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Minolta 58/1.2 AF Conversion with ROM Chip - Build

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JamesLaoT View Drop Down
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Post Options Post Options   Quote JamesLaoT Quote  Post ReplyReply Direct Link To This Post Topic: Minolta 58/1.2 AF Conversion with ROM Chip - Build
    Posted: 16 December 2008 at 13:58
Originally posted by 1969ho 1969ho wrote:

I have received and modded my 58mm f1.2. In addition to using a JamesLaoT adapter as a starting point, and this and other guides as a road map, I believe I have gone one step further than any of the mods I have seen posted on the net thus far.

I retained the internal aperture link ring and modified it to have an external tab corresponding to the correct AF location through the adapter. This allows me to start by manually set the F-stop to my desired setting, but the lens stays wide open during focusing and only stops down automatically for the photo or if I hit the depth-of-field-preview button on my KM-5D.

I haven't really had a chance to take any serious sample photos yet, and I may need a little bit of additional infinity focus adjusting, but so far so good.

Any interest in the details???

Nice idea. It's worth a try.
If you can make the aperture ring have same angular rotation as the AF lens's. You can gain real AE function.
The MD/MC lens have less angular rotation then AF lens. So if you just link the aperture with body. you can gain limited AE,maybe get right metering when aperture below F8. In the other word, you can gain AE in a limited aperture range.
http://eadpt.com

M42 adapter with Focus Confirmation
 



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Gabriel View Drop Down
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Post Options Post Options   Quote Gabriel Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2008 at 09:01
But then you have to use AEL for correct metering, don't you?
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1969ho View Drop Down
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Post Options Post Options   Quote 1969ho Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2008 at 05:54
I have received and modded my 58mm f1.2. In addition to using a JamesLaoT adapter as a starting point, and this and other guides as a road map, I believe I have gone one step further than any of the mods I have seen posted on the net thus far.

I retained the internal aperture link ring and modified it to have an external tab corresponding to the correct AF location through the adapter. This allows me to start by manually set the F-stop to my desired setting, but the lens stays wide open during focusing and only stops down automatically for the photo or if I hit the depth-of-field-preview button on my KM-5D.

I haven't really had a chance to take any serious sample photos yet, and I may need a little bit of additional infinity focus adjusting, but so far so good.

Any interest in the details???
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Post Options Post Options   Quote 1969ho Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2008 at 02:42
Originally posted by Arkku Arkku wrote:

Originally posted by 1969ho 1969ho wrote:

If I am interpreting all of that various posts here and elsewhere I've seen about modding a Minolta f1.2 58mm correctly, if I convert it using a chipped m42 mount (presumably a JamesLaoT single mode f1.1/60mm model), do I essentially end up with a lens that will work with my K/M D5 just like any other AF lens except for no auto-focus? Should all of the exposure modes work like normal or am I missing something?


Only M and A modes will work, because the aperture control is manual as well. Also, the aperture selected in-camera only affects metering, not the aperture on the lens. This means that for using the exposure meter you must set the in-camera aperture wide open all the time and meter stopped down. (Or, alternatively, if the widest aperture programmed in the adapter matches that of the lens exposure compensation, you could meter wide open by setting the aperture in-camera, and then use exposure lock before stopping down. But this can lead to problems with the mechanical aperture actuator getting stuck, so not recommended.)


As for the conversion, I used the 60mm f/1.1 chip kindly provided by JamesLaoT, and installed it on a non-chipped M42 adapter I already had. If you don't already have the adapter, you can certainly use the chipped one directly. I believe some other chipped conversions, such as those featured in this thread, don't use an M42 adapter for parts, however, instead relying on custom-machined replacement mounts. (Personally I prefer the adapter-style conversion for various reasons.)


Thank you for the update. I just picked up a lens, so it's time for a little modding...

Not having had a MC/MD lens in years, I don't have one to look at until my 58mm arrives. Do you think there is any possibility of leaving in/modding the aperture link to allow 'S' mode to work as well? Is it
"just" an alignment issue with the AF mount, or is it just impossible do to a number of issues? I think I remember my old XE-7 having A, S, and Auto modes with the MD lenses I had back then.

Edited by 1969ho - 25 November 2008 at 04:01
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Post Options Post Options   Quote Arkku Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2008 at 00:34
Originally posted by 1969ho 1969ho wrote:

If I am interpreting all of that various posts here and elsewhere I've seen about modding a Minolta f1.2 58mm correctly, if I convert it using a chipped m42 mount (presumably a JamesLaoT single mode f1.1/60mm model), do I essentially end up with a lens that will work with my K/M D5 just like any other AF lens except for no auto-focus? Should all of the exposure modes work like normal or am I missing something?


Only M and A modes will work, because the aperture control is manual as well. Also, the aperture selected in-camera only affects metering, not the aperture on the lens. This means that for using the exposure meter you must set the in-camera aperture wide open all the time and meter stopped down. (Or, alternatively, if the widest aperture programmed in the adapter matches that of the lens exposure compensation, you could meter wide open by setting the aperture in-camera, and then use exposure lock before stopping down. But this can lead to problems with the mechanical aperture actuator getting stuck, so not recommended.)


As for the conversion, I used the 60mm f/1.1 chip kindly provided by JamesLaoT, and installed it on a non-chipped M42 adapter I already had. If you don't already have the adapter, you can certainly use the chipped one directly. I believe some other chipped conversions, such as those featured in this thread, don't use an M42 adapter for parts, however, instead relying on custom-machined replacement mounts. (Personally I prefer the adapter-style conversion for various reasons.)

Edited by Arkku - 16 November 2008 at 00:38
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Post Options Post Options   Quote 1969ho Quote  Post ReplyReply Direct Link To This Post Posted: 15 November 2008 at 21:02
From a modding rookie, a little clarification if possible before I travel down this road...

If I am interpreting all of that various posts here and elsewhere I've seen about modding a Minolta f1.2 58mm correctly, if I convert it using a chipped m42 mount (presumably a JamesLaoT single mode f1.1/60mm model), do I essentially end up with a lens that will work with my K/M D5 just like any other AF lens except for no auto-focus? Should all of the exposure modes work like normal or am I missing something?

Do I also understand that it wouldn't be quite the same if similar mods were done to a zoom/variable-f-stop lens (and that is where the multi-mode chips come into play)?

Thanks in advance,
Al

Edited by 1969ho - 15 November 2008 at 21:03
 



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Post Options Post Options   Quote ricardovaste Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 14:45
Regardless of time, there is no extreme descontruction, you are just removing the rear mount.
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Post Options Post Options   Quote Grubeater Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 14:42
Cleaning the aperture blades of a 50/1.4 can also be done in half an hour, the only difficult part is putting the diaphragm assembly back in the right place. That task alone cost me half an hour yesterday, last year I hit the mark in one attempt, completing the cleaning in 30 minutes.

Edited by Grubeater - 27 September 2008 at 14:44
Missing hood or other weird Minolta stuff? PM me. Maybe I can help.
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Post Options Post Options   Quote Arkku Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 14:42
Originally posted by Grubeater Grubeater wrote:

A question for those who did the conversion themselves: What's easier, converting a lens to A-mount and chip it or cleaning the aperture blades of an AF lens?


Converting the lens. When I did my conversion, it took about 45 minutes from obtaining the lens in the mail, without instructions or prior experience with said lens. It's very straightforward: unscrew old mount, drill holes in new mount, attach it (may require a bit of sanding, but it doesn't require any considerable accuracy). Adjusting infinity focus can be fiddly and takes most of the time, but again that's just turning a screw and/or installing spacers cut from aluminium baking foil. =)

Meanwhile, I find some of the AF lenses are a pain to dis- and reassemble correctly, especially ones that require that this be done from both directions to clean both sides of the aperture blades (though I find it is often possible to cheat and get good results by just cleaning one side).

Edited by Arkku - 27 September 2008 at 14:44
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Post Options Post Options   Quote ricardovaste Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 14:34
Originally posted by Grubeater Grubeater wrote:

A question for those who did the conversion themselves: What's easier, converting a lens to A-mount and chip it or cleaning the aperture blades of an AF lens?
Just curious, yesterday I cleaned the aperture blades of my 50mm F/1.4 again, last time was a year ago.


Converting a lens. If the blades are really messy and the lube from the focus has gone everywhere, that can get pretty messy and you have to take it all apart and remove each blade and then put them back in...

A simple conversion like this can be done in half an hour or so with no extreme deconstruction.
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Post Options Post Options   Quote Grubeater Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 14:31
A question for those who did the conversion themselves: What's easier, converting a lens to A-mount and chip it or cleaning the aperture blades of an AF lens?
Just curious, yesterday I cleaned the aperture blades of my 50mm F/1.4 again, last time was a year ago.
Missing hood or other weird Minolta stuff? PM me. Maybe I can help.
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Post Options Post Options   Quote trygve Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2008 at 11:56
Hello all.
I just recieved a copy of this lens in MD mount. IS there someone out there willing to convert it for me?? For a fee orcourse. I'd love to get a chipped version for it, so I can have focus confirmation and SSS...
Please PM me if you can help me in any way..
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Post Options Post Options   Quote ABramley Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2008 at 13:31
Shaocahoolica - that's absolutely perfect. I'm sure I'll be able to follow that - I'll get back to you with the results!

Cheers :)
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Post Options Post Options   Quote Shaocaholica Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2008 at 09:03
ABramley, did you happen to see my full build gallery I linked in the first post of this thread?

Here it is again. Hopefully, that should answer all your questions about how I did mine. Since you have Pete's mount, the process should be exactly the same if you want to go my route.
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