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07-06-2008, 09:33 AM   #1
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using M lenses in Av mode!

simply hack off the aperture tab and there you go...

i bought a Vivitar 50mm F1.7 today for 10 bucks, and it had the aperture tab and plastic block thingy sawed off, well, guess what slam that sucker in Av mode, and simply rotate the aperture ring and the camera adjusts its metering!

you even get to see the effects on DOF right away.

also i had a katz eye screen with me when i was testing the lens, and even at F22 there was enough visible light to work with a shot.


now i need to go find my file... i have a bunch of M lenses.

07-06-2008, 09:42 AM   #2
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can you post a picture on how severe the hacking off is?
07-06-2008, 09:49 AM   #3
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QuoteOriginally posted by leadbelly Quote
can you post a picture on how severe the hacking off is?
its nothing scary... its just a single tab, if you have a pair of quality metal cutters you dont even have to file


07-06-2008, 09:53 AM   #4
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QuoteOriginally posted by Gooshin Quote
simply hack off the aperture tab and there you go...

i bought a Vivitar 50mm F1.7 today for 10 bucks, and it had the aperture tab and plastic block thingy sawed off, well, guess what slam that sucker in Av mode, and simply rotate the aperture ring and the camera adjusts its metering!

you even get to see the effects on DOF right away.

also i had a katz eye screen with me when i was testing the lens, and even at F22 there was enough visible light to work with a shot.


now i need to go find my file... i have a bunch of M lenses.
I am going to have to notify the members of the "M club" that you are doing forced and brutal mutilation of M-type glass. The horror!

On the other hand...a Vivitar 50mm is not really M glass and after all it is a Vivitar...hand me the dremel tool, that looks like fun! It just occurred to me that surgery on a Tamron P/K mount might accomplish the same slick trick for Adaptall-2 lenses.

Steve

07-06-2008, 09:57 AM   #5
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M glass or not, what kind of idiot at pentax couldnt engineer a proper way to have no-contact lenses meter in AV mode without having to constantly press some silly button.
07-06-2008, 02:14 PM   #6
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Oh this is bad news!!! As bad as I am at any DIY this could be a disaster. Could you you post a little bigger photo? It looks like you have to cut off the tab including the part that moves, is that right?

Thanks,
Ken
07-06-2008, 02:19 PM   #7
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QuoteOriginally posted by regken Quote
Oh this is bad news!!! As bad as I am at any DIY this could be a disaster. Could you you post a little bigger photo? It looks like you have to cut off the tab including the part that moves, is that right?

Thanks,
Ken
Or

You could disassemble the mount and remove the aperture lever as opposed to cutting it off. (Just in case you have second thoughts...)
07-06-2008, 02:24 PM   #8
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QuoteOriginally posted by Gooshin Quote
M glass or not, what kind of idiot at pentax couldnt engineer a proper way to have no-contact lenses meter in AV mode without having to constantly press some silly button.
I agree 100% regarding the current "dumb" lens mount. The original K mount had a mechanical "follower" that communicated the aperture information (or at least an attenuated voltage) back to the camera. Why they did not retain that feature is anyone's guess.

Steve

07-06-2008, 03:00 PM   #9
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Gooshin is absolutely right, I do this mod automatically on some of my manual lenses which also allows mt to mount them on my other system
I do still have to remove that plastic tab sticking up on most lenses, but that just takes a min or 2 as well.
07-06-2008, 03:29 PM   #10
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I really don't want to do that to my 1.2 ...
07-06-2008, 04:03 PM   #11
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QuoteQuote:
Gooshin: M glass or not, what kind of idiot at pentax couldnt engineer a proper way to have no-contact lenses meter in AV mode without having to constantly press some silly button.
__________________
I could not agree any more. I have a good deal of M-glass, so this is a breakthrough for me. I just have to find the courage to mutilate one of the little babies, or else try stevebrot's advice and attempt disassembly. Thank you!

Regards,

Ernest
07-06-2008, 11:23 PM   #12
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Disassembly before mutilation!
07-07-2008, 12:59 AM   #13
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With this kind of mutilation/disassembling you loose the ability
to focuss with the lens wide open, and IMHO it's not a good idea,
if you want use AV mode with K/M lens wide open you can do it
without any modification
07-07-2008, 01:45 AM   #14
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QuoteOriginally posted by pvanni Quote
With this kind of mutilation/disassembling you loose the ability to focuss with the lens wide open
If I remember correctly the book recommends that we focus with the lens wide open, then close the ring to the desired f-stop anyways.
So we're just forced into doing that the book says to do.

Although I haven't had too many problems focusing with my most often used f-stops, unless it's getting dark out.
07-07-2008, 07:00 AM   #15
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QuoteOriginally posted by little laker Quote
If I remember correctly the book recommends that we focus with the lens wide open, then close the ring to the desired f-stop anyways.
So we're just forced into doing that the book says to do.
The camera keeps the lens wide open until you press the green button (in which case it closes the iris to the set value) or when you press the shutter. It's really a simple thing to do. The green button (and the AEL button on K*00Ds) are very near the shutter, it's much, MUCH simpler than having to open the aperture to focus, then take the camera away from your face to reset the aperture ring to the desired value (or try to remember how many notches you turned it).

It would be better if Pentax had not crippled the mount, but hacking at the aperture lever is much more disabling, I would say.

Even after only three weeks with my K20D, I already find manual operation very easy. What's more, you don't even have to press the green button each time, only when your scene changes.

Try focusing with a lens stopped at f11 and see what you prefer
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