M42 Lenses on K-1000 SE - exposure problem

Peter_JDH · 10-16-2019, 07:06 PM

I mounted an SMC Takumar 50 mm f1.4 to my K-1000 and ended up under exposed on every shot. Same lens works well on my Spotmatic F. My A series 50 mm f2 on the K-1000 exposes as expected. It’s not the battery and it is the proper Pentax adapter that I use successfully on my digital body. Any idea why this would be? I did have to slide the auto switch on the side of the M42 lens to get the K -1000’s light meter to even react. Maybe this combo is not fully compatible or is there a trick to this setup? Thanks.

stevebrot · 10-16-2019, 07:27 PM

Originally posted by Peter_JDH

Any idea why this would be?

Is the Auto/Man slider in the M position for both metering and exposure?

This is covered on page 26 of the K1000 camera manual. Pentax Manuals | Manual Focus Cameras (PDF password = "Pentax")

Edit: Unfortunately, the instructions in the manual do not include full details on doing stop-down metering. The key is to stop down the lens to meter and make sure that it is stopped down to the same setting for exposure. There is no need to re-meter unless the subject and/or light changes.

Steve

**UncleVanya** · 10-17-2019, 05:07 AM

Originally posted by stevebrot

Is the Auto/Man slider in the M position for both metering and exposure?

This is covered on page 26 of the K1000 camera manual. Pentax Manuals | Manual Focus Cameras (PDF password = "Pentax")

Edit: Unfortunately, the instructions in the manual do not include full details on doing stop-down metering. The key is to stop down the lens to meter and make sure that it is stopped down to the same setting for exposure. There is no need to re-meter unless the subject and/or light changes.

Steve

Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't.

Not a Number · 10-17-2019, 05:21 AM

Originally posted by UncleVanya

Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't.

Correct, the Spotmatic F supports full aperture metering (lens in auto mode). The K-mount bodies do not have a mechanism to auto stop-down M42 lens thus you have to manually stop-down the lens to meter and take the exposure.

**aslyfox** · 10-17-2019, 05:24 AM

perhaps these articles might be of some help ?

Quote:

Manual Focus Lenses
You may never have realized that manual focus lenses have a lot of uses, some are even more useful for certain types of photography than autofocus lenses. In reverse-chronological order, we'll talk about different types of manual focus lens mounts and how they can be used on your Pentax DSLR body. More information about the Pentax K Mount's evolution can be found in this article.

Using a manual focus lens on your Pentax DSLR requires that you make sure you have some settings in your camera adjusted properly. Chiefly, you need to make sure that you camera will allow the use of the lens's aperture ring. If you're unfamiliar with the required procedure, we recommend that you see our brief video detailing Pentax DSLR settings for manual lens use. If you're still unclear on what to do, see our in-depth guide on how to set your Pentax DSLR to accept legacy lenses. In this article, we won't be getting quit as technical as the aformentioned guide, instead focusing on artistic and practical considerations.

Read more at: Manual Focus Lens Choices for Pentax - Articles and Tips | PentaxForums.com

[ go to article to activate links ]

______________________________________

Quote:

How to Use Manual Lenses on Pentax DSLRs
Virtually all K-mount and M42 lenses are compatible!
By PF Staff in Tutorial Videos on Apr 29, 2013

Read more at: How to Use Manual Lenses on Pentax DSLRs - Tutorial Videos | PentaxForums.com

stevebrot · 10-17-2019, 05:45 AM - **1 Like**

Originally posted by UncleVanya

Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't.

Yes, an adapted M42 lens must be operated as manual aperture (stopped down) for metering and during exposure when adapted to K-mount; and yes, the Spotmatic F does auto aperture actuation with M42 lenses the same as all other Spotmatic models.

How it all works with SMC lenses is fairly complicated, but the gist is...

SMC Takumars (A/M switch on lens in A position) on the Spotmatic F behave the same on that camera as Pentax-K on the K-1000, meaning that the combination meters wide open. Having the switch in the M position with an SMC Tak on that camera is technically possible, but not recommended.
M42 Takumars (SMC included) must be used stopped-down as manual aperture lenses (switch in M position) for both metering and exposure when adapted to a K-mount body. Yes, it was just as cumbersome then as it is now on our dSLRs.
SMC Takumars on M42 bodies other than the Spotmatic F, Electro Spotmatic, ES, and ESII operate the same as non-SMC Takumars
Non-SMC Takumars operate the same on the Spotmatic F, Electro Spotmatic, ES, and ESII as on other metered Spotmatic models

Steve

**pentaxus** · 10-17-2019, 11:28 AM

I think that sometimes people get underexposure using stop down metering because light can come in through the eyepiece if it isn't blocked well enough by the photographer's head. If exposure is better when using f/5.6 compared to using f/16 that can be the problem.

10-16-2019, 07:06 PM	#1
Peter_JDH Junior Member Join Date: Mar 2016 Location: British Columbia Posts: 41	M42 Lenses on K-1000 SE - exposure problem I mounted an SMC Takumar 50 mm f1.4 to my K-1000 and ended up under exposed on every shot. Same lens works well on my Spotmatic F. My A series 50 mm f2 on the K-1000 exposes as expected. It’s not the battery and it is the proper Pentax adapter that I use successfully on my digital body. Any idea why this would be? I did have to slide the auto switch on the side of the M42 lens to get the K -1000’s light meter to even react. Maybe this combo is not fully compatible or is there a trick to this setup? Thanks.

10-16-2019, 07:27 PM	#2
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Peter_JDH Any idea why this would be? Is the Auto/Man slider in the M position for both metering and exposure? This is covered on page 26 of the K1000 camera manual. Pentax Manuals \| Manual Focus Cameras (PDF password = "Pentax") Edit: Unfortunately, the instructions in the manual do not include full details on doing stop-down metering. The key is to stop down the lens to meter and make sure that it is stopped down to the same setting for exposure. There is no need to re-meter unless the subject and/or light changes. Steve Last edited by stevebrot; 10-16-2019 at 07:35 PM.

10-17-2019, 05:45 AM - 1 Like	#6
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by UncleVanya Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't. Yes, an adapted M42 lens must be operated as manual aperture (stopped down) for metering and during exposure when adapted to K-mount; and yes, the Spotmatic F does auto aperture actuation with M42 lenses the same as all other Spotmatic models. How it all works with SMC lenses is fairly complicated, but the gist is... SMC Takumars (A/M switch on lens in A position) on the Spotmatic F behave the same on that camera as Pentax-K on the K-1000, meaning that the combination meters wide open. Having the switch in the M position with an SMC Tak on that camera is technically possible, but not recommended. M42 Takumars (SMC included) must be used stopped-down as manual aperture lenses (switch in M position) for both metering and exposure when adapted to a K-mount body. Yes, it was just as cumbersome then as it is now on our dSLRs. SMC Takumars on M42 bodies other than the Spotmatic F, Electro Spotmatic, ES, and ESII operate the same as non-SMC Takumars Non-SMC Takumars operate the same on the Spotmatic F, Electro Spotmatic, ES, and ESII as on other metered Spotmatic models Steve

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10-17-2019, 05:07 AM	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	Originally posted by stevebrot Is the Auto/Man slider in the M position for both metering and exposure? This is covered on page 26 of the K1000 camera manual. Pentax Manuals \| Manual Focus Cameras (PDF password = "Pentax") Edit: Unfortunately, the instructions in the manual do not include full details on doing stop-down metering. The key is to stop down the lens to meter and make sure that it is stopped down to the same setting for exposure. There is no need to re-meter unless the subject and/or light changes. Steve Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't.

10-17-2019, 05:21 AM	#4
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by UncleVanya Steve does that mean switching the lens to manual/M mode on the k1000? I assume the Spotmatic F automatically stops down while the k mount body doesn't. Correct, the Spotmatic F supports full aperture metering (lens in auto mode). The K-mount bodies do not have a mechanism to auto stop-down M42 lens thus you have to manually stop-down the lens to meter and take the exposure.

10-17-2019, 05:24 AM	#5
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,581	perhaps these articles might be of some help ? Quote: Manual Focus Lenses You may never have realized that manual focus lenses have a lot of uses, some are even more useful for certain types of photography than autofocus lenses. In reverse-chronological order, we'll talk about different types of manual focus lens mounts and how they can be used on your Pentax DSLR body. More information about the Pentax K Mount's evolution can be found in this article. Using a manual focus lens on your Pentax DSLR requires that you make sure you have some settings in your camera adjusted properly. Chiefly, you need to make sure that you camera will allow the use of the lens's aperture ring. If you're unfamiliar with the required procedure, we recommend that you see our brief video detailing Pentax DSLR settings for manual lens use. If you're still unclear on what to do, see our in-depth guide on how to set your Pentax DSLR to accept legacy lenses. In this article, we won't be getting quit as technical as the aformentioned guide, instead focusing on artistic and practical considerations. Read more at: Manual Focus Lens Choices for Pentax - Articles and Tips \| PentaxForums.com [ go to article to activate links ] ______________________________________ Quote: How to Use Manual Lenses on Pentax DSLRs Virtually all K-mount and M42 lenses are compatible! By PF Staff in Tutorial Videos on Apr 29, 2013 Read more at: How to Use Manual Lenses on Pentax DSLRs - Tutorial Videos \| PentaxForums.com

10-17-2019, 11:28 AM	#7
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	I think that sometimes people get underexposure using stop down metering because light can come in through the eyepiece if it isn't blocked well enough by the photographer's head. If exposure is better when using f/5.6 compared to using f/16 that can be the problem.