M42 to K mount adapter covers/shortcuts DSLR contact?

DrRzvn · 08-31-2010, 04:00 AM

I'm interested to buy an adaptor from M42 to K mount in order to use it on a Pentax DSLR. I'm not able to find in my town directly the adapter to check it in advance, so there is something which bothers me: a metal M42 adapter(which drives electricity) will shortcut the contacts on my DSLR? Is there a problem?

Background: on some on-line shop forum from my country, someone posted a comment(for a non Pentax genuine adapter), that he had to ensure that the DSLR body mount contacts had to be covered with some tape, to avoid shortcut made by the adapter. Now, it's strange for me that I cannot find any other reference to such problems with any knid of M42 to k mount adaptex, Pentax made or third party made...

Last edited by DrRzvn; 08-31-2010 at 04:47 AM.

Ira · 08-31-2010, 05:26 AM

It doesn't short them out, but you can use aluminum tape on the base of the lens to accomplish that, and to take advantage of Catch-In Focus.

**Lowell Goudge** · 08-31-2010, 05:39 AM

Lets look at all the issues with M42 adaptors so you understand exactly what happens on a DSLR

First of all, there are 2 different styles of M42 adaptors, those called "flanged" adaptors and those without flanges (i.e. origonal style pentax adaptors)

Flanged adaptors are cheap, and have provision for the lens locking pin, but space thelens out away from the camera body by 0.8mm, which upsets the infinity focus. This can be adjusted on some lenses but not all can be set to retain infinity focus.

Flanged adaptors will short out all th epins to th elens mount. This is OK and is no different than pentax K mount lenses, and the camera design accepts this. in fact shorting the contacts, specifically pins 1, 2, 4, 5, & 6 is how the lens coding for maximum and minimum aperture is done. Shorting pin 3 tells the camera the lens has an A setting, and this is why that specific pin is recessed on the camera body.

Similairly shorting pin 7 tells the camera that the lens is manual focus, and allows the focus confirmation to work.

Pin 7 is a multi use pin, which also conveys the lens ID and focusing distance, focal length etc from the lens to the body

Non flanged or flush mount adaptors mount flus to the body mount surface and do not interfere with the infinity focus but also do not obviously touch the contacts, and not all M42 lenses have wide enough bases or conducting bases to short pin 7 so in most instances focus confirmation is also lost.

DrRzvn · 08-31-2010, 07:35 AM

Thank you for your feddback!

RioRico · 08-31-2010, 12:48 PM

Good info from Lowell! Here's a little more: Shorting the pins is *completely* safe. Some of those flanged adapters are painted black; they will NOT short the pins unless you file the paint off in the 6-o'clock area. I've scraped all mine, so I can use Catch-In-Focus. And I use CIF a LOT. The following is all about preparing for CIF:

I know of *no* M42 lens that shorts the pins when wearing a flangeless (infinity focus) adapter. At least, none of my 55+ M42's do. Many of us employ cheap metallic tape, gummed on one side -- cut a strip, stick it to the 6-o'clock area of the lens, add the adapter, mount on camera, shoot.

WARNING: Do NOT put metallic tape on a painted flanged adapter to short the pins! File off the paint instead. Adding tape WILL make the adapter jam on the camera. This also applies to cheap painted PK macro rings.

Ah, but metallic tape doesn't work with all screwmount lenses, 'cause many have bases too narrow to reach the pins anyway. One trick is to get qa bit of tinfoil under the adapter, shoved down over the pins. But tinfoil easily blows away, and doesn't always work either. Bother.

wannabefishing · 09-05-2010, 08:03 AM

just got my first m42 (helios 44M) and was curious about something... is it okay to back out the 6 o'clock screw 1/16th of an inch to short it out? i can say it shorts it out fine... any issues going forward ya'll think?

Lloydy · 09-05-2010, 03:45 PM

No, don't do that. The backed off screw could foul on the contacts, and possibly the auto focus drive, when the lens was rotated as you mounted and unmounted it.

The easy way is to get some sticky aluminium tape, scrounge some off a heating engineer, and cut a small crescent which you stick on the back of the lens - or scape the paint off in the same area.

The idea is to connect the pins on the camera electrically.

This is how I do my 44-M and this bit of tape has been on there for months now, and I use this lens a lot.

bill. · 09-05-2010, 07:46 PM

What is the point in shorting the contacts?
My K10d confirms focus with all 7 m42 lenses I own, using a flangeless adapter.

Lloydy · 09-06-2010, 05:48 AM

It's not for focus confirmation, it's for focus trap. ( catch in focus - trap in focus )

There's a good description of the technique somewhere in the 'Soviet Lenses Club' topic, somewhere towards the last third of the thread I think.
But a search will also throw up some information.

DrRzvn · 09-06-2010, 12:59 PM

Thank you for all advices! Meanwhile, I've searched deeply on internet and found even on wikipedia a good description of pentax mounts. I feel kind of silly, that I didn't do that before!

Ira · 09-06-2010, 01:31 PM

Originally posted by DrRzvn

Thank you for all advices! Meanwhile, I've searched deeply on internet and found even on wikipedia a good description of pentax mounts. I feel kind of silly, that I didn't do that before!

I would trust the guys here a lot more than I would trust Wikipedia:

Basically, they have no lives, unlike myself, and they spend every waking hour of their days learning about these lenses. I, on the other hand, dedicate my life to loving my wife and children and catering to their every whim and desire.

HAHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

But seriously:

Wikipedia is drek ("drek" is Yiddish for crap) compared to pentaxforums.com

I use all manual lenses (see my sig), but don't use catch focus at all, so this all rolls off my back until I'm ready to do it.

Nesster · 09-07-2010, 08:33 AM

I wish I could remember who posted this a year or two ago - it seemed so elegant though I've yet to make one myself. Essentially, get some fairly heavy gauge copper wire and bend it to shape, it goes around the M42 lens in a way that shorts the contacts but doesn't interfere with infinity.

stevebrot · 09-07-2010, 09:10 AM

Then you have lenses like my Jupiter-9 that have a painted base but also work with catch-in focus. I was surprised until I put an ohmmeter on the base...conductive paint

Steve

Lloydy · 09-07-2010, 10:27 AM

Originally posted by stevebrot

Then you have lenses like my Jupiter-9 that have a painted base but also work with catch-in focus. I was surprised until I put an ohmmeter on the base...conductive paint

Steve

Don't lick the lens, the paint is probably 99% lead and you'll go insane.

Ikarus · 01-23-2011, 11:46 AM

I'm having a problem with the Jupiter-9 and the original Pentax adapter on the K-x. When using live view, it terminates itself as soon as I'm turning the focus ring. The only way I found to keep live view going is by jamming a piece of paper between the lens and the adapter contacts. I don't have this problem with any of my other M42 lenses, supposedly because they don't short out the contacts. Is there another way I can prevent this from happening with the Jupiter-9?

08-31-2010, 04:00 AM	#1
DrRzvn New Member Join Date: Jan 2010 Location: Timisoara Posts: 6	M42 to K mount adapter covers/shortcuts DSLR contact? I'm interested to buy an adaptor from M42 to K mount in order to use it on a Pentax DSLR. I'm not able to find in my town directly the adapter to check it in advance, so there is something which bothers me: a metal M42 adapter(which drives electricity) will shortcut the contacts on my DSLR? Is there a problem? Background: on some on-line shop forum from my country, someone posted a comment(for a non Pentax genuine adapter), that he had to ensure that the DSLR body mount contacts had to be covered with some tape, to avoid shortcut made by the adapter. Now, it's strange for me that I cannot find any other reference to such problems with any knid of M42 to k mount adaptex, Pentax made or third party made... Last edited by DrRzvn; 08-31-2010 at 04:47 AM.

08-31-2010, 07:35 AM	#4
DrRzvn New Member Join Date: Jan 2010 Location: Timisoara Posts: 6 Original Poster	Thank you! Thank you for your feddback!

09-06-2010, 12:59 PM	#10
DrRzvn New Member Join Date: Jan 2010 Location: Timisoara Posts: 6 Original Poster	Thank you! Thank you for all advices! Meanwhile, I've searched deeply on internet and found even on wikipedia a good description of pentax mounts. I feel kind of silly, that I didn't do that before!

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08-31-2010, 05:26 AM	#2
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	It doesn't short them out, but you can use aluminum tape on the base of the lens to accomplish that, and to take advantage of Catch-In Focus.

08-31-2010, 05:39 AM	#3
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Lets look at all the issues with M42 adaptors so you understand exactly what happens on a DSLR First of all, there are 2 different styles of M42 adaptors, those called "flanged" adaptors and those without flanges (i.e. origonal style pentax adaptors) Flanged adaptors are cheap, and have provision for the lens locking pin, but space thelens out away from the camera body by 0.8mm, which upsets the infinity focus. This can be adjusted on some lenses but not all can be set to retain infinity focus. Flanged adaptors will short out all th epins to th elens mount. This is OK and is no different than pentax K mount lenses, and the camera design accepts this. in fact shorting the contacts, specifically pins 1, 2, 4, 5, & 6 is how the lens coding for maximum and minimum aperture is done. Shorting pin 3 tells the camera the lens has an A setting, and this is why that specific pin is recessed on the camera body. Similairly shorting pin 7 tells the camera that the lens is manual focus, and allows the focus confirmation to work. Pin 7 is a multi use pin, which also conveys the lens ID and focusing distance, focal length etc from the lens to the body Non flanged or flush mount adaptors mount flus to the body mount surface and do not interfere with the infinity focus but also do not obviously touch the contacts, and not all M42 lenses have wide enough bases or conducting bases to short pin 7 so in most instances focus confirmation is also lost.

08-31-2010, 12:48 PM	#5
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Good info from Lowell! Here's a little more: Shorting the pins is completely safe. Some of those flanged adapters are painted black; they will NOT short the pins unless you file the paint off in the 6-o'clock area. I've scraped all mine, so I can use Catch-In-Focus. And I use CIF a LOT. The following is all about preparing for CIF: I know of no M42 lens that shorts the pins when wearing a flangeless (infinity focus) adapter. At least, none of my 55+ M42's do. Many of us employ cheap metallic tape, gummed on one side -- cut a strip, stick it to the 6-o'clock area of the lens, add the adapter, mount on camera, shoot. WARNING: Do NOT put metallic tape on a painted flanged adapter to short the pins! File off the paint instead. Adding tape WILL make the adapter jam on the camera. This also applies to cheap painted PK macro rings. Ah, but metallic tape doesn't work with all screwmount lenses, 'cause many have bases too narrow to reach the pins anyway. One trick is to get qa bit of tinfoil under the adapter, shoved down over the pins. But tinfoil easily blows away, and doesn't always work either. Bother.

09-05-2010, 08:03 AM	#6
wannabefishing Junior Member Join Date: Sep 2008 Location: Niagara Posts: 30	just got my first m42 (helios 44M) and was curious about something... is it okay to back out the 6 o'clock screw 1/16th of an inch to short it out? i can say it shorts it out fine... any issues going forward ya'll think?

09-05-2010, 03:45 PM	#7
Lloydy Veteran Member Join Date: Aug 2007 Location: Shropshire, UK Posts: 1,114	No, don't do that. The backed off screw could foul on the contacts, and possibly the auto focus drive, when the lens was rotated as you mounted and unmounted it. The easy way is to get some sticky aluminium tape, scrounge some off a heating engineer, and cut a small crescent which you stick on the back of the lens - or scape the paint off in the same area. The idea is to connect the pins on the camera electrically. This is how I do my 44-M and this bit of tape has been on there for months now, and I use this lens a lot.

09-05-2010, 07:46 PM	#8
bill. New Member Join Date: Aug 2010 Location: toronto Posts: 3	What is the point in shorting the contacts? My K10d confirms focus with all 7 m42 lenses I own, using a flangeless adapter.

09-06-2010, 05:48 AM	#9
Lloydy Veteran Member Join Date: Aug 2007 Location: Shropshire, UK Posts: 1,114	It's not for focus confirmation, it's for focus trap. ( catch in focus - trap in focus ) There's a good description of the technique somewhere in the 'Soviet Lenses Club' topic, somewhere towards the last third of the thread I think. But a search will also throw up some information.

09-06-2010, 01:31 PM	#11
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by DrRzvn Thank you for all advices! Meanwhile, I've searched deeply on internet and found even on wikipedia a good description of pentax mounts. I feel kind of silly, that I didn't do that before! I would trust the guys here a lot more than I would trust Wikipedia: Basically, they have no lives, unlike myself, and they spend every waking hour of their days learning about these lenses. I, on the other hand, dedicate my life to loving my wife and children and catering to their every whim and desire. HAHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! But seriously: Wikipedia is drek ("drek" is Yiddish for crap) compared to pentaxforums.com I use all manual lenses (see my sig), but don't use catch focus at all, so this all rolls off my back until I'm ready to do it.

09-07-2010, 08:33 AM	#12
Nesster Veteran Member Join Date: Oct 2006 Location: NJ USA Photos: Gallery Posts: 13,072	I wish I could remember who posted this a year or two ago - it seemed so elegant though I've yet to make one myself. Essentially, get some fairly heavy gauge copper wire and bend it to shape, it goes around the M42 lens in a way that shorts the contacts but doesn't interfere with infinity.

09-07-2010, 09:10 AM	#13
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Then you have lenses like my Jupiter-9 that have a painted base but also work with catch-in focus. I was surprised until I put an ohmmeter on the base...conductive paint Steve

09-07-2010, 10:27 AM	#14
Lloydy Veteran Member Join Date: Aug 2007 Location: Shropshire, UK Posts: 1,114	Originally posted by stevebrot Then you have lenses like my Jupiter-9 that have a painted base but also work with catch-in focus. I was surprised until I put an ohmmeter on the base...conductive paint Steve Don't lick the lens, the paint is probably 99% lead and you'll go insane.

01-23-2011, 11:46 AM	#15
Ikarus Veteran Member Join Date: Apr 2010 Location: California Photos: Albums Posts: 484	I'm having a problem with the Jupiter-9 and the original Pentax adapter on the K-x. When using live view, it terminates itself as soon as I'm turning the focus ring. The only way I found to keep live view going is by jamming a piece of paper between the lens and the adapter contacts. I don't have this problem with any of my other M42 lenses, supposedly because they don't short out the contacts. Is there another way I can prevent this from happening with the Jupiter-9?