somewhat with the AF lamp on the K-r, so it affects my decision making .

Btw, how is the AF-S comparison in good light? Thanks again
The K-r and K-7 have similar focusing, but where the K-r is much better is when using Live View. It now rivals a good quality P+S camera in terms of speed and flexibility.
11-04-2010, 01:28 AM   #7
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Hmm... so maybe the improvements to the SAFOX 9 is contrast detect AF, and not the phase detect AF... decisions... decisions...

Thanks!
01-28-2011, 09:39 AM   #8
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QuoteOriginally posted by GrinMode Quote
Hey thanks! So with the AF lamp on, this helps negate (or minimize) tungsten focusing inaccuracies .
IF the AF lamp turns on. I mean, if tungsten light is very, very low, will turns on, but many times doesn't turn on. Usually, it turns on only under very low light, almost darkness. And the FF is guaranteed! Unfortunately!

PS: maybe this is the solution to corect the front focus issue: a firmware which allow the AF lamp to turn on if tungsten WB is set, even under good condition of illumination.


Last edited by ursamajor; 01-28-2011 at 09:45 AM.
01-28-2011, 12:09 PM   #9
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QuoteOriginally posted by ursamajor Quote
PS: maybe this is the solution to corect the front focus issue: a firmware which allow the AF lamp to turn on if tungsten WB is set, even under good condition of illumination.
Maybe user should be able to switch it on regardless of light conditions
01-28-2011, 01:21 PM   #10
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Not bad idea...
01-28-2011, 02:48 PM   #11
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QuoteOriginally posted by ursamajor Quote
IF the AF lamp turns on. I mean, if tungsten light is very, very low, will turns on, but many times doesn't turn on. Usually, it turns on only under very low light, almost darkness. And the FF is guaranteed! Unfortunately!
I have read about this FF issue over 100 times now, so I tested my K-r again. I dimmed a 25W tungsten bulb (which are very hard to get in Europe, by the way) down to the lowest level where it produces less light than a single candle. AF-assist did not turn on, but camera focused spot on (with DA35 Ltd). Maybe I am doing something wrong, my K-r obviously does not come with a FF guarantee.

cheers,
d
01-28-2011, 09:45 PM   #12
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Pictures in tungsten (with full Exif, please)? Maybe you had more luck, but I doubt.
And, yes, I saw that camera focuses more accurate if the tungsten light is dim. From this point of view it's possible you're right.
We have a word in RO: "with only a flower, the spring doesn't come".

Last edited by ursamajor; 01-28-2011 at 09:52 PM.
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