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07-22-2010, 09:55 AM   #1
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Attempt to remove actuator arm on K 35mm lens...

Well I just finished putting back together my K 35mm 3.5 lens in an attempt to remove the actuator arm.

The lens mount removal was straightforward enough, though when I revealed the the mechanism underneath it became quickly apparent that my plans to simply remove the lever would not work.
The issue is, that the lever is part of a large ring which rotates atop the lens barrel. The ring(itself) serves a number of purposes such as spring retention(aperture blades) and the aperture blade movement as well. So it's a(sort of) multi-function mechanism and the lever is part of this.

After figuring out the system I had the idea of flipping the ring over... but that wouldn't work either since all of the attachments(posts and spring retainers) would end-up on reversed and useless.

So as far as I can see, the none invasive lever removal on this lens(in particular) would not work. The only alternative I could think of, would be to find an old(junked version) and swap the ring and lever for a modified one.

To bad though
I really don't like the green button metering options with my K lenses.
It's inaccurate and a real time waster in contrast to the totally independent screw mount system.

07-22-2010, 10:08 AM   #2
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John,

I remember reading somewhere that you can "fool" the camera by not turning the K-mount lens all the way into the locked position, but only going about halfway. I've not tried that, but may try it this afternoon. I vaguely remember reading that someone even used a Dremel tool to make a little detent for the lens-locking pen to engage the lens in this halfway position.

I have done what you describe with some other lenses (just to try it), and it works fine using them as if they were S-mount lenses. Too bad there is not an option to disable the aperture mechanism in the menus. Surely it could be done in microcode.

-Joe-
07-22-2010, 10:50 AM   #3
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Hi, that sounds like a good plan.
Though the idea that the value of the lens would be affected by this bothers me alot
I guess(ultimately), I could just assume I'll keep the lens for good and be done with it.
I certainly agree with the usefulness of having a none invasive way of dealing with this issue(like you pointed out).

Makes me wonder why the heck the camera engineers didn't do that.
07-22-2010, 01:11 PM   #4
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John,

I just tried the half-twist partial mount with my Pentax-M 40mm f2.8 pancake lens, using it in Av mode with my K100D Super, and it worked perfectly, just like a S-mount lens.

The only problem is the possibility of getting too forceful with the aperture ring or focus ring and twist off the lens and drop it on the floor. However, in my case the lens was a very tight fit so felt secure on the camera half-mounted.

I suppose if a particular lens was too loose, you could just put a little bit of a shim (like very thin brass shim stock) between the lens and mount to make it tight so it would not twist off.

-Joe-

07-22-2010, 01:21 PM   #5
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Yes I tried it as well...
Same feeling.
It worked, but.... it could slip off by mistake.
I guess I'm just going to drill the extra hold and be done with it.
It's not like I'd ever sell the lens since It's the best scenery lens I've ever owned.
07-22-2010, 02:02 PM   #6
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QuoteOriginally posted by JohnBee Quote
I really don't like the green button metering options with my K lenses.
It's inaccurate and a real time waster in contrast to the totally independent screw mount system.
Shouldn't be any more or less accurate either way. Both screw mount lenses and manual K-mount lenses work exactly the same with respect to metering - the metering is done with the lens stopped down. Whether the lens had already been stopped down for a long time before the meter activates or not, or whether the lens stays stopped down after metering or not, is immaterial. You'll get precisely the same meter reading either way, because you're giving the meter the same amount of light either way: the amount of light that passes through the stopped down aperture blades.

So even if you force your K-mount lens to act like a screw mount lens, the metering accuracy won't change one bit. All you'll do is trade the extra time it takes to do the stop down metering for the extra time it takes to repeatedly open up the aperture while focusing and then close it down again to shoot. In term of actual time wasted, there really can't be any doubt that the screw mount method is *far* less efficient. But if you're not accustomed to using "M" mode, the screwmount method does at least have the advantage of you not being as likely to forget to set exposure when the light changes or when changing aperture.
07-22-2010, 05:12 PM   #7
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QuoteOriginally posted by Marc Sabatella Quote
In term of actual time wasted, there really can't be any doubt that the screw mount method is *far* less efficient. But if you're not accustomed to using "M" mode, the screwmount method does at least have the advantage of you not being as likely to forget to set exposure when the light changes or when changing aperture.
I'm not sure if I understand correctly but... I find Av mode with screw mount with Av mode seems so much better in contrast to the green button. And if we couple that with the ability to cope with light changes automatically(as you mentioned), then it really seems much more efficient than what we get with K or M lenses.
07-22-2010, 07:14 PM   #8
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John - why not just trade it for an SMC Takumar 35mm f/3.5? They are far more common than the K models. I have one, and would be happy to trade. :-) Then you could make the m42 --> k adapter permanent and not deface a beautiful classic K series lens. Plus you would have an auto-manual switch for quick focus adjustment!

07-22-2010, 07:15 PM   #9
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I am serious about the trade, I'll throw in an adapter too if you need one.
07-22-2010, 07:39 PM   #10
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QuoteOriginally posted by Nick Siebers Quote
I am serious about the trade, I'll throw in an adapter too if you need one.
If memory serves me right, the Takumars don't have the same coatings or optics that the K variants have. Whatever the case, I know the review system doesn't show anything comparable to the K 35mm 3.5, and I sure do love the IQ this lens has been giving me with scenery work(unbeatable f11-f16 performance).


Having said that, I think I have a 35mm Super-Multi-Coated Takumar laying around somewhere. And I don't think it was that great a performer. I might run some tests tomorrow, because I honestly don't remember.
07-22-2010, 07:56 PM   #11
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Same optical design, I think (and others have said too) but the coatings may be better. the ratings lump in the earlier auto- and super- tak version, which may drag the SMC tak down. I would love to see a comparison between the SMC tak and K versions, although with these old lenses sample variation probably weighs almost as much as inherent goodness. Try before you drill! :-)
07-22-2010, 07:59 PM   #12
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QuoteOriginally posted by Nick Siebers Quote
Try before you drill! :-)
I will do that!
Seems to me, my Takumar has a bit of a yellow cast on the front element. I'm not sure if its the right one at this point, I'll have to dig in my early storage bins.
But... if it is the version you mentioned, I guess I could setup a chart and do a little head to head and share my findings. Who knows!.. it might even pump some adrenaline into the review section.
07-23-2010, 08:25 AM   #13
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QuoteOriginally posted by JohnBee Quote
I'm not sure if I understand correctly but... I find Av mode with screw mount with Av mode seems so much better in contrast to the green button.
Are you talking about the metering here, or just how you feel about using it? If you are talking about metering, do you have any lenses that can be used in both ways so you can do a controlled comparison? If you see any difference at all in such a test, it would indicate a problem, I think. Perhaps aperture blades that are too slow, thus throwing off the Green button results. But assuming everything is working properly, there is no way there should be a difference - like I said, you're giving the meter the *exact* same input either way.

QuoteQuote:
And if we couple that with the ability to cope with light changes automatically(as you mentioned)
Right, if you're not used to using M mode, that's a big difference. I use M mode exclusively, so there really is no major difference for me.
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