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07-16-2009, 05:25 PM   #1
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K-7 and metering with "K" and "M" lenses

The K10D and the K20D have a bad time metering with the older manual lenses. I did a search both here and the Rumors forum for info and came up blank. Has this issue been fixed with the K-7?

NaCl(enquiring minds want to know)H2O

07-16-2009, 08:32 PM   #2
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Yes and no

I have not done enough, but I have found one thing, putting my TC on my 70-200 F2.8 no longer requires exposure compensation, It used to over expose by 1.5 stops.

I still think there are some issues I just have not had time to do a lot of tests yet.
07-16-2009, 08:41 PM   #3
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I didn't test all of my K and M lenses, but I did tests with 2 lenses, using the green button to meter. My first test was to take the 77 Ltd off of the A setting and set the aperture on the lens - metered perfectly at f8. Then I used an SMC M50mm 1.4 lens. The K20 always struggled and was inconsistent with this lens. I shot a series with both lenses, using everything from f1.4 up to f32. The K20 was it's usual inconsistent self - some shots were better exposed than others, depending on the aperture. The K-7 was exactly the same exposure for all apertures f22 and below. The f32 picture was very underexposed, more so than the K20 (which was also underexposed). I didn't get a chance to test the SMC 24mm 2.8, which was the lens that both the K10 and K20 struggled the most with - perhaps this weekend. But it sure is hugely better with the M50 1.4.
07-16-2009, 09:16 PM   #4
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I did some test here:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/62819-experiences-...s-imgs-13.html

Seems manual lenses work better w/ K-7 than w/ K10D/K20D.

07-16-2009, 10:06 PM   #5
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This is good to hear !!!
07-17-2009, 03:27 AM   #6
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Have to echo Stratman above, or as my young next door neighbor would say "Yea and hooray!" The only unfortunate side to all of this is that I now have massive K-7 lust. But I bought a DS when the prices fell below 700, and the K10D when prices fell below 700, and the K20D when prices fell below 700, so I guess I can wait till the K-7 prices fall below 700 to keep my streak going, but it sure is hard.

NaCl(my other recourse is to rob a bank)H2O
07-17-2009, 05:24 AM   #7
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Now they just have to put in that contact for open aperture metering, then we're gold

How much would that cost to implement anyway? I'm sure people would like to have open aperture metering back...
07-17-2009, 09:02 AM   #8
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QuoteOriginally posted by Andi Lo Quote
Now they just have to put in that contact for open aperture metering, then we're gold

How much would that cost to implement anyway? I'm sure people would like to have open aperture metering back...
That would be wonderful, but it's been gone for so long that I doubt it would come back now. Besides if they put it back on the next body, I'd break my perfect string and buy the new body right away.

NaCl(not sure I could handle such largess)H2O

07-17-2009, 09:07 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
I have not done enough, but I have found one thing, putting my TC on my 70-200 F2.8 no longer requires exposure compensation. It used to over expose by 1.5 stops.

Oh, as I bought the exact same combination on your recommendation I suppose I will have to upgrade my K10D to a K-7 now.

My wife will not be best pleased to learn you have once again led me astray.
07-17-2009, 09:31 AM   #10
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QuoteOriginally posted by NaClH2O Quote
The K10D and the K20D have a bad time metering with the older manual lenses. I did a search both here and the Rumors forum for info and came up blank. Has this issue been fixed with the K-7?

NaCl(enquiring minds want to know)H2O
After reading this thread I'm somewhat surprised. I've never had the slightest trouble with green-button metering on Pentax-M lenses with my K20D. I had (recently sold out all my old glass and bought new stuff) the M 50 1.4, the M 100 f4 Macro, the M 135 f2.5, and I have a Tamron 180 f2.5 with a P/K-M mount on it, and they all expose flawlessly - that is to say, very similar to my Pentax FA and DA lenses.

I'm surprised because this would (should!) be the absolute easiest way to meter accurately, as you're measuring actual incident light, not predicting the amount of light that WILL be available. I would have been quite upset to discover that it metered inconsistently with those lenses. Consistent behavior I can compensate for - inconsistent behavior makes that impossible!
07-17-2009, 09:36 AM   #11
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QuoteOriginally posted by jstevewhite Quote
After reading this thread I'm somewhat surprised. I've never had the slightest trouble with green-button metering on Pentax-M lenses with my K20D. I had (recently sold out all my old glass and bought new stuff) the M 50 1.4, the M 100 f4 Macro, the M 135 f2.5, and I have a Tamron 180 f2.5 with a P/K-M mount on it, and they all expose flawlessly - that is to say, very similar to my Pentax FA and DA lenses.

I'm surprised because this would (should!) be the absolute easiest way to meter accurately, as you're measuring actual incident light, not predicting the amount of light that WILL be available. I would have been quite upset to discover that it metered inconsistently with those lenses. Consistent behavior I can compensate for - inconsistent behavior makes that impossible!
It has been the subject of many, many threads. The 50/1.4 is the very worst. For most of us who have tried it, the exposure is very inconsistent--over at some settings and under on others. I found the K 135/2.5 more consistent, but still off at several apertures. If this has really been fixed in the K-7, it is the best reason yet to upgrade--when the price settles down.
07-17-2009, 09:38 AM   #12
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QuoteOriginally posted by mtngal Quote
...The K-7 was exactly the same exposure for all apertures f22 and below...
This is probably due to inadequate light to the sensor. The sensor is only sensitive to 0 EV (ISO 100). In moderate light with the lens stopped down, this value is reached fairly easily even at f/16.

I would be more interested in the behavior at larger apertures. All of my non-A lenses underexpose terribly at apertures wider than f/4.

Steve
07-17-2009, 09:42 AM   #13
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What I found when using m42 is that metering really changes when lens is turned a bit . Usually k200d underexposes and then i turn lens a bit and believe me that makes a sense
07-17-2009, 10:02 AM   #14
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QuoteOriginally posted by kent Quote
What I found when using m42 is that metering really changes when lens is turned a bit . Usually k200d underexposes and then i turn lens a bit and believe me that makes a sense
That is scary...

Steve

(A couple of my lenses vary by 1/2 stop between infinity and close focus on the K10D...also scary!)
07-17-2009, 10:18 AM   #15
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QuoteOriginally posted by stevebrot Quote
(A couple of my lenses vary by 1/2 stop between infinity and close focus on the K10D...also scary!)
That makes sense and is nothing to be scared about.

The f-stop in the lens specs is at infinity focus. At close focus, the lens is a bit longer and thus a bit slower.

Take a macro lens for example, at 1:2 magnification ratio, the f-stop is about 1 stop slower the setting of the aperture ring. At 1:1, 2 stops slower.
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