Takumar 55mm, m42 only works in manual mode

Laci.4400 · 10-21-2020, 01:40 PM

Hi all,

I’m planning to get a SMC Takumar 55mm, 1.4, an optically pristine one for 86 bucks however it only works in manual mode. The pin stucks in and only the manual twist could help it. The owner says it might be the spring which might be weak or something is tight inside the lens.
I’m wonderig if it’s curable or not? I feel that it’s a yes but I’m far not an expert. I think even with the cost of repair it would worth it but I might be not right.
What you think? Should I invest?

Last edited by Laci.4400; 10-21-2020 at 02:44 PM.

reh321 · 10-21-2020, 02:35 PM

Originally posted by Laci.4400

Hi all,

I’m planning to get a SMC Takumar 55mm, 1.4, an optically pristine one for 86 bucks however it only works in manual mode. The pin stucks in and only the manual twist could help it. The owner says it might be the spring which might be weak or something is tight inside the lens.
I’m wonderig if it’s curable or not. I feel that it’s a yes but I’m far not an expert. I think even with the cost of repair it would worth it but I might be not right.

Yes, it is a M42-mount lens - a mount that Pentax put behind them when they switched to K-mount in 1975.
It is working correctly - the way it was designed to work.

The K-mount was designed to have the same flange distance that M42-mount has - so a simple adapter suffices - but it is still not the same.

See https://www.pentaxforums.com/articles/photo-articles/the-evolution-of-the-pentax-m42-mount.html

stevebrot · 10-21-2020, 02:46 PM - **1 Like**

I am not sure that I understand the problem from your description. With the Auto/Man switch in Auto, the aperture diaphragm should stop down when the silver pin to the rear is depressed and should otherwise remain wide open. If this is not the behavior, the mechanism is either broken or gummed up.

Physical damage is a very real possibility. The aperture mechanism on SMC/S-M-C Takumar lenses is different than that on earlier model Takumar lenses and may be easily damaged if used improperly. The rules were in the lens and camera manuals of the time and go like this:

The Auto/Man switch on the side of the lens should never be forced to the Man position.
The Auto/Man switch should always be in the Auto position when used with a Spotmatic F, Spotmatic ES, Spotmatic ESII, or Electro Spotmatic camera and on those cameras is locked in the Auto position.
The Auto/Man switch may be used in either position if a rear cap is attached, if attached to a mount adapter, or if it's mounted to a camera other than those listed above.
The Auto/Man switch may be safely moved from the Man to the Auto position at any time.

I don't know if the lens has been misused in that way or whether it can be repaired, though a competent lens technician might know. If I were considering purchase, I would consider it good for parts only unless told otherwise by someone able to do the repair.

Steve

stevebrot · 10-21-2020, 02:51 PM - **1 Like**

...forgot to mention above that Pentax has never made a 55mm f/1.4 lens. The 55mm lenses were all either f/1.8 or f/2.0 maximum aperture. They did make a 50mm f/1.4 SMC Takumar, but you will want to confirm the focal length and maximum aperture with the seller. $89 would be a fair price for an SMC Takumar 50/1.4 in very good or better condition, but would be on the high side for an SMC Takumar 55mm f/1.8, at least in my opinion.

Steve

reh321 · 10-21-2020, 03:10 PM

To provide more detail:

With an adapter, you can use a M42-mount lens set for 'man' on a K-mount camera - like a K-1, K-3, K-70, or KP - in "M' mode.
No modern Pentax camera can use a M42-mount lens set for 'auto'.

Laci.4400 · 10-21-2020, 05:00 PM

Originally posted by stevebrot

...forgot to mention above that Pentax has never made a 55mm f/1.4 lens. The 55mm lenses were all either f/1.8 or f/2.0 maximum aperture. They did make a 50mm f/1.4 SMC Takumar, but you will want to confirm the focal length and maximum aperture with the seller. $89 would be a fair price for an SMC Takumar 50/1.4 in very good or better condition, but would be on the high side for an SMC Takumar 55mm f/1.8, at least in my opinion.

Steve

Many thanks for your response! Yes, I made a mistake; it’s indeed a 50mm 1.4 lens. I was thinking about it since then and you’re right it’s a bit high for a partly functional lens so I think I skip this piece of glass.

10-21-2020, 01:40 PM	#1
Laci.4400 Junior Member Join Date: May 2020 Posts: 27	Takumar 55mm, m42 only works in manual mode Hi all, I’m planning to get a SMC Takumar 55mm, 1.4, an optically pristine one for 86 bucks however it only works in manual mode. The pin stucks in and only the manual twist could help it. The owner says it might be the spring which might be weak or something is tight inside the lens. I’m wonderig if it’s curable or not? I feel that it’s a yes but I’m far not an expert. I think even with the cost of repair it would worth it but I might be not right. What you think? Should I invest? Last edited by Laci.4400; 10-21-2020 at 02:44 PM.

10-21-2020, 02:35 PM	#2
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,180	Originally posted by Laci.4400 Hi all, I’m planning to get a SMC Takumar 55mm, 1.4, an optically pristine one for 86 bucks however it only works in manual mode. The pin stucks in and only the manual twist could help it. The owner says it might be the spring which might be weak or something is tight inside the lens. I’m wonderig if it’s curable or not. I feel that it’s a yes but I’m far not an expert. I think even with the cost of repair it would worth it but I might be not right. Yes, it is a M42-mount lens - a mount that Pentax put behind them when they switched to K-mount in 1975. It is working correctly - the way it was designed to work. The K-mount was designed to have the same flange distance that M42-mount has - so a simple adapter suffices - but it is still not the same. See https://www.pentaxforums.com/articles/photo-articles/the-evolution-of-the-pentax-m42-mount.html Last edited by reh321; 10-21-2020 at 02:58 PM.

10-21-2020, 02:46 PM - 1 Like	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I am not sure that I understand the problem from your description. With the Auto/Man switch in Auto, the aperture diaphragm should stop down when the silver pin to the rear is depressed and should otherwise remain wide open. If this is not the behavior, the mechanism is either broken or gummed up. Physical damage is a very real possibility. The aperture mechanism on SMC/S-M-C Takumar lenses is different than that on earlier model Takumar lenses and may be easily damaged if used improperly. The rules were in the lens and camera manuals of the time and go like this: The Auto/Man switch on the side of the lens should never be forced to the Man position. The Auto/Man switch should always be in the Auto position when used with a Spotmatic F, Spotmatic ES, Spotmatic ESII, or Electro Spotmatic camera and on those cameras is locked in the Auto position. The Auto/Man switch may be used in either position if a rear cap is attached, if attached to a mount adapter, or if it's mounted to a camera other than those listed above. The Auto/Man switch may be safely moved from the Man to the Auto position at any time. I don't know if the lens has been misused in that way or whether it can be repaired, though a competent lens technician might know. If I were considering purchase, I would consider it good for parts only unless told otherwise by someone able to do the repair. Steve

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10-21-2020, 02:51 PM - 1 Like	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	...forgot to mention above that Pentax has never made a 55mm f/1.4 lens. The 55mm lenses were all either f/1.8 or f/2.0 maximum aperture. They did make a 50mm f/1.4 SMC Takumar, but you will want to confirm the focal length and maximum aperture with the seller. $89 would be a fair price for an SMC Takumar 50/1.4 in very good or better condition, but would be on the high side for an SMC Takumar 55mm f/1.8, at least in my opinion. Steve

10-21-2020, 03:10 PM	#5
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,180	To provide more detail: With an adapter, you can use a M42-mount lens set for 'man' on a K-mount camera - like a K-1, K-3, K-70, or KP - in "M' mode. No modern Pentax camera can use a M42-mount lens set for 'auto'.

10-21-2020, 05:00 PM	#6
Laci.4400 Junior Member Join Date: May 2020 Posts: 27 Original Poster	Originally posted by stevebrot ...forgot to mention above that Pentax has never made a 55mm f/1.4 lens. The 55mm lenses were all either f/1.8 or f/2.0 maximum aperture. They did make a 50mm f/1.4 SMC Takumar, but you will want to confirm the focal length and maximum aperture with the seller. $89 would be a fair price for an SMC Takumar 50/1.4 in very good or better condition, but would be on the high side for an SMC Takumar 55mm f/1.8, at least in my opinion. Steve Many thanks for your response! Yes, I made a mistake; it’s indeed a 50mm 1.4 lens. I was thinking about it since then and you’re right it’s a bit high for a partly functional lens so I think I skip this piece of glass.