Issue Using M Lens On K-X

Hawkfan · 12-20-2019, 02:59 PM

Took out my M-28 mm to use on my K-x. Have settings set to manual focus, green button Optical Preview, and menu item 22 aperture ring use permitted. Correct focal length is set to 28mm on startup.

I compose and focus and stop down with green button and set shutter speed until meter reads 0.0 correct exposure. The problem is is that even though meter reads correct exposure, my photos are over +3 over exposed. Would anyone have a clue as to would would cause this?

Adam · 12-20-2019, 03:22 PM

Because matrix metering isn't available with manual lenses, it's possible for exposure issues to happen. It may be beneficial to try live view to get a more accurate reading, or to try to manually lock the exposure on something a little brighter in the scene.

dantonvb · 12-20-2019, 03:25 PM - **1 Like**

You must set the manual exposure mode (M in dial). Then, when you press the green button, the camera sets the shutter speed to the correct value. Nothing more is needed.

M_D_K · 12-20-2019, 03:27 PM

Are you using manual mode? Anything else (Av, TV, Auto, etc) doesn't seem to work with a M lens on my K-X

Wasp · 12-20-2019, 03:58 PM

Originally posted by M_D_K

Are you using manual mode? Anything else (Av, TV, Auto, etc) doesn't seem to work with a M lens on my K-X

You can use Av with wide open aperture. I think you can use Tv in this way if you also set ISO to auto, but I will have to check.

Hawkfan · 12-20-2019, 05:38 PM

Yes in M mode. I dial in aperture on lens and press green button set to optical preview. Lens does stop down as it should and in viewfinder window I have a shutter speed that can be adjusted with F... showing on screen of course for aperture setting. Also the exposure meter reading on screen. I set shutter speed in conjunction with meter reading to achieve a 0.0 meter reading. As far as the camera setting the speed automatically, that does not happen as the shutter speed only changes when I change with e-dial. My experience this afternoon was completely blown out photos approaching 3 stops over exposed. Upon a few more tries as day grew darker, my results appear to vary. Almost as if there is an intermittent meter issue. Funny thing is if I swap back to the DAL lens, no such issues.

Hawkfan · 12-20-2019, 05:44 PM

I do find that yes I can set to AV and camera will select speed. No exposure meter appears in viewfinder in AV in AV and green button no longer activates stop down and shutter speed doesn't change pointing camera from a light to dark area. Hmmm. Perhaps things just don't work the way I would wish with a manual lens on the K-x. Perhaps a newer model operates with a manual lens a little more "normally"?

---------- Post added 12-20-19 at 06:15 PM ----------

Also it does appear that in AV, the camera shoots wide open no matter the F-stop set on lens. Is this "normal"?

**TwoUptons** · 12-20-2019, 06:26 PM

Your AV behavior is normal. It will set a shutter speed based on the lens being wide open.

In full manual, pressing the green button should automatically set the shutter speed based on your aperture setting. (At least it does that on my K01 and K1). On my K1, the meter only shows up for a moment in manual.

Anything you do with the shutter speed after that will be based on the prior reading regardless of what happens to the light.

-Eric

**arnold** · 12-20-2019, 07:47 PM

Are the aperture blades snappy? They may be slow to close.

Hawkfan · 12-20-2019, 07:58 PM

Oh yeah. It's a nice clean snappy lens. I will try one of my K lenses tomorrow, but after searching around on this great forum, I have seen other posts mentioning "issues" in attempting to use stop down metering and older lenses. Seems it can be done but I am finding out that the ability to use older glass on the DSLR's is not all tea and cookies after all.

blacklite · 12-20-2019, 08:33 PM

Do you get correct exposure if you expose immediately after pressing the green button without changing any settings?

**Serkevan** · 12-21-2019, 10:17 AM

Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly?

Not a Number · 12-21-2019, 11:15 AM

Are you in spot-metering mode? You should get better results with center-weighted metering depending on the scene/subject/lighting.

Hawkfan · 12-21-2019, 11:19 AM

Here are two photos. Taken with my K-X with M 28 2.8 Lens. First photo using M mode and green button to stop down and meter with a selected shutter speed of 250 which according to meter gives my spot on exposure 0.0. As you can see. photo is blown out even though exposure meter reads 0.0.

Second photo using Av in which camera shoots wide open aperture selecting shutter automatically it appears.

---------- Post added 12-21-19 at 11:30 AM ----------

Originally posted by Serkevan

Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly?

No Tv shift on K-X. It is set to Optical Preview which it should be as that is stop down metering. Also, metering is center weighted.

---------- Post added 12-21-19 at 11:31 AM ----------

Originally posted by Serkevan

Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly?

Exposure compensation set to 0.0.

**grog85361** · 12-21-2019, 11:31 AM

Originally posted by Serkevan

Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly?

The KX doesn't give you that option. Also, in M exposure mode, exposure compensation, even if set in another mode, has no effect.

I have been trying to duplicate your problem with my KX, but when I adjust the exposure to "0", it is right on. I would suspect a problem with your lens, since the DA lens works properly. Do you have other M lenses to try? This is a stumper. Best of luck.

---------- Post added 12-21-19 at 11:36 AM ----------

What aperture is your lens ring set to? In your second sample, a shutter speed of 1/2000 with ISO 200 would be appropriate for a very open aperture, like around f4.

12-20-2019, 02:59 PM	#1
Hawkfan Banned Join Date: Dec 2019 Location: Traveling The US Posts: 313	Issue Using M Lens On K-X Took out my M-28 mm to use on my K-x. Have settings set to manual focus, green button Optical Preview, and menu item 22 aperture ring use permitted. Correct focal length is set to 28mm on startup. I compose and focus and stop down with green button and set shutter speed until meter reads 0.0 correct exposure. The problem is is that even though meter reads correct exposure, my photos are over +3 over exposed. Would anyone have a clue as to would would cause this?

12-20-2019, 03:22 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Because matrix metering isn't available with manual lenses, it's possible for exposure issues to happen. It may be beneficial to try live view to get a more accurate reading, or to try to manually lock the exposure on something a little brighter in the scene. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

12-21-2019, 11:19 AM	#14
Hawkfan Banned Join Date: Dec 2019 Location: Traveling The US Posts: 313 Original Poster	Here are two photos. Taken with my K-X with M 28 2.8 Lens. First photo using M mode and green button to stop down and meter with a selected shutter speed of 250 which according to meter gives my spot on exposure 0.0. As you can see. photo is blown out even though exposure meter reads 0.0. Second photo using Av in which camera shoots wide open aperture selecting shutter automatically it appears. ---------- Post added 12-21-19 at 11:30 AM ---------- Originally posted by Serkevan Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly? No Tv shift on K-X. It is set to Optical Preview which it should be as that is stop down metering. Also, metering is center weighted. ---------- Post added 12-21-19 at 11:31 AM ---------- Originally posted by Serkevan Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly? Exposure compensation set to 0.0. Last edited by Hawkfan; 11-25-2020 at 07:50 AM.

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12-20-2019, 03:25 PM - 1 Like	#3
dantonvb Forum Member Join Date: Aug 2019 Photos: Gallery Posts: 86	You must set the manual exposure mode (M in dial). Then, when you press the green button, the camera sets the shutter speed to the correct value. Nothing more is needed.

12-20-2019, 03:27 PM	#4
M_D_K Forum Member Join Date: Oct 2019 Location: North Carolina Posts: 85	Are you using manual mode? Anything else (Av, TV, Auto, etc) doesn't seem to work with a M lens on my K-X

12-20-2019, 03:58 PM	#5
Wasp Pentaxian Join Date: Mar 2017 Location: Pretoria Photos: Gallery Posts: 4,661	Originally posted by M_D_K Are you using manual mode? Anything else (Av, TV, Auto, etc) doesn't seem to work with a M lens on my K-X You can use Av with wide open aperture. I think you can use Tv in this way if you also set ISO to auto, but I will have to check.

12-20-2019, 05:38 PM	#6
Hawkfan Banned Join Date: Dec 2019 Location: Traveling The US Posts: 313 Original Poster	Yes in M mode. I dial in aperture on lens and press green button set to optical preview. Lens does stop down as it should and in viewfinder window I have a shutter speed that can be adjusted with F... showing on screen of course for aperture setting. Also the exposure meter reading on screen. I set shutter speed in conjunction with meter reading to achieve a 0.0 meter reading. As far as the camera setting the speed automatically, that does not happen as the shutter speed only changes when I change with e-dial. My experience this afternoon was completely blown out photos approaching 3 stops over exposed. Upon a few more tries as day grew darker, my results appear to vary. Almost as if there is an intermittent meter issue. Funny thing is if I swap back to the DAL lens, no such issues.

12-20-2019, 05:44 PM	#7
Hawkfan Banned Join Date: Dec 2019 Location: Traveling The US Posts: 313 Original Poster	I do find that yes I can set to AV and camera will select speed. No exposure meter appears in viewfinder in AV in AV and green button no longer activates stop down and shutter speed doesn't change pointing camera from a light to dark area. Hmmm. Perhaps things just don't work the way I would wish with a manual lens on the K-x. Perhaps a newer model operates with a manual lens a little more "normally"? ---------- Post added 12-20-19 at 06:15 PM ---------- Also it does appear that in AV, the camera shoots wide open no matter the F-stop set on lens. Is this "normal"?

12-20-2019, 06:26 PM	#8
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,223	Your AV behavior is normal. It will set a shutter speed based on the lens being wide open. In full manual, pressing the green button should automatically set the shutter speed based on your aperture setting. (At least it does that on my K01 and K1). On my K1, the meter only shows up for a moment in manual. Anything you do with the shutter speed after that will be based on the prior reading regardless of what happens to the light. -Eric

12-20-2019, 07:47 PM	#9
arnold Site Supporter Join Date: Aug 2012 Location: Queensland Photos: Gallery \| Albums Posts: 4,295	Are the aperture blades snappy? They may be slow to close.

12-20-2019, 07:58 PM	#10
Hawkfan Banned Join Date: Dec 2019 Location: Traveling The US Posts: 313 Original Poster	Oh yeah. It's a nice clean snappy lens. I will try one of my K lenses tomorrow, but after searching around on this great forum, I have seen other posts mentioning "issues" in attempting to use stop down metering and older lenses. Seems it can be done but I am finding out that the ability to use older glass on the DSLR's is not all tea and cookies after all.

12-20-2019, 08:33 PM	#11
blacklite Junior Member Join Date: Jan 2011 Location: Brisbane Posts: 25	Do you get correct exposure if you expose immediately after pressing the green button without changing any settings?

12-21-2019, 10:17 AM	#12
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly?

12-21-2019, 11:15 AM	#13
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Are you in spot-metering mode? You should get better results with center-weighted metering depending on the scene/subject/lighting.

12-21-2019, 11:31 AM	#15
grog85361 Site Supporter Join Date: Dec 2010 Location: Phoenix Arizona Photos: Gallery \| Albums Posts: 894	Originally posted by Serkevan Try changing the Green Button to Tv-Shift. Can you post the problematic images? Also, just checking but have you made sure that Exposure Compensation is set correctly? The KX doesn't give you that option. Also, in M exposure mode, exposure compensation, even if set in another mode, has no effect. I have been trying to duplicate your problem with my KX, but when I adjust the exposure to "0", it is right on. I would suspect a problem with your lens, since the DA lens works properly. Do you have other M lenses to try? This is a stumper. Best of luck. ---------- Post added 12-21-19 at 11:36 AM ---------- What aperture is your lens ring set to? In your second sample, a shutter speed of 1/2000 with ISO 200 would be appropriate for a very open aperture, like around f4.