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04-07-2014, 10:04 AM   #1
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Exposure Meter on K10D when using SMC-M 50mm 1.7?

Hi, my sister has a K10D with the 18-55 kit. I recently picked up an SMC-M 50mm 1.7 for her. Of course it can only shoot in manual mode in conjunction with the green button with a manual lens. This works out well. However, the viewfinder doesn't display an exposure meter when using this lens. Is this just a design limitation? Thanks!

04-07-2014, 10:13 AM   #2
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If you have the DOF preview set to optical it will stop the lens down and should display the meter. That is how it works on the K100D and K-5 at least.
04-07-2014, 12:39 PM   #3
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QuoteOriginally posted by elliott Quote
If you have the DOF preview set to optical it will stop the lens down and should display the meter. That is how it works on the K100D and K-5 at least.
Hi Elliott! Thank you for the reply! Unfortunately, yes DoF preview is set to optical Any other suggestions? If anyone who owns a K10D with manual lens experience can chime in that would be much appreciated!
04-07-2014, 12:53 PM   #4
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If you pull the on/off switch over to depth of field preview, and hold it there, a meter will appear in the viewfinder. It's a pain having to turn the front dial with one finger while holding the power switch over with another finger, but that's the way the K10D works. Don't know why they didn't just design it to have the meter showing permanently.

Edit: Come to think of it, I do know why the meter doesn't show permanently. There's no aperture follower on the K10D mount, so it can only meter a pre-A series lens if you physically pull the DoF preview and stop the lens down.


Last edited by Dartmoor Dave; 04-07-2014 at 01:05 PM.
04-07-2014, 01:04 PM   #5
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QuoteOriginally posted by Dartmoor Dave Quote
It's a pain having to turn the front dial with one finger while holding the power switch over with another finger, but that's the way the K10D works.
You can't swap the dials on the K10D? That is inconvenient, that is one of the first things I did on the K-5.

I do wish they would allow full time metering with M42 lenses in M mode, the camera can identify the difference between M42 and K/M so it wouldn't be a big deal.
04-07-2014, 01:09 PM   #6
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QuoteOriginally posted by Dartmoor Dave Quote
If you pull the on/off switch over to depth of field preview, and hold it there, a meter will appear in the viewfinder. It's a pain having to turn the front dial with one finger while holding the power switch over with another finger, but that's the way the K10D works. Don't know why they didn't just design it to have the meter showing permanently.
Correct. I meter my K10D using the Optical Preview Lever rather than the Green Button (the GB does actually stop down the lens momentarily). Even so, metering a manual K/M lens is not perfect on the K10D - much better on later bodies. M42 lenses have issues.

Last edited by monochrome; 04-07-2014 at 05:01 PM.
04-07-2014, 01:14 PM   #7
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QuoteOriginally posted by elliott Quote
You can't swap the dials on the K10D? That is inconvenient, that is one of the first things I did on the K-5.
You probably can swap the dials, but I've never bothered. I incident meter most of the time, and when I occasionally do want to use the camera's own meter for spot metering I just use the green button. In my dreams Pentax releases a full frame DSLR one day with an uncrippled mount and a K1000 style match needle meter. But I think a dream is all it will ever be.
04-07-2014, 03:58 PM   #8
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Have a look at my page

How to use K mount manual focus lenses on Pentax (and Samsung) DSLR's: metering and other issues, hacks and tricks

On my K-r, you can use optical preview to meter (in the sense that a matching shutter speed will be set to match the meter reading when the optical preview is activated using the green button). But I believe the K10 is the same as the samsung GX20 (= K20D). Optical preview didn't set a shutter speed but a bar relating the meter reading to the current set shutter speed would be displayed. On my page I refer to a page by Robert Donovan which also comments on this.

04-07-2014, 04:13 PM   #9
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QuoteOriginally posted by Dartmoor Dave Quote
Edit: Come to think of it, I do know why the meter doesn't show permanently. There's no aperture follower on the K10D mount, so it can only meter a pre-A series lens if you physically pull the DoF preview and stop the lens down.
Huh? There is no way to implement this since metering should only happen with the lens is stopped down. I have my K10D in front of me, mounted to a Pentax-M 50/1.7. Here is the flow:
  • Aperture ring enabled in menu settings
  • Camera in M mode
  • AF off
  • Set desired aperture on lens
  • Frame and focus on subject
  • Press green button. Camera should set shutter speed.
  • Confirm focus and release shutter
  • Continue shooting until either your subject or the light changes
- or -
  • First three steps as in the list above
  • Set desired shutter speed on the body
  • Frame and focus on subject
  • Engage optical DOF preview to stop down the lens, activate the meter, and display the meter bar in the viewfinder
  • Adjust aperture on lens until the meter bar centers
  • Release the DOF preview
  • Confirm focus and release shutter
  • Continue shooting until either your subject or the light changes
This second sequence is essentially the same as using a 60s-era Pentax Spotmatic.

Those are the steps, though there is one HUGE gotcha. The exposure metered by the camera may be appropriate or it may not.* If the set aperture is wider than about f/4, the meter reading will result in underexposure. This may be as severe as 2+ stops at f/2 and wider. The excepted solution is to review the histogram for the first shot and adjust either aperture or shutter to provide the required compensation. Again, you need only do the metering and any compensation once per subject in a given light regime.


Steve

P.S. The e-dial assignment is not programmable for M mode on the K10D, at least not through firmware v1.20.

* Known issue with Pentax cameras later than the *ist D series up to the K-7. No there is no magic workaround. If it existed, I would be using it, believe me.

Last edited by stevebrot; 04-07-2014 at 04:29 PM.
04-07-2014, 04:26 PM   #10
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QuoteOriginally posted by stevebrot Quote
First three steps as in the list above Set desired shutter speed on the body Frame and focus on subject Engage optical DOF preview to stop down the lens, activate the meter, and display the meter bar in the viewfinder Adjust aperture on lens until the meter bar centers Release the DOF preview Confirm focus and release shutter Continue shooting until either your subject or the light changes
Tha'ts a technique I hadn't appreciated with my GX20 Steve. I'll have to add st to my page.
04-07-2014, 04:28 PM   #11
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QuoteOriginally posted by marcusBMG Quote
Tha'ts a technique I hadn't appreciated with my GX20 Steve. I'll have to add st to my page.
Using the DOF preview is what Monochrome and a few others were alluding to above. It is really pretty cool and very close to center-needle stop-down meter on a Spotmatic or similar camera.


Steve
04-08-2014, 05:17 AM   #12
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QuoteOriginally posted by Dartmoor Dave Quote
If you pull the on/off switch over to depth of field preview, and hold it there, a meter will appear in the viewfinder. It's a pain having to turn the front dial with one finger while holding the power switch over with another finger, but that's the way the K10D works. Don't know why they didn't just design it to have the meter showing permanently.

Edit: Come to think of it, I do know why the meter doesn't show permanently. There's no aperture follower on the K10D mount, so it can only meter a pre-A series lens if you physically pull the DoF preview and stop the lens down.
Thank you, Dave! This works! Although slightly awkward it does the job nevertheless

---------- Post added 04-08-14 at 08:23 AM ----------

QuoteOriginally posted by stevebrot Quote
Those are the steps, though there is one HUGE gotcha. The exposure metered by the camera may be appropriate or it may not.* If the set aperture is wider than about f/4, the meter reading will result in underexposure. This may be as severe as 2+ stops at f/2 and wider. The excepted solution is to review the histogram for the first shot and adjust either aperture or shutter to provide the required compensation. Again, you need only do the metering and any compensation once per subject in a given light regime.
Steve, thank you very much for the info. By the way, is the underexposure issue more prevalent with the K10D? Are newer bodies better at metering at wider apertures?
04-08-2014, 10:58 AM   #13
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QuoteOriginally posted by RiverKayaker Quote
Steve, thank you very much for the info. By the way, is the underexposure issue more prevalent with the K10D? Are newer bodies better at metering at wider apertures?
The underexposure issues for stop-down metering are legendary on the K10D. From the K-7 on, green button metering in M mode has been pretty good with K-mount lenses. Functionality with M42 lenses in M mode is also pretty good except for the most recent bodies which decouple this functionality for lenses lacking conductive bases. Go figure.


Steve
04-08-2014, 03:36 PM   #14
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QuoteOriginally posted by RiverKayaker Quote
Hi Elliott! Thank you for the reply! Unfortunately, yes DoF preview is set to optical Any other suggestions? If anyone who owns a K10D with manual lens experience can chime in that would be much appreciated!
Yes, the exposure metering has some flaws. Auto aperture Aseries anid later lenses with contacts tell the body the native aperture of the lens and correct for the error in the body. There were a lot of posts on this when the K10 came out. Shoot a uniformly lit block wall at each aperture using green button and measure the greyscale value, or look at the offset in the histogram. OnlyF5.6 is accurate because this is where the kit lens and consumer lenses are wide open, faster lenses under expose below f5.6 and over expose over f5.6 with worst error between F11 and F16
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