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05-18-2012, 11:26 PM   #16
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QuoteOriginally posted by Anvh Quote
Does the screw turn the same way around as Pentax?
You might damage your lens and camera if motor turns counter clockwise to focus forward but the lens needs to turn clockwise for the same motion.
You scared me there for a minute. On the yashica the screw turns clockwise when the front of the lens turns counter clockwise, where on a pentax lens I checked the screw turns clockwise when the front of the lens turns clockwise. On both though, when the screw turns clockwise it makes the lens go towards infinity (or maybe the reverse but they are the same in that regard so it should be fine).

Anyway I have had a rather bad dose of impatience and stupidity and trashed a perfectly good pentax lens. I took the least valuable AF lens I had as I just wanted to check things out under the mount (a pentax fa 28-80mm power zoom with a broken power zoom switch that I got on ebay for less than 10$). I pulled the mount, saw that there was just a ribbon cable for the contacts, not anything solid and mountable so I figured that would not be the lens to use. I tried to reassemble it and lost one of the contacts (they were just loose pins with tiny springs and I spent about a half hour trying to get it together before loosing the part). I got mad and just ripped it apart. It took better than an hour to get it apart (what a beast). Its completely trashed. I did get the monstrosity of electronics out nearly intact (I may have damaged a few traces in one spot). I held the ribbon on the camera body contacts and the AF drive ran. I held the lens off to the side with the screw drive engaged and it turned the lens, ending with a thunk when it got to the end of its range (my pentax F 100-300mm does that so I guess they are designed to take that thunk?).

This is going to be a giant pain (I guess I'll make it a longer term project).

Here is the mass of crap I got out of the lens.

IMGP9565.JPG photo - Richard Homeyer photos at pbase.com

The lens has a pretty bad rating here. I didn't think it was that bad though its nothing special either. The one thing I did like is the AF was very quick and accurate with this lens (at least my copy). Its gone now though but at least it wasn't an expensive one. Frankly, I have tried to get broken lenses for parts before and I always wind up being able to get working lenses cheaper. People seem to want a lot for broken lenses on ebay sometimes.

05-19-2012, 01:52 AM   #17
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QuoteOriginally posted by Anvh Quote
But look at the contacts that are on your lenses, my DA lenses have different contact formation some have 5 others have 6 but they are all missing the contact next to the 7th contact but thats a contact the MZ-60 has and that contact is used on A mount for the aperture.
The contact is also missing on the DFA macro which works on A mount bodies so things are very confusing.
I googled up images of the mounts for the DA18-55, DA16-15, DA35/2.4, DA55-300, DA*55/1.4, F50/1.7 and FA35/2. They all have all the contacts the MZ-60 has (are you counting from the wrong end perhaps?), and the DA*55 has one more, probably because of SDM.

Here's a thread with several such images

QuoteOriginally posted by Anvh Quote
Look at the MZ-60 mount and look at the contacts that are missing.
It are the two M contacts that are use to indicate the minimum aperture, most likely it doesn't use them since it's crippled.

Beside that you run in the problem if what you say is true, that those 4 contacts are needed for digital information, since 3 of these contacts are certainly used to indicate the maximum aperture on older bodies it means you cant use F, FA, FAJ and DFA lenses on bodies with A mount and we know that isnt true.
So what do you think is the work around for that?
I already explained this, when unpowered the lens leaves them floating or grounded as appropriate. But I'll explain it again with different words, this time with concrete examples of exactly how it could work. (Note however that I'm not saying it does work exactly this way, I don't care enough to test it.)

Let's first make the numbering system clear, I've been counting counter clockwise on the camera mount, or clockwise on the lens mount. Pins 1, 2, 4, 5, 6 are used to indicate aperture range on A lenses. Pin 3 is used to indicate A mode. Pin 7 is only present on AF lenses. Pins 2 and 4 are missing on the MZ-60.

Now how A lenses work. The camera uses the mount as ground, and has pull-ups on all the pins. The pins that have insulators on the lens get pulled up, the others are pulled down (grounded). All these go to some circuitry that calculates the aperture range.

And now AF lenses. The camera applies a pull-up to pin 7. If this gets pulled down, the lens is an A lens, and the old system is used. If it doesn't get pulled down, the new system is used. I'll assume pin 7 is power, and the camera now feeds power to it. Pins 1, 5 and 6 can be used for serial data.

And finally, the actual question, how an AF lens can still work with the old A system. Well, there's no power to pin 7 (since there is no pin 7 on the A cameras). If pin n was supposed to be insulated, the unpowered circuit must have high impedance on this input. If it was supposed to be grounded, it must sink current through it. You might want to google "tri-state logic".
05-19-2012, 01:58 AM   #18
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QuoteOriginally posted by ripit Quote
Anyway I have had a rather bad dose of impatience and stupidity and trashed a perfectly good pentax lens. I took the least valuable AF lens I had as I just wanted to check things out under the mount (a pentax fa 28-80mm power zoom with a broken power zoom switch that I got on ebay for less than 10$). I pulled the mount, saw that there was just a ribbon cable for the contacts, not anything solid and mountable so I figured that would not be the lens to use. I tried to reassemble it and lost one of the contacts (they were just loose pins with tiny springs and I spent about a half hour trying to get it together before loosing the part). I got mad and just ripped it apart. It took better than an hour to get it apart (what a beast). Its completely trashed. I did get the monstrosity of electronics out nearly intact (I may have damaged a few traces in one spot). I held the ribbon on the camera body contacts and the AF drive ran. I held the lens off to the side with the screw drive engaged and it turned the lens, ending with a thunk when it got to the end of its range (my pentax F 100-300mm does that so I guess they are designed to take that thunk?).
I don't think I can work up any sadness about such a lens, so at least you got that choice right. I don't think any of them will have anything "solid and mountable", but if you take the whole mount that should be ok? I guess you were planning on keeping the original mount? In that case a bit of drilling should let you mount the pins through it, and then you glue the ribbon cable to that?

As far as I know the only way lenses tell the camera that they can't focus further in that direction is by running into a physical stop. When the motor stops turning the camera knows it reached the end.
05-19-2012, 08:58 AM   #19
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QuoteOriginally posted by drougge Quote
I already explained this, when unpowered the lens leaves them floating or grounded as appropriate. But I'll explain it again with different words, this time with concrete examples of exactly how it could work. (Note however that I'm not saying it does work exactly this way, I don't care enough to test it.)
Might work, but it will be a complicated system with several diodes.

QuoteOriginally posted by drougge Quote
Let's first make the numbering system clear, I've been counting counter clockwise on the camera mount, or clockwise on the lens mount. Pins 1, 2, 4, 5, 6 are used to indicate aperture range on A lenses. Pin 3 is used to indicate A mode. Pin 7 is only present on AF lenses. Pins 2 and 4 are missing on the MZ-60.

Now how A lenses work. The camera uses the mount as ground, and has pull-ups on all the pins. The pins that have insulators on the lens get pulled up, the others are pulled down (grounded). All these go to some circuitry that calculates the aperture range.
I know how the aperture settings work...

QuoteOriginally posted by drougge Quote
And now AF lenses. The camera applies a pull-up to pin 7. If this gets pulled down, the lens is an A lens, and the old system is used. If it doesn't get pulled down, the new system is used. I'll assume pin 7 is power, and the camera now feeds power to it. Pins 1, 5 and 6 can be used for serial data.
NO it doesn't... it's pin 3, that's the only one that moves not PIN 7 besides that, there is no reason for pin 7 to move up or down.
If it's a digital lens the lens gives through more accurate information so why would you want to disable that?

QuoteOriginally posted by drougge Quote
And finally, the actual question, how an AF lens can still work with the old A system. Well, there's no power to pin 7 (since there is no pin 7 on the A cameras). If pin n was supposed to be insulated, the unpowered circuit must have high impedance on this input. If it was supposed to be grounded, it must sink current through it. You might want to google "tri-state logic".
Easy enough to measure if the camera puts any power on the contacts, i don't have a volt meter so cant do it.
I got a degree in electricity and electronics

05-19-2012, 10:47 AM   #20
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QuoteOriginally posted by drougge Quote
I don't think I can work up any sadness about such a lens, so at least you got that choice right. I don't think any of them will have anything "solid and mountable", but if you take the whole mount that should be ok? I guess you were planning on keeping the original mount? In that case a bit of drilling should let you mount the pins through it, and then you glue the ribbon cable to that?

As far as I know the only way lenses tell the camera that they can't focus further in that direction is by running into a physical stop. When the motor stops turning the camera knows it reached the end.
The original yashica mount is about 1mm larger on each side in most dimensions (the center hub, the lugs etc) so I don't think that it would work. The mount off the pentax I tore apart looks like it would actually work. The diameter of the circle for the contacts and screws is about the same (the yashica has a larger flange and bayonet and the screw drive is set out just a touch more but the contacts and screws are about the same). If I try to use any of the existing screw holes or the existing AF drive hole it places the contacts over a screw hole. I think my only choice is to drill new mount screw holes and a new AF drive hole and use the existing contact holes. The contact holes would be a lot harder to replicate anyway.

The ribbon cable originally mounted to the lens, not the mount. I guess I have 2 choices. If I go on 1 side, there may be a tiny gap (or I can cut one) where the ribbon will basically get pinched between the mount and the lens. Perhaps I could use a little rubber (or rubber cement) to provide pressure. I of course would not do it that way if it is actually tightening down hard on the ribbon. It would basically have the original contacts and the ribbon cable pressed right against them. Then again, that might wind up crushing the ribbon with the pressure on the contacts each time the lens is removed or put on (plus 1 I'll have to make unless I find the missing one or figure which one I can do without).

Alternatively there is a cutout on the lens where it had its contacts. It would give me plenty of room to work and use the original contact pins and springs. I'll have to check it out more to see what looks like it will work best. Either way I'll have to drill new screw and AF drive screw holes. It looks like its going to be a much harder project than originally intended (mainly just due to the AF electronics).
05-19-2012, 10:50 AM   #21
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QuoteOriginally posted by Anvh Quote
NO it doesn't... it's pin 3, that's the only one that moves not PIN 7 besides that, there is no reason for pin 7 to move up or down.
Pin 3 moves physically. Pulled up/down is an electricity thing. I am very nearly sure this is the correct English term. Wikipedia seems to agree.

QuoteOriginally posted by Anvh Quote
If it's a digital lens the lens gives through more accurate information so why would you want to disable that?
I have no idea, I described how a camera that can use digital communications can detect if the lens can. Nothing suggesting you would disable it.
05-19-2012, 10:52 AM   #22
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QuoteOriginally posted by ripit Quote
It looks like its going to be a much harder project than originally intended (mainly just due to the AF electronics).
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