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12-02-2010, 10:47 AM   #1
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K-5 metering with K and M lenses?

We know that the K-7 is much better at metering with K and M lenses than the K10/K20D were. I'm wondering if anyone out there lucky enough to own the new K-5 can verify that metering with K & M lenses is the same as with the K-7? I manage to make do with the vagrancies of K20D metering but I would be a happy camper if I didn't have to deal with it.

NaCl(I want to hear "it's like the K-7, only better" )H2O

12-02-2010, 12:12 PM   #2
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I too would love to see this.

In fact, I wish forum members who have a K50F1.4 would do my block wall test, (metering with green button at each aperture) for every pentax DSLR body and focusing screen combination out there.

I have posted the results for my *istD, K10D and K7, plus the K10 with both *istD and a split image (jinfinance single diagonal split) but think if people sent me the test shots for their bodies and combos we could really have a useful characterization of all the cameras etc.
12-02-2010, 02:40 PM   #3
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Add my name to those who would like to see some K and M samples form the new K5.

Tom G
12-02-2010, 02:45 PM   #4
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I think that the nature of the beast is that manual K lenses will only shoot wide open, and that for M42 lenses, Av mode metering is totally inaccurate, and you can only depend on M mode with Green Button/Ev Button for proper exposure.

I seriously doubt that new camera releases change this simple fact.

12-02-2010, 02:50 PM   #5
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Ira

I disagree

the K5 will still meter in manual mode with green button this is what we want to see. how does the green button compare in metering accuracy for example to the *istD, K10D and K7D. The *istD is pretty good, drifting slightly upward in exposure as you stop down to F22, The K10D and K20D are terrible, to be polite about it. the K7D is much better than K10/20 especially at large apertures, but still has issues at small apertures.

as for the under exposure with M42 lenses, that is what EV comp is for, set that up and then shoot AV mode.
12-02-2010, 02:57 PM   #6
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QuoteOriginally posted by Ira Quote
I think that the nature of the beast is that manual K lenses will only shoot wide open
I didn't get this part. why would K lenses only shoot wide open?
12-02-2010, 03:03 PM   #7
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QuoteOriginally posted by Pablom Quote
I didn't get this part. why would K lenses only shoot wide open?
In automatic mode they only shoot wide open, but in M or bulb they stop down to the aperture ring setting.

Ira is confusing the use of the word "metering" with Av mode. The two are different .
12-02-2010, 03:04 PM   #8
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QuoteOriginally posted by Lowell Goudge Quote
Ira

I disagree

the K5 will still meter in manual mode with green button this is what we want to see. how does the green button compare in metering accuracy for example to the *istD, K10D and K7D. The *istD is pretty good, drifting slightly upward in exposure as you stop down to F22, The K10D and K20D are terrible, to be polite about it. the K7D is much better than K10/20 especially at large apertures, but still has issues at small apertures.

as for the under exposure with M42 lenses, that is what EV comp is for, set that up and then shoot AV mode.
Ev comp is a moot point in M mode. Not only don't M42 lenses require it in M, the concept of it in M makes no sense at all:

If you're in manual mode, you're in manual. You have to do compensation in your head. And this is why the Ev button on the K-x doesn't even act like an Ev button in the first place:

It acts like the green button, locking in the shutter speed based on your selected aperture.

Additionally, Av mode sucks with M42 lenses. Way underexposure. M is the only way to go.

12-02-2010, 03:06 PM   #9
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QuoteOriginally posted by Lowell Goudge Quote
In automatic mode they only shoot wide open, but in M or bulb they stop down to the aperture ring setting.

Ira is confusing the use of the word "metering" with Av mode. The two are different .
I don't think so.

Isn't Av mode a form of metering?
12-02-2010, 04:01 PM   #10
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QuoteOriginally posted by Ira Quote
Ev comp is a moot point in M mode. Not only don't M42 lenses require it in M, the concept of it in M makes no sense at all:

If you're in manual mode, you're in manual. You have to do compensation in your head. And this is why the Ev button on the K-x doesn't even act like an Ev button in the first place:

It acts like the green button, locking in the shutter speed based on your selected aperture.
No actually EV Comp in manual makes a lot of sense, and that is why the *istD has it, and also it was put back on the K20 after removing it on the K10D. If you have a lens that ALWAYS under or over exposes, but you like to shoot manual mode, it is still nice to push the green button and get the correct exposure, that is what EV comp is all about. Also, when you want to deliberately under expose a series of shots, and are checking metering it is nide to be able just to push the button and get the metering you want, with compensation included. Can't comment on single wheel bodies that don't have green button, but on the dual wheel bodies it is nice to have EV comp in manual. I was really pissed when they took it away in the K10D, ALso note, when shooting flash in manual mode it is nice to see the metering with EV comp corrected for the lens, so you can properly judge the exposure balance between natural and fill flash
QuoteQuote:

Additionally, Av mode sucks with M42 lenses. Way underexposure. M is the only way to go.
Again correcting the under exposure with EV comp is just as good, and especially with presets which are easy to open and stop down, it is nice to have Av mode

QuoteOriginally posted by Ira Quote
I don't think so.

Isn't Av mode a form of metering?
Av mode isn't a form of metering exactly, it is a form of automatic exposure using the results from the meter. Metering is measuring not controlling. But that is a fine point.
12-02-2010, 06:14 PM   #11
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I can only comment on 1 lens a K50 f/1.2 and if anything the K-5 tends to overexpose slightly. I am getting far more blown highlights than I ever did with the K20D which is known to underexpose. @ f/1.2 I will meter with the green to get a baseline and then dial in -0.3EV to -0.7EV depending on the overall brightness, i.e. a sunny afternoon will definitely demand -0.7EV, a dull cloudy day -0.3EV and a maybe a click slower on speed. I will try and do the brick wall test on Saturday and report findings with K50 f/1.2, K55 f/1.8 and FA43 as a datum.
ps Lowell, if you have a process that you wish me to follow can you pm the details?

S!
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12-02-2010, 06:30 PM   #12
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The process is as follows

Pick an area where you can shoot a uniformly lit surface. Block walls and paved roads work well

Then pick an iso that lets you shoot wide open below 1/2000 ( I don't trust max shutter speed to be accurate) set contrast to neutral. In manual mode starting wide open take a shot using green button to set shutter speed. Then take successive shots at every aperture detent using the green button to set the exposure at each f stop. I measure histogram in the center 10% of the frame to measure exposure
12-03-2010, 06:21 AM   #13
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Thanks Robbie for doing this. It will be a great help to all of us.

NaCl(anything is better than the educated guesses I use on the K20D)H2O
12-03-2010, 06:42 AM   #14
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Robbie

In re-reading your post, I would prefer no EV compensation at all.

Shoot as the camera would meter with all settings neutral.

The idea behind the test is to see how the camera meters each scene with no adjustment. What I have found in thepast, is that with completely neutral settings, between about 25 and 230 greyscale on the histogram each 1EV change in exposure is almost perfectly linear at 45 greyscale. the camera should meter at between 110 and 125 greyscale if all is correct, although none of the cameras are quite perfect.

One thing to be careful of, and I found this with my K50/1.4 is that you will probably need to be in the shade, or on a cloudy day, because full sunlight will really push the shutter speed up, at F1.2, although I think you can set ISO a little lower on the K5,

The end result, should look like the following, which I have posted before.

As you can see, the *istD starts off wide open quite good, droops a little, and then rises constantly as you stop down to about +.7ev at F22. Dealing with a -.5+.7 EV drift over the entire exposure range is not too bad. The K10D is a lot worse starting at -.7 drooping to -1EV and rising to +1.7 EV at the top end. Putting the Jinfinance split image into theK10D resolved most of the large aperture errors, but did not address the intermediate and small aperture errors. In theory this could be better centered with a -.7ev shift on the entire exposure, but sadly the K10D lacks the ability to add EV compensation in manual mode. Both the K7 and *istD permit EV comp in manual. Some say manual is manual and you don't need EV comp, but in cases where a lens shows a consistent tendancy to under / over expose at all apertures, it is useful

The K7 overall is better but still no where near as good as my "gold standard" the *istD




Last edited by Lowell Goudge; 12-03-2010 at 06:48 AM.
12-04-2010, 03:18 PM   #15
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QuoteOriginally posted by Ira Quote
for M42 lenses, Av mode metering is totally inaccurate
Can anyone say if that's still the case with the K-5. I know about the significant underexposure with my K100D, but I somehow had in mind that it had been fixed with the K-7.

I too would love to know if the consistency of metering has been improved per Lowell Groudge's work.
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