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09-01-2016, 05:32 PM   #1
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Help with "M"

I have a number of legacy lenses and have the K-10-D operations for these lenses down pat. Even though I have had the K-5 for a couple of years I have been using AF lenses and just started trying to use it with my super long telephoto lenses which are all M or K mount manuals. In reading the K-5 owners manual I thought I would be able to tell the camera the f-stop the lens was set too but it doesn't work. Shutter speed adjusments work fine. What am I doing wrong????????????????

09-01-2016, 05:40 PM   #2
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QuoteOriginally posted by kacansas03 Quote
n reading the K-5 owners manual I thought I would be able to tell the camera the f-stop the lens was set too but it doesn't work.
Using your legacy lenses is the same on the K-5 as it was on your K10D. For K-mount:
  • Enable aperture ring in your custom settings
  • M mode
  • Set the desired aperture on the lens barrel
  • Press the green button to momentarily stop down the lens. The camera will set an appropriate shutter speed.

Steve
09-01-2016, 05:41 PM   #3
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QuoteOriginally posted by kacansas03 Quote
I have a number of legacy lenses and have the K-10-D operations for these lenses down pat. Even though I have had the K-5 for a couple of years I have been using AF lenses and just started trying to use it with my super long telephoto lenses which are all M or K mount manuals. In reading the K-5 owners manual I thought I would be able to tell the camera the f-stop the lens was set too but it doesn't work. Shutter speed adjusments work fine. What am I doing wrong????????????????
Here are the instructions:

https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

The camera will never know the actual F stop, but you can still meter per the steps above. The aperture is set via the aperture ring.

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09-01-2016, 06:13 PM   #4
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I don't think I made myself clear. I am using T-mount lens adaptor which only have the K mount flanges, no bayonet or pin for the stop down preview to use to set shutter speed. I thought I could tell the camera what aperture and what shutter speed I had the lens and camera set to but Hyper Manual, the "M" position, does not allow all this. I id control the ISO just fine and the shutter speed fine on the K-5. Is there any methode to tell the K-5 what my aperture setting is when setting up the shot???

09-01-2016, 08:04 PM   #5
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QuoteOriginally posted by kacansas03 Quote
Is there any methode to tell the K-5 what my aperture setting is when setting up the shot???
No...it does not work that way and I am unaware of any system that works that way.

If the lens you are using does not support control by the body and you want to use the built-in meter, you are limited to stop-down metering. Since you are using a lens with a fully manual aperture, Av mode will allow you to use whatever aperture you prefer and the body will follow with a metered shutter speed as an alternative to M mode with green button. Note that in no case will the body "known" the aperture ring setting. As a result, that setting will not be written into the image's EXIF metadata.

Edit: There is a rude hack that may be used, but it requires an uncoupled lens and wise use of M mode. The hack is to short the "A" pin on the body mount face with a small wad of foil. When the "A" pin is shorted, the body will think it is controlling the aperture. Since there is no coupling no such thing is happening. Dial in whatever value you wish and that number will be recorded in the EXIF.


Steve

Last edited by stevebrot; 09-01-2016 at 08:16 PM.
09-01-2016, 10:56 PM   #6
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QuoteOriginally posted by stevebrot Quote
No...it does not work that way and I am unaware of any system that works that way.

If the lens you are using does not support control by the body and you want to use the built-in meter, you are limited to stop-down metering. Since you are using a lens with a fully manual aperture, Av mode will allow you to use whatever aperture you prefer and the body will follow with a metered shutter speed as an alternative to M mode with green button. Note that in no case will the body "known" the aperture ring setting. As a result, that setting will not be written into the image's EXIF metadata.

Edit: There is a rude hack that may be used, but it requires an uncoupled lens and wise use of M mode. The hack is to short the "A" pin on the body mount face with a small wad of foil. When the "A" pin is shorted, the body will think it is controlling the aperture. Since there is no coupling no such thing is happening. Dial in whatever value you wish and that number will be recorded in the EXIF.


Steve
Thanks Steve. Now I have to look up which pin is the A pin, should not be hard.
09-02-2016, 06:38 AM   #7
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The "A' pin is easily found as it is the one that is slightly recessed on the camera mount.

If the mount is non-conductive shorting the "A" pin will register the aperture range from f/2.8 to f/16. If the mount is conductive the range will be f/1.2 to f/22. The range is used in matrix metering, which will be available if the "A" pin is shorted, among other things.

As with the K10D you can set the DOF preview to Optical. With non-"A" lenses in M mode operating the DOF preview will stop down the lens (where applicable), turn on the meter and activate the EV bar. You can then set the exposure by changing the shutter speed (edial) or aperture ring (where applicable).
09-02-2016, 08:16 AM   #8
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QuoteOriginally posted by Not a Number Quote
As with the K10D you can set the DOF preview to Optical. With non-"A" lenses in M mode operating the DOF preview will stop down the lens (where applicable), turn on the meter and activate the EV bar. You can then set the exposure by changing the shutter speed (edial) or aperture ring (where applicable).
Thanks for mentioning this alternative. If used with the "A" contact hack, care should be taken that the aperture ring setting and number dialed in with the e-dial are the same and also the same as what will be used in the actual exposure. It is important to realize that the "A" contact hack only buys matrix metering and the ability to document aperture in the EXIF and should only be used with a non-coupled lens (no aperture actuator).* It does not magically provide open-aperture metering or aperture control by the body.


Steve

* The aperture diaphragm actuation mechanism of most standard K-mount lenses is not calibrated for body control. The "A" contact hack has been tried along with setting the aperture ring to minimum opening and allowing the body to set the aperture opening. Results with most lenses have been mixed. I know...I helped pioneer the hack. Not in my current bag of tricks


Last edited by stevebrot; 09-02-2016 at 08:25 AM.
09-02-2016, 11:15 AM   #9
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Thanks very much guys. I plan to be real careful with the "A" contact point. Would polishing the paint off the plain "M" mount work the same as the alumin foil ball on the contact point Steve? I use Pentax M42-K mount converter rings which are either chromed or just shiny steel or alumminium. ALthough I am pretty sure they are steel. I don't think I see anything about the f-stop in the viewfinder when I mount my Super Tak 300mm f4 lens which has the m42-K converter on the back. Thank You all again for all the help.!!!!!!!!!!!
09-02-2016, 12:04 PM   #10
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QuoteOriginally posted by kacansas03 Quote
Would polishing the paint off the plain "M" mount work the same as the alumin foil ball on the contact point Steve?
No...the hack is to short the inner surface of the "A" contact to the mount face on the body via the lens mount flange. The "A" contact is recessed by design so fiddling with the lens side does nothing. The contact on the lens side is a spring-loaded ball designed to drop into the recess. A circuit is made when the aperture ring is in the "A" position signalling the body that it can control the aperture, allowing program and shutter-priority exposure automation. A small wad of foil fills in for the spring-loaded ball.


Steve
09-02-2016, 12:44 PM   #11
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QuoteOriginally posted by stevebrot Quote
No...the hack is to short the inner surface of the "A" contact to the mount face on the body via the lens mount flange. The "A" contact is recessed by design so fiddling with the lens side does nothing. The contact on the lens side is a spring-loaded ball designed to drop into the recess. A circuit is made when the aperture ring is in the "A" position signalling the body that it can control the aperture, allowing program and shutter-priority exposure automation. A small wad of foil fills in for the spring-loaded ball.


Steve
Ok Steve, I understand now. Somewhere I read that it was desirable to have the "M", plain "K" with no stop down lever in the lens short out all the contacts on the digital bodies. It is obvious that the A contact would not be affected in that manner. Again my Thanks on this matter. I thought It would be good to have the F-stop setting in the EXIF data when I post pictures on here.
09-02-2016, 01:04 PM   #12
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QuoteOriginally posted by kacansas03 Quote
I thought It would be good to have the F-stop setting in the EXIF data when I post pictures on here.
I don't think anyone will mind

It is possible to add the aperture information to the file later using EXIF editing software, but usually not worth the trouble.


Steve
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