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03-29-2008, 09:22 PM   #1
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K10d and M lenses

Maybe someone can help....

I'm still getting to know my K10d. With my 16-45 zoom everything goes smooth. The problems start when I use my SMC-M lenses. My 50mm 1.7 and my 135mm 3.5. They take great pictures. Very sharp.

The problem is the exposure and the way the camera handles it. I've read a lot of threads about the problems with exposure and the M lenses. And I get it...unless you change focusing screens, the exposure will be off slightly.

What I don't understand is when I get the exposure right and take a good picture, the camera, almost automatically changes the shutter speed for the next picture. In other words, I constantly have to change my settings with every single shot.

Is this normal, and why does this happen?

Thanks, Steve

03-29-2008, 09:24 PM   #2
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what mode are you using?
03-29-2008, 09:53 PM   #3
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I use M exposure with my M lenses. Av will work, apparently, but only wide open, and I found that exposure was a bit problematic even then. My "technique" is to stop the M lens down to a stop that I personally have tested with my lens to give an accurate meter reading, and interpolate my exposure from that. With my 400, for example, it gives good readings between f/8 and f/16, matching the "sunny 16" rules. So I can meter at f/8, and change my shutter speed and aperture to maintain the same exposure with this lens and expect decent results.

My next lens to test for exposure range will be my 100 macro, and I will have to try that at several magnifications to see what comes out. It's work, but a lot cheaper than trading the lenses in on something newer.
03-29-2008, 09:57 PM   #4
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I'm using the manual mode.

03-29-2008, 10:05 PM   #5
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If you use the M mode I dont think the camera should change the settings.
In Av mode it will change the exposure.
I use m42 lenses, normaly the expouser is correct in Av mode, but you have to be careful when using flash.
I dont have M lenses, so exactlu cant tell you about them. but A & m42 work fine.
03-29-2008, 10:08 PM   #6
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QuoteOriginally posted by deaner Quote
I'm using the manual mode.
All right, I agree this is the only way to go with M and K lenses. Here is my step by step process:
  1. In the menus, make sure you have the dof preview set to Optical, not Digital
  2. Set the camera to take RAW images. (Much finer grades of exposure available)
  3. Set the ISO to a single setting: [OK] plus front edial, anything from 100 to 400 will do.
  4. Mode dial to M
  5. Use a tripod so that you are taking the same image.
  6. Select an image with mixed tones.
  7. Set the meter switch to center weighted (matrix will switch automatically to this).
  8. Open the lens to the widest aperture (5.6 on my 400)
  9. Use the depth of field position on the switch around the shutter release and set the +/- to a zeroed exposure, neither over nor under exposed according to the meter.
  10. Take an image
  11. Repeat for all the f/stops that you will use, or all.
  12. Examine the RAW images in Pentax Browser, or your favourite program and select the range of apertures where the exposure is what you like.
This is what I did to come up with the exposures in my Flickr site with the 400. That's where I found that the meter was not reliable with my K10D and my M 400, except between f/8 and f/16. At those f/stops, the exposure meter indicated the "sunny 16" exposure, and all was well.

The reason for the multiple exposures was to determine whether it was the meter or, as some speculated, the mechanical stop down, that was causing the variable exposures.

Long winded, I know, but then I am an old fart.
03-30-2008, 01:24 AM   #7
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That is not normal. This is how I use my M-lenses.
Manual mode.
Select the desired aperture on the lens.
Aim at photo subject and press green button followed by a digital preview and watch the histogram.
Adjust shutter if needed.
Ready to shoot, and the selected shutter speed stays as I have set it.
03-30-2008, 03:54 PM   #8
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QuoteOriginally posted by Gimbal Quote
That is not normal. This is how I use my M-lenses.
Manual mode.
Select the desired aperture on the lens.
Aim at photo subject and press green button followed by a digital preview and watch the histogram.
Adjust shutter if needed.
Ready to shoot, and the selected shutter speed stays as I have set it.
You can use this system, but the metering is only accurate at some of the apertures, not all. That is why I use that complex system to find out the good apertures for the meter. Once I have determined an aperture that works the meter correctly, I simply use that. It's actually easier than using an external meter. Don't forget that the histograms are based on the jpeg conversions. I find the highlight "blinkies" are more useful than the histogram in camera.

03-30-2008, 05:17 PM   #9
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Steve,
I've got good results with my M 200/4 using the green button on M mode. I do have an LL-60 screen on my K10D, though, which may have improved the metering with M lenses.

But even without the screen, try what Gimbal suggested and if you still have problems let us know...
03-30-2008, 07:15 PM   #10
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Well, I got most of the problem figured out. Someone on photo.net pointed out that I may have had exposure bracket mode on. I don't remember setting it, but it was on.

That only solves half of the problem, though. Metering is still spotty.I've read, and understand all everyone has posted here. I could adjust for every shot like some have, but if changing focusing screens solves the metering problem, then I think that is what I will do.

Thanks everyone.
03-30-2008, 09:20 PM   #11
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QuoteOriginally posted by deaner Quote
Well, I got most of the problem figured out. Someone on photo.net pointed out that I may have had exposure bracket mode on. I don't remember setting it, but it was on.

That only solves half of the problem, though. Metering is still spotty.I've read, and understand all everyone has posted here. I could adjust for every shot like some have, but if changing focusing screens solves the metering problem, then I think that is what I will do.

Thanks everyone.
Unfortunately, I have read that changing the focusing screen to the LL60 series makes the K10D meter inaccurately with the DA lenses. Anyone confirm or deny this?
03-31-2008, 12:16 AM   #12
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QuoteOriginally posted by deaner Quote
Well, I got most of the problem figured out. Someone on photo.net pointed out that I may have had exposure bracket mode on. I don't remember setting it, but it was on.
I've done that!
03-31-2008, 06:10 AM   #13
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QuoteOriginally posted by deaner Quote
Well, I got most of the problem figured out. Someone on photo.net pointed out that I may have had exposure bracket mode on. I don't remember setting it, but it was on.
I've done that... threw me for a spin for at least an hour!

I find that my M lenses always over-expose by at least a stop.

- Andrew
04-02-2008, 07:46 AM   #14
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When i use my M50mm 1.7 with my k10d I've noticed that it's sometimes spot-on, when other times I need to compensate. I just do some shots at the place to see if it's metering correct and then compensate if needed. So everytime i push the green button, i compensate with some stops. I must say that I'm probably less concerned than some other people here with "The Perfect Picture'. Sometimes I like it sloppy
04-04-2008, 01:31 AM   #15
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QuoteOriginally posted by Canada_Rockies Quote
Unfortunately, I have read that changing the focusing screen to the LL60 series makes the K10D meter inaccurately with the DA lenses. Anyone confirm or deny this?
I swapped the focus screen on my k10 for a DS screen. my K and M lenses now meter correctly, and metering with FA and DA lenses is not affected. The reason for this is that it is the "stop-down " metering that doesnt work well on the K10 with the default focus screen. FA and DA lenses dont use the "stop down" meter method so the focus screen cannot interfere with metering.
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