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11-30-2007, 09:21 AM   #1
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Any special way to screw the M42 lenses?

Hello,

I have a few screw mount lenses; but randomly pick a point to screw it on, since there is no red dot to line up as for the bayonnet mount

Is there any special way to screw this lens; or if you do not prefer where your apterture and distance numbers are then no problem right???

thanks

11-30-2007, 10:37 AM   #2
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It will only screw in one way. You cant pick the orientation, so you just live with where it ends up once the lens is snugged down. My Taks vary a little where the lens lines up, but probably not more then a few degrees.
11-30-2007, 01:30 PM   #3
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A thread is a thread but I know where you're coming from.
11-30-2007, 01:58 PM   #4
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Screw No Need in K mount

I don't need any screwing for my M42 lens anymore as I turn them into a K mounted lens. And the RED dot in the adapter will work just like any K mounted lens.

I think I can't highly recommend the Bower adapter anymore as an alternative choice to the genuine Pentax adapter as the clipping mechanism get worn out easily that may get you a stuck adapter permanently onto your K100/10D boides --

Pentax M42 adapters - Hin's Tech Corner

Though the Bower adapter share the same mechanics as the genuine adapter, it has a very fragile clipping plate with a small screw that are worn very easily and I got my adapter stuck on the K mount socket in K100D body yesterday night. Ouuuch, but luckily I found a way to free the dislocated clip in the stuck adapter along with the tiny screw that you are likely to lose when it gets warn out. If the screw gets dropped onto the floor, you may never found it again as it is quite tiny.

And I make the change yesterday night to remove the clip in my bower adapter, and use my 2 bower adapters to mount onto my M42 lens turning my M42 lens into a K mounted lens. Cool, you may think! And yes, I heard about other people doing that. I did that last night without choice after the clip fell off from the adapter and got stuck in the K100D body for 20 minutes.

Here are the new use of my bower adapters, after the clip is removed, and it changes any of my M42 lens to a K mount

#1
Pentacon 50mm f/1.8 with bower adapter with clip removed
Pentacon 50mm f/1.8 in K mount (after the conversion)


#2
Pentacon 50mm f/1.8 with bower adapter with clip removed
Pentacon 50mm f/1.8 in K mount (after the conversion)


Apology on the wordy post, I am just too excited with the new setup in turning any of my M42 lens to K mount. And I can use any K mount rear end caps to unscrew the adapter back out to turn the modified K lens back to its original M42 lens' form

Thanks,
Hin

11-30-2007, 03:11 PM   #5
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How did you attach the adapter to the lens? Did you use some kind of glue, or just screw it on very hard?
11-30-2007, 03:25 PM   #6
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If you turn the rings for focusing or aperture, are you not afraid the lens will fall off?

Or did you do something to prevent that from happening?
11-30-2007, 03:25 PM   #7
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I only use normal force to put it on

QuoteOriginally posted by jms698 Quote
How did you attach the adapter to the lens? Did you use some kind of glue, or just screw it on very hard?
Only normal force to put it on. I find no need to screw it on hard. But a warning from others that there are lens that may fall out in that configuration but I don't see that I have a problem yet as I tried this setup on two different lens and see no issues yet:

1. Pentacon 50mm f/1.8 (works like a charm)
2. Schneider 135mm f/3.5 (works like a char)
3. SuperTakumar 35 mm f/3.5 (to be tested)
4. Prakticar 28-70 f/3.5-4.8 (to be tested)

My M42 gears in M42 section:
Inexpensive gear with Pentax - Hin's Tech Corner

Thanks,
Hin
11-30-2007, 03:31 PM   #8
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Thanks! Will keep trying to see the problems...

QuoteOriginally posted by Syb Quote
If you turn the rings for focusing or aperture, are you not afraid the lens will fall off?

Or did you do something to prevent that from happening?
It is tight enough for me to do both focusing and aperture. Aperture is definitely not an issue for me as all of my M42 lens have easy turning on apertures. But yes, the focusing ring would get the lens to fall off easily if you have a stiff focusing ring and that the mounting is not tight enough in the setup. I find it a concern but yet not a big concern yet as I do shoot bunch of beautiful photos yesterday night with a lot of focusing turn from testing out the setup with 2 lens

1. Schneider 135mm f/3.5. Quite stiff focusing ring and yet no problem

2. Pentacon 50mm f/1.8. No issue at all in shooting my dismounted cap of my Vivitar 28mm f/2.5 PK lens


And the pentacon looks like this upon shooting in the setup with springed clipping removed


Disclaimer & Warnings: I may not know all the negatives and dangers to go with my setup. I would be the guinea pig to report on noted problems first hand. Please exercise your caution in trying any abnormal setup such as what are illustrated on this thread.

Thanks,
Hin


Last edited by hinman; 11-30-2007 at 03:37 PM.
11-30-2007, 04:34 PM   #9
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How do you remove the lens from the body?

QuoteOriginally posted by hinman Quote
It is tight enough for me to do both focusing and aperture. Aperture is definitely not an issue for me as all of my M42 lens have easy turning on apertures. But yes, the focusing ring would get the lens to fall off easily if you have a stiff focusing ring and that the mounting is not tight enough in the setup. I find it a concern but yet not a big concern yet as I do shoot bunch of beautiful photos yesterday night with a lot of focusing turn from testing out the setup with 2 lens...
Thanks,
Hin
Hi Hin --

How do you remove the modified lens from the body? Just simple "un-screwing"? Or are you able to do it the same way as with any K-mount lens (i.e., pressing the lens-release button, and then turning lens counter-clockwise)? If the former, I wonder what keeps the lens on the body, since that locking lever is gone.

I'm sure I'm just missing something.
11-30-2007, 05:21 PM   #10
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QuoteOriginally posted by ycl Quote
Hi Hin --

How do you remove the modified lens from the body? Just simple "un-screwing"? Or are you able to do it the same way as with any K-mount lens (i.e., pressing the lens-release button, and then turning lens counter-clockwise)? If the former, I wonder what keeps the lens on the body, since that locking lever is gone.

I'm sure I'm just missing something.
Yes, it is the former part without the locking lever. I have been able to release it similar to other K mounted lens. Though I still press the release lever unconsciously as if it is a real K mount lens.

The mechanism is not as a real K mounted lens as you can see the dependency on how tight you put the lens on. But I would say with my limited tries on two M42 lens converted to K mount, I would roughly guess a 85% similarity. And I have full confidence to be your guinea pig to report on problems first hand as I find them. And I will report problems with a blog post dedicated to my M42->K mount conversion. I am sure there are many previous threads that individual users talk about it. All warnings and disclaimer that I stated earlier hold true for the danger of falling lens upon abrupt focusing ring turn that unscrews you lens by mistakes as there is no mechanism of locking the lens in place in the K mount socket.

Again, my M42 lens are of the cheap side of the spectrum and hence my 100% confidence in being the guinea pig, please check on M42 section on all of my M42 lens:

Inexpensive gear with Pentax - Hin's Tech Corner

Thanks,
Hin

Disclaimer & Warnings: I may not know all the negatives and dangers to go with my setup. I would be the guinea pig to report on noted problems first hand. Please exercise your caution in trying any abnormal setup such as what are illustrated on this thread.

Last edited by hinman; 11-30-2007 at 05:27 PM.
11-30-2007, 07:53 PM   #11
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to keep the lens locked on the cam all you have to do is drill a small hole in the right spot so the cam's locking pin engages it. you would then have to depress the button on the cam to remove the lens..
11-30-2007, 08:06 PM   #12
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Thanks Roy

QuoteOriginally posted by roy Quote
to keep the lens locked on the cam all you have to do is drill a small hole in the right spot so the cam's locking pin engages it. you would then have to depress the button on the cam to remove the lens..
Thanks for the valuable and logical suggestion. What size of drill would you see that hole size need to be? I would research on the topic and post picture if I manage to find it appropriate to share with others.

Much thanks,
Hin
12-01-2007, 07:08 AM   #13
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look at the size of the hole on one of your K mount lenses.. that will also give you a close estimate of location also.
12-01-2007, 12:28 PM   #14
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I find that cleaning the front element with wet'n'dry is a special way to screw a lens... ;-)

Oh, that's not what you were talking about...

OK run your fingernail along the thread of your M42 lens. No matter where you start in the thread, you'll find that it 'ends' in the same place, in other words, there is just one thread, so whatever way you screw the lens into the adapter it will always end up screwing into the same position.

Like Hin I have bought some cheap Asahi-clone adapters (in my case, Kood), I have removed the spring and I screw them onto my M42 lenses. In effect, this 'converts' an M42 into a K mount. As ycl points out, there is no 'locking pin' hole on a M42 lens, so when you focus there is a danger of unscrewing the lens. But even with the genuine Asahi adapter you are just relying on screwing the M42 lens tightly into the adapter. And those of us that remember using M42 cameras (and people who still do) would recognise that too.

Roy's suggestion of drilling a hole is a possibility, but from my past record of drilling holes in DIY projects, that would mean drilling several holes and swearing a lot ;-)

Richard
12-01-2007, 03:03 PM   #15
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Thanks, Roy

After checking on the various K mount lens, not all holes look the same, some are more refined than others. I will look for a possible drill bit to try it. Which lens should I pick on, ouch! My Pentacon 50mm f/1.8 can be had for another $10 if I get lucky in ebay, I my pick on that one. I have other lens that I can practice on drilling an extra hole for training purpose, but of course, I will try on a metal surface with no value first.

Thanks,
Hin

Last edited by hinman; 12-01-2007 at 06:30 PM.
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