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12-19-2008, 03:28 AM   #1
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Screw to K mount adapters

My brother in law just dropped off a box of old Tak len's still in original case with filters, caps and original lens shades. Free.

A 28mm 3.5, 55mm 2.0, 105mm 2.8.

Anyway looking on the net adapters sell from 7 to 30 bucks. thought I'd just get three of the cheapo adapters, screw them on and leave them on. Any big problem with that instead of buying the original Pentax adapters?

Thanks

12-19-2008, 03:39 AM   #2
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QuoteOriginally posted by wildman Quote
My brother in law just dropped off a box of old Tak len's still in original case with filters, caps and original lens shades. Free.

A 28mm 3.5, 55mm 2.0, 105mm 2.8.

Anyway looking on the net adapters sell from 7 to 30 bucks. thought I'd just get three of the cheapo adapters, screw them on and leave them on. Any big problem with that instead of buying the original Pentax adapters?
Thanks
Without the pentax genuine adapter, lens will not focus at infinity
12-19-2008, 03:45 AM   #3
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Yes, there's a big problem. It's a camera mount adapter, and not a lens mount adapter.

Basically, they're designed to be fitted into the k mount (drops in the middle, and locks in like a lens), and then, once that's secure you screw the lens in.

I have only used the official Pentax converter, but I definitely wouldn't want to be switching between bayonet and screw mount lenses in the one session, except perhaps maybe a studio session (which isn't my thing anyway).
12-19-2008, 05:17 AM   #4
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No, you don't want those free lenses, especially when you need to buy that adaptor... why don't you send them to me, I'll even pay the postage, save you the money and the hassle...


There's two routes with the adapter - the real Pentax is the best, you only need one, like cpopham says. The other kind is sold under a variety of names, I have the Bower version. These come with a tool to insert/remove the adapter, and importantly do not have a flange. The adapter should be entirely within the K mount. These work fine as well, though in time there will be some problems - it comes off with the lens, or bayonets too far and you get scared you just ruined your camera

Any adapter with a flange is no good, as you won't get infinity focus.

You then simply screw in the lens, the camera becomes essentially a Spotmatic .


Nice lenses by the way, every one is excellent - the 105 will fetch more than the other two, due to rarity, if you ever sell.

12-19-2008, 06:19 AM   #5
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Here are useful modifications to add a K-mount adapter to an M-42 lens:


1) The adpater's spring clip was removed (broken off) to avoid adapter's locking to the camera.
2) A notch was cut into the lens' base to lock the lens in place on the camera (optional & easy do do with a file).
3) Paint was sanded off the lens base to allow electrical contact for exposure measurement. (some use aluminum foil.)

The adapter was purchased from Fotodiox.com for about $13 as I recall. I've done this to 3ea. M42 lenses. These modifications in effect turn the M42 lens into a K-mount manual lens. This adapter focuses to infinity. Avoid any adapter with a large flange which will prevent the lens from seating all the way & prevent infinity focus.

Last edited by newarts; 12-19-2008 at 06:42 AM. Reason: added comment RE flange & aluminum foil
12-19-2008, 06:33 AM   #6
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I would remove the screw and spring, rather than snapping the spring off. The screw has been known to work loose and jam up the camera, and lens.
12-19-2008, 06:39 AM   #7
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QuoteOriginally posted by wildlifephotog Quote
I would remove the screw and spring, rather than snapping the spring off. The screw has been known to work loose and jam up the camera, and lens.
Yes, that would be much better - I couldn't find the right screwdriver at the time I'm embarrassed to admit.

Dave
12-19-2008, 06:43 AM   #8
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I use one Pentax original adapter. It's still the best way to go IMO. You mount it on the camera first as cpopham describes. This adapter is around $30 direct from Pentax and worth it.

The advantage is a proper fit and you can easily remove it with your fingernail. No tools required. The modification post by newarts above is fine (I did this once myself) and the lens locks on like a K mount but I would not sand the paint off. An M42 actually works better than a K or M series lens because you still have Av. K and M lenses are only Manual control setting and loose all program modes. So if you decide to use a cheaper adapter to each lens and cut the locking pin slot, don't sand the paint off the back.

Btw, great gift. Those 28 and 105mm' are great lenses. The 55 isn't too shabby either. Now you should get a bellows and these would make a great macro kit as well.

See the following: https://www.pentaxforums.com/forums/post-your-photos/41367-takumar-105mm-bell...mike-cash.html

https://www.pentaxforums.com/forums/pentax-photography-knowledge-base/24622-m...l-bellows.html

https://www.pentaxforums.com/forums/pentax-photography-knowledge-base/11161-a...-question.html

12-19-2008, 07:16 AM   #9
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QuoteOriginally posted by Peter Zack Quote
The advantage is a proper fit and you can easily remove it with your fingernail. .... I would not sand the paint off. An M42 actually works better than a K or M series lens because you still have Av.
Fit with the Fotodiox adapter is fine and fingernail removal works, but I prefer not taking the extra time.

Regarding the removal of paint I had to do it to get proper metering (Av mode) with my K100D. Without electrical contact the camera's metering was a stop off.

It was also necessary to get focus trapping to work (the camera must know the lens is there.)

Perhaps it depends on the specific camera model? I just checked again and am certain it is necessary with my camera.

I'd try it with & without aluminum foil providing the contact; if the foil improves things, then remove the paint - it isn't hard to do.
12-19-2008, 07:23 AM   #10
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By all means, spend the $30 for the original Pentax adapter - comes off with a fingernail, never gets stuck on camera, etc. I owned the Bower adapter once - never will again.

(congrats, BTW - that 105 alone is worth a lot, depending on condition of course.)
12-19-2008, 08:11 AM   #11
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QuoteOriginally posted by Peter Zack Quote
The modification post by newarts above is fine (I did this once myself) and the lens locks on like a K mount but I would not sand the paint off. An M42 actually works better than a K or M series lens because you still have Av. K and M lenses are only Manual control setting and loose all program modes. So if you decide to use a cheaper adapter to each lens and cut the locking pin slot, don't sand the paint off the back.
I don't know of any advantage to not shorting the contacts like a K or M lens will. In my experience (K10D), you certainly can use Av mode with a K or M lens--your aperture will just always be wide open. It works fine until you want to shoot stopped down; then you have to switch to M mode. I usually prefer to shoot in M mode with these lenses anyway, because I get more consistent exposure that way, but I have shot in Av mode before.
12-19-2008, 09:13 AM   #12
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OK...

First of all it is VERY important to me to simply have ALL the lens' converted over PERMANENTLY to a K mount. When I grab a lens out in the field I want to know it's ready to go without loosing time messing about with additional hardware and trying to remember what lens I last used that had the adapter on or to find I forgot to bring the lens with the adapter on etc - just grab it and use it.

In other words switching the adapter from one lens to the other is NOT an issue because we are talking about an adapter for each lens - three.

Given all that is the Pentax adapter still the only way to go?
If not what specifically would you recommend?
If yes than I'll go with Pentax if I'm convinced I really have to.
Also can the adapter by set up so once the lens is snapped in it is right side up? - So you can read the settings from the top down and not rotated out of view?

Thanks to all

Last edited by wildman; 12-19-2008 at 09:28 AM.
12-19-2008, 09:48 AM   #13
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QuoteOriginally posted by wildman Quote
Given all that is the Pentax adapter still the only way to go?
If not what specifically would you recommend? If yes than I'll go with Pentax if I'm convinced I really have to.

Also can the adapter by set up so once the lens is snapped in it is right side up? - So you can read the settings from the top down and not rotated out of view?

Thanks to all
The non-Pentax adapter will over-rotate; that's one of the reasons for the slot. But maybe the Pentax adapter without the spring will also over-rotate. I hope some can give a definitive answer.



Regarding reading the settings, the Flash gets in the way a little, but not too bad. Pacerr on dpreview said ...
QuoteQuote:
- The thread pattern on the adapters is adjusted to seat the lens for focus registration with the aperture scale at the top. Flash housing overhang wasn't a factor when the A, K, and M lenses were designed. When cutting the latch notch, I intentionally offset the scale to the 10 or 2 o'clock position for convenience in viewing the scale. You can add more than one index notch to suit various conditions too.

Last edited by newarts; 12-19-2008 at 09:50 AM. Reason: spelling
12-19-2008, 10:15 AM   #14
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QuoteOriginally posted by wildman Quote
OK...

First of all it is VERY important to me to simply have ALL the lens' converted over PERMANENTLY to a K mount. When I grab a lens out in the field I want to know it's ready to go without loosing time messing about with additional hardware and trying to remember what lens I last used that had the adapter on or to find I forgot to bring the lens with the adapter on etc - just grab it and use it.

In other words switching the adapter from one lens to the other is NOT an issue because we are talking about an adapter for each lens - three.

Given all that is the Pentax adapter still the only way to go?
If not what specifically would you recommend?
If yes than I'll go with Pentax if I'm convinced I really have to.
Also can the adapter by set up so once the lens is snapped in it is right side up? - So you can read the settings from the top down and not rotated out of view?

Thanks to all
Given that's how you want to use the lens. I would get 3 of these or something similar. Pentax M42 42mm to PK K Mount K Bayonet Adapter Ring - eBay (item 250327882881 end time Jan-17-09 10:44:31 PST)

Then when they arrive, remove the locking tab from each. Put it on the back of each lens and mount it on the camera in the correct orientation. Mark the spot on both the body and the now mounted lens where the locking pin is. Then take a dremel and cut the slot in the back of the lens body so the locking pin will hold the lens in place.

Test it out in both M and AV. See how accurate the metering is. If you like it as is, then make sure the adapter is on nice and tight so it won't unscrew. Now you can mount it like any K mount lens much faster.

As for removing the paint. For many of these lenses (the 105mm which I have) is a wasted step. It would also for the locking pin on this lens as well. I use the Pentax original adapter and that works fine. The lens body is so small it does not touch the electrical contacts and focus trap will not work anyway. But AF confirmation is still there and you can use that to assist focus. It works fine for me.
12-19-2008, 10:44 AM   #15
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QuoteOriginally posted by Peter Zack Quote
Given that's how you want to use the lens. I would get 3 of these or something similar. Pentax M42 42mm to PK K Mount K Bayonet Adapter Ring - eBay (item 250327882881 end time Jan-17-09 10:44:31 PST)

Then when they arrive, remove the locking tab from each. Put it on the back of each lens and mount it on the camera in the correct orientation. Mark the spot on both the body and the now mounted lens where the locking pin is. Then take a dremel and cut the slot in the back of the lens body so the locking pin will hold the lens in place.

Test it out in both M and AV. See how accurate the metering is. If you like it as is, then make sure the adapter is on nice and tight so it won't unscrew. Now you can mount it like any K mount lens much faster.

As for removing the paint. For many of these lenses (the 105mm which I have) is a wasted step. It would also for the locking pin on this lens as well. I use the Pentax original adapter and that works fine. The lens body is so small it does not touch the electrical contacts and focus trap will not work anyway. But AF confirmation is still there and you can use that to assist focus. It works fine for me.
This looks like the same adapter I used. In my experience it will over-rotate so the slot is nice to have to prevent over rotation or the lens falling off the camera.

Regarding paint removal (or shorting the contacts with AL foil); it enables focus trap & correct manual exposure on a K100D at least for these M42's:

Macro-Takumar 50mm 1:4 (1:1 macro)
Super-Takumar 55mm 1:2
Super-Takumar 135mm 1:2.5
Super-Takumar 200mm 1:4

I have tested these, converted them, and am confident in my statements.

Dave
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