Why Pentax F TC X1.7 not work on M42 lens?

RTogog · 11-23-2009, 04:07 AM

Just curious this TC doesn't work on M42 lens as stated on the manual of this TC.
Are there technical issues so only work w specific lens?.
Many thanks,
RTogog

Asahiflex · 11-23-2009, 04:13 AM

Originally posted by RTogog

Just curious this TC doesn't work on M42 lens as stated on the manual of this TC.
Are there technical issues so only work w specific lens?.

I believe the contacts on the AF adapter need to be shorted in order to make it work. A k-mount lens will short the contacts, but some M42 lenses are smaller or the back of the lens does not reach the contacts, or the back of the M42 lens is not conductive.

pcarfan · 11-23-2009, 04:31 AM

I don't think it says in the manual that it will AF with M42 lenses, does it?....When I had mine, I had to short the circuits with a foil and then The AFA will AF the m42 lenses, and even does P-TTL flash.

RTogog · 11-23-2009, 05:39 AM

Originally posted by pcarfan

I don't think it says in the manual that it will AF with M42 lenses, does it?....When I had mine, I had to short the circuits with a foil and then The AFA will AF the m42 lenses, and even does P-TTL flash.

It is true on the manual stated that will not work w m42 lens. How did you do? patch it w foil on the m42 lens? I 've tried directly put a m42 to K adapter on the lens directly but still doesn't work?

pcarfan · 11-23-2009, 05:48 AM

Originally posted by RTogog

It is true on the manual stated that will not work w m42 lens. How did you do? patch it w foil on the m42 lens? I 've tried directly put a m42 to K adapter on the lens directly but still doesn't work?

The electrical contacts have to be shorted on the camera. So place a foil over the electrical connections on the camera and burnish the foil so the sunken contact touches the foil as well. And then attach the lens making sure the foil doesn't move.

I did not like this method as there are shreds of foil that falls into the camera. I tried to scrape the metal of the lens barrel to make contact. It didn't work for me, some say it works for them, but I can't see how the barrel will ever make contact with the sunken contact. Some say the M42-K adapter with the flange which doesn't allow for infinity focus will short the circuit. I didn't try this, but again I don't see how that sunken electrical contact will touch the flange ?

I've long since sold the AFA and all my MF lenses.

11-23-2009, 04:07 AM	#1
RTogog Forum Member Join Date: Dec 2006 Posts: 77	Why Pentax F TC X1.7 not work on M42 lens? Just curious this TC doesn't work on M42 lens as stated on the manual of this TC. Are there technical issues so only work w specific lens?. Many thanks, RTogog

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11-23-2009, 04:13 AM	#2
Asahiflex Pentaxian Join Date: Jan 2008 Location: Netherlands Photos: Gallery Posts: 2,795	Originally posted by RTogog Just curious this TC doesn't work on M42 lens as stated on the manual of this TC. Are there technical issues so only work w specific lens?. I believe the contacts on the AF adapter need to be shorted in order to make it work. A k-mount lens will short the contacts, but some M42 lenses are smaller or the back of the lens does not reach the contacts, or the back of the M42 lens is not conductive.

11-23-2009, 04:31 AM	#3
pcarfan Veteran Member Join Date: Sep 2007 Location: Dayton, Ohio Photos: Gallery \| Albums Posts: 2,978	I don't think it says in the manual that it will AF with M42 lenses, does it?....When I had mine, I had to short the circuits with a foil and then The AFA will AF the m42 lenses, and even does P-TTL flash.

11-23-2009, 05:39 AM	#4
RTogog Forum Member Join Date: Dec 2006 Posts: 77 Original Poster	Originally posted by pcarfan I don't think it says in the manual that it will AF with M42 lenses, does it?....When I had mine, I had to short the circuits with a foil and then The AFA will AF the m42 lenses, and even does P-TTL flash. It is true on the manual stated that will not work w m42 lens. How did you do? patch it w foil on the m42 lens? I 've tried directly put a m42 to K adapter on the lens directly but still doesn't work?

11-23-2009, 05:48 AM	#5
pcarfan Veteran Member Join Date: Sep 2007 Location: Dayton, Ohio Photos: Gallery \| Albums Posts: 2,978	Originally posted by RTogog It is true on the manual stated that will not work w m42 lens. How did you do? patch it w foil on the m42 lens? I 've tried directly put a m42 to K adapter on the lens directly but still doesn't work? The electrical contacts have to be shorted on the camera. So place a foil over the electrical connections on the camera and burnish the foil so the sunken contact touches the foil as well. And then attach the lens making sure the foil doesn't move. I did not like this method as there are shreds of foil that falls into the camera. I tried to scrape the metal of the lens barrel to make contact. It didn't work for me, some say it works for them, but I can't see how the barrel will ever make contact with the sunken contact. Some say the M42-K adapter with the flange which doesn't allow for infinity focus will short the circuit. I didn't try this, but again I don't see how that sunken electrical contact will touch the flange ? I've long since sold the AFA and all my MF lenses.