Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-12-2020, 01:16 PM   #1
Pentaxian
Dartmoor Dave's Avatar

Join Date: Aug 2012
Location: Dartmoor, UK
Photos: Gallery
Posts: 3,857
Which metal is used for the K mount?

Does anyone know which metal is used in the K mount on DSLR bodies, in particular on the K-S1? I'm assuming aluminium, but I really need to know for certain.

I've recently figured out a hack for the K mount that enables TAv mode with M42 lenses, but so far I've only done it by shorting out the correct contacts on my K-S1 with little bits of foil held in place by electrical tape. I'd now like to make the hack permanent, but I know that aluminium can be a pig to solder. So if anyone can confirm which metal I'm actually dealing with on the camera mount it'll make preparing for the job easier.

01-12-2020, 01:21 PM - 1 Like   #2
Loyal Site Supporter
Loyal Site Supporter
Kevin B123's Avatar

Join Date: Jul 2016
Location: Hampshire
Photos: Gallery | Albums
Posts: 3,162
I believe the mount is stainless steel, aluminium would wear too fast.
Soldering will not really be viable, I would try self adhesive aluminium foil:
Aluminium Foil Tape - ALUM001
01-12-2020, 01:26 PM - 1 Like   #3
Pentaxian




Join Date: Dec 2019
Location: Mohave county Arizona
Photos: Albums
Posts: 1,076
It looks like Aluminum, but may also be the magnesium alloy used in camera bodies. Either way it's tough to solder The electrical contacts are brass.
01-12-2020, 01:36 PM   #4
Pentaxian
Dartmoor Dave's Avatar

Join Date: Aug 2012
Location: Dartmoor, UK
Photos: Gallery
Posts: 3,857
Original Poster
Thanks to both of you for the quick replies. The aluminium tape sounds like a great idea, so I think I'll try that first.

01-12-2020, 01:51 PM   #5
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 10,510
The mount on the camera is non-magnetic so it's either a magnesium or aluminum alloy.

I saw somewhere that someone used a piece of an old aluminum beverage can and cut out a collar to attach to the lens base. Since the can is coated you can remove the coating on the spots for the contacts.
01-12-2020, 02:04 PM   #6
Pentaxian
Dartmoor Dave's Avatar

Join Date: Aug 2012
Location: Dartmoor, UK
Photos: Gallery
Posts: 3,857
Original Poster
QuoteOriginally posted by Not a Number Quote
I saw somewhere that someone used a piece of an old aluminum beverage can and cut out a collar to attach to the lens base. Since the can is coated you can remove the coating on the spots for the contacts.
I'd been thinking of a sort of similar approach, but modifying the mount on the camera itself rather than having to adapt each lens. It's just a case of shorting three contacts to trick the camera into thinking it's got an A series f/1.2 lens mounted, and I've been happily shooting the K-S1 in TAv mode with my Takumars since Christmas. (Tricking the camera into thinking it's an f/1.2 lens makes it assume that the opening and closing of the physical aperture on the lens is just a change in the real-world light level, so it sets the correct ISO automatically in TAv mode.)

My K-S1 has got aperture block failure, so I use it as an M42 only camera anyway.
01-12-2020, 02:25 PM - 1 Like   #7
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 10,510
Okay, since you don't care if the contacts change with the lens what I've seen done before is to remove the mount and lay a strip of metallic foil over the contacts you want to short and replace the mount. Just be careful not to break the ground wire connected to the mount ring.

01-12-2020, 02:26 PM - 1 Like   #8
Pentaxian




Join Date: May 2009
Location: Somewhere over the rainbow
Photos: Gallery
Posts: 1,528
Its plated brass
01-12-2020, 02:28 PM - 1 Like   #9
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 5,113
The K-10D, K-5, and K-1 all have brass mount rings plated with maybe nickel and perhaps chrome.
01-12-2020, 02:44 PM   #10
Pentaxian
Dartmoor Dave's Avatar

Join Date: Aug 2012
Location: Dartmoor, UK
Photos: Gallery
Posts: 3,857
Original Poster
So perhaps I could file it down to brass on the inside of the mount and then permanently short the contacts by soldering? I just feel like a soldered solution would be more robust than any of the different foil methods I've seen online.

What I'd really like to do is get a machinist to fabricate a replacement mount that shorts the contacts and has an M42 screw thread rather than the K bayonet, but I expect the cost would be prohibitive.
01-12-2020, 02:46 PM   #11
Site Supporter
Site Supporter
Madaboutpix's Avatar

Join Date: Dec 2011
Location: North Rhine-Westphalia
Posts: 1,429
QuoteOriginally posted by photoptimist Quote
The K-10D, K-5, and K-1 all have brass mount rings plated with maybe nickel and perhaps chrome.

Just intrigued: Is there any definite source on this?

Last edited by Madaboutpix; 01-12-2020 at 03:57 PM. Reason: Typo eliminated
01-12-2020, 03:10 PM   #12
Pentaxian




Join Date: Jan 2018
Location: Jersey C.I.
Posts: 3,575
QuoteOriginally posted by Madaboutpix Quote
Just intrigued: Is there any definite source on this?

The mount on my old P30t "test" body is definitely plated brass, as is my K-70, which is the only other body I've got which shows sufficient wear to determine such things. I doubt things would have changed for any other body.

---------- Post added 01-12-20 at 03:37 PM ----------

QuoteOriginally posted by Dartmoor Dave Quote
So perhaps I could file it down to brass on the inside of the mount and then permanently short the contacts by soldering? I just feel like a soldered solution would be more robust than any of the different foil methods I've seen online.

What I'd really like to do is get a machinist to fabricate a replacement mount that shorts the contacts and has an M42 screw thread rather than the K bayonet, but I expect the cost would be prohibitive.


Why not just modify your existing mount (or maybe one from an old "donor" camera) then "fit and forget" an OEM M42-PK adaptor.


I'll admit to being happy to work in Manual with my 42-screw lenses, so I've not bothered to consider modifying my camera, but my *ist DS is permanently fitted with an M42-PK adaptor and I treat it just like it was a screw-mount body. Just a pity Pentax never saw fit to enable the auto-stop-down of screw-mount lenses on their bayonet bodies, like Fujica did, so each of my auto-aperture screw-mount lenses that don't have an a/m switch have had to be modified to hold the pin in
01-12-2020, 05:36 PM   #13
Site Supporter
Site Supporter
Larrymc's Avatar

Join Date: Jun 2014
Location: Mississippi, USA
Posts: 5,245
QuoteOriginally posted by Not a Number Quote
The mount on the camera is non-magnetic so it's either a magnesium or aluminum alloy.

I saw somewhere that someone used a piece of an old aluminum beverage can and cut out a collar to attach to the lens base. Since the can is coated you can remove the coating on the spots for the contacts.
It could be plated brass, best way to find out is to find an area that is not critical and file a very small V notch in it.
01-12-2020, 06:10 PM   #14
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 10,510
It could be plated brass, which is the traditional material for lens and camera mounts.

However my K10D mount has a score in it, maybe as much as 1/2 mm deep and there is no brass color evident. I examined it with a 15× magnifier under bright light.

Update: Closer examination of the "slots" for the k-mount tabs shows some "brassing" in the corners and edges so most likely plated brass.
01-12-2020, 07:49 PM   #15
Otis Memorial Pentaxian
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 42,007
Good question. The conventional and traditional answer here has been stainless steel on the body and plated brass on the lenses. That said, I have a number of old cameras, some of which show brassing, though none of those are Pentax-brand. I have seen some ads for Pentax dSLRs where severe scoring was present, and don't recall brassing.


Steve
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
adaptor, aluminium, bayonet, body, brass, camera, chemistry, contacts, dslr, hack, k-s1, lenses, m42-pk, metal, mount, photography, screw-mount
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
DA 35mm 2.4 Plastic Fantastic metal mount conversion ? Ronald Oakes Pentax SLR Lens Discussion 31 11-14-2020 04:19 PM
SMC DA 35mm f/2.4 AL All Metal mount McLaughlin Pentax SLR Lens Discussion 8 04-21-2018 01:12 AM
Has anyone used "Image on Metal" for metal prints millsware Digital Processing, Software, and Printing 2 01-10-2015 07:27 AM



All times are GMT -7. The time now is 06:11 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top