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05-15-2007, 03:39 PM   #16
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QuoteOriginally posted by pentkon52 Quote
I have owned Dslr's since the D1 arrived on the scene. I would all ways carry a hand meter in my film days, espesially if using them in winter B&W shots. However, i have noticed and call me wrong if i am, that if i set the digital on the hand held reading, i'm way over exposed. I find, even in winter, what ever the meter says plus +0.3 ev and i'm fine.

Dave
Just to clarify: Are you talking about metering the light with a modern lens (A, F, FA, DFA, FAJ...) or with a lens with manual aperture (typically some third party, M42, K and M models)?

05-15-2007, 06:57 PM   #17
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QuoteOriginally posted by carpents Quote
Are you sure it is underexposing? That is the opposite of the 'normal' K10 exposure problems. Typically it experiences a gradual overexposure as the aperture gets to f/8-f/11 at the worst.
in my case, the K10D suggests the same shutter speed as I move up from f/8 onwards, pointing at the same subject. did I get a dud camera?
05-19-2007, 09:26 PM   #18
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I've read this thread with great interest. My K10 will properly expose manual lenses at f2 (maybe 2.8) and bigger - if I use anything f4 or smaller pictures are significantly overexposed, and I've found that a manual lens I have is better than my DA 50-200 (which has some type of problem). My first thought was to just keep the manual lens on the K100 and use either a longer or shorter lens on the K10, but really would like to have the ability to use manual lenses on the K10. This might be a dumb question, but where did people get their DS focusing screens? Camera shops or mail-order or???
05-19-2007, 11:00 PM   #19
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You can buy your DS screen from B+H, or directly from Pentax, or from any camera dealer (ordering it from Pentax for you).

05-20-2007, 08:10 PM   #20
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Thanks for the information - turns out Pentax is more expensive than B&H. I think I'll talk to my local camera store and see how much they would charge for one installed - I'm not the best person at doing this type of thing.

Would it make a difference which one I get? I saw a couple of them listed on Pentax's web site. The one with the third lines on it might be nice, but not necessary.
05-20-2007, 08:22 PM   #21
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QuoteOriginally posted by mtngal Quote
Would it make a difference which one I get? I saw a couple of them listed on Pentax's web site. The one with the third lines on it might be nice, but not necessary.
I don't think it matters. I have used the LL-60 screen (the one you mention) only. As they all work the same with the DS they probably work the same with another camera as well.
05-21-2007, 07:48 AM   #22
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QuoteOriginally posted by pentkon52 Quote
However, i have noticed and call me wrong if i am, that if i set the digital on the hand held reading, i'm way over exposed. I find, even in winter, what ever the meter says plus +0.3 ev and i'm fine.

Dave
That's pretty much been my experience with the K10D so far. I pretty much dial in +0.3 or +0.6 for every shot.
05-21-2007, 08:00 AM   #23
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So if the DS screen fits and meters properly, why not just buy a Katz Eye DS screen and put it into your K10D?


Personally, I find that a Sekonic meter takes care of the whole issue for me.

05-21-2007, 09:26 AM   #24
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QuoteOriginally posted by Dana G Quote
So if the DS screen fits and meters properly, why not just buy a Katz Eye DS screen and put it into your K10D?
Personally, I find that a Sekonic meter takes care of the whole issue for me.
Katz-eye screens are reported to behave more like the original K10 screen. It is NOT a solution. Hand held meter and/or DS screen is........
05-21-2007, 09:40 AM   #25
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QuoteOriginally posted by vinzer Quote
in my case, the K10D suggests the same shutter speed as I move up from f/8 onwards, pointing at the same subject. did I get a dud camera?
If you're at the bottom end of the meter (i.e. it is very dark and blinking a very long exposure time) then you are seeing something normal. If you're pointing at something in bright daylight and you still have reasonably fast shutter speeds, there could be something wrong.
05-24-2007, 10:52 AM   #26
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Could the exposure problems on older manual lenses be related to "F" stops verses "T" stops?

For those that don't know, F-stops are calibrated based on the physical opening of the apeture and doesn't compensate for light losses. An F-stop difference is exactly half the area, but not necessarily half the light.

T-stops are calibrated so that the next stop is exactly half the light and the physical opening is adjusted to make sure it is exactly half the light.

Still photography mainly uses F-stops and not T-stops. Todays lenses are designed and fabricated much better, making T-stops and F-stops almost equivalent. However, older lenses suffer from differences, especially as one stops down to a smaller apeture. And some lenses will not lose as much light as others as it is stopped down because of differences in design and materials.

If the new cameras meter based on the light levels while the lens is wide open, their could be a difference from the actual amount of light that the program assumes will get through the smaller apeture.

Perhaps this isn't the case at all.. it is just a thought.
05-24-2007, 11:19 AM   #27
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QuoteOriginally posted by LV Dan Quote
Could the exposure problems on older manual lenses be related to "F" stops verses "T" stops?

For those that don't know, F-stops are calibrated based on the physical opening of the apeture and doesn't compensate for light losses. An F-stop difference is exactly half the area, but not necessarily half the light.

T-stops are calibrated so that the next stop is exactly half the light and the physical opening is adjusted to make sure it is exactly half the light.

Still photography mainly uses F-stops and not T-stops. Todays lenses are designed and fabricated much better, making T-stops and F-stops almost equivalent. However, older lenses suffer from differences, especially as one stops down to a smaller apeture. And some lenses will not lose as much light as others as it is stopped down because of differences in design and materials.

If the new cameras meter based on the light levels while the lens is wide open, their could be a difference from the actual amount of light that the program assumes will get through the smaller apeture.

Perhaps this isn't the case at all.. it is just a thought.
Unfortunately no. You can get the errors w/ "modern" f stop lenses. ie "a" lenses off a ect....These same lenses performed well on d series and k100 as far as I know. It is just some oddity of the new "bright" screen/ meter interaction at reduced light levels. The physics/engineering/logic behind this is somewhat baffelling.
And the lenses are used in "stop down" mode so even t vs f would be a moot issue.
An off the top of my head guess is that the dimmer light/smaller aperature is no longer being spread out over the lightmeter (as they would in a more matt/diffuse screen) and therefore the edges of the meter (even center weighted) are darkened in proportion to the amount of the tighter the beam is caused by the aperature blade opening. Thus the "average" is reduced and exposure time is increased.
Of course the problem w/ this theory (besides my lack of basic knowledge ) is that it should behave better in "spot meter" mode. Not sure this is the case.
Anyways, just rambling...

Last edited by jeffkrol; 05-24-2007 at 11:27 AM.
05-24-2007, 07:14 PM   #28
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Interesting theory - I don't know that I've noticed a difference between the various metering options (something to check during lunch tomorrow).

I don't think it has anything to do with the lenses themselves - my K100 meters perfectly with my old manual lenses, while my K10 does not. I've ordered a DS focusing screen from my local camera shop - they said they'd install it for free (yes, I'll pay more than from B&H but I figured getting the installation done by them, and I get to watch and find out how its done is worth the little extra it will cost.
05-26-2007, 09:24 PM   #29
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Spent lunch yesterday playing with both cameras and two different lenses. Interesting about the exposure changing as soon as you take an FA lens off of the A setting - metering problems just like a manual lens. Tried all 3 metering modes and found no difference between center-weighted and matrix metering. The spot metering was a little better when I metered off of the brightest part of the scene, but it still wasn't right (1/30 sec for the green button vs. 1/125 with the AE-L button on the K100, same lens).
06-29-2007, 05:38 AM   #30
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It seems to me that this whole issue of metering with the older lenses could be solved very easily by a small firmware fix.
The existing focus screen works just fine for metering, provided that the camera has information about the actual aperture settings so that it can meter through a wide-open lens and make the necessary calculations about the exposure required when the lens stops down.

What is the difference between an A-series lens and an older K or M series lens? Or between an A series lens on and off the ´A´ position? As far as I can see the only difference is that in the case of the older lenses (or the A lenses in manual mode) the camera does not know what the wide-open apature is, or to what aperture the lens will go to when taking the photo. It can obviously stop down the aperture to the selected value with the green button, or the optical preview, but this is evidently not a satisfactory solution for metering with the hardware in the k10.

The fix to this problem is to give the computer in the camera the information it has when using A series and later lenses. This is 1. the wide open aperture and 2. the aperture to which the lens will go to when the shutter is open.

The wide-open apeture could be entered in the menus in the same way as the focal length is, and perhaps one of the e-dials could be used to tell the camera where the manual apeture ring was set to. This would give the camera the same information that it has available to it when using an A series lens, and would probably enable multi-segment metering with any of the old lenses as well.

Pentax need to be persuaded to implement this in a firmware upgrade. It would be very easy for them to do - no new actual features, just an extra entry in one of the menus. Probably the place to put it would be in with the ´use aperture ring´ selection.

Ian
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