K-1 issue with green button on auto mode of old lenses

Snakeisthestuff · 06-30-2018, 08:13 AM

I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering.
This works with my old K-10D and I was always wondering why it is not working with my K-1, anyone else noticed that? Is this maybe just a setting or ist the K-1 missing something here which the older cameras had?

I just recently tried this with my SMC Takumar 135mm F3.5 using the genuine Pentax m42 to K adapter.

Not a Number · 06-30-2018, 08:50 AM

Do you mean correct exposure rather than aperture? The aperture is set by the ring on the lens, not the camera. Pressing the green button activates stop-down metering and the K-1 should set the appropriate shutter speed. As long as you have "Use Aperture Ring" enabled and "Green button in TAv and M" to TV shift. If you set DOF Preview to Optical activating the DOF preview will turn on the meter and you can adjust the EV bar with shutter speed eDial and the aperture with the ring.

All K-mount bodies lack the auto aperture mechanism for screw mount lenses. The only way a screw mount lens with an Auto/Man switch will stop down when set to "auto" is if the lens was modified to keep the stop-down pin engaged or with a flanged M42 adapter that will press in the pin. The genuine Pentax adapter does not have this flange.

**twilhelm** · 06-30-2018, 09:38 AM

The flanged adapters make infinity focus not possible, which is why Pentax does not have one.

stevebrot · 06-30-2018, 11:48 AM

Originally posted by Snakeisthestuff

I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering.

The "auto" on the lens slider refers to automatic aperture actuation (works only with M42 bodies) vs. fully manual aperture. On your K-1, the slider should be in the M/Man position for metering or when making the exposure.

Steve

pschlute · 06-30-2018, 11:57 AM

Originally posted by Snakeisthestuff

This works with my old K-10D

No it doesn't

**UncleVanya** · 06-30-2018, 12:06 PM

Originally posted by Snakeisthestuff

I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering.
This works with my old K-10D and I was always wondering why it is not working with my K-1, anyone else noticed that? Is this maybe just a setting or ist the K-1 missing something here which the older cameras had?

I just recently tried this with my SMC Takumar 135mm F3.5 using the genuine Pentax m42 to K adapter.

How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

**RobA_Oz** · 06-30-2018, 03:10 PM

Originally posted by twilhelm

The flanged adapters make infinity focus not possible, which is why Pentax does not have one.

Only some poorly-made adapters with an extended flange do that. The original Pentax adapter allows infinity focus, but I’m not sure if they’re still made, or not. Of the rest, it’s a bit of a lottery whether they do, but some do, even while they have the registration angle wrong, or are hard to remove. Needless to say, I have a few.

**UncleVanya** · 06-30-2018, 03:14 PM

Originally posted by RobA_Oz

Only some poorly-made adapters with an extended flange do that. The original Pentax adapter allows infinity focus, but I’m not sure if they’re still made, or not. Of the rest, it’s a bit of a lottery whether they do, but some do, even while they have the registration angle wrong, or are hard to remove. Needless to say, I have a few.

The Pentax adapter isn't typically considered flanged. The flanged ones all deny infinity focus although some lenses can be adjusted to compensate by changing infinity focus. Mostly those flanged adapters work well with macro work.

Not a Number · 06-30-2018, 04:17 PM

Originally posted by twilhelm

The flanged adapters make infinity focus not possible, which is why Pentax does not have one.

This is true for the adapters that have an external flange with a cut-out for lens mount locking pin but I'm speaking of those with an internal flange such as the Kipon adapter:

Kipon Pentax Screw M42 Lens to Pentax K Camera Lens Adapter (with Inner Ring) KP-LA-PXK-PXS

**twilhelm** · 06-30-2018, 04:22 PM

Originally posted by Not a Number

This is true for the adapters that have an external flange with a cut-out for lens mount locking pin but I'm speaking of those with an internal flange such as the Kipon adapter:

Kipon Pentax Screw M42 Lens to Pentax K Camera Lens Adapter (with Inner Ring) KP-LA-PXK-PXS

Those I had forgotten about. I was referring to the external flange type.

**RobA_Oz** · 06-30-2018, 05:00 PM

Originally posted by UncleVanya

The Pentax adapter isn't typically considered flanged. The flanged ones all deny infinity focus although some lenses can be adjusted to compensate by changing infinity focus. Mostly those flanged adapters work well with macro work.

Yes, I realise that’s the shorthand usage, but it does have a small flange. Call me picky.

**UncleVanya** · 06-30-2018, 05:03 PM - **1 Like**

Originally posted by RobA_Oz

Yes, I realise that’s the shorthand usage, but it does have a small flange. Call me picky.

Picky! LOL. I get the point you were trying to make now. I guess a better way to differentiate would be externally flanged adapters that rest above the mount and internally flanged adapters that rest inside the K mount entirely.

**RobA_Oz** · 06-30-2018, 10:44 PM

Originally posted by UncleVanya

Picky! LOL. I get the point you were trying to make now. I guess a better way to differentiate would be externally flanged adapters that rest above the mount and internally flanged adapters that rest inside the K mount entirely.

True, but I was also trying to warn the OP about the other types of non-OEM adapters that were on the market – the type that does rest inside the K-mount, but which may have other problems.

Snakeisthestuff · 07-01-2018, 03:29 AM

Originally posted by pschlute

No it doesn't

Yes it does xD.
As already told, I have confirmed this with my K10D already.
When I press the green button there I hear and see the aperture closing temporarily for correct metering.
My K-1 on the other hand does not do this while using the same lens with same adapter.

FYI: The genuine pentax m42 to K adapters are still for sale in Japan, where I got mine.

Ronald Oakes · 07-01-2018, 04:01 AM

Originally posted by Snakeisthestuff

Yes it does xD.
As already told, I have confirmed this with my K10D already.
When I press the green button there I hear and see the aperture closing temporarily for correct metering.
My K-1 on the other hand does not do this while using the same lens with same adapter.

FYI: The genuine pentax m42 to K adapters are still for sale in Japan, where I got mine.

No it doesn't !!! Not on a M42 lens.

06-30-2018, 08:13 AM	#1
Snakeisthestuff Senior Member Join Date: Jul 2011 Photos: Gallery Posts: 136	K-1 issue with green button on auto mode of old lenses I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering. This works with my old K-10D and I was always wondering why it is not working with my K-1, anyone else noticed that? Is this maybe just a setting or ist the K-1 missing something here which the older cameras had? I just recently tried this with my SMC Takumar 135mm F3.5 using the genuine Pentax m42 to K adapter.

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06-30-2018, 08:50 AM	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Do you mean correct exposure rather than aperture? The aperture is set by the ring on the lens, not the camera. Pressing the green button activates stop-down metering and the K-1 should set the appropriate shutter speed. As long as you have "Use Aperture Ring" enabled and "Green button in TAv and M" to TV shift. If you set DOF Preview to Optical activating the DOF preview will turn on the meter and you can adjust the EV bar with shutter speed eDial and the aperture with the ring. All K-mount bodies lack the auto aperture mechanism for screw mount lenses. The only way a screw mount lens with an Auto/Man switch will stop down when set to "auto" is if the lens was modified to keep the stop-down pin engaged or with a flanged M42 adapter that will press in the pin. The genuine Pentax adapter does not have this flange.

06-30-2018, 09:38 AM	#3
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	The flanged adapters make infinity focus not possible, which is why Pentax does not have one.

06-30-2018, 11:48 AM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Snakeisthestuff I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering. The "auto" on the lens slider refers to automatic aperture actuation (works only with M42 bodies) vs. fully manual aperture. On your K-1, the slider should be in the M/Man position for metering or when making the exposure. Steve

06-30-2018, 11:57 AM	#5
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,202	Originally posted by Snakeisthestuff This works with my old K-10D No it doesn't

06-30-2018, 12:06 PM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,407	Originally posted by Snakeisthestuff I noticed my old m42 Takumar lenses will not set the correct aperture while having the lens switch on "auto" und pressing the green button for metering. This works with my old K-10D and I was always wondering why it is not working with my K-1, anyone else noticed that? Is this maybe just a setting or ist the K-1 missing something here which the older cameras had? I just recently tried this with my SMC Takumar 135mm F3.5 using the genuine Pentax m42 to K adapter. How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

06-30-2018, 03:10 PM	#7
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,197	Originally posted by twilhelm The flanged adapters make infinity focus not possible, which is why Pentax does not have one. Only some poorly-made adapters with an extended flange do that. The original Pentax adapter allows infinity focus, but I’m not sure if they’re still made, or not. Of the rest, it’s a bit of a lottery whether they do, but some do, even while they have the registration angle wrong, or are hard to remove. Needless to say, I have a few.

06-30-2018, 03:14 PM	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,407	Originally posted by RobA_Oz Only some poorly-made adapters with an extended flange do that. The original Pentax adapter allows infinity focus, but I’m not sure if they’re still made, or not. Of the rest, it’s a bit of a lottery whether they do, but some do, even while they have the registration angle wrong, or are hard to remove. Needless to say, I have a few. The Pentax adapter isn't typically considered flanged. The flanged ones all deny infinity focus although some lenses can be adjusted to compensate by changing infinity focus. Mostly those flanged adapters work well with macro work.

06-30-2018, 04:17 PM	#9
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by twilhelm The flanged adapters make infinity focus not possible, which is why Pentax does not have one. This is true for the adapters that have an external flange with a cut-out for lens mount locking pin but I'm speaking of those with an internal flange such as the Kipon adapter: Kipon Pentax Screw M42 Lens to Pentax K Camera Lens Adapter (with Inner Ring) KP-LA-PXK-PXS

06-30-2018, 04:22 PM	#10
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	Originally posted by Not a Number This is true for the adapters that have an external flange with a cut-out for lens mount locking pin but I'm speaking of those with an internal flange such as the Kipon adapter: Kipon Pentax Screw M42 Lens to Pentax K Camera Lens Adapter (with Inner Ring) KP-LA-PXK-PXS Those I had forgotten about. I was referring to the external flange type.

06-30-2018, 05:00 PM	#11
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,197	Originally posted by UncleVanya The Pentax adapter isn't typically considered flanged. The flanged ones all deny infinity focus although some lenses can be adjusted to compensate by changing infinity focus. Mostly those flanged adapters work well with macro work. Yes, I realise that’s the shorthand usage, but it does have a small flange. Call me picky.

06-30-2018, 05:03 PM - 1 Like	#12
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,407	Originally posted by RobA_Oz Yes, I realise that’s the shorthand usage, but it does have a small flange. Call me picky. Picky! LOL. I get the point you were trying to make now. I guess a better way to differentiate would be externally flanged adapters that rest above the mount and internally flanged adapters that rest inside the K mount entirely.

06-30-2018, 10:44 PM	#13
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,197	Originally posted by UncleVanya Picky! LOL. I get the point you were trying to make now. I guess a better way to differentiate would be externally flanged adapters that rest above the mount and internally flanged adapters that rest inside the K mount entirely. True, but I was also trying to warn the OP about the other types of non-OEM adapters that were on the market – the type that does rest inside the K-mount, but which may have other problems.

07-01-2018, 03:29 AM	#14
Snakeisthestuff Senior Member Join Date: Jul 2011 Photos: Gallery Posts: 136 Original Poster	Originally posted by pschlute No it doesn't Yes it does xD. As already told, I have confirmed this with my K10D already. When I press the green button there I hear and see the aperture closing temporarily for correct metering. My K-1 on the other hand does not do this while using the same lens with same adapter. FYI: The genuine pentax m42 to K adapters are still for sale in Japan, where I got mine.

07-01-2018, 04:01 AM	#15
Ronald Oakes Pentaxian Join Date: Jul 2017 Location: Virginia Posts: 1,583	Originally posted by Snakeisthestuff Yes it does xD. As already told, I have confirmed this with my K10D already. When I press the green button there I hear and see the aperture closing temporarily for correct metering. My K-1 on the other hand does not do this while using the same lens with same adapter. FYI: The genuine pentax m42 to K adapters are still for sale in Japan, where I got mine. No it doesn't !!! Not on a M42 lens.